Utilization of black-tailed gull (Larus crassirostris) eggs for monitoring of mercury levels in coastal areas of South Korea: Preliminary study

摘要

Studies on the monitoring of mercury accumulation using high trophic-level predators of the marine ecosystem have been scarce in South Korea. In this study, we compared the mercury concentrations of the eggs of the black-tailed gulls, a higher-order predator, breeding in two coastal areas. Breeding sites with varying mercury concentrations in land-origin freshwater fish and freshwater and marine sediments were selected in the southeastern (Hongdo Island) and western (Baengnyeongdo Island) seas. The 5-year mean total mercury concentration in eggs collected during the breeding seasons from 2012 to 2016 was higher in those collected from Hongdo than in those collected from Baengnyeongdo. This difference in mercury concentration in eggs was observed for each year. In addition, the total mercury concentration in eggs was consistently higher on Hongdo, which also had higher mercury pollution, than on Baengnyeongdo Island. These results support the suitability of black-tailed gull eggs for monitoring of mercury pollution.