Mar Environ Res. 2025 May 16;209:107225. doi: 10.1016/j.marenvres.2025.107225. Online ahead of print.
ABSTRACT
This study examined the effect of aquaculture on benthic macrophytes growing on coastal hard substrates across Greece. Stations were categorized into ‘near’ (60-80 m from fish farms), ‘far’ (more than 80 m), and ‘no farm’ (potential future aquaculture sites). Photographic samples were taken between July and September 2021, followed by analysis of macrophyte identification, diversity indices, and ecological assessments. Additionally, the composition of epiphytic microalgae on macrophytes was studied. The overall observation of macrophyte communities revealed a difference between “near” and “far”/”no farm” stations, and a possible shift of the algal communities driven by the aquacultures. Based on the EEI-c index, all – except one – stations, were found to be in a Good or High Ecological Status, in accordance with the provisions of the Water Framework Directive. However, diversity indices, such as the Shannon-Wiener index, provided more nuanced insights into biodiversity changes, revealing differences. For all indicators, but also for the composition of the biocommunities of macrophytes, the effect of the geographical area emerged as statistically significant, but it was not found to show interactions with the distance factor. The photographic sampling method used in the study is easy, economical, and non-destructive, allowing cost effective, long-term monitoring, while improvement actions for the better application for the calculation of EEI-c were suggested. Regarding epiphytic microalgae, the analysis revealed no statistically significant differences between “near”/”far” sites, but no definitive conclusion can be drawn on the impact of aquaculture, as nutrient availability, especially the N:P ratio, exerts a stronger influence on community composition. This study highlights the importance of combining multiple ecological tools and indices to gain a comprehensive understanding of aquaculture’s impact on coastal ecosystems, as reliance on a single indicator may lead to misleading conclusions.
PMID:40398006 | DOI:10.1016/j.marenvres.2025.107225
