Measuring functional redundancy in chronically trawled benthic communities

Abstract

Functional redundancy, i.e. different species sharing similar functional roles, is a community property that contributes in the assessment of benthic ecosystem integrity. This property highlights the importance of exploring the performance of different approaches to measure functional redundancy. In this study we suggest that redundancy may be achieved through trait abundance (i.e. large amounts of a trait), what we called >common traits>, or through trait richness (i.e. large numbers of distinct taxa exhibiting the same trait), what we called widespread traits>. We assessed the variability of both measures on the epifaunal communities inhabiting eight sites located in four Mediterranean soft-bottom areas subjected to different levels of trawling effort. Both redundancy measures were based on the analysis of twenty biological traits linked to key soft-bottom¿s functions such as nutrient cycling, bentho-pelagic coupling and habitat provision. Common traits and Widespread traits measures provided complementary information on epifaunal functional redundancy, thus we suggest that a combination of the two measures should be used to appropriately assess ecosystem resilience in trawling grounds