Patterns of fish occupancy of artificial habitats in the eastern Mediterranean shallow littoral

Coastal ecosystems act as spawning grounds, settlement areas or nurseries for a diversity of fish species. Today, these ecosystems are under various anthropogenic stressors. One of these disturbances is the structural modification of the shallow littoral by coastal infrastructure such as ports, piers, marinas and roads. Here, we investigate whether there are differences between modified (artificial) and non-modified (natural) habitats in central Greece in terms of the fish assemblage structure, species diversity and richness, fish abundance and the proportion of juveniles. We carried out underwater visual census from September 2020 to August 2021 across two habitats (natural and artificial) in three locations of central Greece. The fish community and Shannon diversity index did not vary across habitat type; however, both species richness and total abundance were significantly higher in artificial habitats. The abundance of five (out of ten examined in total) taxa was significantly affected by habitat type. Higher abundance in the artificial habitat in the warmer or more productive months was found, possibly relevant to food availability. The significance of habitat interactions with location and the temporal component in community composition and species abundance models indicated intense heterogeneity in species-specific occupancy and may be linked to the type and characteristics of artificial habitats. Modeling of the percentage of small-sized individuals indicated patterns of juvenile occupancy requiring further investigation about the potential role of artificial habitats for some species. Future research should examine the impact of specific artificial habitat types on population dynamics and investigate the implications of artificial habitat construction for conserving fish diversity and maintaining coastal ecosystem functioning.

Automated summary

Coastal ecosystems play important roles in the life cycle of fish species, but they are facing various anthropogenic stressors, including the structural modification of littoral areas by coastal infrastructure. In a study conducted in central Greece, researchers compared modified (artificial) and non-modified (natural) habitats in terms of fish assemblage structure, species diversity, abundance, and the presence of juveniles. They found that while the fish community and diversity did not differ between habitat types, species richness and total abundance were higher in artificial habitats. The abundance of certain taxa was significantly affected by habitat type, and the presence of smaller individuals indicated potential importance of artificial habitats for juvenile occupancy. The findings highlight the need for further research on the impact of artificial habitat construction on fish population dynamics and the conservation of coastal ecosystems.