PARENT SESSION
PW3 - In Situ Bioassays Using Transplanted Aquatic Organisms
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P748) Comparison Between Laboratory and In Situ Sediment Toxicity Tests with the Haustoriid Amphipod Eohaustorius estuarius.
Anderson, Brian*,1, Hunt, John1, Phillips, Bryn1, Patricia, Nicely1, Tjeerdema, Ron1, Martin, Michael2, 1 Department of Environmental Toxicology, University of California, Davis, CA, USA2 California Department of Fish and Game, Monterey, CA, USA
ABSTRACT- In this study we assessed amphipod survival in laboratory and in situ exposures using the eastern Pacific Haustoriid species Eohaustorius estuarius. We also compared results of toxicity tests using intact (unhomogenized) and homogenized sediment samples to investigate possible mixing artifacts. Experiments were conducted in Moss Landing Harbor, California, a 303 (d) listed waterbody. Synoptic laboratory and in situ sediment toxicity tests were conducted at two stations: Sandholdt Bridge (SB), the most contaminated station in the Harbor, and at the South Jetty (SJ), a more marine station near the mouth of the Harbor. The results indicated that Eohaustorius is amenable to in situ testing. Despite highly variable salinity regimes (6 - 32 ppt at SB and 21 -34 ppt at SJ), in situ control survival was 87% and 84% at SB and SJ, respectively. Amphipod survival was lower in the in situ exposures relative to the laboratory exposures at both sites. Survival at SB was 30% and 76% in the homogenized in situ and laboratory samples, respectively, and 40% and 64% in the intact (unhomogenized) in situ and laboratory samples, respectively. Neither the homogenized or intact samples from the SJ station were toxic in laboratory experiments, but amphipod survival was only 40% in the intact in situ exposure at this station, possibly due to predation. The results of these experiments suggest that the interaction of contaminants and variable physical parameters such as salinity and temperature resulted in lower survival in the in situ exposures. Sediment homogenization prior to in situ deployment may have reduced predation.
Key words: Toxicity, sediment, in situ, homogenization