Abstract
Coastal fishes are not only valuable elements of marine biodiversity, but they also play an important ecological role in the functioning of coastal ecosystems: food resource, transfer of nutrients, predators. Therefore, data on the compositions of fish assemblages are of great importance. The objectives of the present study were to (i) define the faunistic characteristics of a typical fish community on the Mediterranean coast; (ii) investigate spatiotemporal changes in fish assemblages. Based on a set of indices (Fast protocol) and a long-term data set (6 years, 612 visual counts, 154 h of diving), changes in coastal fish communities were analyzed. Our results indicated that there was a significant shift in fish community structure, with a general decline of the calculated indices. In our study, part of the observed variability in fish assemblage structure could be due to different factors as site location and sampled year. The changes in the fish assemblages associated with inter-annual fluctuations observed in this study also provide important insights into how fish communities may change under environmental and anthropogenic influences.
Highlights
The PERMANOVA tests on the four indices (MI, Relative Species Richness (RSR), carnivores’ proportion (CP), Large Proportion (LP)) revealed that there were significant differences between zones and years (p-value = 0.001, for all, Table 2)
We found no significant correlation between bottom seawater temperature and the values of RSR, LP, CP, and mean index (MI) (Spearman test, p 0.05)
The Fish Assemblage Sampling Technique (FAST) indices showed spatial and temporal variations, with significant interannual variations but no seasonal changes
Summary
Changes in faunal assemblages have been observed; these changes can be explained by environmental factors (temperature, salinity, pH) and anthropogenic stressors, such as fishing (removal of key predators and pastures) [2], pollution [3], invasive species [4], and/or climate change [5]. These drivers can impact marine communities at different levels, from individual physiology and population-level changes (altering growth, reproductive capacity, and mortality) to community and ecosystem shifts (modifying productivity, structure, and composition) [6]
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