Assessing functional diversity in marine benthic ecosystems: a comparison of approaches

Abstract

Two methods traditionally employed to investigate functional diversity in marine benthic ecosystems are relative taxon composition analysis, which interprets changes in the distribution of taxa in terms of the characteristics they exhibit, and trophic group analysis, which investigates differences in feeding mechanisms between assemblages. An alternative approach, biological traits analysis, considers a range of biological traits expressed by organisms to assess how functioning varies between assemblages. This study compares biological traits analysis to the relative taxon composition and trophic group approaches. Biological trait scores were assigned to a range of epibenthic invertebrate taxa from the southern North Sea and eastern English Channel and differences in the relative proportions of these traits were investigated using multivariate methods. The traits important in differentiating stations were attachment, flexibility, body form, mobility, feeding method and life habit. Such assemblages were spatially heterogeneous and there was no obvious distinction between different geographical sectors. This contrasted with the results of the relative taxon composition approach, which showed broad patterns in assemblage distribution in the eastern English Channel and southern North Sea. The biological traits approach provided information on a larger variety of ecological functions than the other techniques and revealed very different relationships between assemblages. It highlighted a greater diversity of assemblage types and was resistant to large-scale biogeographic variation. Therefore, it is potentially more useful than the traditional approaches for assessing ecosystem functioning on both large and small scales in benthic environments.

Functional diversity of nematode communities in the southwestern North Sea

“…A biological traits analysis, following the approach described for macrobenthic communities (Frid et al, 2000;Bremner et al, 2003) was carried out to assess the functional structure of nematode communities in the southwestern North Sea. Five traits were used, buccal morphology, tail shape, adult length, adult shape and life history strategy.…”

“…Bremner et al, 2003;Boström et al, 2006). This suggests that taxonomic and functional analyses should complement each other when deriving general descriptions of benthic diversity, and that using only taxonomic analyses to infer the effects of environmental variables and human activities on biota may omit key functional attributes (Frid et al, 2000;Bremner et al, 2003).…”

Economic Valuation of Marine and Coastal Ecosystems: Is it currently fit for purpose?

“…This approach provides a measure of functional diversity and may lend itself more easily to a linkage with ecosystem valuation. An important potential benefit of this approach is that the identity of species or the composition of the assemblages is represented by their combined functional attributes and those attributes can theoretically be compared across systems (Bremner et al 2003). This may allow a more generic approach to making the critical ecosystem function-ecosystem service flows link to economic valuation.…”

Can biological invertebrate traits resolve effects of multiple stressors on running water ecosystems?

“…Harsh, homogenous traits Habitat harshness as trait filter (Thienemann, 1918) Temporal heterogeneity = disturbance/stress Running water predictions (Southwood, 1977) Spatial heterogeneity = provision of refugia stream bryophytes (Muotka & Virtanen, 1995), stream and lake hydrophytes (Willby, Abernethy & Demars, 2000;Demars & Harper, 2005), benthic pond invertebrates (Verberk, Siepel & Esselink, 2008), marine benthic invertebrates (Bremner, Rogers & Frid, 2003b) or fluvial floodplain plants and birds (Bournaud, 1994;Pautou & Arens, 1994). These theoretical studies also stimulated work on applied aspects of trait responses to human-caused stressors (or release from stress after restoration) of organisms such as benthic stream invertebrates Dolédec et al, 1999), stream fish (Ferreira et al, 2007;Schmutz et al, 2007), benthic pond or lake invertebrates (Menetrey et al, 2005;Van Kleef et al, 2006), waterway hydrophytes (Willby, Pygott & Eaton, 2001), lagoon fish, benthic invertebrates, macrophytes and plankton (Mouillot et al, 2006;Pravoni, Da Ponte & Torricelli, 2008), marine benthic invertebrates (Bremner, Frid & Rogers, 2003a;Frid et al, 2008), marine fish (Jennings, Greenstreet & Reynolds, 1999), fluvial floodplain plants, molluscs and insects (Dziock, 2006;Foeckler et al, 2006;Henle et al, 2006) or forest birds (Hausner, Yoccoz & Ims, 2003).…”