Validity of acid volatile sulfide as environmental index and experiment for fixing its standard value in aquaculture farms along the coast of Wakayama Prefecture, Japan

Abstract

  This study examined the validity of acid volatile sulfide (AVS) content in sediment as an environmental index in aquaculture farms and conducted an experiment for fixing its standard value.
   AVS in the sediment in summer reflects organic loads, and is closely relatied to communities of macrobenthos that are well known as an environmental index reflected the history of organic loads. An experiment showed that AVS is valid as an index for evaluating the environment of aquaculture farms.
   According to the results of analyzing the relationships between two parameters in the sediment (total organic carbon (TOC) and AVS) and biomass of macrobenthos, the environment of aquaculture farms can be classified into four types. AVS concentration below 0.22 mg g^-1 is considered to be ‘the healthy area’ in which the macrobenthos biomass increases with increase of TOC. ‘The eutrophicating area’ and ‘the warning area’ are AVS of 0.22-0.43, 0.43-0.71 mg g^-1, respectively. In former AVS concentrations, the decrease of biomass progresses with increase of TOC, while the latter AVS concentrations have poor macrobenthos communities. AVS concentration exceeding 0.71 mg g^-1 is the azoic condition called ‘the critical area’.