Zonación y estructura de la comunidad macrofaunística en playas de arena del Sur de Chile (Mehuín, Valdivia)

Abstract

Two beaches of Mehuin (Valdivia) were studied to determine the zonation and structure of the macrofaunistic community in sandy beaches of Southern Chile. Some variability was present between the species composition of the 2 beaches studied. A general scheme for the zonation of the beaches at Mehuin was proposed. The upper level of the midlittoral zone is occupied by talitrid amphipods (Orchestoidea tuberculata) and cirolanid isopods (Excirolana braziliensis). The intermediate level by cirolanids (E. braziliensis, E. hirsuticauda and E. monodi), the inferior level by anomuran decapods (Emerita analoga), polychaetes (Nephtys impressa) and bivales (Mesodesma donacium) and the upper level of the infralittoral zone by idotheid isopods (Chaetilia paucidens, Macrochiridothea mehuinensis, M. setifer and M. aff. lilianae), haustorid amphipods (2 spp.), anomuran decapods (Lepidopa chilensis and Blepharipoda spinimana) and brachyuran decapods (Bellia picta), further of E. analoga, N. impressa and M. donacium. These results were discussed and compared with some of the zonation schemes previously proposed. Of all the specimens captured the crustacea are the numerically dominant group and among these the peracrids are the most represented taxa. The possible causes for the macrofauna distribution on the beaches at Mehuin, along with the density values and diversity indexes calculated for each site, were discussed.