The Effect of Nereis virens on the Densities of Other Infaunal Species at Federal Harbor, Maine

Abstract

To test the hypothesis that an increase in the density of Nereis virens would result in a corresponding decrease in the densities of other infaunal species, a transplant experiment in which N. virens density was manipulated was carried out at Federal Harbor, Maine. Instead of the anticipated decrease in the density of other infaunal species, a statistically significant increase in infaunal densities occurred. The spionids (primarily Streblospio benedicti), tubificid oligochaetes, and capitellids, which together made up 95% of the total individuals in the community, showed dramatic increases in the N. virens addition treatments. Possible mechanisms for this observation were considered; it was concluded that no single mechanism was responsible for the enhancement effect. A complex interaction hypothesis was proposed in which sediment disturbance by N. virens and the effects of the intermediate predator Nephtys incisa played a major role in the increase of infaunal densities.