Differences in soft-sediment macrobenthic assemblages invaded by Caulerpa taxifolia compared to uninvaded habitats

Publisher:
Inter-Research
Publication Type:
Journal Article
Citation:
Marine Ecology Progress Series, 2009, 380 (1), pp. 59 - 71
Issue Date:
2009-01
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Caulerpa taxifolia is a habitat-forming green alga that has invaded several temperateregions worldwide. Although C. taxifolia covers large areas of soft-sediment habitat, little is knownabout its effects on soft-sediment invertebrate assemblages. We compared soft-sediment macroinvertebrateassemblages in 2 estuaries in southeastern Australia invaded by C. taxifolia to examine 2main predictions: (1) areas covered with C. taxifolia will have different assemblages compared tounvegetated sediment because infauna are inhibited but epifauna are facilitated, and (2) areas withC. taxifolia will have different assemblages compared to those with native seagrasses (Halophilaovalis and Zostera capricorni) because infauna are inhibited but epifauna are not. Multidimensionalscaling and ANOSIM showed differences in invertebrate assemblages between all habitats. In C. taxifolia,infauna were less abundant and epifauna were more abundant compared to unvegetated sediment.However, when compared to native seagrasses, epifauna in C. taxifolia were more abundantthan in H. ovalis in one estuary but less abundant than in Z. capricorni in another estuary, whileinfauna in C. taxifolia were less abundant than in both seagrass species. The consistently low infaunalabundance in C. taxifolia, irrespective of infaunal feeding mode, suggests C. taxifolia impactsinfauna generally. Examination of environmental factors potentially responsible for the low abundanceof infauna indicated that differences in redox potential (and associated chemical changes) mayexplain patterns in abundance of infauna among habitats. Our findings indicate that invasion by C.taxifolia causes important changes to soft-sediment macroinvertebrate assemblages and suggest thatinfauna may be particularly vulnerable to invasion because of changes to sediment chemistry.
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