POTENTIAL ROLE OF MICROPREDATORS IN DETERMINING RECRUITMENT INTO A MARINE COMMUNITY

Recruitment rates of marine benthic invertebrates are a function of the number of planktonic larvae settling onto the bottom and mortality among the earliest post-settlement life-stages. Unfortunately, rates of mortality are seldom measured for the time between settlement and recruitment and little is known about the importance of such mortality, its causes, or how it compares to other processes affecting recruitment. In our investigations of a New England, USA, marine community, we found significant predation exclusively on the earliest life-stages of several dominant species. The predators were 2 species of tiny gastropods, Mitrella lunata and Anachis avara. They preyed selectively on newly-settled colonial ascidians, greatly lowering or eliminating recruitment of these species. This brief predation on early life-stages enabled other species to replace the competitively superior ascidians within the developing community.