Abstract
Abstract: We examined the short-term impact of Capitella sp. I on the bacterial abundance and the chemical characteristics in organically-enriched sediment in the laboratory microcosms after three days of incubation. The vertical profiles of the number of aerobic and anaerobic bacteria and ATP content of the sediment in the microcosms indicate that the presence of Capitella sp. I in the sediment markedly enhances the bacterial growth and metabolic activities in the sediment, particularly at relatively shallow subsurface sediment(0.5-2.0cm in depth). The chemical characteristics of the sediment including organic matter content(TOC and TN)and AVS content indicate that the degradation of organic matter and oxidation of the sediment are promoted in the presence of the worms, particularly at relatively deep subsurface sediment(2.5-3.0cm in depth). These differences in vertical profiles of bacterial abundance and organic matter content appear to be ascribable to feeding and defecating activities of the worms. The worms mainly feed the sediment at relatively deep subsurface(2-3cm in depth), decompose the organic matter there and stimulate bacterial growth and activities in relatively shallow subsurface sediment.
