20030180 Ver 7_Other Agency Comments_20100528 (4)

S aT OF
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Q?? gyp United States Department of the Interior
FISH AND WILDLIFE SERVICE
e ' Asheville Field Office
MggCH a BA 160 Zillicoa Street
Asheville, North Carolina 28801
May 28, 2010
Mr. John Dorney
North Carolina Division of Water Quality
2321 Crabtree Boulevard, Suite 250
Raleigh, NC 27604

Subject: Public Notice of Application for a Section 401 Water Quality Certificate, and
Addendum No. 1, Addendum No.3, Franklin Hydroelectric Project, FERC No. 2603,
DWQ #03-0180, Macon County, North Carolina
Dear Mr. Dorney:
This letter is in response to the May 4, 2010 Public Notice, DWQ #03-0180. On June 16, 2009,
Duke Energy Carolinas, LLC (Duke) filed an Application for 401 Water Quality Certificate to
the North Carolina Division of Water Quality (NCDWQ) for the Franklin Project.
The United States Fish and Wildlife Service (USFWS), has been engaged in ongoing discussions
with Duke, NCDWQ, North Carolina Division of Water Resources (NCDWR) and the North
Carolina Wildlife Resources Commission (NCWRC) to prepare a Lake Level and Flow
Management Plan, a Maintenance and Emergency Protocol and a Sediment Study Plan to help
further define how the hydro project could operate under a Subsequent License from the FERC.
These discussions culminated in agreement about how the Project should be operated to protect
water quality, fish and wildlife resources, and endangered species habitats.
On May 26, 2010, Duke filed additional information to its 401 Application as Addendum #1
regarding the Franklin Project Lake Level and Flow Management Plan along with the Nantahala
Area Run-of-River Projects Maintenance and Emergency Protocol (as an Appendix to the
Franklin Project Lake Level and Flow Management Plan). On May 27, 2010, Duke also filed
additional information to its 401 Application as Addendum #3 regarding its Sediment Study
Plan.
Important aquatic habitats and biota are present in the Little Tennessee River downstream
of the Franklin Hydroelectric project. The receiving waters for this water quality certificate
are the Little Tennessee River, which provides important habitat for a great diversity of fish,
mollusks, and other aquatic species. The Little Tennessee River has one of the most significant
aquatic faunal assemblages in the state. The receiving waters support, and are designated as
critical habitat for, populations of the federally endangered Appalachian elktoe (Alasmidonta
raveneliana), endangered little-wing pearlymussel (Pegias Tabula), and a federally threatened
fish species, the spotfin chub (Erimonax monachus) and is also designated as critical habitat for
the spotfin chub. The Sicklefin Redhorse (Moxostoma sp.) is a Candidate for listing under the
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Franklin Hydroelectric Project
Endangered Species Act, and also occurs here. The Little Tennessee River contains natural
aquatic communities of high quality and rarity.
The effects of excessive sediment on aquatic biota are known. In general, excessive fine
sediments impair surface waters. The impacts of suspended and bedded sediment in surface
waters have been reviewed by a number of authors. Recent reviews of the effects of excessive
sediment in aquatic systems include Waters (1995), Naiman and Baily (1998), Reid and Dunne
(1996), Wilber and Clarke (2001). Excessive suspended and bedded sediments have two major
avenues of action in streams and rivers: 1) direct effects on biota and 2) direct effects on physical
habitat, which results in indirect effects on biota. Examples of direct effects on biota include
suppression of photosynthesis by shading primary producers; increased drifting of, and
consequent predation on, benthic invertebrates; and shifts to turbidity-tolerant fish communities.
Indirect effects on biota will occur as the biotic assemblages that rely upon aquatic habitat for
reproduction, feeding, and cover are adversely affected by habitat loss or degradation of this
habitat. A noteworthy example of indirect effects of excessive fine sediments in streams and
rivers is the loss of spawning habitat for fishes by an increase in embeddedness, caused by the
entrapment of fine material in the gravel. Increased sedimentation can limit the amount of
oxygen in the spawning beds which can reduce hatching success, or trap the fry in the sediment
after hatching.
The effects of excessive fine sediment in streams and rivers span the scales of biota. The
biological responses to this stressor at a site are related to site-specific effects (turbidity, shading,
substrate embeddedness) and to the cumulative loadings of sediments from the catchment above
the site. Waters (1995) considered the effects of increased deposition of sediments on benthic
invertebrates as one of the most important concerns within the sediment pollution issue,
especially in regards to the dependence of freshwater fisheries on benthic productivity.
The effects of impoundments on sediment are known. The useful life or remaining capacity
of reservoirs can be predicted from their trap efficiencies. The most widely known and used
method for predicting trap efficiency are the empirical curves of Brune (1953), which are based
on data collected from 40 normally ponded USA reservoirs (these included 1 site in the
Hiwassee River upstream of Mission Dam). Brune presented 2 curves, an upper and lower curve
to fit his collected data and suggested a third middle curve for use in design.
Sediment accumulates in Franklin Reservoir. There is a high rate of sediment transport from
the watershed. Erosion and sedimentation are natural processes, but in most populated areas they
are significantly elevated as compared to "natural" conditions. It is safe to say that the great
majority of streams in the upper watershed carry sediment loads in excess of what they would
carry in an undeveloped landscape. A study of sediment transport in the upper Little Tennessee
River basin characterized bed and suspended-sediment loads into Lake Emory from the main
stem and major tributaries - Cartoogechaye Creek and the Cullasaja River (Oblinger 2003).
The mainstem Little Tennessee River has two very different characters. The river upstream of
the Project meanders northward across an ancient, low-gradient valley. This reach of river is
characterized by low-gradient and small substrate, bordered by regionally-significant wetland
habitats. Near Franklin, the river doubles in size with the confluence of the Cullasaja River and
Cartoogechaye Creek. Downstream of the Project, the much larger river increases in gradient as
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USFWS comments
Franklin Hydroelectric Project
it cuts to the northwest, creating the most ecologically-intact warm-water river system in the
Southern Blue Ridge.
Sediment is redistributed at differential times and rates due to the operation of the Franklin
Project. We have observed this during prior planned and unplanned drawdowns of the reservoir.
Sediment that is deposited on the streambed is bed material. Small particles can be resuspended
during periods of elevated streamflow to produce suspended sediment load. Larger particles that
are too heavy to be suspended in the water column during elevated streamflows may move along
the streambed as bed load. Much of the larger bedload particles (gravel, cobble) in the Little
Tennessee River are deposited in the upstream areas of the Franklin Reservoir because of the
reduced bedload transport capacity of the impoundment. Suspended sediments are transported at
varying rates through the Franklin Reservoir, or resuspended from depositional areas when
reservoir levels and/or velocities are altered - this occurs with changes in operation and with
changes in inflow rates, especially noticeable with large storm events.
Sediment Management is crucial. Comprehensive management of gravel, sand, and silt in the
Little Tennessee River and at the Franklin Project should be based on recognition of the natural
flow of sediment through the drainage network and the nature of impacts (to ecological resources
and to infrastructure) likely to occur when the continuity of sediment is disrupted. A sediment
budget should be developed for present and historical conditions as a fundamental basis for
development of long-term management plans, including identification of management actions,
mitigation measures, and to allow for evaluation of these impacts, many of which are cumulative
in nature. A sediment budget is an accounting of the sources and disposition of sediment as it
travels from its point of origin to its eventual exit from a drainage area. In its full form, a
sediment budget accounts for rates and processes of erosion and sediment transport in the
watershed and in stream channels, for temporary storage of sediment in bars, alluvial fans, and
other depositional sites, and for weathering and breakdown of sediments while in transport or
storage. Although complete sediment budgets are of scientific interest, they are frequently more
detailed than is necessary to address problems encountered in resource management. Here, we
recommend a focus on the sediment budget associated with the Project - an accounting of the
inflow, outflow, and what happens in the reservoir.
RECOMMENDATIONS
We recommend these measures to compensate for the ongoing impacts of this project and its
operation on the natural resources of the area. These measures should include mitigation for
ongoing project impacts and project-induced effects on fish and wildlife populations and their
habitats.
Run-of-river Operation. The Project should be operated in a run-of-river mode, with outflow
(discharge) equivalent to inflow. The Lake Level and Flow Management Plan (May 2010), the
Maintenance and Emergency Protocol (May 2010), the Trash Removal Program (July 2003)
should be incorporated in their entirety in the 401 certification for each of the 3 ROR projects.
USFWS comments
Franklin Hydroelectric Project
Shoreline Management. Consistent with the Tuckasegee Settlement Agreement and Nantahala
Stakeholders Settlement Agreements, we agree that the Franklin project is too small to have
private boat ramps, docks, or piers. And, according to Duke Power's Nantahala Area Shoreline
Management Guidelines, filed with FERC, private boat ramps are not allowed. Therefore, we
recommend that to protect and improve the water quality of the Project, private shoreline
developments should be excluded from the Project waters. A vegetated riparian area should be
maintained (and restored wherever currently degraded) at the Project. Appropriate public access
areas should be developed and maintained consistent with the Tuckasegee Settlement Agreement
and Nantahala Stakeholders Settlement Agreements.
Sediment Management. Downstream habitats are being negatively impacted by sediment
releases (pulses) from the Project and Duke should develop a long-term Sediment Management
Plan to describe its strategy and implementation of a reservoir-wide sediment monitoring and
management. Duke should develop a Long-Term Sediment Management Plan, based upon
results of the Sediment Removal Pilot Study, to guide future sediment removal operations at the
Nantahala Area ROR Projects. The Long-Term Sediment Management Plan should include a
maintenance drawdown and refill protocol that minimizes flow fluctuations and reservoir
sediment mobilization by addressing rates of draw down and refill (to coincide with precipitation
events and rising hydrograph) and scheduling drawdowns to coincide with season of least
potential for harm to downstream aquatic communities, whenever possible.
After the initial pilot Sediment Study, and after FERC has issued the Subsequent License for the
Franklin Project, Duke has fully implemented the Lake Level and Flow Management Plan at the
Franklin Project and the two hydro units at the Franklin Project are fully restored to operational
status, Duke also proposes a Short-Term Sediment Monitoring Study. This short-term study will
look at turbidity and/or suspended solids at the Franklin Project for a period of two years under
the new operating conditions. The monitoring will cover a range of operating conditions and
river flows and will be used in the development of the Long-Term Sediment Management Plan
for the Nantahala Area Run-of-River Hydro Projects. After this two-year monitoring period,
Duke will prepare a report summarizing the information and consult with the USFWS, NCWRC,
NCDWQ, and NCDWR on study results.
The Long-term Sediment Management Plan should include the following elements at a
minimum:
1. Sediment Assessment
2. Evaluation of Sediment Management Options for Project Operations and protection
of downstream habitats
3. Monitoring/Notification/Reporting
4. Schedule for implementation
We recommend permit conditions that are consistent with the proposed pilot Sediment Study
Plan and Short-term Sediment Monitoring Study proposed in Addendum #3 by Duke, as well as
that described in the License Application for this Project.
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Franklin Hydroelectric Project
Endangered Species consultation is required. We have not completed our formal consultation
with FERC for the Project effects on endangered species and designated Critical Habitats.
Current federal regulations (50 CFR, subsection 402.12(b)(1)) require federal agencies to assess
the effects of their actions and to consult with the Service on any action that may affect a listed
species. These regulations require the preparation of a biological assessment (of any endangered
and threatened species impacts) for any major Federal activity affecting the quality of the human
environment, such as the significant changes in these project licenses. The consultation must
include an assessment of not only direct impacts associated with the projects but also those
cumulative and secondary impacts associated with the actions or that are likely to result from the
actions. We believe this project may result in both direct and indirect impacts to the
Appalachian elktoe, littlewing pearlymussel, Virginia spiraea, spotfin chub, sicklefin redhorse,
and may lead to modifications of designated critical habitat within the project area. We will
provide you with a copy of the Biological Opinion for this Project once it is completed.
Appalachian Elktoe. The endangered Appalachian elktoe occurs within the Little Tennessee
River just below the Franklin Project. The Little Tennessee River is designated as critical habitat
for the Appalachian elktoe (Critical habitat units were described and depicted in maps in the
Federal Register (FR 67:61016-61040 (2002), with the lateral extent of each designated unit
bounded by the ordinary high-water line.). Within designated critical habitat, the primary
constituent elements include:
1. Permanent, flowing, cool, clean water;
2. Geomorphically stable stream channels and banks;
3. Pool, riffle, and run sequences within the channel;
4. Stable sand, gravel, cobble, and boulder or bedrock substrates with no more than low
amounts of fine sediment;
5. Moderate to high stream gradient;
6. Periodic natural flooding; and
7. Fish hosts, with adequate living, foraging, and spawning areas for them.
Littlewing_pearlymussel. The littlewing pearlymussel (Pegias fabula), an endangered mussel
occurs in very small numbers in the Little Tennessee River downstream of the Project. This
small mussel is extremely rare.
Spotfin Chub. Spotfin chub populations have been variable, though persistent, in the tailwaters
of the Franklin Project. The Franklin Project's works and operation continue to influence the
distribution of this species in the Little Tennessee River. Previous dockets have included
information on the resuspension and release of sediments during project operations and
maintenance. Consider the enclosed "Effects of Excessive Sediment on Stress, Growth and
Reproduction of Two Southern Appalachian Minnows, Erimonax monachus and Cyprinella
galactura" by Meyer and Sutherland (2005). The report contains important information about
the spotfin chub in the tailwaters of the Franklin Project and provides valuable insight into the
life history of the spotfin chub as well as how the species may be affected by suspended
sediment from the Franklin Project. We urge you to consider the implications of this report
when making determinations for issuance of water quality certificate and when making your
determination of effects for this species.
USFWS comments
Franklin Hydroelectric Project
Sicklefin Redhorse. The Sicklefin redhorse is currently confined to the Hiwassee and Little
Tennessee rivers of the upper Tennessee River basin. Both populations are confined within
reaches enclosed by water impoundments. The population in the Little Tennessee system is
enclosed downstream by Fontana Dam and upstream by Franklin, Bryson, and Cullowhee dams.
Due to the limited geographic distribution and threats associated with physical alteration of the
habitat, restoration and reintroduction efforts for this undescribed species are critical to its long-
term existence.
The species is currently known to occupy cool to warm, moderate gradient creeks and rivers,
and, during at least parts of its early life, large reservoirs (Jenkins 1999). In streams, it is
generally associated with moderate to fast currents, in riffles, runs, and well-flowing pools and
feeds and spawns over gravel, cobble, boulder, and bedrock substrates with no, or very little, silt
overlay (Jenkins 1999, Favrot 2008).
Like many other redhorse species, the Sicklefin Redhorse is known mainly from flowing
streams. Current observations indicate that adults are year-round residents of rivers and large
creeks (Jenkins personal communication 2007; Favrot 2008) and that young, juveniles, and sub-
adults occupy primarily the lower reaches of creeks and rivers and near-shore portions of certain
reservoirs (Jenkins 1999). It is likely that after emerging from the stream substrata, many of the
larvae and post-larvae are carried downstream to the mouths of streams or into reservoirs
(Jenkins 1999). Newly mature fish (>5 years of age) appear to migrate from the reservoirs to
spawn; after which, most remain in the streams with the other adults (Jenkins 1999). Although, a
few adult Sicklefin Redhorse have been observed in the Hiwassee and Fontana Reservoirs,
Favrot (2008) reported in his study of Sicklefin Redhorse movement and habitat utilization
within the Hiwassee River system that he was unable to detect radio-tagged adult Sicklefin
Redhorse utilizing Hiwassee Reservoir for other than brief periods between occupying a
spawning tributary and the Hiwassee River or Valley River, suggesting these fish were only
migrating between streams. This suggests that, while reservoirs may serve as maturation sites
for sub-adult Sicklefin Redhorse, they do not provide suitable spawning, foraging, or winter
habitat for adults of the species but rather are a factor limiting habitat for adult Sicklefin
Redhorse.
Stomach analysis indicates that the Sicklefin Redhorse feeds on benthic macroinvertebrates
(insect larvae, crustaceans, snails, etc.) (Jenkins, personal communication 2004). The species
has rarely been observed foraging on substrates with even a thin covering of silt (Jenkins 1999).
When feeding, the species exhibits a well-defined preference for the coarse substrates with
abundant riverweed (Podostemum ceratophyllum). Studies indicate that riverweed significantly
enhances the abundance of benthic macroinvertebrates and that after spawning, the species
typically relocates to stream reaches supporting high densities of river weed, where individuals
appear to feed almost exclusively over riverweed beds (Favrot 2008).
Sicklefin redhorse spawning typically occurs over cobble, with usually only a small portion of
sand and gravel, in moderate to fast flowing water in open areas and pockets formed by boulders
and outcrops (Jenkins 1999, Favrot 2008). Unlike the Sicklefin Redhorses' foraging habitat, the
species' appears to spawn exclusively over coarse substrates lacking riverweed (Favrot 2008).
Favrot's study (2008) indicates the species begins upstream migration to spawning sites in late
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Franklin Hydroelectric Project
winter/early spring when water temperatures reach 10.0-12.0 degrees Celsius and peak at water
temperatures of 15.0-16.0 °C. The species appears to exhibit strong spawning site fidelity,
returning to the same stream and stream reach each year to spawn (Favrot 2008), possibly
returning to their natal streams and spawning reaches similar to many salmonids (Favrot 2008).
Following spawning, the species appears to generally move downstream to deeper waters and
more suitable foraging areas (Favrot 2008); and, to migrate further downstream to even deeper
waters for the winter (Favrot 2008). Except during its migrations to and from spawning and
wintering sites, the Sicklefin Redhorse appears relatively sedentary at its spawning, post-
spawning, and wintering sites, travelling only short distances up and down stream within the
occupied river reach; and, in addition to exhibiting strong spawning site fidelity, the Sicklefin
Redhorse also appears to show a high degree of site fidelity to its post-spawning and wintering
sites, returning to the same stream, and generally the stream reaches each year (Favrot 2008).
Assuring the long-term survival of the Sicklefin Redhorse will require, at a minimum: (1)
protecting the existing water and habitat quality of the reaches of the river systems were the
species is still surviving; and (2) improving degraded portions of the species' habitat to allow for
the expansion of existing populations and reestablishment of the extirpated populations.
The Sicklefin Redhorse has been observed feeding and spawning only in substrates with no or
very little silt accumulation. Excessive siltation and suspended sediment affects the habitat of
the Sicklefin Redhorse by making it unsuitable for feeding and reproduction. It eliminates
breeding sites and results in increased mortality of eggs and juveniles; it eliminates feeding
areas, reduces the species' ability to detect prey, and eliminates aquatic insect larvae and other
food items of the Sicklefin. Suspended sediment also irritates and clogs fishes' gills affecting
their respiration (Waters 1995, Sutherland and Meyer 2007). Favrot (2008) reported that fine
sediments are abundant in the section of the Hiwassee River between Mission Dam and
Hiwassee Reservoir and that Brasstown Creek appears to be a significant contributor to this
sediment loading.
Fish Passage. The USFWS has reserved authority under § 18 of the Federal Power Act to
prescribe fishways at the Project. We recommend the water quality certificate include similar
provisions to incorporate any future Fishway prescriptions, in order to maintain or restore the
biological integrity of the Project waters. In particular, we are concerned about the needs of
potamodromous fishes, including the "sicklefin" redhorse (Moxostoma sp.) Hydropower
projects such as the subject run-of-river projects can fragment a river system, impede or block
fish movement, and kill or injure fish. The viability and mobility of fish species that would
otherwise move to and from different habitats within the river system may diminish
substantially, if not completely, due to a hydropower project. These species can be important
components of aquatic food webs and can support populations of commercially and
recreationally important fish that are of economic significance to the nation.
Fishways help mitigate the impacts of hydropower projects by providing safe, timely, and
effective fish passage around a project for spawning, rearing, feeding, growth to maturity,
dispersion, migration, and seasonal use of habitat. Fishway prescriptions also help to achieve
resource goals and objectives. These goals and objectives may be identified in national,
USFWS comments
Franklin Hydroelectric Project
regional, or watershed-level planning documents or may be established by the Services on a site-
specific basis. Examples of resource goals and objectives include: (1) the enhancement,
protection, or restoration of existing fish populations within a river system; (2) the reunification
of fragmented fish populations; and (3) the reintroduction or reestablishment of fish runs. In
addition, fishways may be necessary to protect tribal resources for the exercise of American
Indian rights.
Summary. We are quite concerned about the continued downstream impacts of reservoir
drawdowns at the Franklin Project. We have identified the need for additional study to
determine and refine drawdown procedures. This study should be conducted at the Franklin
Project, in accordance with the Franklin Project Lake Level and Flow Management Plan (Duke
May 2010) and the Nantahala Area Run-of-River Projects Maintenance and Emergency Protocol
(Duke 2010). The process of lowering the reservoir level may resuspend sediments that have
accumulated in the reservoir. This impact may be minimized by the development of adequate
procedures to control resuspension or discharge of sediments from the reservoir. To avoid
impacts from unforeseen operational actions that could negatively affect fish and wildlife
resources by sediment release and low flows, we recommend that the project be operated in a
run-of-the-river mode (±0.1 foot) and that any operational changes ensure that downstream flows
are always maintained at least equivalent to the September median flow (309 cfs at the Franklin
Project) during any infrequent refill situations.
We reiterate our recommendation for detailed monitoring of water quality and sediment transport
during any drawdown and refill so that flows may be adjusted accordingly to limit the
downstream effects of drawdowns. We anticipate working closely with Duke and the other
natural resource agencies and others to implement the pilot Sediment Study for the next
scheduled drawdown at Franklin.
The best populations of the endangered Appalachian elktoe and threatened spotfin chub occur
within the Little Tennessee River just below the Franklin Project. The only North Carolina
population of the endangered littlewing pearlymussel occurs in this reach of the Little Tennessee
River. The Little Tennessee River is designated as critical habitat for the spotfin chub and the
Appalachian elktoe. Though not an aquatic species, the threatened riparian plant, Virginia
spiraea (Spiraea virginiana) is found on the shore of the Franklin Reservoir and depends upon
appropriate flow regime and riparian conditions to persist..
CONCLUSION
We appreciate the opportunity to provide these comments and information about water quality at
the Franklin Hydroelectric Project. If you have questions, please contact me at 828/258-3939,
Ext. 227.
Sincerely,
- original signed -
Mark A. Cantrell
USFWS comments
Fish & Wildlife Biologist
Enclosures
cc: Duke Energy Carolinas, LLC, Lineberger, Johnson
NCWRC, Goudreau
NCDWR, Mead
NCDWQ, Barnett
Franklin Hydroelectric Project
USFWS comments
Literature Cited or relied upon.
Franklin Hydroelectric Project
Box, J.B. and J. Mossa. 1999. Sediment, land use, and freshwater mussels: prospects and
problems. J. of the Am. Benthological Soc. 18:99-117.
Brune, G.H. 1953. Trap efficiency of reservoirs, Am. Geophysical Union Trans., 34:
Collier, M., R.H. Webb, and J.C. Schmidt. 1996. Dams and rivers: primer on the downstream
effects of dams. U.S. Geological survey Circular 1126, Tucson, Arizona. 94 pp.
Duke Energy Carolinas, LLC. 2010. Franklin Project Lake Level and Flow Management Plan.
7pp.
Duke Energy Carolinas, LLC. 2010. Nantahala Area Run-of-River Projects Maintenance and
Emergency Protocol. 14pp.
Ellis, M.M. 1936. Erosion silt as a factor in aquatic environments. Ecology 17:29-42.
Etnier, D.A. and W.C. Starnes. 1993. The Fishes of Tennessee. The University of Tennessee
Press, Knoxville, Tennessee.
Favrot, S.D. 2008. Sicklefin Redhorse (Catostomidae) reproductive and habitat ecology in the
upper Hiwassee River basin of the southern Appalachian Mountains. Master of Science
Thesis, North Carolina State University, Raleigh.
Jenkins, R.E. 1999. Sicklefin Redhorse (Moxostoma sp.), undescribed species of sucker (Pisces,
Catostomidae) in the upper Tennessee River drainage, North Carolina and
Georgia--description, aspects of biology, habitat, distribution, and population status.
Unpublished report to the U.S. Fish and Wildlife Service, Asheville Field Office,
Asheville, NC, and the North Carolina Wildlife Resources Commission, Raleigh, NC. 34
pp., tables 1-7, and figures 1-15.
Lajczack, A. 1995. Proposed model for long-term, Course of mountainous reservoir
sedimentation and estimating the useful life of dams. Proc. Of Sixth International Symp.
on River Sedimentation, New Dehli, India, pp.699-711.
Moyer, G.R. , J.D. Rousey, and M.A. Cantrell. 2009. Genetic evaluation of a conservation
hatchery program for reintroduction of Sicklefin Redhorse Moxostoma sp. in the
Tuckasegee River, North Carolina. North American Journal of Fisheries Management
29:1438-1443.
Naiman, R.J., and R.E. Baily. 1998. River ecology and management. Springer-Verlag, New
York, NY.
Newcombe C.P., and D.D. MacDonald. 1991. Effects of suspended sediments on aquatic
ecosystems. N. Am. J. Fish Manag. 11:72-82.
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Newcombe C.P., and J.O.T. Jenson. 1996. Channel suspended sediment and fisheries: a
synthesis for quantitative assessment of risk and impact. N. Am. J. Fish Manag. 16:693-
727.
Oblinger, C.J. 2003. Suspended Sediment and Bed Load in Three Tributaries to Lake Emory in
the Upper Little Tennessee River Basin, North Carolina, 2000 - 02. U.S. Geological
Survey, Water-Resources Investigations Report 03-4194.
Reid, L.M., and T. Dunne. 1996. Rapid Evaluation of Sediment Budgets. Reiskirchen:
Germany, Catena Verlag. 164pp.
Simmons, J.W., and S.J. Fraley. 2010. Distribution, status, and life-history observations of
crayfishes in western North Carolina. Southeastern Naturalist 9(Special Issue 3):79-126.
Singh, K.P., and A. Durgunoglu. 1991. Remedies for sediment buildup. J. of Hydro Review,
December 1991, pp90-97.
Sutherland, A.B. 2006. Effects of increased suspended sediment on the reproductive success of
an upland minnow. Trans. of the Am. Fish. Soc. 136:416-422.
Sutherland, A.B. and J.L. Meyer. 2006. Effects of increased suspended sediment on growth
rate and gill condition of two southern Appalachian minnows. Environmental Biology of
Fishes; Available online: DOI 10.1007/s10641-006-9139-8.
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USFWS (U.S. Fish and Wildlife Service). 1983. Spotfin chub recovery plan. U.S. Fish and
Wildlife Service, Atlanta, GA, 46pp.
USFWS. 1989. Littlewing Pearly Mussel Recovery Plan. U.S. Fish and Wildlife Service,
Atlanta, GA, 29pp.
USFWS. 1996. Recovery plan for the Appalachian elktoe (Alasmidonta raveneliana) Lea. U.S.
Fish and Wildlife Service, Atlanta, Ga. 31pp.
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for the Appalachian. Federal Register 67(188):61016-61040.
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Fishery Society Monograph 7. Bethesda, MD. 251pp.
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Wilber, D.H. and D.G. Clarke. 2001. Biological effects of suspended sediments: a review of
suspended sediment impacts on fish and shellfish with relation to dredging activities in
estuaries. N. Am. J. Fish. Manage. 121:855-875.
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Environ Biol Fish
DOI 10.1007/s10641-006-9139-8
Effects of increased suspended sediment on growth rate
and gill condition of two southern Appalachian minnows
Andrew B. Sutherland • Judy L. Meyer
Received: 29 March 2006 /Accepted: 11 August 2006
© Springer Science+Business Media B.V. 2006
Abstract Despite the recognition that increased
suspended sediment concentration (SSC) is a
correlate of imperilment for native riverine fishes,
research is limited on the effects of SSC on small
non-game species. This study quantifies the
impact of suspended sediment on fish growth
and gill condition of two stream-dwelling min-
nows. Specific growth rate (i.e., percent change in
mass per day) and gill condition (i.e., lamellar
thickness and interlamellar area) were measured
in young-of-year whitetail shiners, Cyprinella
galactura, and federally threatened spotfin chubs,
Erimonax monachus, exposed for 21 days to
increased SSC (0, 25, 50, 100, and 500 mg L-1).
Exposure to elevated SSC caused a significant
decrease in specific growth rate in both species
and at all life stages tested. The effect of increased
SSC was greatest in spotfin chubs, which exhibited
a 15-fold decrease in specific growth rate at
the highest treatment (500 mg L-1). Effects of
increased SSC were least for 8-9-month-old
whitetail shiners, which had growth rates similar
to controls for 25, 50, and 100 mg L-1 treatments.
These minnows exhibited a greater response to
increasing SSC than salmonids at low to moderate
SSC, and a lesser response at higher sediment
levels. Gill damage was minimal at the three
lowest treatment levels, moderate at 100 mg L-1
and severe at 500 mg L-1, indicating that respira-
tory surfaces of upland minnows may be much
more sensitive than other species. Specific growth
rate decreased significantly with increasing gill
lamellar thickness, suggesting that respiratory
impairment is one mechanism responsible for
negative impacts of excessive sediment on small
riverine fishes.
Keywords Turbidity • Spotfin chub • Physiology
Respiration • Whitetail shiner
Introduction
Increased sedimentation of rivers and streams has
been linked to the decline of imperiled fishes
throughout the US (Walsh et al. 1995; Burkhead
et al. 1997; Warren et al. 2000). Sediment-induced
habitat loss and habitat fragmentation are asso-
ciated with fish assemblage homogenization and
loss of sensitive endemic species in the southeast-
ern US (Burkhead et al. 1997; Scott and Helfman
2001; Sutherland et al. 2002; Walters et al. 2003).
Direct impacts of excessive sediment loading may
also be contributing to the decline of native fishes.
Among the possible sub-lethal effects are
growth rate reduction, abrasion of gill tissue and
subsequent respiratory and osmoregulatory
A. B. Sutherland (H) • J. L. Meyer
Institute of Ecology, University of Georgia, Athens,
GA 30602, USA
e-mail: [e-mail]
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Environ Biol Fish
impairment. An abundant literature focuses on
the lethal impacts of high-suspended sediment
concentrations (SSC) on game-fishes (primarily
salmonids; see Newcombe and MacDonald 1991).
In contrast, relatively few studies have explored
the effects of lethal and sub-lethal concentrations
of sediment on non-game species.
Within the southeastern US, cyprinids are the
second most diverse fish family (-30% of species)
and among the most imperiled (Walsh et al. 1995;
Warren et al. 2000). Southeastern cyprinid diver-
sity is greatest in the southern Appalachians
(Walsh et al. 1995) and within this region one of
the primary threats to minnows is excessive
sedimentation (Burkhead et al. 1997; Warren
et al. 2000). Despite these facts, very few studies
have investigated sediment effects on cyprinids
(e.g., Gradall and Swenson 1982; Burkhead and
Jelks 2001).
The research on non-game fishes that exists has
focused on adults, with even less known about
direct effects of sediment on young-of-year
(YOY) non-game and imperiled fishes. This is
an important area of research because the events
that occur in the first few months of life are
crucial for the survival of most fish species
(Wooten 1.990; Helfman et al. 1997). Along with
reproductive success, survival of sensitive early
life stages is one of the most important
determinants of interannual population dynamics
(Helfman et al. 1997). Age and size play critical
roles in affecting survivorship. YOY mortality
rates are inversely related to size (Wooten 1990).
Fish with lower growth rates will spend more time
at a smaller size and are hence more susceptible
to predation and removal by floods.
Excessive sedimentation has other deleterious
impacts as it can affect growth rates by reducing
visual acuity (Sigler et al. 1984; Newcombe and
MacDonald 1991), prey capture success, and
feeding efficiency (Barrett et al. 1992). Increased
levels of suspended sediment may also reduce
growth rates of YOY salmonids by increasing
scour, physiological stress and metabolic rates,
and by reducing feeding rates (Sigler et al. 1984;
Redding et al. 1987; Newcombe and MacDonald
1991). One objective of this study was to deter-
mine if increased suspended sediment impacts the
growth of non-salmonid YOY fishes.
Another direct effect of increased SSC is
respiratory impairment. However, the effects of
SSC on gill condition have not been quantified for
non-salmonid species, and the literature on
salmonid gill condition presents an unclear pic-
ture. Sediment-induced gill abnormalities suggest
that increased SSC may cause gill abrasion,
hyperplasia and hypertrophy, which in turn may
cause decreased fitness and growth rate (Herbert
and Merkens 1961; Berg and Northcote 1985;
Bruton 1985; McLeay et al. 1987; Goldes et al.
1988; Servizi and Martens 1992). Abrasion by
sediment particles may increase the chance of
infection of gill epithelium, thereby increasing
susceptibility of fish to disease (Herbert and
Merkens 1961). Conversely, other studies suggest
minimal impact, even at very high SSC. A second
objective of this study was to explore these effects
in species other than salmonids by determining
sediment effects on gills of cyprinid species.
As part of the US Fish and Wildlife Service
Spotfin Chub Recovery Plan (per objective 1.3.1;
USFWS 1983), we investigated the effects of
excessive sedimentation on the federally threa-
tened spotfin chub, Erimonax monachus. Specif-
ically, we examine the effect of increased SSC (0,
25, 50, 100, and 500 mg U) on the growth rate
and gill condition of two southern Appalachians
minnows, the spotfin chub, and the whitetail
shiner, Cyprinella galactura.
Materials and methods
Growth trials
Study organisms
Four growth trials were conducted using the
whitetail shiner. This species shares many
morphological, behavioral and physiological char-
acteristics with the spotfin chub (Jenkins and
Burkhead 1994) and their physiological responses
were expected to be similar. One 30-day white-
tail shiner growth trial was conducted using
8-9-month-old juveniles and three 21-day trials
were conducted using 2-3-month-old post-larvae.
All whitetail shiners YOY were propagated from
adults collected in the upper Little Tennessee
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Environ Biol Fish
River (LTR) (Swain Co., Bryson City and Macon
Co., Franklin, NC, USA), and reared in the
laboratory. YOY were fed brine shrimp nauplii,
Artemia spp., and a high-protein micro-encapsu-
lated commercial starter diet (< 100 pm; Zeigler®
Larval Diet, Gardners, PA, USA).
Four growth trials were conducted using YOY
spotfin chubs. Larvae were obtained from Con-
servation Fisheries Inc. (CFI; Knoxville, TN,
USA), who reared them from eggs spawned by
adults collected in the Buffalo River (Lewis Co.,
Hohenwald, TN, USA). We reared larvae in 30-L
flow-through tanks and fed them the diet
described above. Spotfin chubs used in growth
trials were post-larvae and ranged in age from 4
to 6 months; they were reared for this time period
to ensure their transition from a benthic to
pelagic life stage. It was assumed that the exper-
imental apparatus paddles would be very stressful
to the benthic stage of this fish.
Experimental procedure
The apparatus used for these experiments con-
sisted of very slow (--3-5 mm s-1) motor-driven
paddles within each of 20 30-L experimental
tanks (Sutherland 2006). Paddles were each fitted
with two baffles that slowly sweep the floor of a
given tank, while delivering a column of com-
pressed air that suspended sediment particles. A
series of stress trials were conducted on post-
larval whitetail shiners reared in tanks containing
this apparatus (with 0 mg L-1 SSC) and in tanks
without the apparatus. Stress hormone levels
were not significantly different between the two
groups (Sutherland 2005), suggesting that the
apparatus did not significantly stress YOY white-
tail shiners.
Sediment used in growth experiments was
collected from the LTR basin (Macon Co.) and
wet-sieved to obtain the <45 µm fraction. Sedi-
ment within this size fraction was primarily clay
and mica-based silt. This size fraction was chosen
because it was the largest naturally occurring
sediment that could be held in suspension using
the experimental apparatus (Sutherland 2006).
Test sediment was determined to be free of
organic pesticides and heavy metals by the Soil,
Plant, and Water Laboratory at the University of
Georgia, College of Agricultural and Environ-
mental Science (Athens, GA, USA). SSC
treatments used in this study (0, 25, 50, 100, and
500 mg L-1) are within the range of conditions
observed in the LTR (turbidity range: 10-
1,500 mg L-1, W. O. McLarney, unpublished
data). Turbidity [nephelometric turbidity units
(NTU)] measurements were taken once daily in
the middle of each tank, using a Hach® 2 Model
2100P turbidimeter (Hach® Co., Loveland, CO,
USA). The turbidimeter was calibrated every
5 days using StablCalo Primary Turbidity Stan-
dards (Hach® Co.). Turbidity measurements were
converted to SSC using a sediment rating curve
determined for test sediment (Sutherland 2006).
The ages of whitetail shiners varied slightly
because they were randomly chosen from differ-
ent cohorts based on size similarity to minimize
variability of initial fish mass. The initial growth
trial (using 8-9 months old) lasted 30 days, and
the following three trials (using 2-3 months old)
each lasted 21 days. In each growth trial three
whitetail shiners were reared in each of 20
experimental tanks. Five suspended sediment
treatments (0, 25, 50, 100, and 500 mg L-) were
randomly assigned to the 20 experimental tanks
(four replicates per treatment).
At the start of each growth trial, all tanks and
paddles were cleaned thoroughly. Tanks were
filled with 30 L of well water, warmed in a head-
tank to 25°C (a typical late-summer temperature
in rivers and streams inhabited by both species).
Photoperiod was controlled in the laboratory and
was the same (14 h light and 10 h dark) during all
growth trials for both species. A sulfa-based
antibiotic (Sulfa-4®; Fishy Farmacy, Tucson,
AZ, USA) was then added to each tank to
prevent bacterial blooms. Individual unanesthe-
tized fish were briefly and carefully placed on a
dry towel to reduce excess water weight, placed in
a pre-weighed beaker of water, and weighed to
the nearest 0.1 mg. Each fish was introduced
randomly into a tank and allowed to acclimate for
48 h before sediment was added. Starting on the
second day of acclimation, fish were fed twice a
day at a rate of 10% initial body mass per day.
Fish in the first trial were fed a diet of dry pelleted
fish food (1304; 1.5 mm; Purina® AquaMax,
Nestle Purina PetCare Company, St. Louis, MO,
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Environ Biol Fish
USA), and fish in the three subsequent trials were
fed a high-protein micro-encapsulated commer-
cial starter diet (400 gm; Zeigler® Larval Diet).
Maintaining SSCs precluded the use of biolog-
ical filtration in the experimental tanks. This
requirement made periodic water changes neces-
sary to minimize water quality problems. During
the first growth trial water and sediment were
replaced on days 9, 17, and 25. For the remaining
three trials sediment and water changes were
performed on days 7 and 14. During water
changes, fish were removed to one of four
temporary holding tanks for --10 min while fresh
well water warmed in head tanks and new
sediment were added after cleaning each tank.
Fish were then returned to the tanks. Total
ammonia nitrogen (TAN) was measured using a
ammonia nitrogen test kit (LaMotteo; Chester-
town, MD, USA). TAN was converted to union-
ized ammonia (UTA) based on a temperature of
25°C and a pH of 7.
At the end of each growth trial, fish were
anesthetized by adding 10 ml of eugenol (a 1:5
mixture of eugenol in ethanol) to each tank,
which anesthetized post-larval and juvenile white-
tail shiners within 2 min. Each fish was then
removed and weighed. Because individuals could
not be identified, initial and final weights used to
calculate growth rates are the sum of weights
from the three fish in each tank. Specific growth
rates were calculated as the percent change in
mass per initial mass per day (100 x [(final mass-
initial mass) per mass] per day).
For the spotfin chub growth trials, a single post-
larvae was placed in each of 20 tanks as described
above. Fish were treated and tested as described
for whitetail shiners. After the final weighing,
spotfin chubs were placed in scintillation vials
containing a 10% solution of neutral buffered
formalin, to preserve for later determination of
gill condition. Each treatment replicate repre-
sents the daily specific growth rate of one spotfin
chub.
Gill condition
The effects of increased suspended sediment on
gill condition was determined for spotfin chubs
reared in the first growth trial. To avoid confusion
with terminology, primary gill lamellae are hence-
forth referred to as `filaments,' secondary lamel-
lae are referred to as `lamellae,' and
`interlamellar' refers to the space between sec-
ondary lamellae. Two measures of gill condition
were determined: mean thickness of lamellae and
mean space between adjacent lamellae. These
two metrics of gill impairment were chosen
because lamellar thickening and reduction in
interlamellar space may reduce capacity for
respiration and reduce osmoregulatory perfor-
mance. Although gill thickening is often associ-
ated with decreasing interlamellar space, both
parameters were measured because the latter may
also occur due to excess mucous production.
The right operculum was removed from pre-
served spotfin chubs and the first gill arch was
excised. Gill arches were stained for 30 min using
fluorescein dye (excitation = 488 nm; emis-
sion = 530 nm). After rinsing off excess dye, 2-5
filaments were removed from the center of each
excised gill arch and placed on a hydrophobic-
coated glass slide (Cel-Linen HTCTM, Erie Scien-
tific Co., Portsmouth, NH, USA). Micrographs of
gill lamellae (400x magnification) were created
using a spectral confocal microscope (Leica TCS
SP2 with Coherent Ti : sapphire multiphoton
laser; Mira Optima 900-F, Leica Microsystems,
Bannockburn, IL, USA), with a 40x water
immersion objective. Optical sectioning of fluo-
rescent gill lamellae was standardized by always
capturing the optical section at 50% of lamellar
height (i.e., vertical thickness, t2 µm).
Micrographs of lamellae generated by confo-
cal microscopy were analyzed using Image-Pro
Plus° software (Version 4.5.1, Media Cybernet-
ics Inc., Silver Springs, MD, USA). Gill thick-
ness (gm) was measured perpendicular to the
long axis of each lamella. Fifty gill thickness
measurements were taken for each fish using
10-20 lamellae and 1-6 measurements on each
lamella. Thickness measurements were taken
from the center of lamellae (i.e., the vertical
center; not near tip or base). The number of
lamellae and measurements per lamella were a
function of micrograph quality. Interlamellar
area (µm) was determined as the space
between adjacent lamellae for 25 interlamellar
regions per fish.
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Environ Biol Fish
Data analyses
Specific growth rates were compared using anal-
ysis of variance (ANOVA; JMP, SAS Institute,
Cary, NC, USA), followed by pairwise compar-
isons using the Tukey-Kramer test (a = 0.05).
Differences among experimental trials were
determined using ANOVA blocked by trial,
after using Levene's test to assure that group
variances were equal. Differences in mean spe-
cific growth rates were determined between
species (i.e., 2-3-month-old whitetail shiners vs.
4-6-month-old spotfin chubs) using two-factor
ANOVA. The differences in ages between the
two species was thought to not present a
problem because both groups of fish were similar
in size and both exhibited similar behavior (i.e.,
they had both just switched from benthic feeding
and swimming to pelagic). If two-factor ANO-
VA showed a significant effect, each treatment
was compared (i.e., between species) using the
Student's t-test. Slopes of the regression of mean
specific growth rate as a function of SSC were
compared between species using analysis of
covariance (ANCOVA).
As expected, a small fraction of sediment
settled during the course of each growth trial, so
SSCs were not constant. Therefore, sediment
settling was estimated during the first whitetail
shiner growth trial, and the first spotfin chub
growth trial (Sutherland 2005). These sediment
settling curve data were used to estimate the
average SSC during the course of a growth trial.
These estimated average SSC were used for the
previously described regression analyses.
Mean gill lamellar thickness and mean interl-
amellar area were compared among sediment
treatments using ANOVA followed by pairwise
comparisons using the Tukey-Kramer test
(a = 0.05). Linear regression was used to deter-
mine if there was a significant relationship
between estimated SSC and gill lamellar thick-
ness or interlamellar area, between gill condition
and natural log (mean specific growth rate), and
between gill lamellar thickness and the more
time consuming measure, interlamellar area
(a = 0.05).
Results
Growth rates
Water quality was measured as presence of UTA.
UTA was measured as TAN and then converted
using temperature of 25°C and pH of 7. High
levels of UTA were never a problem, presumably
because of weekly water changes and relatively
low amounts of food added to a large volume
of water. UTA was consistantly below 10 µg/L
(average UTA = 7 µg/L; range = 3-9 µg/L).
Specific growth rates (% day-) of young
whitetail shiners (2-3 months) did not differ
significantly among experimental trials (ANOVA;
P = 0.435), so all trials were combined in further
analyses. Specific growth rates were significantly
different among suspended sediment treatments
(ANOVA; P < 0.0001). Growth rates at the
highest SSC were significantly lower than at all
other SSC (Fig. 1, Tukey-Kramer multiple com-
parison; a = 0.05). Furthermore, specific growth
rate was significantly and inversely related to
increasing SSC (Fig. 2, RZ = 0.47, P < 0.0001).
Specific growth rates for older whitetail shiners
(8-9 months) were significantly different among
SSC treatments (ANOVA; P = 0.001). Growth
rates at the highest SSC were significantly lower
than at all other SSC (Fig. 1, Tukey-Kramer
multiple comparison; a = 0.05). Specific growth
rate was significantly and inversely related to
increasing SSC (Fig. 2, RZ = 0.41, P < 0.0001).
Specific growth rates for spotfin chubs
(4-6 months) did not differ significantly among
experimental trials (ANOVA; P = 0.729), so all
trials were combined in further analyses. Growth
rates for spotfin chubs were significantly different
among suspended sediment treatments (ANOVA;
P < 0.0001). Spotfin chub growth rates decreased
steadily with increasing SSC; all treatments
(except 25 and 50 mg L-) were significantly
different from each other (Fig. 1, Tukey-Kramer
multiple comparison; a = 0.05). Specific growth
rate was significantly and inversely related to
increasing SSC (Fig. 2, RZ = 0.79, P < 0.0001).
Specific growth rate (% day-) differed signif-
icantly between species (i.e., 2-3-month-old
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Environ Biol Fish
Fig. 1 Results of Tukey-
Kramer multiple
comparison tests, of
specific growth rate (%
initial mass (g) per day)
versus suspended
sediment concentration
(SSC; mg L-1). Means
comparisons are
presented for 2-3 and
8-9-month-old whitetail
shiners and 4-6-month-
old spotfin chubs. Note
the difference in scales.
Bars with different letters
above them are
significantly different
(a = 0.05). Sediment
treatments presented as
initial SSC added to each
tank
0.300
0.250
0.200
0.150
0.100
0.050
0.000
Whitetail shiners (2-3 months old)
a
V 0.160
Z0.140
Q 0.120
, 0.100
C 0.080
to
0.060
0.040
0.020
0 0.000
a
0.200
0.150
0.100
0.050
0.000
Whitetail shiners (8-9 months old)
Spotfin chubs (4-6 months old)
whitetail shiners vs. 4-6-month-old spotfin chubs;
two-factor ANOVA; P < 0.0001). Growth rates
were significantly different between species at the
four lowest treatments, but not at 500 mg L-1.
Whitetail shiner (2-3 months old) growth rate
declined more with increasing SSC than did
spotfin chub (4-6 months old) growth rate
(ANCOVA; P = 0.008); growth rate decrease in
young whitetail shiners was -2 times greater than
that of spotfin chubs (Fig. 2).
Gill condition
Confocal microscopy provided not only gross
observations, but also allowed quantification of
gill lamellae changes of fish exposed to elevated
SSC. In general, the gill tissue of spotfin chubs
reared in the three lowest sediment concentra-
tions appeared similarly undamaged when viewed
with the naked eye or under a dissecting scope
(Fig. 3). Gill cavities appeared free of sediment
and mucous, and individual gill filaments were
readily discernable. Gills of fish grown in
100 mg L-1 were similar to those of lower treat-
ments, but slightly more opaque, and individual
filaments were less discernable. Gills of spotfin
chubs reared at 500 mg L-1 appeared very differ-
ent from all other treatments. Gill cavities were
filled with mucous and sediment. Some gill arches
and filaments were fused, making it difficult to
discern individual filaments. While gross appear-
ance (i.e., dissecting microscopy) of gills of fish
exposed to 100 mg L-1 appeared similar to lower
treatments, gill micrographs (i.e., confocal
4@ Springer
0 25 50 100 500
0 25 50 100 500
0 25 50 100 500
Added SSC (mg/L)
Environ Biol Fish
0.400 • whitetail shiners (post-larvae)
¦ whitetail shiners Quveniles)
p spotfin chubs (post-larvae)
>.
t0 0.300 =
• • - - whitetail shiners Quveniles)

X

=

•

_ spotfin chubs (post-larvae)
• ? - - - whitetail shiners (post-larvae)
Cr 0.200 •
0
•
c '
y

0.100
L • •

? a n
S 0
000
p .
50 100 150 200 250 300 350 400 450 v

? o
n
-0.100
i
Estimated SSC (mg/L) •
-0.200 J
Fig.2 Regressions of individual replicates of specific
growth rate (% initial mass (g) per day) versus suspended
sediment concentration (SSC; mg L-1), for 2-3 and
8-9-month-old whitetail shiners and 4-6-month-old spotfin
chubs. Note difference in scales. The regression equations
are as follows: 2-3-month-old whitetail shiners: specific
growth rate = -0.097 (log SSC) + 0.3391 (R2 = 0.47,
P < 0.0001); 8-9-month-old whitetail shiners: specific
growth rate = -0.031 (log SSC) + 0.15 (R2 = 0.41,
P < 0.0001); 4-6-month-old spotfin chubs: specific growth
rate = -0.067 (log SSC) + 0.182 (R2 = 0.79, P < 0.0001).
Sediment concentrations sed in regression analyses are
SSC estimated from sediment settling curves
microscopy) revealed moderate epithelial hyper-
plasia (increased cell growth), gill fusion and
other abnormalities. Gill micrograph analysis also
suggested severe gill epithelial hypertrophy (i.e.,
thickening) for fish exposed to 500 mg L-1
(Fig. 3). While lamellar thickness typically
increases with fish size, this was not the case for
spotfin chubs reared in this study. Gills of fish
reared in the highest treatments were significantly
thicker than those of the three lowest treatments,
despite the fact that growth rates were lower at
higher sediment levels (Table 1).
Gill lamellar thickness differed significantly
among treatments (ANOVA; P < 0.001) and was
significantly greater for spotfin chubs reared at
the highest sediment concentration (Fig. 4).
Interlamellar area also differed significantly
among treatments (ANOVA; P < 0.01). Space
between gill lamellae was significantly smaller for
spotfin chubs reared at 100 mg L-1 than for the
three lowest treatments (Fig. 4). Space between
lamellae was smallest at the 500 mg L-1 treat-
ment; interlamellar area for this treatment was
significantly lower than for all other treatments
(Fig. 4). Gill lamellar thickness increased signif-
icantly with increasing SSC (Fig. 5, R2 = 0.99,
P = 0.0004). Gill interlamellar area was signifi-
cantly and inversely related to increasing gill
thickness (Fig. 5, R2 = 0.97, P = 0.003). The
natural log of specific growth rate was signifi-
cantly and inversely related to increasing gill
thickness (Fig. 6, R2 = 0.95, P = 0.005).
Discussion
Despite increasing correlational evidence of
increased suspended sediment being harmful to
stream fish, we still lack a clear understanding of
the mechanisms behind these observations, espe-
cially for non-salmonid species. Previous research
primarily relates excessive sedimentation to
habitat loss and fragmentation with concomitant
fish assemblage homogenization and loss of
sensitive and endemic fish species (Berkman
and Rabeni 1987; Burkhead et al. 1997; Scott
and Helfman 2001; Sutherland et al. 2002; Walters
et al. 2003). The present study increases our
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Environ Biol Fish
Fig.3 Dissecting
microscope photographs
of gills and spectral
confocal micrographs of
gill filaments of spotfin
chubs reared for 21 days
in growth trial 1.
Photographs ( A) and ( B)
show typical gill arches of
fish reared in controls
(i.e., 0 mg L-1 SSC).
Micrograph ( C) shows
lamellae of fish reared in
controls; this is typical of
fish reared in the three
lowest treatments (0, 25,
and 50 mg L-1).
Photographs ( D) and ( E)
show gills typical of fish
reared at the highest
treatment (i.e., 500 mg L-1
SSC). Micrograph ( F)
shows lamellae typical of
fish reared in the highest
treatment. Note arrows
showing where
interlamellar area and
lamellar thickness
measurements were
typically taken
understanding of the possible underlying mecha-
nisms responsible for observed effects of elevated
sediment on declining native fish populations.
Growth rates
One of the primary ways in which SSC may affect
fish populations is by reducing individual growth
rates (Sigler et al. 1984; Waters 1995). Reduced
growth rates of YOY fish negatively impact both
the fitness and survivability of individual fish, and
affect year-class strength through reduced recruit-
ment. Most experimental studies relating
sediment concentration to fish growth rates have
explored the acute lethal effects of high SSC
(i.e., 10,000-100,000 mg L-1) (Newcombe and
MacDonald 1991.). Studies investigating the
effects of lower SSC (10-100 mg L-1) are less
common. However, relatively low-turbidity levels
have been shown to reduce growth rates of YOY
salmonids (Sykora et al. 1972; Crouse et al. 1981;
Sigler et al. 1984; MacKinley 1987), golden
redhorse, Moxostoma erythrurum, and spotted
bass, Micropterus punctulatus) (Gammon 1970).
Conversely, the growth of larval lake whitefish
(Coregonus artedii, was not affected by relatively
low SSC (1-28 mg L-1; Swenson and Matson
1976).
The present study contributes to further under-
standing of the impacts of low SSC on fish growth.
In general, exposure to elevated but still relatively
low-SSC caused a significant decrease in growth
rate for both life stages of whitetail shiners and
for spotfin chubs. Growth rates are within the
same order of magnitude (0.01-0.25 g day-) of
those previously documented for YOY steelhead,
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Environ Biol Fish
Oncorhynchus mykiss, and coho salmon,
Oncorhynchus kisutch, reared in similar SSC
(84 mg L-1; Sigler et al. 1984). However, when
Table 1 Initial and final masses (in g) for spotfin chub
post-larve used in gill condition analyses (growth trial 1).
Treatments (SSC; mg U) and relative growth rates
(% day-) are also presented
SSC Initial mass Final mass Growth Rate
(mg L-) (g) (g) (% day-)
0 0.0383 2.0800 2.54
0 0.0334 1.6120 2.25
0 0.0329 2.0300 2.89
0 0.0364 2.6430 3.41
25 0.0460 0.4320 0.40
25 0.0308 0.5740 0.84
25 0.0326 0.1280 0.14
25 0.0410 0.8160 0.90
50 0.0333 0.8240 1.13
50 0.0374 0.5010 0.59
50 0.0406 0.1170 0.09
50 0.0307 1.0300 1.55
100 0.0364 0.0746 0.05
100 0.0432 0.1611 0.13
100 0.0474 0.2265 0.18
100 0.0329 0.2470 0.31
500 0.0292 0.0290 0.00
500 0.0334 0.2158 0.26
500 0.0453 0.0834 0.04
500 0.0430 0.1062 0.07
Fig. 4 Results of Tukey-
Kramer multiple
comparison tests of
spotfin chub gill lamellae
thickness (gm) versus
suspended sediment
concentration (SSC;
mg U), and
interlamellar area (Arn )
versus SSC. Bars with
different letters above
them are significantly
different (a = 0.05).
Sediment treatments
presented as initial SSC
added to each tank
50
40
N
y 30
20
-5) 10
0
r 800
700
?v 600
4)
500
400
300
E
is 200
100
0
growth rate change relative to controls is com-
pared, differences between the two studies
become apparent. At 100 mg L-1 spotfin chubs
and 2-3-month-old whitetail shiners exhibited
four to fivefold greater decreases in growth rate,
than did YOY steelhead (Sigler et al. 1984). In
contrast, steelhead YOY reared in 265 NTU, and
whitetail shiners and spotfin chubs reared in
500 mg L-1 (=411 NTU; test sediment
NTU = 0.81 * SSC + 5.83), exhibited similar
reductions in growth rate relative to controls.
These findings suggest that the rate of response to
increasing SSC differs between upland minnows
and salmonids, with minnows exhibiting a greater
response at lower treatment levels.
Several potential mechanisms link increased
SSC to decreases in fish growth rates. Many
studies relate increasing SSC with decreasing
feeding efficiency of fish. Two interrelated
mechanisms are sediment-induced decreases in
reactive distance and feeding efficiency. As reac-
tive-distance decreases, more time is needed to
search a given volume of water. This reduced
feeding efficiency results in higher energy expen-
diture per prey captured, thus potentially reduc-
ing growth. Turbidity as low as 30-60 NTU has
b
Added SSC (mg/L)
Springer
0 25 50 100 500
0 25 50 100 500
Environ Biol Fish
Fig. 5 Regressions of gill
lamellar thickness (gm)
versus suspended
sediment concentration
(SSC; mg L-1) and gill
lamellar thickness (pm)
versus interlamellar area
(µm2), for spotfin chubs
(4-6 months old) reared
for 21 days in growth trial
1. The regression
equations are as follows:
lamellar thickness = 0.05
(SSC) + 23.2 (R2 = 0.99,
P = 0.0004); lamellar
thickness = -0.0365
(interlamellar
area) + 45.389 (R2 = 0.97,
P = 0.003). Sediment
concentrations used in
first regression analysis
are SSC estimated from
sediment settling curves
50
45
N 40
d
Y 35
t 30
H 25
A 20
E 15
J 10
_ 5
C7 0
0
700
E
600
500
d 400
A
m 300
E
200
100
been shown to reduce the reactive distance of
juvenile coho salmon (Berg and Northcote 1985).
Others have also documented an inverse rela-
tionship between turbidity and reactive distance
of bluegill, Lepomis macrochirus, and rainbow
trout (Gardener 1981; Barrett et al. 1992). Cut-
throat trout stopped feeding when exposed to
SSC as low as 35 mg L-1 (Wilber 1983). Increased
turbidity also negatively affected feeding rates for
two large cyprinids (Barbus spp. and Labeo spp.;
Bruton 1985) and for bluegill (Gardener 1981).
Several studies documented reduced feeding
ability of salmonids exposed to high SSC
(McLeay et al. 1987; Redding et al. 1987;
Reynolds et al. 1989). In turbid prairie streams,
feeding efficiency was lower for minnows not
usually associated with high turbidity, and higher
for those species historically found in turbid
streams (Bonner and Wilde 2002).
Increased SSC may also inhibit normal feeding
by increasing physiological stress (Redding et al.
1.987). SSCs used in the present study were
sufficient to severely stress both YOY whitetail
shiners and spotfin chubs (Sutherland 2005).
Stress-induced inhibition of normal feeding may
thus reduce performance capacity and growth
rate (Redding et al. 1987; Waters 1995). Highly
stressful environments have been associated with
growth rate suppression in fishes (Schreck et al.
1997). Other research suggests that suspended
sediment-induced physiological stress may nega-
tively affect fish growth more than indirect effects
such as decreased prey abundance (Shaw and
Richardson 2001). Hence, stress may play a role
in the observed growth reduction of whitetail
shiners and spotfin chubs at elevated SSC.
Gill condition
Sediment-related increase in stress response and
reduction of growth rates may both be partially
due to increased gill damage, which could operate
via respiratory impairment (Schreck 1981; Waters
1995). Some research suggests that increased
suspended sediment causes gill thickening and
fusion, presumably due to continual abrasion and
irritation of gill lamellae (Herbert and Merkens
1961). Thickening of lamellae and reduction in
interlamellar space may result in reduced respi-
ratory surface area and reduced capacity for ion
regulation. The present study showed a strong
inverse relationship between gill thickness and
specific growth rate (Fig. 6). While these data are
only correlational, they suggest that tissue
? Springer
100 200 300 400 500
0
0 100 200 300 400 500
Estimated SSC (mg/L)
Environ Biol Fish
Fig. 6 Regression of 50
natural log of specific E 45
growth rate (% initial
mass per day) versus gill 40

lamellae thickness (gm), CD
c
35
for spotfin chubs ?C
30
(4-6 months old) reared s
for 21 days in growth trial F 25
1. The regression ? 20
equation is as follows: In 4) 15
specific growth
rate = -0.1159 (lamellae ? 10
thickness) + 0.428
2 = 5
(R
= 0.95, P = 0.005) 0
20
0
0
r_ -1
a
q!
C .2-
.3-
4)
R
W -4-
.5-
.6-
damage and subsequent impairment of respira-
tory function may be a possible mechanism for
reduced growth rate. An interesting finding was
the difference in response of interlamellar area
versus lamellar thickness to the 100 mg L-1
treatment. The former was significantly different
from the three lowest treatments, while the latter
was not different. While not quantified, excessive
mucus was found in the gill cavities of all fish
reared in the two highest treatments, and mucus
production is thought to be the reason for this
significant decrease in interlamellar area for
spotfin chubs reared in the 100 mg L-1 treatment.
The results reported here do not support the
assessment by some researchers that acute gill
damage occurs only after exposure to very high
levels of suspended sediment (i.e., many g L-1;
see Henley et al. 2000). In fact, results from other
studies vary considerably and present no clear
pattern. Some studies report an effect on gill
Gill Lamellar Thickness (um)
25 30 35 40 45 50
thickening at low SSC, some report effects only at
high SSC, and some report no effect even at very
high SSC (Table 2). Some studies present quali-
tative results, reporting that increased SSC results
in clogging of gill filaments and gill rakers
(Bruton 1985). Others mention behavioral
changes that suggest gill irritation, such as
increased gill flaring and coughing (Berg and
Northcote 1985; Servizi and Martens 1992). Both
gill flaring and coughing are thought to remove
excess sediment particles and concomitant excess
mucous lodged in fish gills.
Although some studies report sediment-
induced thickening of gill lamellae, the severity
of these effects is generally much less than
documented here. Brown trout, Salmo trutta,
exhibited gill epithelial thickening similar to what
we observed but only when exposed to SSC
>1,000 mg L-1 (Herbert et al. 1.961). In general,
gill abnormalities in the present study are more
L) Springer
0 100 200 300 400 500 600 700
Interlamellae Area (um2)
Environ Biol Fish
Table 2 Studies documenting effects of elevated suspended sediment concentration (mg L-1) on fish gills
Species Life SSC Duration Effect Reference
stage (mg L-I) (d)
Rainbow A 270 13 Gill thickening Herbert and Merkens
trout (1961)
White perch A 650 5 Gill thickening; increase in goblet cells Sherk et al. (1975)
Rainbow A 810 21 Gill thickening Herbert and Merkens
trout (1961)
Brown trout A 1,040 730 Gill thickening Herbert et al. (1961)
Arctic YOY 1,250 2 Moderate gill damage Simmons (1982)
grayling
Arctic YOY 1,388 4 Gill hyperplasia and hypertrophy Simmons (1982)
grayling
Coho salmon J 1,547 4 Gill damage Noggle (1978)
Rainbow J 4,887 64 Slight gill thickening Goldes et al. (1988)
trout
Sockeye YOY 9,850 4 Gill hyperplasia, hypertrophy, separation and Servizi and Martens
salmon necrosis (1987)
Coho salmon J 40,000 4 Distal deterioration of gill filaments Lake and Hinch (1999)
Arctic YOY 250,000 4 No gill damage McLeay et al. (1987)
grayling
Experiment durations are in days (d). Studies are listed in order of increasing SSC (mg L-1
Fish life stages are as follows: A adult, J juvenile, YOY young-of-year
similar to results reported for YOY brown trout
exposed to acidic (pH = 4.9-5.4) stream water
containing aluminum (Ledy et al. 2003), and
juvenile channel catfish, Ictalurus punctatus,
exposed to high levels of ammonia (Mitchell
and Cech 1983). Belontiids, Colisa fasciatus, with
similarly severe gill hyperplasia and lamellar
fusion were exposed to sub lethal chromium
concentrations (48 ppm; Nath et al. 1997).
Other factors that may cause differential
effects of SSC on gill condition are the charac-
teristics of sediments used in experiments, partic-
ularly their abrasiveness. Angular sediment
particles are known to increase stress response
(e.g., increased hematocrit) relative to more
rounded particles (Lake and Hinch 1999). Sharp,
angular sediment is more abrasive and can
become lodged more easily in gill lamellae. This
can cause excessive mucous discharge, causing
further respiratory problems such as reduction or
loss of ion regulation capacity. One of the few
studies that found sediment-induced gill damage
similar to the present study, involved brown trout
exposed to china-clay waste water that contained
a large amount of angular mica particles (Herbert
et al. 1961). The sediment used in the present
study consisted of clay and silt. The silt-sized
particles (2-45 µm) were composed of mica and
quartz, and as such were very sharp and angular.
These particles also have a high-electrostatic
charge, making them potentially harder for fish
to expel from their gills.
Dose response
Growth rates and gill condition measured in the
present study may also vary from previous
research due to differences in sediment dose.
Suspended sediment dosage (i.e., concentration
times exposure duration), may better explain
sediment-induced impacts to fish than concentra-
tion alone (Newcombe and MacDonald 1991;
Newcombe and Jensen 1996; Shaw and Richard-
son 2001). One of the few studies testing the
effects of exposure duration determined that the
mass and length of rainbow trout were negatively
correlated with increased duration when SSC was
held constant (Shaw and Richardson 2001).
Recognizing the importance of sediment dose,
Newcombe and Jensen (1996) developed a series
of models that predict impairment due to both
sediment concentration and exposure duration.
Some researchers have found that these models
consistently predict their observed results (Shaw
Springer
Environ Biol Fish
and Richardson 2001). Other researchers found
that these models underestimated the severity of
sediment-induced impairment (Burkhead and
Jelks 2001). When our SSCs and experiment
duration were used as input data, Newcombe and
Jensen's model predicted 20-60% mortality; we
observed none. This difference may arise because
the model was developed for younger more
sensitive life stages (i.e., eggs and larvae),
whereas the fish used in the present study were
post-larvae.
Few studies have reported the extent of gill
damage we observed (although see Herbert et al.
1961). The severity of impairment (i.e., severe gill
damage but no mortality) we found seems to fall
midway between the model prediction (i.e.,
substantial mortality) and previous observations
of minimal impact to gills of game fish species.
Model inaccuracy may result from differences in
sediment tolerances among fish families coupled
with the fact that data from only a few families
were used for model creation (Salmonidae,
Centrarchidae and Clupeidae; Newcombe and
Jensen 1996). Supporting this idea of family- or
species-specific sediment tolerance, YOY arctic
grayling, Thymallus arcticus, exhibited growth
rates twice as high as in our study despite being
exposed to similar SSC for twice the duration
(McLeay et al. 1987). Also, lethal levels of
suspended sediment are known to vary greatly
among fish species and life stage (Newcombe and
Jensen 1.996).
Potential growth of spotfin chubs under
ambient sediment conditions
Our results indicate that spotfin chubs exposed
for 21 days to 100 and 500 mg L-1 exhibit three
and 15-fold reductions in growth rate, respec-
tively. In the upper LTR, which harbors one of
the few remaining populations of spotfin chubs,
stormflow >22 m3 S-1 is sufficient to elevate
turbidity above 100 mg L-1, and 48 m3 S-1 is
sufficient to elevate turbidity above 500 mg L-1
(SSC = 26.24 discharge-241.3, R2 = 0.59,
P = 0.02; USGS 2001). During 1964-2003, daily
discharge in the upper LTR exceeded 23 m3 sl
for -50% of the time, and exceeded 48 m3 S-1
>10% of the time (water years 1964-2003; USGS
2003). Our experiments were conducted for
21 days, so it is also useful to consider the number
of times the upper LTR exceeded 23 and 48 m3 S-1
for a continuous 3-week period. Between 1964
and 2003, discharge exceeded 23 m3 s-1 for a
3-week period 258 times and 48 m3 S-1 23 times
(USGS 2003). Based on these discharge data, our
results suggest that YOY spotfin chubs in the
upper LTR have been exposed to sediment doses
sufficient to reduce growth rates threefold for
-38% of the time (i.e., -6 times per year), and
sufficient to reduce growth rates 15-fold for -3%
of the time (i.e., approximately once every
2 years).
Summary/Conclusion
This study has demonstrated under laboratory
conditions how increased SSCs may directly
affect whitetail shiner and spotfin chub YOY.
Chronic exposure to high SSC (i.e., 500 mg L1)
may overwhelm the ability of spotfin chubs to
remove excess sediment from their gills, resulting
in severe gill damage. This negative impact on gill
condition may be one factor leading to the
observed elevated physiological stress (Suther-
land 2005) and thereby reducing spotfin chub
growth rates. These results suggest that despite
morphological and behavioral similarities
between spotfin chubs and whitetail shiners,
spotfin chubs may be more sensitive to moderate
and high levels of suspended sediment.
Acknowledgments This research was supported by a
grant from the US Fish and Wildlife Service (grant no.
1434-HQ-97-RU-01551), through the Georgia Cooperative
Fish and Wildlife Research Unit. We thank E. Henderson,
V. Vaughan, and B. Ritchie for their support in the
development of the experimental apparatus used in this
study, and for vital support, including providing facilities
for fish holding tanks and experimental apparatus. We
thank P. Rakes and J. R. Shute at Conservation Fisheries
Inc. for their support and advice. Thanks also to J. Shields
and M. Farmer, at the University of Georgia Center for
Ultrastructural Research, for their invaluable help with gill
histology technique. Finally, we thank M. Freeman,
G. Helfman, C. Jennings, D. Leigh, J. Maki and the
Meyer lab group for their helpful comments throughout
this research, and for comments that have greatly
improved this manuscript.
IL Springer
Environ Biol Fish
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Transactions of the American Fisheries Society 136:416-422, 2007 [Article]
© Copyright by the American Fisheries Society 2007
DOI: 10.15 77 fr06-046.1
Effects of Increased Suspended Sediment on the Reproductive
Success of an Upland Crevice-Spawning Minnow
ANDREW B. SUTHERLAND*1
Institute of Ecology, University of Georgia, Athens, Georgia 30602, USA
Abstract.-Little is known about the effects of increased suspended sediment on the reproductive behavior
and spawning success of fishes, especially North American nongame fishes. I investigated the effects of
increased suspended sediment concentration (SSC; 0, 25, 50, 100, and 500 mg/L) on the spawning success of
the crevice-spawning whitetail shiner Cyprinella galactura. Spawning success was measured during two
week-long experiments in terms of spawning effort (the number of replicate tanks in which spawning
occurred) and spawning output (number and developmental stages of propagules). Spawning effort decreased
from seven of eight control tanks to four of eight tanks at 500 mg/L. The total mean number of propagules at
500 mg/L was 10-14% of the output in the lower SSC treatments. The fact that significantly more eggs than
larvae were observed with increasing SSC suggests that spawning was delayed in tanks with higher SSC. A
comparison of propagule developmental stage with sediment settling curves allowed an estimation of mean
SSC when propagules were spawned. The number of propagules spawned was inversely and significantly
related to mean SSC during spawning. Whitetail shiner spawning success was moderately affected by the
SSCs used in this study. Comparison of these results with those of a similar study involving the tricolor shiner
C. trichroistia suggests that whitetail shiners are slightly more tolerant of excessive sedimentation but show
reduced spawning success at SSCs commonly observed in southern Appalachian Upland rivers.
North America has the highest diversity of temperate
freshwater fishes in the world, and the southeastern
United States is the center of this rich fish fauna,
harboring over 600 species (Warren et al. 2000).
Within the Southeast, the greatest diversity (70%) is in
upland rivers and streams of the Appalachian Moun-
tains (Walsh et al. 1995). In addition to high diversity,
the southeastern United States has very high rates of
fish imperilment (28%; Warren et al. 1997; Master et
al. 1998; Warren et al. 2000). In the southern
Appalachians, 21% of darters (Percidae) and minnows
(Cyprinidae) are imperiled (Walsh et al. 1995).
Southeastern U.S. rivers and streams are negatively
affected by numerous anthropogenic stressors. Exces-
sive sedimentation, as the primary pollutant, is
responsible for about 40% of fish imperilment (Envier
1997). Elevated sediment deposition from poor land-
use practices results in the degradation, fragmentation,
and elimination of suitable habitat for many benthic
fish species (Neves and Angermeier 1990; Walsh et al.
1995; Burkhead et al. 1997; Richter et al. 1997;
Johnston 1999; Burkhead and Jelks 2001). Although
habitat destruction from deposited sediment is the
primary impact in southeastern U.S. riverine systems
(Burkhead et al. 1997; Richter et al. 1997; Warren et al.
* E-mail: [e-mail]
t Present address: University of New Brunswick, Freder-
ickson, NB E38 6E1, Canada
Received February 21, 2006; accepted October 27, 2006
Published online March 12, 2007
2000), some evidence suggests that turbidity-related
effects on reproductive behavior may severely impact
southeastern fishes (Burkhead and Jelks 2001).
Twenty years ago Bruton (1985) noted that our
understanding of the effects of sediment on fish
reproduction was poor; today we know only slightly
more, especially regarding the effects on nongame
fishes. A high percentage of southeastern U.S.
nongame fishes with declining abundance and range
are benthic-specialized species that require unembed-
ded heterogeneous substrate for reproduction (Jenkins
and Burkhead 1994; Burkhead et al. 1997; Warren et
al. 2000). Despite this awareness, very little research
has been conducted on the relationship between
sediment and spawning success of these species. The
majority of research on the effects of sediment on fish
reproduction has involved game fishes (primarily
Salmonidae and Centrarchidae). Other studies have
focused on egg and fry survival in spawning redds
(Chapman 1988; Montgomery et al. 1996), on
overwinter success and production of various life
stages (Hartman and Scrivener 1990), and on habitats
of various life stages (see review by Waters 1995).
Most of what is known about the relationship
between increased sediment and game fish reproduc-
tion deals with habitat modification caused by sediment
deposition. Less is known about the effects of
increased suspended sediment on fish reproductive
behavior. However, some researchers have found that
excessive siltation caused cutthroat trout Oncorhyn-
chus clarkii to abandon spawning grounds (Wilber
416
SUSPENDED SEDIMENT AND REPRODUCTIVE SUCCESS
1983) and delay timing of spawning in several families
of warmwater fishes (Muncy et al. 1979). Some
researchers suggest that sediment-induced habitat
degradation and physiological stress affect fishes more
severely than do behavioral effects (Newcombe and
Jensen 1996). However, one study suggests that by
disrupting spawning behavior, increased suspended
sediment concentration may impact the population
stability of some benthic-specialized fishes (Burkhead
and Jelks 2001). Reproductive success of the tricolor
shiner Cyprinella trichroistia was shown to be
negatively affected by high levels of suspended
sediment (100-600 mg/L), presumably because visual
cues necessary to induce spawning behavior were
disrupted by increased turbidity (Burkhead and Jelks
2001).
The purpose of this study was to increase under-
standing of the effects of suspended sediment on
nongame fish reproduction. The whitetail shiner C.
galactura is typical of benthic-specialized nongame
fishes in the southern Appalachians. They are common
throughout clear upland montane streams in the
Tennessee and Cumberland river drainages and are
also found in the southern Ozarks (Jenkins and
Burkhead 1994). Whitetail shiners spawn fractionally
(i.e., multiple clutches over protracted spawning
period) in bedrock and boulder crevices (Jenkins and
Burkhead 1994). The objective of this study was to
determine the effects of increased suspended sediment
on the spawning success of the whitetail shiner.
Specifically, the objectives were to determine the
relationship between suspended sediment concentra-
tion (SSC; 0, 25, 50, 100, and 500 mg/L) and whitetail
shiner spawning effort (the number of experimental
units where spawning occurred) and spawning output
(the number of propagules spawned). A final objective
was to determine whether the effects of sediment dose
(i.e., sediment concentration X duration) on whitetail
shiner spawning are within the range of impairment
predicted by a severity-of-ill-effect (SEV) model
developed by Newcombe and Jensen (1996).
Methods
Two spawning trials were conducted, each for 1
week (168 h) at 25°C. At that temperature, a week is
sufficient time for eggs hatched in controls to develop
into larvae (personal observation and Noel Burkhead,
U.S. Geological Survey, personal communication).
Each trial consisted of four replicates of five suspended
sediment treatments (0, 25, 50, 100, and 500 mg/L).
SSCs were within the lower range of conditions
observed in the upper Little Tennessee River (LTR;
turbidity range: 10-1500 mg/L, W. O. McLamey,
Little Tennessee Watershed Association, unpublished
417
data). The apparatus used for experiments consisted of
slow moving (-3-5 mm/s) motor-driven paddles
within each of twenty 30-L experimental tanks
(Sutherland 2006). Each paddle was fitted with two
baffles that slowly swept the floor of a given tank,
while delivering a column of compressed air that
suspended sediment particles. Sediment used in growth
experiments was collected from the Little Tennessee
River basin (Macon County, North Carolina) and wet-
sieved to obtain the less than 45-µm particle fraction.
Test sediment was determined to be free of organic
pesticides and heavy metals by the Soil, Plant, and
Water Laboratory at the University of Georgia, College
of Agricultural and Environmental Science (Athens,
Georgia).
Spawning substrate within each tank consisted of a
stack of five unglazed tiles separated by metal washers,
held together by two stainless steel bolts (Figure 1).
Similar tile "towers" have been used with success to
spawn crevice-spawning Cyprinella species (Gale and
Gale 1977; Rakes et al. 1999; Burkhead and Jelks
2001). Instead of resting on the bottom of the tank,
towers were suspended from a wooden board that
spanned the top of each tank. The bottom tile of each
tower was 18.5 cm X 30 cm, the next tile was 11.5 cm
X 30 cm, and the final three tiles were each 10 cm X 30
cm. Suspending the tower enabled the paddle to move
freely below the bottom tile. The bottom tile was made
larger than the rest so that it would serve as a "false
bottom", thereby inducing the fish to spawn in the
crevices above it. Each tank was equipped with a small
powerhead pump to generate current over the spawning
towers, similar to the procedure in Burkhead and Jelks
(2001).
Whitetail shiner adults used in spawning experi-
ments were dipnetted while snorkeling in the upper
LTR (Swain County, North Carolina). All fish used in
this study were collected on two separate days. I
attempted to collect only nuptial males (i.e., those that
were tuberculate with pale blue iridescence) and gravid
females. After transporting fish to the laboratory, males
and females were kept in separate 830-L (220-gal)
holding tanks at 20-22°C, and fed frozen chironomid
larvae, frozen adult brine shrimp Artemia spp., and a
dry pelleted prepared food (Purina AquaMax D04; 1.5
mm). Each fish was used only one time, ensuring that
all fish used in experiments were behaviorally naive.
Normal operation of the experimental apparatus
caused about 5-10% of suspended sediment to settle
over the course of 1 week (Sutherland 2006). The
presence of the tile towers within each tank caused a
marked increase in sediment settling during each 7-d
spawning trial. Suspended sediment dissipation was
estimated by measuring turbidity each day for 1 week
418
A
B
SUTHERLAND
1
20 crn/s
2
FIGURE 1.-Schematics showing the "tower" of spawning
tiles used in whitetail shiner spawning experiments. Panel (A)
presents a side view of the tank showing the orientation of the
paddle and tile tower. Numbered features are as follows: 1, the
wooden board that spans the tanks and from which the tile
tower is suspended; 2, one of the two metal bolts used to
suspend the tower; 3, the tile tower made of five nonglazed
tiles; and 4, the polyvinyl chloride apparatus paddle. Panel (B)
presents a top view of the experimental tank showing the
orientation of the tile tower and powerhead pump. Numbered
features are as follows: 1, the wooden board from which the
tower is suspended; and 2, the powerhead pump attached to
the side of the tank (velocity - 20 cm/s).
in two replicates of each sediment treatment. Sediment
settling experiments were conducted in tanks contain-
ing no fish. Turbidity data were converted to SSC by
means of the following rating curve developed for test
sediment:
SSC = 1.2316 • t - 6.8426,
where SSC = suspended sediment concentration (mg/
L), t = turbidity (nephelometric turbidity units [NTU]);
R2 = 0.99, p < 0.001. During sediment settling
experiments, 58-71% of suspended sediment settled.
SSC at spawning was estimated by comparing
sediment settling curves (i.e., SSC over time) and time
(h) necessary to attain three developmental stages
(clear eggs, eyed eggs, and larvae). Similar to Burk-
head and Jelks (2001), the development intervals used
were 45 h for eye development, and 120 h for hatching
to larval stage; intervals were based on published rates
for other Cyprinella spp. at similar temperatures (Gale
and Gale 1977; Snyder 1993).
At the start of each trial, two females and one male
were taken from their respective holding tanks and
randomly assigned to each experimental tank. Fish
with more advanced secondary sexual characteristics
(i.e., coloration and tubercles for males; abdomenal
swelling for females) were preferentially selected.
Males ranged in size from 120 to 140 mm, and
females were 90-110 mm. After fish were placed in
each tank, sediment treatments were begun. Fish were
not fed during spawning trials. Experimental trials were
conducted with a constant photoperiod of 14 h light: 10
h dark, and water temperatures were increased from
holding tank temperatures to about 25°C. At the end of
each trial, fish were removed from tanks, and the tile
towers were removed and examined for propagules.
Then the water from each tank was siphoned through a
net, and the net was examined for propagules. All
propagules were preserved in a 10% solution of
buffered formalin.
Regression analysis was used to determine whether
there was a significant relationship between SSC and
spawning effort, defined as the number of tanks per
treatment in which spawning occurred. The assump-
tions of one-way analysis of variance (ANOVA) were
explored to determine whether ANOVA was appropri-
ate for testing if there was a significant relationship
between mean SSC at initiation of spawning and the
number of propagules spawned. Because data were not
normally distributed (Shapiro-Wilks test; P < 0.0001)
and did not meet Levene's test for homogeneity of
variance (P < 0.001), the Kruskal-Wallis (a < 0.05)
test was applied. The Mann-Whitney U-test was
performed to test whether there was a significant
difference in spawning output between experimental
trials. The Kruskal-Wallis test was used to test whether
differences in the numbers of each developmental stage
spawned (larvae, eyed eggs, and clear eggs) were
significant; stage and treatment were considered fixed
effects, and trial was a random effect in the model.
Results
Spawning effort (the number of tanks where
spawning occurred) decreased with increasing SSC
(Figure 2). No change occur-red until SSC was above
25 mg/L. Above 25 mg/L, spawning effort declined
steadily. Fish spawned in only half of the tanks at 500
mg/L, and only two of eight tanks at that treatment had
more than three eggs. In addition to the decrease in
SUSPENDED SEDIMENT AND REPRODUCTIVE SUCCESS

f'
p

I

al

z
a
0 25 60 100 Soo
Treatment (SSC; moll.)
FIGURE 2.-Whitetail shiner spawning effort (number of
tanks where spawning occurred) for each suspended sediment
concentration treatment (SSC; mg/L).
spawning effort with increasing SSC, mean spawning
output (i.e., the mean number of propagules spawned
per treatment) declined consistently with increasing
SSC (Figure 3). Although total spawning output was
not significantly different among treatments, the results
do suggest a trend of decline with increasing SSC (P =
0.084; Table 1). Spawning output was not significantly
different between experimental trials but was signifi-
cantly different among development stages (Table 1).
For each developmental stage, and for total propa-
gules spawned, mean spawning output at 500 mg/L
was 10-14% of the output at the four lower SSCs. The
number of eyed eggs and clear eggs spawned were
significantly higher than the number of larvae produced
(P < 0.001; Table 1), indicating a delay in timing of
reproduction. The number of propagules spawned was
inversely and significantly related to the loglo trans-
formed mean SSC (R2 = 0.36, P = 0.02; Figure 4).
Examining propagule developmental stage allows
100
90 1. ¦ larvae
¦ eyed eggs
j
Y Cl clear eggs
c
1. 70
m 13 total propagules
o
60
m
_m
50

a
c 30 j
20
10

0 25 so 100 Soo
SSC (mglL)
FIGURE 3.-Whitetail shiner spawning output (number of
propagules spawned per experimental tank) for each sediment
treatment (SSC; mg/L). Standard error bars are presented; n =
8 (4 replicates per trial X 2 trials).
419
TABLE 1.-Results of Kruskal-Wallis analyses for the
number of propagules spawned by whitetail shiners versus
suspended sediment treatment (mg/L) and developmental
stage (clear eggs, eyed eggs, or larvae). Also presented are the
results of Mann-Whitney U-tests of the number of propagues
spawned versus experimental trial (n = 2).
Source df Test statistic P-value
Treatment 4 8.22 0.0084
Stage 2 15.28 <0.001
Trial 1 1,736.00 0.697
estimation of the conditions under which the propa-
gules were spawned. For example, in the 500-mg/L
tanks, only clear eggs were found. Because eye
development occurs after about 45 h in Cyprinella
spp. (Gale and Gale 1977), this indicates that spawning
in these tanks took place after 123 h (i.e., 168 - 45 h).
Development rate, combined with sediment settling
curves (Figure 5), indicates that eggs in the 500-mg/L
tanks were spawned when the mean SSC was about
209 mg/L. Only eyed and clear eggs were found in
100-mg/L tanks. Clear eggs were spawned after 123 h,
and eyed eggs were spawned between 48 and 123 h
after trial initiation. Therefore, in the 100-mg/L tanks,
clear eggs were spawned when mean SSC was about
44 mg/L, and eyed eggs were spawned when mean
SSC was about 54 mg/L.
Discussion
Whitetail shiner spawning success was moderately
affected by increasing SSC. Spawning effort decreased
significantly above 25 mg/L SSC. This suggests a
350 -
300-

250
\
\ •

200-
\
\
s \
150-
\
\
E t
E \
\
100 -
X \

7 \
50 - ? \
0 - . .-- e
0.00 0.50 1.00 1.50 2.00 2.50 3.00
log I mean SSC (mg/L)]
FIGURE 4.-Regression of the number of propagules
spawned on suspended sediment concentration (SSC; mg/L).
Each data point represents the total number of larvae, eyed
eggs, or clear eggs spawned in eight replicate tanks at each of
five initial sediment concentrations. The SSCs are mean
values measured during sediment dissipation experiments. The
regression equation is as follows: number of propagules =
-89.564-log (mean SSC) + 273.9 (R2 = 0.36, P = 0.02).
420
600
600
,00
000
200
120
,0o i{
so
eo ;
40 `w
X._
20 { x... ,
0*
0
SUTHERLAND
?- 500 mgvL ,.
?••- t00myl
50 mgt
20 b 60 so 100 120 140 160 160
Elapsed time (hours)
FIGURE 5.-Sediment settling curves for five suspended
sediment treatments over a 7-d trial, The light shading
represents the approximate period from spawning required to
produce larvae at the end of a 7-d experimental trial, the dark
shading the period from spawning required to produce eyed
eggs, and the clear region the period required to produce clear
eggs. Eyed egg and larvae development times are based on the
literature (Gale and Gale 1977; Snyder 1993; Burkhead and
Jelks 2001).
possible threshold effect between 0 and 25 mg/L SSC.
Further testing of sediment concentrations between 0
and 25 mg/L SSC are required to determine where
whitetail shiner sensitivity to suspended sediment
begins. The total number of propagules also decreased
significantly with increasing SSC. The fact that
significantly more eggs than larvae were observed
with increasing SSC suggests that spawning was
delayed in tanks with higher SSC.
Whitetail shiners appear to be slightly less sensitive
to increasing SSC than the only other crevice-spawning
minnow whose spawning response to elevated SSC has
been studied, the tricolor shiner (Burkhead and Jelks
2001). Tricolor shiner spawning effort, output, and
timing were all significantly affected by increased SSC
(Burkhead and Jelks 2001). At the highest treatment
(600 mg/L) tricolor shiner spawning effort dropped to
25%v, as opposed to 50% in 500 mg/L for the whitetail
shiner. The mean number of tricolor shiner eggs in
100-mg/1- tanks decreased to 50% of controls; the
number of whitetail shiner propagules at the same SSC
decreased to 70% of controls.
The moderate impact of increased SSC on whitetail
shiner reproduction supports previous anecdotal evi-
dence of sediment tolerance in this species (Jenkins and
Burkhead 1994). Previous research has documented
whitetail shiner persistence in heavily sedimented
tributaries (Sutherland et al. 2002), and nowhere are
they known to be in jeopardy (Warren et al. 2000).
Sediment tolerance may partly explain the success of
whitetail shiners relative to other upland crevice-
spawning minnows that are experiencing dramatic
declines in population and range (e.g., the spotfin chub
Erimonax monachus and the blue shiner C. caerulea).
However, some other aspect of life history may also
give whitetail shiners an advantage in disturbed
systems. Life history differences have been suggested
as an explanation for the differential success of four
crevice-spawning Cyprinella species of the upper
Coosa River system (Burkhead and Jelks 2001). The
two species that are widespread spawn in swift, deep
riffles and are thus able to survive in river reaches
affected by chronic sedimentation. The two less
common species spawn in slow riffles, a habitat more
vulnerable to sedimentation. Just as "sediment toler-
ance" appears to be related to the life history of the two
widespread Cyprinella species in the Coosa River, this
may be the case for the whitetail shiner. Whitetail
shiners spawn in a variety of habitats, including under
trash (e.g., tires, sheet metal, plywood) and in logs
located above the substrate (Jenkins and Burkhead
1994; personal observations). Burkhead and Jelks
(2001) noted that spawning in swift current may be
advantageous to some Cyprinella species in sediment-
ed systems. The ability to spawn in crevices above the
riverbed may give whitetail shiners a similar advan-
tage. Just as spawning in swift current does not
correspond to Cyprinella phylogeny (Mayden 1989),
perhaps neither does sediment intolerance.
Whitetail shiners may also be less sensitive to
elevated SSC than are other Cyprinella spp. because of
a lower reliance on visual cues during spawning.
Tricolor shiners are thought to delay spawning until
SSCs decline because they rely on visual cues during
spawning (Burkhead and Jelks 2001). Visual cues are
thought to be important to the reproductive success of
sexually dimorphic, brightly colored, displaying fish
(Muncy et al. 1979; Kodric-Brown 1998; Burkhead
and Jelks 2001). Whitetail shiners are less brilliantly
colored than other fishes for which visual cues are
presumed to be important. Even in turbid water, the
white pigment on their caudal peduncle and base of
caudal fin is evident (personal observations). The fact
that no larvae were found in the two highest SSC
treatments in the current study indicates that whitetail
shiners may delay their spawning longer than tricolor
SUSPENDED SEDIMENT AND REPRODUCTIVE SUCCESS
shiners. However, whitetail shiners spawned at a
minimum of 209 mg/L versus 70-170 mg/L for tricolor
shiners (Burkhead and Jelks 2001). This indicates that
the whitetail shiner may initiate spawning after a longer
period of time but at higher SSCs than the tricolor
shiner.
The moderate response of whitetail shiners to
elevated SSC is within the range of impairment
predicted by a sediment dose-response model (New-
combe and Jensen 1996). This model, which uses SSC
(mg/L) and exposure duration (h) to predict severity of
impairment to various fish taxa and life stages,
predicted moderate physiological stress when mean
SSC and duration from the present study were applied.
In general, the results from this study agree with the
model's prediction of sublethal impairment. Although
impairment to larvae and eggs is not lethal, sediment
effects on reproductive behavior may still severely
harm the long-term stability and longevity of native
fish populations (Burkhead and Jelks 2001). Because
sediment-induced alterations of spawning reduces or
precludes the production of eggs and larvae, reproduc-
tive behavior effects are more severe than is indicated
by sediment-related egg and larvae mortality alone.
Whitetail shiner spawning in the highest treatment
tanks (SSC, -209 mg/L), makes it difficult to
understand why fish in the 100-mg/L tanks did not
spawn immediately but rather waited between 48 and
123 h (when SSC had dropped to between 44 and 54
mg/Q. One possible explanation is that fish exposed to
SSC (above some threshold concentration) attempt to
wait until conditions improve, and then after some
sediment dosage (duration at given concentration), they
initiate spawning despite less than suitable conditions.
If SSC is high (as in the 500-mg/L tanks), whitetail
shiners may wait longer but eventually will spawn if
enough time elapses. If initial SSC is lower (as in the
100-mg/L tanks), they may still attempt to wait for
better conditions but will initiate spawning if enough
time elapses. It is plausible that fish that have evolved
in habitats where sediment pulses are natural (from
natural bank slumping and low-recurrence-interval
floods, for example) have a strategy to "weather the
storm." For whitetail shiners and other upland fishes,
the cues that delay spawning may be related not only to
sediment concentration but also to some maximum
elapsed time. Further experimentation would be
beneficial to try to tease apart the relationship between
spawning success and sediment dose. Further study is
also needed to determine the threshold SSCs necessary
to initiate delayed spawning and the SSCs above which
spawning will not occur in upland nongame fishes.
Although the whitetail shiner seems to be tolerant of
moderate levels of sedimentation, it is most abundant
421
in streams with clean, coarse substrate (personal
observations; Jenkins and Burkhead 1994). It may be
more abundant and widespread than the sympatric and
ecologically similar spotfin chub, because of its ability
to utilize a variety of spawning substrates. However,
the present study suggests that even this relatively
tolerant species displays a marked decrease in
spawning success with increasing SSC. The negative
effects of excessive sediment inputs on the spawning
success of stream fish are often described as operating
through habitat homogenization and the smothering of
eggs and larvae (Waters 1995; Burkhead et al. 1997).
The current study is one of only two (see Burkhead and
Jelks 2001) that demonstrates the importance of
elevated suspended sediment to the spawning success
of benthic specialized upland fishes.
Acknowledgments
This research was supported by a grant from the U.S.
Fish and Wildlife Service (grant no. 1434-HQ-97-RU-
01551), through the Georgia Cooperative Fish and
Wildlife Research Unit. I would like to thank E.
Henderson, V. Vaughan, and B. Ritchie for their
support in the development of the experimental
apparatus used in this study, and for vital support,
including providing facilities for fish holding tanks and
experimental apparatus. I thank W. McLarney for
sediment data used in this manuscript. Finally, I thank
M. Freeman, G. Helfman, C. Jennings, D. Leigh, J.
Maki, the Meyer laboratory group, and especially J.
Meyer for helpful comments throughout this research
and for comments that have greatly improved this
manuscript.
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