Susan Allen-Gil (biology) gave two presentations at the Society of Environmental Toxicology and Chemistry's 24th annual meeting in Austin, Texas, this month.
"PCB composition in sea run vs. resident whitefish in subsistence fisheries of northern Alaska,"
Allen Gil, S.; Ford, J.; Seigle, J.; Akpik, M.A.; Woods, J.; and Nashagnik, J.
This project examines the role of the two amphidromous fish species (least cisco and broad whitefish) in biotransport of pollutants in northern Alaska. At selected coastal plain subsistence lakes, we collected sediment, plankton, and several fish species. Trophic position of fish is being examined using Delta 15N. The relative influence of the marine system to individual fish is being examined using Delta 8 13C and 832S in muscle as well as Sr/Ca in otoliths.
Otolith microchemistry indicated that resident and migratory behaviors were seen in both fish species, with resident behavior being more prevalent. For least cisco, marine migration was less common in inland lakes compared to coastal lakes. Sigma PCB concentrations were typically quite low (<3 µg/g lipid) and correlated with increasing trophic position for all species except burbot (Lota lota).
Tri-, tetra-, and penta-CBs comprised the majority of SPCBs. There was no difference in the Sigma PCBs concentration between resident and sea run least cisco, and there was no difference between the relative concentration of individual congeners between these two groups. These two observations combined suggest that POPS are not biotransported by fish into inland systems from the marine environment to a significant extent, and that atmospheric and local sources are probably more important.
“Pokeweed (Phytolacca americana) as a potential molluscicide for use in aquaculture," Allen Gil, S.M. and Aldea, M.; Biology Department, Ithaca College, Ithaca, NY, USA.
The aquatic snail Vinipiarus georgianus is an invasive species of mollusk in the eastern United States. Ripe berries of the putative molluscicidal plant pokeweed (Phytolacca americana L.) were used in toxicity tests on V. georgianus and fathead minnow larvae (Pimephales promelas). Static toxicity tests were conducted on the snails and the fish separately to assess acute and chronic toxicity at two levels of exposure (200 mg L 1 and 500 mg L 1).
Dry pokeweed berries were applied to the experimental tanks in three identical applications, two days apart, each meant to maintain the desired concentration, accounting for natural degradation rates. At seven days the snail mortality for the 500 mg/L treatment (55 percent, P<0.01) was significantly higher than the 200 mg/L (10 percent, P<0.01) and control (0 percent, P<0.001). At 30 days after the initial exposure (same snails used for the seven day) the treatment effect was still significant with a snail mortality of 95 percent (P<0.001) for the highest concentration, 75 percent (P<0.01) for the 200 mg/L, and 15 percent for control (P<0.001).
In an eight-day exposure test identical to the one used on the snails, there was no significant increase in mortality (P=0.39) at any of the tested concentrations on larval (30 days old) fathead minnows (P. promelas). There were, however, indications of sublethal effects for the 500 mg L 1 treatment, manifested as impaired growth (P=0.04). Pokeweed is the American variety of the Ethiopian plant Endod (Phytolacca dodecandra), which has been reported to contain the highly potent molluscicidal substance oleanolic acid glucoside. Yet, LC/MS/MS investigations of pokeweed berry extracts showed no definitive evidence to support that any type of oleanolic acid glycoside or oleanolic acid itself were present in the preparations. We conclude that pokeweed berries have significant molluscicidal properties, but in concentrations far too high for use in practical applications.
Contributed by Nancy Pierce, npierce@ithaca.edu
