Influence of port breakwaters on surrounding polychaete fauna

Harbours represent unique, complex and vulnerable environments from many points of view. Macrobenthic communities are important components of the harbour biota and polychaetes are the assemblage that best represents their state of well-being and can be used as indicators of environmental quality. The structure of the macrobenthic community and of the population of polychaete annelids that characterize the softbottom habitats of two ports of the Comunidad Valenciana (port of Sagunto, port of Calpe) was analysed and compared to verify the existence of a relationship between the variation in the species composition of the populations of polychaetes and the variation in the abiotic variables (granulometric classes of fine and medium sands, mud and the content of organic matter) in force in the two environments and at the two depths (2-3 m and 8-9 m). Sampling took place on 19 May in Sagunto and 20 May 2021 in Calpe and 24 replicates were obtained for each site: 12 for each depth interval (6 were necessary for the taxonomic study and 6 for the others analysis). The analysis of the polychaete fauna carried out in the sediment samples of the port of Sagunto made it possible to identify 303 individuals distributed in 76 taxa among 26 families, while those carried out for the port of Calpe allowed to identify 221 individuals distributed in 52 taxa between 17 families. The communities of the two ports differ in terms of abundance of individuals, species composition and presence / absence of Phyla Plantae, Sipuncula, Bryozoa, Chordata. All the abiotic variables above together with the depth had influenced the structure of the communities and polychaete assemblages, as demonstrated by the correlation existing between them. These last were characterized by low specific richness, diversity and a majority of species with low abundances that can be attributed to anthropogenic stress, especially pollution and / or other environmental stress factors, which act synergistically or not.