This chapter describes data on natural history and metal levels in a range of species that contribute to the food web for coastal birds. Horseshoe Crabs can be bioindicators because they serve a pivotal role in coastal bays and estuaries where they spawn. Horseshoe Crabs are obviously an important part of food webs for many coastal bays and estuaries—eggs for birds and other predators, juveniles for fish, and adults for sea turtles, other marine predators, and people. The life cycles and natural history of fish differ among species, but coastal and estuarine habitats are extremely important as nurseries for both shellfish and finfish. Many ocean fish are estuarine dependent, moving into estuaries and streams to breed.