Population dynamics of Capitella capitata (Polychaeta; Capitellidae) in an organically polluted cove

Abstract

The population dynamics of a sibling species of CapiteUa capitata (Fabricius) in a cove organically polluted by fish farrn~ng were characterized by early recolonizahon m azoic areas, very rapid population growth, and extinction following development of extremely anaerobic conditions during summer. The remarkably high potential for population growth results from the short life cycle and continual reproduction as a population. Previously, the production of planktonic larvae with the ability to disperse over a wide area was considered one of the most important life history characteristics of opportunistic polychaetes in unpredictable habitats. In the present study, however, Capitella sp. exhibited opportunistic population dynamics during benthic recovery after defaunation in heavily polluted areas, despite production of a small number of large eggs with restricted dispersal ability via lecithotrophic larvae. The size cornposibon of the recolonizing population suggested that some of the worms were recruited as mature adults from a very small population maintalned in the immediate vicinity of the sampling station in an environment disturbed by organic pollution. Although the populahon dynamics of Capitella sp. appear to be characteristic of highly opportunisbc organisms, results suggest that populations may be maintained within each habitat by reliance only on a remarkably large potential for population growth. In general, organically polluted areas may not be temporary habitats that Capitella sp. can utilize only during benthic recovery immediately after defaunation, but rather such areas may be their native habitats.