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Pollutant Concentrations in Abnormal Young Terns from Long Island Sound

1972; Oxford University Press; Volume: 89; Issue: 1 Linguagem: Inglês

10.2307/4084057

1938-4254

Helen Hays, Robert W. Risebrough,

Marine and coastal ecosystems

TH•S paper reports the results of preliminary analyses for chlorinated hydrocarbons and mercury in young terns with visible abnormalities fo.und in a colony on Great Gull Island, 72 ø 07' W, 41 ø 12' N. Analyses are also reported on eight species of fish brought to the colony as food for the young or as part of behavioral displays. Great GullIsland lies at the eastern end of Long Island Sound about 170 km east ooe New York City and almost 16 km east-northeast ooe the eastern tip.o.fLong Island.In the late 19th century the island supported a large colony of Common Terns, Sterna hirundo, and Roseate Terns, Sterna dougallii, until a military fort built there in 1895 displaced them.When the U.S. Army abandoned the island in the late 1940s, many ooe the tern breeding grounds in Long Island Sound and along the Connecticut shore had either been destroyed by real estate encroachment or were permanently disturbed by improved transportation and the development of recreational facilities in the metropolitan area.Aware ooe the island's history as the site of a large tern colony, the American Museum of Natural History and the Linnaean Society of New York cooperated to.acquire the island hoping that terns might once again nest HAYS AND RISEBROUGlt [Auk, Vol.89 MATERIALS ANI) METYIODS In 1966 a grid was set up dividing Great Gull Island, which has an area of 17 acres, into quadrats 25 X 25 m square.For the production study undertaken in 1969 and 1970, all nests were located and recorded by quadrat; this helped finding the nests as they were rechecked.Both years daily checks were made from the time the first egg in the first nest was found until the last young in a sample of 1,500 nests had been ringed on a leg with a plastic band.Each nest was marked with a numbered wooden stick (commercial tongue depressor) placed in the ground beside it, and the nest number, location, and number of eggs were recorded.The eggs in each clutch were marked when found with a dri-mark pen to permit following the development of each egg.Both Roseate and Common Terns lay small clutches varying in size from one to four eggs that hatch, as a rule, 20-28 days after they are laid.Eggs are normally laid at the rate of one per day, but as a day or two may be skipped between eggs occasionally, each clutch was checked for 7 days to insure that it was complete.In order to band the young terns as they hatched, a recheck date of 20 days after the laying of the first egg was assigned each nest.In both years over 1,500 nests were marked in this fashion before the young terns began hatching.Upon hatching each young tern was given a numbered plastic band.Individuals of the same clutch were given the same number, but different colors.Birds from 1-egg clutches received purple bands, birds from 2-egg clutches yellow and green, and those from 3-egg clutches red, white, and blue respectively.Intensive nest checks for newly hatched terns were carried out daily during both years from the time the first young hatched during the first 10 days in June until 4 July in 1969 and until 19 July in 1970 when more people were able to participate later in the season.Checks were continued at less regular intervals both years until the middle of August when the last young on the island hatched.During the final phase of the study, the numbered plastic bands were removed and replaced with a unique combination of three color bands and the aluminum U.S. Fish and Wildlife Service band, so that individual birds could be recognized and followed.On all checks of the colony dead young were picked up and their numbers recorded.Abnormal young terns were either frozen or preserved in 10 percent formalin.In 1970 all fish found on the ground in the colony were collected and preserved in 10 percent formalin.Both the abnormal young and the fish samples were analyzed for total mercury, DDT, and PCB compounds using the following techniques: For determination of total mercury, a portion of the left lobe of the liver was removed and sent to Gulf General Atomic, San Diego, California, for analysis by neutron activation, according to the following procedure as described by the company."Weighed portions of each sample were sealed in vials and irradiated at a flux of 10 •2 thermal neutrons per cm2-per second together with a mercury comparator standard.The irradiated samples were digested, in the presence of mercury carrier, in a mixture of HNOa and H•SO• under reflux conditions.Multi-channel gamma ray spectrometry was used to identify and quantirate mercury."DDT and PCB compounds were measured by methods previously described (Risebrough et al., 1970).The composition of the PCB compounds in both the terns and the fish closely resembled that of Aroclor 1254 (Monsanto Chemical Company, St. Louis, Missouri).PCB was therefore quantified as Aroclor 1254 using the peak with retention time 1.33 relative to p,p•-DDE on a QF-1 column as a standard (Peak 8, Ahling and