Benthic monitoring of macrofaunal communities is a fundamental tool for understanding and mitigating the repercussions of aquaculture in coastal environments. In the Eastern Mediterranean Sea, adhering to the Pearson & Rosenberg model of macrofaunal succession in response to organic enrichment, several benthic indices are employed for monitoring within the European Water Framework Directive (WFD) framework. One such index is the BQI-Family, which offers a cost-effective, taxonomically sufficient approach with Ecological Quality boundaries fine-tuned for the Eastern Mediterranean region. The assessment of the ecological status in Greek aquaculture via the BQI-Family index can serve as a measure for the extent of organic enrichment and the aquaculture’s impact on the surrounding ecosystems. Nevertheless, the magnitude of this impact is subject to various factors, including the geographical placement and depth of the fish farming site, the type of the habitat and substrate, and spatial planning aspects of the fish farm, such as the arrangement of cage structure, etc. The cumulative influence of these parameters can lead to fluctuations in the composition of macrobenthic communities, thereby potentially influencing the outcomes of ecological status evaluation.
Under this concept, benthic macrofaunal samples collected from multiple fish farming sites across Greece during the years of 2020 to 2023, were analyzed. These sampling efforts were conducted at a distance of 50 meters from the fish farm cages, adhering to the maximum Allowable Zone of Effect (AZE) as commonly stipulated by Mediterranean regulatory practices. Sampling was carried out using a Van Veen grab with a surface area of 0.1m2. Subsequently, the collected samples were sieved using a 1mm sieve, followed by fixation in 4% formalin. Taxonomic analysis was performed at the family level. In addition to the biological samples, various environmental parameters were measured including sampling depth, Secchi depth, substrate type and geochemical parameters. Furthermore, data on habitat type, fish farm structure and distance from shore were recorded. To evaluate the ecological status of each fish farm, the BQI-Family index was calculated and the ecological status of each farm was determined. Subsequently, a comparative analysis of relative ecological status classifications was conducted. This comparison aimed at identifying the optimal set of parameters explaining the observed variation in the ecological assessment.