TEMPORAL TRENDS IN METAL LEVELS IN EGGS OF THE ENDANGERED ROSEATE TERN (STERNA-DOUGALLII) IN NEW-YORK

Female birds sequester certain organic and inorganic compounds in thei r eggs which have been widely used as a bioindicator for examining the body burdens of contaminants and therefore the temporal and spatial t rends of the contaminants in the environment. The same analyses can al so reflect the status or vulnerability of the indicator species. Exten sive bridge de-leading activities in the New York Eight (Cape May to M ontauk) in the early 1990s coincided with a long-term study of the end angered roseate tern (Sterna dougallii) on Long Island, New York, affo rding the opportunity to test the utility of such fish-eating species as bioindicators of lead contamination, as well as the potential impac t on the bird population itself. In this paper we test the null hypoth esis that there were no temporal trends between 1989 and 1994 in metal levels in eggs of roseate terns nesting at Cedar Beach, Long Island, where the birds have been declining since the late 1980s. We report le vels and trends for cadmium, chromium, manganese, mercury, and seleniu m as well as lead in abandoned eggs collected each year. There were si gnificant interyear differences for all metals, with 1990 to 1992 gene rally having higher levels than 1989 and 1994. The yearly differences were particularly prominent for lead, where the 10-fold increase may h ave been partially due to the increased removal of leaded paint from b ridges in the early 1990s, leading to increased lead in the aquatic en vironment. Cadmium and chromium are also released during de-leading. T he causes for the higher levels in the other metals in the early 1990s are unclear. Metal levels in roseate tern eggs are several times high er than the median reported for most birds, and the possible impact on the population requires study. (C) 1998 Academic Press.