BIOLOGICAL RESPONSES TO SUSPENDED-SEDIMENTS

ERDC TN-DOER-E9

May 2000

BIOLOGICAL RESPONSES TO SUSPENDED-SEDIMENTS

Estuarine and Coastal Fish Eggs and Larvae

Hatching Success. The eggs and larvae of estuarine and coastal fish exhibit some of the most

sensitive responses to suspended-sediment exposures of all the taxa and life history stages for which

data are available. Hatching is delayed for striped bass (Morone saxatilis) and white perch (M.

americana) eggs at concentrations of 100 mg/L for a 1-day exposure. These species release eggs

in freshwater habitats. Egg development of Atlantic herring (Clupea harengus), an oceanic

spawner, was not impaired by suspended-sediment dosages of 300 and 500 mg/L for 1 day (Kiorboe

et al. 1981). Messieh, Wildish, and Peterson (1981) reported that although burial of Atlantic herring

eggs under even a thin veneer of sediment caused substantial mortality, direct exposure to

suspended-sediment concentrations as high as 7,000 mg/L had no observable effect on hatching

success.

Direct Mortality. Mortality occurred at relatively low suspended-sediment concentrations sus-

tained for several days for the larvae of anadromous fish that occur in freshwater and brackish

habitats at this life history stage. Striped bass, American shad (Alosa sapidissima), yellow perch

(Perca flavescens), and white perch larvae exhibited increased mortality at suspended-sediment

dosages less than or equal to 500 mg/L for 4 days (3 days for striped bass) (Auld and Schubel 1978).

Pacific herring (C. harengus pallasi), which has an estuarine larval form, reduced feeding at a

suspended-sediment dosage of 2,000 mg/L for one day (Boehlert and Morgan 1985), whereas

Atlantic herring larvae reared at concentrations above 540 mg/L tended to be small, and those

exposed to 19,000 mg/L for 48 hr suffered 100 percent mortality (Messieh, Wildish, and Peterson

1981).

Estuarine and Coastal Juvenile and Adult Fish

Behavioral Responses. Foraging patterns and success are commonly studied behavioral responses

of estuarine fish to suspended sediments. Turbid water reduced feeding in adult Atlantic croaker

(Micropogonias undulatus) and pinfish (Lagodon rhomboides) (Minello, Zimmerman, and

Martinez 1987). Feeding rates of the silverside (Atherina breviceps) were also significantly reduced

at a high turbidity level (120 NTU), presumably due to a decrease in the reactive distance of the

fish to their planktonic prey, which can occur at turbidities as low as 28 NTU (Hecht and van der

Lingen 1992).

Sublethal Responses. Sherk, O'Connor, and Neumann (1975) and Sherk et al. (1974) have

conducted the most extensive bioassays of suspended-sediment impacts on estuarine fishes, how-

ever only for short exposures. They assessed sublethal effects of fuller's earth suspensions by

measuring blood cell counts, hemoglobin levels, blood ionic composition, carbohydrate utilization,

and gill histology. Common sublethal responses were increased red cell counts, hematocrit levels,

and hemoglobin concentrations in the peripheral blood, all of which are consistent with the responses

of fish deprived of oxygen (O'Connor, Neumann, and Sherk 1976). Fine particles coated the

respiratory epithelia of the fish, which hindered gas exchange with the water. Larger sediment

particles were trapped by the gill lamellae and blocked the passage of water, leading to asphyxiation.