A revised classification system describing the ecological quality status of organically enriched marine sediments based on total dissolved sulfides

Abstract

A field study is presented that provides an alternative method and system for classifying the ecological quality status (EQS) of organically enriched marine sediments based on total free sulfide concentrations (S^2-). Sediments collected adjacent to coastal aquaculture activities across a broad biogeographic range were analysed using three S^2- methods. S^2- is a product of organic matter mineralization and is a major cause of benthic community impacts from excess organic enrichment. The results confirm that the ion-selective electrode protocol that is widely used in monitoring programs to classify benthic impacts provides unreliable data and site classifications. An EQS classification system is presented that employs S^2- data measured rapidly and simply in the field by direct ultraviolet spectrophotometry. Interrelations between S^2- concentrations and several benthic macrofauna community health metrics were employed to develop the EQS system. These relationships were consistent regardless of organic matter source, geographic region or sediment grain size.

Keywords: Aquaculture; Benthic macrofauna; Biodiversity; Ecological quality status; Eutrophication; Free sulfide; Impact assessment; Toxicity.