Invertebrates, benthic

Problems associated with excessive levels of nutrients and unwanted nuisance species have already been mentioned. There are cases in which intentional fertilization is used by aquaculturists in order to produce desirable types of natural food for the species under culture. Examples of this approach include inorganic fertilizer appHcations in ponds to promote phytoplankton and zooplankton blooms that provide food for young fish such as channel catfish, the development of algal mats through fertilization of milkfish ponds, and the use of organic fertilizers (from Hvestock and human excrement) in Chinese carp ponds to encourage the growth of phytoplankton, macrophytes, and benthic invertebrates. In the latter instance, various species of carp with different food habits are stocked to ensure that all of the types of natural foods produced as a result of fertilization are consumed. 

Kick net 500 micron white mesh net is designed to meet the requirements of groups performing USEPA Rapid Bioassessment Protocols for Benthic Invertebrates. (Benthic = bottom dwelling). 

Sediment Analysis. Sediment is the most chemically and biologically active component of the aquatic environment. Benthic invertebrate and microbial life concentrate in the sediment, a natural sink for precipitated metal forms, and an excellent sorbent for many metal species. TTie extent to which potentially toxic trace element forms bind to sediment is determined by the sediment s binding intensity and capacity and various solution parameters, as well as the concentration and nature of the metal forms of interest. Under some conditions sediment analyses can readily indicate sources of discharged trace elements. 

Benthic invertebrates are macroscopic animals that live at or near the sediment/water interface. Some benthic invertebrates, particnlarly mnssels, readily accnmnlate metals, prompting their use as biological indicators of mercnry contamination (Smith... 

The dietary importance of benthic invertebrates to many species of fish, birds, and mammals (Vander Zanden and Vadeboncoenr 2002) signifies their importance in the trophic transfer of MeHg and their potential relevance as biological indicators. Some benthic invertebrates (e g., oysters, clams, shrimp, crabs, and crayfish) are consumed by humans, providing a direct pathway for exposure to MeHg. In the United States, shellfish rank below fish as a source of dietary MeHg in the human population (NRC 2000 Schober et al. 2003). 

Benthic invertebrate communities are taxonomically and trophically complex, and their abundance and species composition in a water body often vary seasonally and among years. Sediment-dwelling invertebrates can be readily sampled but considerable effort is often required to remove benthic organisms from grab samples of sediment, to determine their taxonomic composition, and to obtain sufficient sample mass of a target taxon for analysis. Sampling would not substantially affect target populations. 

Criterion Importance of criterion Periphyton Phytoplankton Zooplankton Benthic invertebrates Prey fish Piscivorous fish... 

Jackson DA, Harvey HH. 1993. Fish and benthic invertebrates community concordance and community-environment relationships. Can J Fish Aquat Sci 50 2641-2651. 

Trivalent chromium was less effective than Cr+6 in reducing fecundity of Daphnia magna 44 pg Cr+VL vs. 10 pg Cr+6/L (USEPA 1980). Annelid worms (Tubifex sp.) accumulated about 1 mg total chromium/kg whole body during exposure for 2 weeks in sediments containing 175 mg ( T+3/kg, suggesting that benthic invertebrates have only a limited ability to accumulate chromium from sediments or clays (Neff et al. 1978). 

It is emphasized that Cr+3, probably because of its very low solubility in seawater, appears to have a much lower bioavailability to most groups of marine animals than Ct 6, which is more water soluble (Carr et al. 1982). The clam Rangia cuneata appears to be an exception it accumulated up to 19 mg Cr/kg in soft parts, on a dry weight basis, during exposure for 16 days to chromium-contaminated muds, and retained most of it for an extended period the estimated biological half-time was 11 days (Carr et al. 1982). In general, benthic invertebrates rarely accumulate chromium from contaminated sediments (82 to 188 mg Cr+Vkg) only a few examples have been recorded (Neff etal. 1978). 

Miller, P.A., K.R. Munkittrick, and D.G. Dixon. 1992. Relationship between concentrations of copper and zinc in water, sediment, benthic invertebrates, and tissues of white sucker (Catostomus commersoni) at metal-contaminated sites. Canad. Jour. Fish. Aquat. Sci. 49 978-984. 

West, C.W., V.R. Mattson, E.N. Leonard, G.L. Phipps, and G.T. Ankley. 1993. Comparison of the relative sensitivity of three benthic invertebrates to copper-contaminated sediments from the Keweenaw waterway. Hydrobiologia 262 57-63. 

Woodward, D.F., W.G. Brumbaugh, A.J. Deloney, E.E. Little, and C.E. Smith. 1994. Effects on rainbow trout fry of a metals-contaminated diet of benthic invertebrates from the Clark Fork River, Montana. Trans. Amer. Fish. Soc. 123 51-62. 

Wong, A.H.K., D.J. McQueen, D.D. Williams, and E. Demers. 1997. Transfer of mercury from benthic invertebrates to fishes in lakes with contrasting fish community structures. Canad. Jour. Fish. Aquat. Sci. 54 1320-1330. 

Most species of zooplankton and benthic invertebrates decreased in abundance at 0.25 pg/L and higher... 

BaP was not detectable in muscle and gut, indicating that BaP on sediments may be mobilized and made available to benthic invertebrates and fish but that the process was highly inefficient with minor biomagnification a similar case is made for fluoranthene... 

Sediments containing 50-1600mg kgy1 of triphenyl phosphate altered the drift dynamics of benthic invertebrates. Invertebrates exposed to contaminated sediments drifted almost immediately when threshold toxicity was reached [4],... 

Significant concentrations of cyanotoxins have been found to accumulate in the tissues of macroinvertebrates such as mollusks and crustaceans, presenting an indirect route of exposure for invertebrates, fish, and aquatic mammals at higher trophic levels (Negri and Jones 1995). In natural systems, mortality among benthic invertebrate herbivores is probably low because most bloom-forming bacteria are planktonic and only periodically come into contact with the benthos. Nevertheless, Kotak et al. (1996) determined that enhanced mortality of snails at the end of a bloom cycle in Canadian lakes was due to consumption of Microcystis cells that had formed a scum on the surface of macrophytes. Oberemm et al. (1999) found that aqueous microcystins, saxitoxins, and anatoxin-a all resulted in developmental delays in fish and salamander embryos. Interestingly, more severe malformations and enhanced mortality were observed when larvae were exposed to crude cyanobacterial extracts than to pure toxins applied at natural concentrations (Oberemm et al. 1999). 

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