Bioremediation of organically enriched sediment deposited below fish farms with artificially mass-cultured colonies of a deposit-feeding polychaete Capitella sp. I

Abstract

For bioremediation of organically enriched sediment deposited below fish farms, the extremely high potential for population growth of a deposit-feeding polychaete, Capitella sp. I, in the organically enriched sediment, and the effect on decomposition of organic matter in the sediment, were examined. A mass-culturing technique was conducted for this species. Bioremediation experiments were conducted on the organically enriched sediment in a fish farm in Kusuura Bay, Japan in 2003-2006. Approximately 1.7 million individuals of the worms were placed on the sediment below one net pen in December 2003, 9.3 million individuals in November 2004, and 2.2 million individuals in November 2005. After the worms were spread on the sediment, they rapidly increased in number and reached the highest densities of approximately 134 000 inds/m 2 in February 2004, 527 000 inds/m 2 in March 2005 and 103 000 inds/m 2 in January 2006.In the process of rapid population growth, the decomposition of the organic matter of the sediment was enhanced markedly. Our results demonstrate that the promotion of population growth by spreading cultured colonies of Capitella can enhance the decomposition rate of organic matter markedly in organically enriched sediment below fish farms. This method is promising for minimization of the negative effects of fish farms.

Cosmopolitan or Cryptic Species? A Case Study ofCapitella teleta(Annelida: Capitellidae)

“…I sensu Grassle and Grassle (1976) from Massachusetts (USA) based on the karyotype, ability to interbreed, and lifehistory; this taxon has subsequently been reported from Japan in various ecological papers under the name Capitella sp. I (e.g., Tsutsumi, 2005;Tsutsumi et al, 2005a, b;Kinoshita et al, 2008) or C. teleta (Nishi et al, 2010;Kanaya, 2014;Kanaya et al, 2015). These records, together with reports from California and the Mediterranean , suggested that C. teleta is broadly distributed ( Fig.…”

Increase in Alphaproteobacteria in association with a polychaete, Capitella sp. I, in the organically enriched sediment

“…I on the sea floor in early November in 2004(Tsutsumi et al, 2005aKinoshita et al, 2008). The Capitella colonies increased rapidly in the cold seasons, and reached a peak density in March 2005 (528 000 individuals per m 2 ) and January 2006 (1 028 000 individuals per m 2 ) (Figure 1a).…”

“…Kusuura Bay is an enclosed bay (11.4 km 2 area, 4 Â 3.5 km 2 ), located between Amakusa Kamishima and Amakusa Shimoshima Islands in Kyushu, (Tsutsumi et al, 2005a;Kinoshita et al, 2008).…”

“…ORP of the sediment in each layer was determined with a platinum electrode (RM-20P, TOA DKK). TOC of sediment was determined following Kinoshita et al (2008). We calculated the TOC content of the surface and subsurface layers of the sediment, and expressed as TOC g m -2 , using the sediment density data.…”

“…I on the sea floor in autumn. In the bioremediation experiments, the introduced Capitella colonies increased explosively on the organically enriched sediment during the late autumn and winter, and the amount of sedimentary organic matter decreased significantly following the rapid population growth (Tsutsumi et al, 2005a;Kinoshita et al, 2008). Kunihiro et al (2008) found a significant positive correlation between Capitella biomass and the quinone content of the sediment as an indicator of the biomass of microorganisms (Saitou et al, 1999;Hiraishi et al, 2003), and a marked increase of ubiquinone-10 (UQ-10) among the quinones when dense patches of the worms were established in the organically enriched sediment.…”