Beaches are dynamic transitional environments subject to numerous natural and anthropic alterations. In these ecosystems, the infralittoral-sublittoral macrofauna communities play a key role in the food web. The objective of this study was to compare macrofauna communities on six beaches on the Gulf of Cádiz coast, which were classified according to the anthropic alterations they support, and evaluate the influence of abiotic factors on the species distribution. Sampling was done in the infralittoral-sublittoral zone of each beach using a modified manual dredge. Five perpendicular transects of 25 m, each separated by 10 m, were performed per beach, with a total sample area of 43.75 m2 per beach. A total of 27 species were found, of which Donax trunculus, Diogenes pugilator, and Tritia grana were the most abundant. Anthropogenic effects are appreciable in the infralittoral-sublittoral although they are areas that are permanently submerged and less exposed than the intertidal. Beach nourishments carried out with large volumes of sand can alter the grain size, the most influential parameter on the distribution of the species, and consequently, affect the macrofauna community that inhabits these beaches.
Keywords: Grain size; Gulf of Cádiz; Human impact; Macroinfauna community; Manual dredge; Nourishment; Sandy beaches; Urbanization.
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