Reproduction of the Bloodworm (Glycera dibranchiata) in the Sheepscot Estuary, Maine

Abstract

The population of bloodworms (Glycera dibranchiata) at Wiscasset, Maine, is composed of five assumed year-classes. Most spawners are probably large 3- and 4-year-old bloodworms. At Wiscasset eggs are released into the coelom at a size of 21 μ. The rate of egg growth varies with season. In June 1–10 million eggs are spawned at a diameter of 151–160 μ. A bottom temperature in excess of 13 C seems necessary for spawning to occur. Spawning occurs in the afternoon, between 2 hr before and 1 hr after high water. Males emit streams of sperm while swimming at the surface; females swim rapidly at the surface and suddenly rupture, liberating all the eggs at once. Females are slightly more abundant than males in the flats. Spawning bloodworms are preyed upon by herring gulls (Larus argentatus) and striped bass (Morone saxatilus), while spent epitokes are consumed by the mud shrimp (Crangon septemspinosus), which in turn is eaten by striped bass.