The composition and density of fauna utilizing burrow microhabitats created by a non-native burrowing crustacean (Sphaeroma quoianum)

Abstract

The non-native isopod, Sphaeroma quoianum, has invaded many estuaries of the Pacific coast of North America. It creates extensive burrow microhabitats in intertidal and subtidal substrata that provide habitat for estuarine organisms. We sampled burrows to determine the effects of substratum type on the community of inquilines (burrow inhabitants). The density of inquilines was higher in wood and sandstone than marsh banks. Inquilines, representing 58 species from seven phyla, were present in 86% of samples. Inquilines equaled or outnumbered S. quoianum in 49% of the samples. Non-native fauna comprised 29% of the species and 35% of the abundance of inquilines, which is higher than other estuarine habitats in Coos Bay. Sessile non-native species were found living within burrows at tidal heights higher than their typical range. Thus, the novel habitat provided by burrows of S. quoianum may alter the densities and intertidal distribution of both native and non-native estuarine fauna.