Relationship between growth of Capitella sp. and organic enrichment of the sediment

Abstract

Laboratory colonies of Capitella sp., which 1s found densely distributed in organically enriched or polluted areas, were cultured in sediments with various levels of organic matter to examine the relationship between level of sediment organic matter and growth of individuals. Growth was independent of absolute levels of sediment organic matter, but was significantly correlated with increases in the level of sediment organic matter on addition of algal powder to the sediment. These results indicate that Capitella species predominating in organically enriched areas have a physiological requirement for organic materials discharged from sources of organic enrichment, e.g, abundant growth of algae, fish farming, industrial effluent, sewage, if they are to grow normally. Although associat~on of some Capitella species with sediment organic enrichment has been previously recognized as a reflection of their opportunistic characteristics, a physiological requirement for organic materials discharged from sources of organic enrichment may be the single factor most responsible for the concentration of CapiteNa species in organically enriched areas. However, it is unlikely that they can directly ingest and assimilate such organic materials. Since the additional organic materials are easily decomposed in the sediment, Capitella species may require either (1) some specific microorganisms, the levels of which increase with levels of the organic materials, or (2) certain substance(s) produced during decomposition of the organic materials.