Taxonomic resolution needed to describe invertebrate assemblages and to detect harvesting effects on coral reef ecosystems

Abstract

Due to the cost and time required for species identification, the taxonomic sufficiency approach has been developed in order to detect community response to a disturbance, using high taxonomic level without great loss of information. This concept has been widely applied to pollution monitoring studies but rarely to other forms of perturbations such as anthropogenic exploitation of marine resources. We applied this method both to soft-bottom (seagrasses) and hard-bottom (coralline) tropical invertebrate communities in New Caledonia, South Pacific. The objective was to test whether intermediate or high taxonomic levels (genus, family, class or phylum instead of species) are good descriptors of community patterns and changes in assemblages related to harvesting, by comparing harvested to non-harvested areas for the 2 habitats. We pooled species data into coarser taxonomic categories (from genus to phylum) and showed that matrices at different taxonomic resolutions were highly correlated, particularly for genus and family level for both habitats. Differences between harvested and non-harvested locations appeared to be clearly habitat-dependent; for soft habitats, genus and family resolution allowed the detection of changes between exploited and protected assemblages, while for hard habitats, the separation between harvested and non-harvested areas was less clear at high taxonomic level and required species-level identifications. These results suggest that the taxonomic sufficiency approach could be carefully applied to poorly known environments. Family level is a good descriptor of community composition for tropical reef invertebrates. Detecting changes due to anthropogenic exploitation requires different taxonomic resolutions depending on the considered habitat. KEY WORDS: Taxonomic resolution · Data transformation · Tropical reef invertebrates · Harvesting effect · Marine protected areasResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 406: 211-222, 2010 patterns (Ellis 1985), in particular for disturbancerelated changes in benthic communities (Somerfield & Clarke 1995). This method uses coarser taxonomic levels when performing community comparisons, instead of species level. Several papers have addressed the validity of TS in marine ecosystems (Warwick 1988, Ferraro & Cole 1990, 1992, Gray et al. 1990, Warwick & Clarke 1993, Somerfield & Clarke 1995, Karakassis & Hatziyanni 2000. As well as a reduced need for taxonomic expertise, expected benefits include the removal of ecological redundancy attributed to the use of multiple species, when loss of information has no significant effect (Gray et al. 1988, Warwick 1988, 1993. Despite its increasing popularity on impact assessment, TS is still controversial (May 1990, Maurer 2000, in particular in the context of a global decline of taxonomic resources and species knowledge (Scheltema 1996, Boero 2001.Most studies using TS were in marine benthic habitats, including temperate soft-bottom benthic communities suc...

Taxonomic Level Needed to Detect Significant Changes in Polychaete Communities Over Different Macrophyte Assemblages on Rocky Intertidal Shores

“…Considering the significant level, the sample size, and the need of taxonomist, this study suggested that familybased data analysis is the best option in analysing significant relationships between polychaete communities and macrophyte assemblages on rocky intertidal shores. This agrees with many previous studies that family is a good descriptor to analyse the community structure of invertebrates (Olsgard et al, 1997;Thompson et al, 2003;Jimenez et al, 2010).…”

“…These suggest that the polychaete samples do not have to be identified until species level to detect a significant change of polychaete communities. Hence, this supports previous studies that a higher taxonomic resolution can be used to do a rapid assessment on the environmental changes (Olsgard et al, 1997;Defeo and Lercari, 2004;Jimenez et al, 2010). In this study, it is true that order data are sufficient to analyse relationships between polychaetes and macrophytes, except to detect a significant change in order richness.…”

“…Alternatively, many studies on marine invertebrates have shown that a higher taxonomic level (e.g. family and genus) can be applied in the ecological monitoring to reduce the expenditure for those resources (Olsgard et al, 1997;Defeo and Lercari, 2004;Jimenez et al, 2010). Unfortunately, those studies analysed non-associated invertebrates in the soft-bottom communities, so the results cannot be used to estimate the taxonomic level needed in the ecological monitoring of polychaetes associated with macrophyte assemblages on the rocky intertidal shores.…”

Analyses of coral community survey data at different taxonomic resolution: implications for reef monitoring

“…In contrast, species is better when obtaining information on areas with natu ral condition as it is more sensitive to natural processes (Warwick 1988a;Ferraro and Cole 1990). However, there was some variation in the pattern, particularly for hard bottom communities, wherein anthropogenic exploitation was only clearly evident at species level (Jimenez et al 2010). In coral reefs, both natural and anthropogenic disturbances occur, and it is clear that branching corals are most affected by any of the disturbances (Lewis 1998;Loya et al 2001).…”

“…Further, Olsgard et al (1998) found that variation in pattern between finer and coarser taxonomic resolution was greater in more pristine envi ronments. More recently, Jimenez et al (2010) showed that, for detecting changes due to anthropogenic exploi tation, the effective taxonomic resolution varied among habitats in tropical marine invertebrates. Some other studies have also indicated that the use of coarser reso lution may be enough to detect impact of environmental change and disturbance (Warwick 1988a(Warwick , 1988bSomer field and Clarke 1995).…”