The impact of aquaculture on the marine environment is known for causing organic enrichment and eutrophication. Aquaculture monitoring in Cyprus (Eastern Mediterranean) has been consistently conducted since 2010, using annual sampling. The locations of the monitored fish farms have remained largely unchanged. As a result, the time series dataset created is optimal for long-term monitoring studies of aquaculture effects and the aim of the study is to assess these effects in the coastal zone of Cyprus and evaluate the efficacy of the current monitoring plan.
During 2010-2021, sediment samples were collected from 8 fish farms in accordance to the Cypriot National Environmental Monitoring Protocol. Two different monitoring companies were responsible for the monitoring process with different fish farms assigned to each company each year. Sampling was done at increasing distances from fish cages (0m, 50m, 200m, 500m, and a reference station), with three replicates per station, totaling 1244 samples. The macrofaunal community identified at the species level was used for Ecological Quality Status (EcoQs) assessment based on different benthic biotic indices (i.e. BENTIX, AMBI and others). Environmental data measured included depth, sediment type, organic matter content, sediment phosphorus levels, and water column nutrients, and Chlorophyll-a.
The results revealed that the factor related to the company in charge of the analysis of samples (codenamed “Prepared by”), was the most influential factor in explaining the variation of the macrofaunal community. Other significant factors included sediment type, depth and distance from the fish farm.
Despite this company-related variation in macrofaunal community attributed to differences in sample analysis, the ecological status assessment remained consistent between the two companies, as indicated by the levels of agreement (Kappa values) in the EcoQs observed between each benthic index. Notably, the BQI-Family index aligns closely with BENTIX, the current index utilized by WFD (Water Frame Directive) in Cyprus. The majority of EcoQs of the fish farms was Good, and did not deteriorate over the years, despite variability in benthic species composition. The national aquaculture legislative framework in relation to the operation of open sea aquaculture farms and the environmental monitoring programme of the Republic of Cyprus that is being implemented, seems to be an effective tool in preventing ecosystem degradation