AB 2:47-56 (2008)  -  DOI: https://doi.org/10.3354/ab00034

ABSTRACT: Introduction vectors for marine non-native species, such as oyster culture and boat fouling, often select for organisms dependent on hard substrates during some or all life stages. In soft-sediment estuaries, hard substrate is a limited resource, which can increase with the introduction of hard habitat-creating non-native species. Positive interactions between non-native, habitat-creating species and non-native species utilizing such habitats could be a mechanism for enhanced invasion success. Most previous studies on aquatic invasive habitat-creating species have demonstrated positive responses in associated communities, but few have directly addressed responses of other non-native species. We explored the association of native and non-native species with invasive habitat-creating species by comparing communities associated with non-native, reef-building tubeworms Ficopomatus enigmaticus and native oysters Ostrea conchaphila in Elkhorn Slough, a central California estuary. Non-native habitat supported greater densities of associated organisms—primarily highly abundant non-native amphipods (e.g. Monocorophium insidiosum, Melita nitida), tanaid (Sinelebus sp.), and tube-dwelling polychaetes (Polydora spp.). Detritivores were the most common trophic group, making up disproportionately more of the community associated with F. enigmaticus than was the case in the O. conchaphila community. Analysis of similarity (ANOSIM) showed that native species’ community structure varied significantly among sites, but not between biogenic habitats. In contrast, non-natives varied with biogenic habitat type, but not with site. Thus, reefs of the invasive tubeworm F. enigmaticus interact positively with other non-native species.

KEY WORDS: Ficopomatus enigmaticus · Ostrea conchaphila · Elkhorn Slough · Biological invasion · Biogenic habitat · Invasion meltdown · Non-native species · Introduced species