A caridean grass shrimp (Palaemonetes pugio Holthius) as an indicator of sediment quality in Florida coastal areas affected by point and nonpoint source contamination

Grass shrimp are one of the more widely distributed estuarine benthic organ isms along the Gulf of Mexico and Atlantic coasts, but they were used infre quently in contaminated sediment assessments. Early-life stages of caridean grass shrimp, Palaemonetes pugio (Holthius), were used in this baseline su rvey as indicators of sediment pore water quality for several Florida coast al areas affected by nonpoint and point sources of contamination. Static to xicity tests were conducted using 24 well culture plates assessing embryo a nd larval survival after 12 days exposure to pore water (interstitial water ). Acute toxicity was observed in 28% of pore waters (15 of 53 samples) sug gesting that sediment contamination was not widespread in the study area ba sed on the response of this species. When toxicity was observed, grass shri mp pore water toxicity test was usually a more sensitive indicator of conta mination than solid-phase tests conducted with the epibenthic invertebrate, Mysidopsis bahia. P. pugio embryos were more sensitive than larval form an d response of different brood stocks usually were similar (P > 0.05) when e xposed to same pore waters. Based on all considerations, this early-life st age toxicity test shows promise being useful detecting pore water toxicity. This conclusion is based on availability of a test methodology which requi res minimal space and effort, and the test species widespread geographical distribution. However, there are several remaining research needs, includin g the important issue of its sensitivity relative to that for other pore wa ter test species as well as for species used in solid-phase toxicity tests. (C) 2000 by John Wiley & Sons, Inc.