A revised classification system describing the ecological quality status of organically enriched marine sediments...

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.