Ascidian-associated polychaetes: ecological implications of aggregation size and tube-building chaetopterids on assemblage structure in the Southeastern Pacific Ocean

摘要: Epifaunal polychaetes inhabit a range of habitat structures built by other organisms, such as ascidians. Here, we examine: i) the polychaete fauna inhabiting aggregations ascidian Pyura chilensis in central Chile; ii) rela- tionship between sample volume (aggregation size) and poly- chaete assemblage variables; iii) effect tube- building chaetopterid on structure. The tube load determines two morphotypes, those with high tubes (HT morphotype) low (LT morphotype). From total 38 ag- gregationsstudied,wefound5,524specimensbelongingto35 species polychaetes. Three were most abundant (Phyllochaetopterus socialis, Nicolea lobulata ,a ndTyposyllis magdalena), reaching 22% abundance. number individuals increased volume, but only varied morphotypes. Sample influenced structure, evidencing differences We suggest that both structuring capacityof chaetopteridtubes changethe complex- ity and, hence, produce differ- ences morphotypes related to assem- blage