David J. Hansen

The sheepshead minnow (Cyprinodon variegatus). an estuarine fish of the Atlantic and Gulf Coasts, is suitable for both partial chronic and chronic (egg-lo-egg) bioassays. The fish is easily held at high population densities in the laboratory and. at about 30 C, produces numerous eggs. The average 3o-day survival of the fish from fertile egg to fry is 75%. Generation time for this species is short (3-4 months) and its small adult size (male average standard Iength=48mm) provides for relatively inexpensive bioassays. This killifish's susceptibility to organochlorine toxicants is similar to...

Acute (96-hour) bioassays were performed with endrin and the following estuarine organisms: American oyster (Crassostrea virginica), pink shrimp (Penaeus duorarum), grass shrimp (Palaemanete's pugio). sailfin molly (Poecilia latipinna) and sheepshead minnow (Cyprinodon variegatus). Endrin was acutely toxic to all organisms tested, except oysters, whose shell growth was appreciably inhibited by 56 ug/1 (parts per billion) of the chemical. Pink shrimp were the most sensitive animal tested, but significant numbers of both species of shrimps and fishes died when exposed 10 concentrations of...

The effect of the polychlorinated biphenyl (PCB), Aroclor 1254, in eggs of the sheepshead minnow, Cyprinodon variegatus, on fertilization success and survival of embryos and fry was investigated. Adult fish were exposed for four weeks to 0.1,0.32, 1.0,3.2 or 10.0 ug/l of PCB, then injected twice with 50 lU of human chorionic gonadotrophin to stimulate egg production. The eggs were fertilized, placed in PCB-free flowing seawater and observed for mortality. Fertilization success was unimpaired by concentrations in eggs as high as 201 ug/g but survival of embryos and fry was reduced. Usually...