''Labidesthes sicculus'', also known as the Brook silverside is a

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

n species of Neotropical silverside. The brook silverside lives in slow moving

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s and

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s from the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...

to the

Mississippi Basin The Mississippi River is the primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri. From its traditional source of Lake Itasca in northern Minnesota, ...

and Gulf Coastal Plains. The brook silverside survives best in clear water with aquatic vegetation. ''L. sicculus'' feeds on a diet of

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s, insect

larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

, and winged

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s. The spawning season of the brook silverside occurs during the spring and early summer. The survival of freshwater fishes such as the brook silverside is increasingly threatened. In order to ensure survival of the brook silverside, turbidity of natural habitats should be monitored.

Geographic distribution

The distribution of brook silverside populations range from the Great Lakes southward through the Mississippi Basin and Gulf Coastal Plains (including 27 U.S. states and parts of Canada). It is native to the majority of this distribution, but has also been stocked outside of its natural range as forage food for sport fishes.Jonna, R. (2004)
Actinopterygii.
NatureServe. The brook silverside occupies freshwater lakes, ponds, quiet pools and small rivers. The environment ranges from cool to warm water Marsden, J.E., Langdon, R.W. & Good, S.P. (2000): First occurrence of the brook silverside (''Labidesthes sicculus'') in Lake Champlain, Vermont. ''Northeastern Naturalist, 7 (3): 248–254.'' with variability in levels of gradient and vegetation. Consistently, however, the brook silverside prefers clear water with low substrate concentrations. The brook silverside is vulnerable to turbid waters.Powles, P.M. & Sandeman, I.M. (2008): Growth, summer cohort output, and observations on the reproduction of brook silverside, ''Labidesthes sicculus'' (Cope) in the Kawartha Lakes, Ontario. ''Environmental Biology of Fishes, 82 (4): 421–431.'' In

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

, brook silverside populations were shown to have decreased shortly after the construction of the Tennessee-Tombigbee Waterway. Populations likely declined because of introduced competition.Strongin, K., Taylor, C.M., Roberts, M.E., Neill, W.H. & Gelwick, F. (2011): Food Habits and Dietary Overlap of Two Silversides in the Tennessee-Tombigbee Waterway: The Invasive ''Menidia audens'' Versus the Native ''Labidesthes sicculus''. ''The American Midland Naturalist, 166 (1): 224–233.''

Ecology

The brook silverside is on the lower end of the food chain, and is preyed on by many larger fish. The diet of the brook silverside consists mostly of

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

. They are highly specialized feeders with

cladocera The Diplostraca or Cladocera, commonly known as water fleas, is a superorder (biology), superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory. Over 1000 sp ...

ns comprising 80% of their diet, (40%) small flying insects, and (20%) midge larvae. Their diet varies with life stages and seasons. At a younger age, the brook silverside preys mostly on smaller fish. Their diet shifts to immature insects later. During winter, the brook silverside eats mostly planktonic crustaceans. Because of both intentional and unintentional species introduction, the brook silverside must compete for food sources. Specifically, the brook silverside has been forced to compete with the non-native '' Menidia audens'', which was introduced by waterway construction. This forced competition of resources has led to a decrease in brook silverside populations.

Life history

The brook silverside breeds in the summer from late May to mid-August. Their life span is only one year. During the first year, they have rapid growth, growing up to one millimeter per day. Brook silversides quickly reach a maximum size of approximately eight centimeters. They reach sexual maturity by the first summer in order to reproduce. Some studies report that brook silversides reproduce by internal fertilization, although this has not been entirely confirmed. When the eggs are produced, they have an attached filament, which allows for the eggs to be deposited on logs, plants and rocks. Temperature does not affect the sex of fish. After the eggs hatch, they immediately swim away from the shore into deeper water, but still stay just under the surface. They congregate in large schools. The brook silverside migrates throughout its life cycle. No human-induced changes are reported as affecting the life history.Hubbs, C.L. (1921): An Ecological Study of the Life-History of the Fresh-Water Atherine Fish ''Labidesthes sicculus''. ''Ecology, 2 (4): 262–276.'' Human-induced changes are reported as more strongly affecting populations rather than behaviors.

Current management

Human intervention through species introduction, habitat alteration, pollution, and construction are causing the decline of the brook silverside and other freshwater fishes. Freshwater fishes account for the majority of extinctions in ray-finned fishes. To stabilize and increase populations, no more dams or waterways should be built. Additionally, pollution must be stopped. Agricultural runoff creates turbid waters, which the brook silverside cannot thrive in. Stream sampling occurs through organizations such as USFWS and TVA (locally). This allows for populations to be monitored and stream chemistry to be controlled. Over-fishing and hybridization aren't causing brook silverside populations to decline. Invasive species and habitat destruction have the greatest impact on population decline. Areas are being reserved for the preservation of endemic fish, but more must still be done.

References

{{Taxonbar, from=Q143344 Brook silverside Fish of the Great Lakes Fish described in 1865 Freshwater fish of North America Taxa named by Edward Drinker Cope