Polychaete assemblages associated with the invasive green alga Avrainvillea amadelpha and surrounding bare sediment patches in Hawaii

Abstract

Magalhães, W.F. and Bailey-Brock, J.H. 2014. Polychaete assemblages associated with the invasive green alga Avrainvillea amadelpha and surrounding bare sediment patches in Hawaii. Memoirs of Museum Victoria 71: 161–168. Avrainvillea amadelpha is one of the most widespread invasive green algae on Hawaii's reefs, but virtually nothing is known about its associated fauna. A total of 16 sampling stations were selected: ten stations were distributed in areas where the invasive alga occurred abundantly ('A' stations) and six stations were placed on bare sand patches ('S' stations). Three replicates of ~475 cm³ each were collected in March 2010 at each station, by hand, using a nalgene corer (11 cm in diameter by 5 cm deep). Based on the comparison between Avrainvillea amadelpha-dominated bottoms and the surrounding bare sediment patches, our study demonstrates that these habitats support a diverse and abundant polychaete assemblage, with 2621 individuals and 84 species collected. The species Sphaerosyllis densopapillata (34.14%), Phyllochaetopterus verrilli (8.32%), Protocirrineris mascaratus (5.9%), Exogone longicornis (4.9%) and Syllis cornuta (4.47%) are the dominant taxa. The non-metric multidimensional scaling clearly separated the 'A' stations from the 'S' stations. ANOSIM has shown that stations within the a priori-defined group 'A' are significantly dissimilar from the stations in the group 'S' (R = 0.527; P = 0.1%). SIMPER analysis has confirmed the slight but greater dissimilarity between algae and sediment stations (average dissimilarity = 60.12) than within either algae (52.27) or sediment stations (52.04). The invasive green alga A. amadelpha facilitates the development of above-ground polychaete communities, but the negative effects of this invader on the infaunal communities should be further investigated.