MACROFAUNA ASSOCIATED WITH PHYLLOCHAETOPTERUS SOCIALIS AGGREGATIONS IN THE SOUTHWESTERN ATLANTIC
Obenat, S.1; Ferrero, L.2 & Spivak, E.1
1Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata Funes 3250, 7600 Mar del Plata, Argentina
2Centro de Geología de Costas y el Cuaternario, Argentina
The aggregations of polychaete tubes, mainly Serpulidae and Sabellidae, are frequently cited as the habitat of complex and diverse benthic communities. Phyllochaetopterus socialis (Chaetopteridae) is a small worm that build horny tubes often aggregated into branched "colonies". It has been collected in both sides of Northern and Southern Atlantic, the Mediterranean Sea and the Indic Ocean. Aggregates of Phyllochaetopterus socialis have been found near the Rio de la Plata mouth (35° 23' - 35° 31' S; 55° 36' W - 55° 48' W) in November 1997. The depth of the sandy bottom was 11-12 m and the salinity of the water was 26-30‰. Each aggregate (ca. 20 cm diameter) arose from a shell or another small hard object. The main goal of this communication is to characterize the aggregates (size, form, number of tubes and branching pattern) and to identify the invertebrates that live in or on them. Several sessile species (serpulid polychaetes, thoracic cirripedia, bryozoa and ascidiae) grow on the tubes. On the other hand, various polychaete species, anomuran and brachyuran decapod crustaceans and ophiuroidea find refuge in the spaces between tubes.