No abstract

The marine diatom Minutocellus polymorphus is suited for use as a test species in algal toxicity tests. Its responses to 19 toxicants in a modification of Aquil, a chemically defined phytoplankton culture medium, compared favorably with those of Skeletonema costatum, a common test species. M. polymorphus grows rapidly, allowing a test duration of 48 h and thus minimizing complications due to toxicant degradation, volatilization and adsorption to test vessel walls. These and other characteristics indicate that M. polymorphus is an ideal standard organism for algal toxicity tests.

No abstract

Eggs of the sheepshead minnow (Cyprinodon variegatus) were artificially fertilized and maintained at temperatures from 15 to 35 C and in salinities from 0 to 35%o to determine efficient culture conditions. Fertilization was not affected by temperature or salinity ranges chosen, but hatching success was greatest (x2; a • 0.01) at a temperature range of 24 to 35 C and a salinity range of 15 to 30%•.Artificially fertilized sheepshead minnow eggs were exposed to logarithmic concentrations of Aroclor 1254 (10.0 to 0.1 •zg/liter) in seawater averaging 30 C and 24%• in a flow-through bioassay. Fertilization was not affected but significantly fewer embryos developed in the 10.0 gg/liter concentration, and fewer fry survived in concentrations greater than 0.1 gg/liter. Fry were more susceptible to Aroclor 1254 than were embryos, juveniles, or adults. Polychlorinated biphenyls (PCB's) occur in estuaries in many states(Butler 1973), and the occurrence of one, Aroclor 1254, in nearby Escambia Bay, Florida and its acute toxicity to estuarine animals has been documented (Duke, Lowe and Wilson 1970). Hansen, Parrish and Lowe (1971) found 5 gg/liter of Aroclor 1254 toxic to the juvenile estuarine fishes, pinfish (Lagodon rhomboides) and spot (Leistomus xanthurus), in 14-to 45day bioassays. Because Escambia Bay is a nursery ground for many marine species of fish, it is important to determine the effect of Aroclor 1254 on the early life stages of these fish.