Freshwater fish tests

Freshwater fish tests are generally conducted on bluegill, a warm water fish, and rainbow trout, a cold water fish. Catfish, fathead minnows and sometimes carp are also used depending on the expected route of exposure. Sheepshead minnow is the commonly used saltwater fish. 

Studies of 30 to 60 days duration with three comparatively sensitive species of freshwater fishes demonstrated that concentrations of >1 and <3 pg Cd/L in water of low alkalinity caused reductions in growth, survival, and fecundity of brook trout (Salvelinusfontinalis), the most sensitive species tested (Table 1.3). Under conditions of increasing alkalinity, the maximum allowable cadmium concentration range for brook trout increased to >7 and <12 pg/L a similar case was made for the walleye (Stizostedion vitreum vitreum Table 1.3). 

Bioconcentration factors of dioxins in fishes are relatively low compared to other chlorinated aromatic compounds because of the low metabolic conversion of dioxins, their low available concentrations in test systems, and their highly variable uptake rates (de Voogt et al. 1990). In general, bioconcentration factors for persistent superlipophilic chemicals, such as OCDD, derived for freshwater fishes from supersaturated solutions may seriously underestimate the true BCF (Geyer... 

Toxaphene is extremely toxic to freshwater and marine biota. In laboratory tests of 96-h duration, 50% mortality was recorded for the most sensitive species of freshwater and marine teleosts, marine crustaceans, and freshwater insects at nominal water concentrations of less than 10 pg/L of toxaphene, and, in several cases, less than 1 pg/L (Table 27.2). Bioassays of longer duration, based on exposure of aquatic organisms for the entire or most of the life cycle, produced significant adverse effects on growth, survival, and reproduction at toxaphene concentrations between 0.025 and 1.0 pg/L (Table 27.3). Toxaphene was most toxic to freshwater fishes in soft water at elevated temperatures (Saleh 1991). Based on its high toxicity and extensive use, it is not surprising that toxaphene was considered a major cause of nationwide fish kills in 1977 (USEPA 1980b). 

Similar tests can be carried out with aquatic organisms (e.g., the LC50 for freshwater fish such as rainbow trout and bluegills), the LC50 for estuarine and marine organisms, the LC50 for invertebrates such as Daphnia, and the effect of chemicals on the early stages of fish and various invertebrates. 

Figure 29 Phospholipid fractions in A, mature oocytes and B, testes in freshwater fish, % of total phospholipids. (After Sidorov, 1983.) 1, Phosphatidyl choline 2, phosphatidyl ethanolamine 3, sphingomyelin 4, cardiolipin S, lyso-phosphatidyl choline.

Requiring low-sample volume micro-scale tests for its cost-effective application, the PEEP index has thus far employed bioassays with bacteria, algae and microinvertebrates. While well-standardized toxicity tests using freshwater fish existed at the time of the PEEP s conception in the early 1990 s (e.g., the Environment Canada fingerling rainbow trout 96-h lethality test to assess industrial wastewaters), they were excluded because of their large sample volume needs (e.g., close to 400 L of effluent sample required to undertake a multiple dilution 96-h LC50 bioassay in the case of the trout test). In addition to effluent sample volume, the cost of carrying out salmonid fish acute lethality bioassays for the 50 priority industrial effluents identified under SLAP I (the first 1988-93 Saint-Lawrence River Action Plan) was prohibitive. 

Bioassays appeared to fit the bill to perform this service to monitor chemical contamination. They have been around for a while. Until relatively recently, however, they remained in the realm of the laboratory. Only over the last two decades have they found a niche in testing for toxic chemicals in water and sediment, but not yet specifically as a tool for routine water quality monitoring. As Small-scale Freshwater Toxicity Investigations, Volumes 1 and 2 amply demonstrates, the science has now come of age. Assays based on bacteria, microscopic or multi-cellular algae, protozoa, invertebrates and vertebrates (freshwater fish cell cultures) are discussed in... 

Stephenson, R.R. (1982) Aquatic toxicity of cypermethrin. I. Acute toxicity to some freshwater fish and invertebrates in laboratory tests. Aquatic Toxicology 2, 175-185. 

The majority of toxicity test data are generated using species from the northern hemisphere (i.e., Holarctic). For example, 9 of the 12 freshwater fish species used in the ecological risk assessment of atrazine (Solomon et al. 1996) and 27 of the 40 freshwater fish species used in the risk assessment of copper (Brix et al. 2001) are from Holarctic habitats. Relatively few data are available for southern hemisphere species, and consequently risk assessments conducted to protect southern hemisphere ecosystems have to utilize toxicity data obtained using northern hemisphere species (Muschal and Warne 2003). Does this matter Based on the limited data currently available, it would appear not. 

ASTM, 1995. Standard E1768-95. Guide for ventilatory behavioral toxicology testing of freshwater fish. American Assoc Testing Materials, West Conshohocken, PA, 14 pp. 

American Society for Testing and Materials (ASTM) (1995d) Standard Guide for Ventilatory Behavioural Toxicology Testing of Freshwater Fish, E1768-1795. ASTM, Philadelphia. 

US Environmental Protection Agency (1985). Acute Toxicity Test for Freshwater Fish -Hazard Evaluation Division Standard Evaluation Procedure. Office of Pesticide Programs. EPA-546/9-85-06. 

The use of reverse osmosis to treat dialysis water does not remove chloramine, but the addition of ascorbic acid does. Treating the dialysis water with activated charcoal effectively removes chloramine, but periodic water testing with o-tol-idine should nevertheless be undertaken. This reagent detects total chloride, i.e., OC1, HOC1, NHC12, and NC13. Interestingly, chloramine contamination of natural waters has also caused hemolysis in several species of freshwater fish (El). 

Successive reduction of TNT to aminodinitrotoluenes (ADNTs) and diamino-nitrotoluenes (DANTs) leads to a sequential decrease of toxicity to the microalga, Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) [32] and in the Microtox test [30], Further toxicity decrease occurs in the latter with an additional reduction to triaminotoluene (TAT) [30] (Table 4.2 and Table 4.3). The ADNTs were also less toxic than the parent compound to the freshwater fish Pimephales promelas [19], and embryos of the frog Xenopus laevis [33], The reduction of 2,3,6-TNT to ADNTs promoted decreased toxicity in studies with P. promelas and D. magna... 

---