Epibiota and attachment substrata of deep-water brachiopods from Antarctica and New Zealand

Abstract

Prevalence (proportion of host organisms covered) and cover of encrusting epibiota were investigated for four Antarctic and two New Zealand species of deep-sea brachiopods. All epibiota was identified to the lowest possible taxonomic level, such that prevalence and dominance of each taxon could be assessed on different brachiopod species. Punctae had no detectable influence on fouling, whereas valve architecture and ornamentation were probably a major influence. Prevalence and percent cover of epibiota were found to decrease with depth (from 50-600 m) in the Antarctic terebratulid Liothyrella uva . A maximum of 5 % epibiotic cover was recorded on the punctate terebratulids from beyond 160 m ( Liothyrella uva , Magellania fragilis and Magellania joubini from Antarctica and Neothyris lenticularis from New Zealand). Epibiotic cover significantly increased with valve area to over 40 % in the Antarctic inarticulate Neocrania lecointei and the New Zealand impunctate rynchonellid Notosaria nigricans . Bryozoans, foraminiferans and polychaetes were the most abundant colonizers, but there were also representatives present from seven other phyla. The epibiotic community structure of the terebratulids Liothyrella uva , Magellania joubini and Neothyris lenticularis , and the inarticulate Neocrania lecointei were broadly similar, suggesting a cosmopolitan nature to deep-sea brachiopod epibiota. The community on Magellania fragilis was notably different, in being almost entirely dominated by foraminiferans, but the reasons for this are unknown. Analyses of attachment substrata for the Antarctic terebratulid brachiopods indicated erect bryozoans were most commonly used, but that sponges, rocks and even echinoid spines were used. The substratum used by the majority of the New Zealand specimens was unknown, but this is possibly because N. lenticularis has been described as degenerating its attachment and becoming free-living with age.