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(P692) Monitoring Amphibian Reproductive Success at a PCB-Contaminated Site Using Fluorescent Pigments.
Lortie, John*,1, Thompson, Michael1, Roy, Robert1, Svirsky, Susan2, 1 Woodlot Alternatives, Inc., Topsham, Maine, USA2 US Environmental Protection Agency, Boston, Massachusetts, USA
ABSTRACT- Amphibian use and reproductive success were assessed in four vernal pools with varying levels of sediment polychlorinated biphenyl (PCB) concentrations in the Housatonic River floodplain, Pittsfield and Lenox, Massachusetts. This study was performed in conjunction with a laboratory study investigating the same endpoints in a controlled environment. One pool with low (1.1 mg/kg dw), one with medium (11.0 mg/kg dw), and two with high (27.4 & 62.1 mg/kg dw) sediment PCB concentrations were surrounded with drift fencing and pit traps from 31 March 1999 to 15 July 1999. All amphibians caught entering or exiting the pools were identified, counted, aged, sexed, and measured. A sample of wood frogs (an obligate vernal pool-breeding species with large breeding population sizes) and all spotted salamanders (an obligate species with small breeding population sizes) were individually marked in a combination of colors and locations by injecting them with fluorescent elastomer pigments, a relatively new technique for marking animals. Egg mass counts, 10-day early development observations, bi-weekly larval collection samples, and metamorph collection and counts were also conducted to fully investigate the reproductive output of the two target species. No definitive correlations between any of these assessment endpoints and sediment-PCB concentrations were observed. Possible factors for the lack of observed effects data include insensitive measurement endpoints, inability to detect microscopic deformities in the field, potentially affected larvae died and thus could not be captured, natural variation in reproductive success, immigration from nearby populations, and effects of other unknown habitat variables. The technique of using fluorescent elastomer pigment injections to individually mark and identify large numbers of adult breeding amphibians worked well for spotted salamanders, a species with firm skin and thick body wall muscles, but poorly for wood frogs due to very thin body wall muscles and loose skin. This technique should be modified and more fully tested for use with wood frogs.
Key words: amphibians, reproductive-success, PCBs, Housatonic
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