Functional gains of including non-commercial epibenthic taxa in coastal beam trawl surveys: A note

The development of ecosystem-based indicators requires the broadening of a view of the community, from fish species to all the species (macrobenthic and fish) correctly captured by a given sampling gear. Many scientific surveys already have such integrated databases. The present note aims to demonstrate that existing databases, herein from dedicated coastal nursery surveys, are actually underexploited. Such databases contain information on non-commercial taxa, which could greatly improve our knowledge on the organisation and functioning of coastal ecosystems. Using two datasets, a “complete” dataset composed of commercial and not-commercial epibenthic trawled species (fish and invertebrate) and a “subset” dataset characterized by commercial and routinely surveyed species (mainly fish and cephalopods), different measures of functional diversity are compared to identify the functional gains of including epibenthic species. The results show that, when included in the analyses, epibenthic taxa provide gains of functional information, associated mainly with the community feeding traits, i.e. organisms composing the primary and secondary consumer levels of the coastal nursery food web. Failure to include some of the primary (zooplanktivores and suspension feeders) and secondary consumers (detritivores–scavengers) in coastal survey analyses may, for instance, hamper our understanding of energy flux between the benthic and water column compartments of these ecosystems. The results also suggest that the exclusion of some taxa associated with these two food web compartments, may lead to the underestimation of the functional redundancy in coastal ecosystems.