Visually-based alternatives to sediment environmental monitoring

Visually-based approaches using techniques such as sediment surface images as well as sediment profile imaging (SPI) have been applied previously in the assessment of benthic impacts of organic enrichment. New visually-based benthic health indices (VBH and Surface Index) that integrate various visual properties was developed for muddy and sandier sediments, respectively. Visual indices were compared to the existing sulfide-based thresholds often used in environmental monitoring programs (EMPs). We utilized both techniques as well as geochemical indicators of eutrophication to detect benthic impacts at shallow shellfish and finfish farms in Nova Scotia, Canada. The visual indices were able to capture a non-sulfidic anaerobic condition in the sediments missed by the current sulfide-based system. Our results indicate that as presently configured, the visual based index will provide a more stringent standard in the EMPs that currently rely on a sulfide-based classification system, and thus affect regulatory judgement.