Epibiosis on Brachiopods from Patagonia, Argentina (40°–55°S): Composition, Spatial Variation, and Preservation

Abstract

Epibiosis is the association between two or more living organisms belonging to the same or different species as a result of surface limitation. Besides the ecological significance , epibiosis is of interest in paleoecological studies of both recent and fossil organisms . Brachiopods provide an ideal biogenic substrate for studying paleoecological questions relating to encrusting biotas . The aim of this preliminary study is to describe brachiopods and their epibionts in living/recent/Holocene shelled assemblages located along the Argentine coast between 40° and 55°S, at different depths. Representative brachiopod samples were collected. Living/recent samples were grouped into latitudinal areas to characterize organisms of high latitude (55°S approx.) and mid-latitude (40°S approx.), and benthic and coastal , depending on the bathymetric location where they were sampled. Six epibiont taxa were found on the living/recent valves of M. venosa and T. dorsata . The most frequent and abundant epibionts on both species were bryozoans and algae . Additional organisms such as polychaetea , barnacles , brachiopods , and molluscs were found. Benthic samples from high latitudes showed a higher overall rate of occurrence of epibionts . This difference is possibly determined by the bryozoans , which have the highest percentage of occurrence in this area and are usually predominant in these environments. The epibiont algae were found in greater amounts in the mid-latitude coastal samples. The absence of encrusting biotas on the Holocene shells of this study is attributed to the fact that many of these individuals are young and small. From this preliminary study, we intend to continue and deepen the analysis to assess potential ecological patterns and contribute to the knowledge of the epibionts and encrusting communities of Patagonian Quaternary brachiopods .