Impact of an oceanic port (Sines, Portugal) on the fish community

Abstract

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Following the development of economic globalization, oceanic ports became important cores of economic activity and, therefore, potential sources of diffuse and chronic impacts on coastal ecosystems. Monitoring biological communities is a very important tool to assess these impacts. In a multi-environment monitoring programme of the oceanic port of Sines running for several years, the rocky subtidal macrobenthic community has been studied, including the fish community. Patterns of spatial and temporal variation of the diversity and structure of the fish community were studied in the summer of 2014 (two random dates sampled) sampling six areas in the port (three sheltered and three exposed) and two areas outside the port. The total number of taxa and the density of each observed taxon were quantified through visual censuses in belt transects by scuba diving. Data were analysed with univariate and multivariate techniques. Substrate physical features (bottom complexity and type) were sampled in the same transects. Outside areas were significantly different from the port areas. These differences were due to a lower number of taxa in the outside areas and, generally, to a greater abundance of several taxa in the port areas, such as some species with commercial value (e.g. seabreams Diplodus spp.). These results suggest that this port may provide favorable conditions for the occurrence of a greater fish diversity and abundance than outside areas, particularly for some species that live in subtidal rocky substrates. Recreational and commercial fishing interdiction, in place in most areas of this port for several years, may be responsible for these patterns.

Keywords

• Monitoring
• SCUBA diving
• SINEs
• Fish community
• Oceanic port