MP6 Mercury in Stream Ecosystems
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() Ontogenetic accumulation of mercury in a northwest Atlantic population of sea lamprey.
Drevnick, P1, Horgan, M1, Oris, J1, Kynard, B2, 1 Miami University, Oxford, OH, USA2 U.S. Geological Survey, Turners Falls, MA, USA
ABSTRACT- We are examining the role of sea lamprey (Petromyzon marinus) in the biogeochemical cycling of mercury in the Connecticut River, USA. Sea lamprey occur as native, anadromous populations along the Atlantic coasts of Europe and North America. The Connecticut River is believed to have the largest population. Multiple age classes of ammocoetes (larvae), spawning adults, and eggs (dissected from gravid females) were collected near Turners Falls, Massachusetts and analyzed for total mercury. Whole body concentrations of total mercury in ammocoetes ranged 221-681 ng/g wet weight and increased with age and size. These are surprisingly high mercury concentrations for ammocoetes, as they are sedentary filter-feeders (i.e., occupy a low trophic level). Lamprey ammocoetes have previously been shown to be suitable biomonitors for mercury, and these concentrations likely reflect contamination of detritus and sediment in the Connecticut River. Whole body concentrations of total mercury in spawning adults had a dichotomous distribution; mean (± SE) concentrations of the two groups were 107 (± 20) and 582 (± 25) ng/g wet weight. Adult sea lamprey are parasitic, primarily feeding on the blood of marine fish. The variation in mercury concentration among adults indicates that sea lamprey parasitize fish at multiple trophic levels. Total mercury concentrations in eggs were low (range 29-72 ng/g wet weight) and positively related to concentrations in females. Total mercury body burdens increase with age in sea lamprey (r2 = 0.980, p < 0.001), with a large increase caused by the ontogenetic diet shift following transformation from ammocoete to adult. Sea lamprey greatly increase in size following transformation and accumulate more than 99% of their body burden of mercury as adults from marine sources. Adult sea lamprey die in lotic environments after spawning. The fate and ecological effects of mercury associated with sea lamprey carcasses are unknown.
Key words: sea lamprey, mercury, bioaccumulation