One of the many threats faced by loggerhead sea turtles - an annual visitor to New Jersey's  coast - is man-made pollution, but the extent of the risk is a question. To begin to look for the answer scientists have measured contaminants in the blood of a group of adult male turtles and tracked their migration along the Atlantic Coast.

The group captured 19 loggerheads near Cape Canaveral, Fla., in 2006 and 2007. Group  members measured and weighed the turtles, took blood samples, and examined their reproductive systems with testicular biopsies. Then they fitted them with satellite transmitters and released them.