The biology of Capitella capitata (Fabricius) and a review of the genus Capitella Blainville

Abstract

The thesis is concerned with the biology of Capitella capitata in British waters and the validity of the genus Capitella throughout the world.

Material from Europe, America and Australia has been examined and an extensive review of the literature on the taxonomy of Capitella has been made. As a result the generic description has been modified to include the genus Capitellides.

The description of C. capitata has been widened to account for variations between populations and the subspecies C. capitata ovincola and C. capitata tripartita have been elevated to specific level.

An ecological study of some British populations has been made and it is shown that while C. capitata will occur under a wide range of conditions, it is predominant where other polychaetes are less common.

The life history has been investigated and it has been shown to reproduce in Britain throughout the year. Two larval types have been found.The effects of various ecological factors have been studied in the laboratory. Both adults and larvae were found to be resistant to conditions of low salinity and, especially, low oxygen tension.

The species is, however, very sensitive to increases in temperature.

The feeding biology has been studied and an estimate of the available organic content in the substrate made.

The relationship of the species to polluted conditions is discussed. In conclusion it is noted that C. capitata owes its worldwide distribution to its adaptability allowing it to penetrate a variety of habitats. This same lack of specialisation, however, makes it unsuccessful as a competitor with species more narrowly adapted to particular sets of environmental conditions.