Macrofauna in Mediterranean and Black Sea transitional aquatic ecosystems: A comparative study of the benthic populations sampled by box corer and leaf bags

This study compares the ethic macrofauna sampled with a box corer and the leaf bag technique, widely used to study plant detritus decomposition processes. The study was carried out in 10 transitional aquatic ecosystems located in the Mediterranean and the Black Sea, covering a wide salinity range. A total of 171 taxa were sampled, 49 only in the sediment samples, 50 only in the leaf bags and 72 common to both. The macroinvertebrate assemblages sampled by the two techniques were different in terms of taxonomic and functional composition; annelids characterized mainly the corer samples, whereas arthropods were a dominant component in the leaf bags. Concerning functional groups, collectors and shredders were dominant respectively in the corer and the leaf bag samples. The taxonomic and the functional dominant composition also varied in relation to water salinity, mainly in the corer samples but less in the leaf bags. The sediment and leaf bag assemblages were significantly different at the scale of the lagoon and in most of the sampling sites. Primary biological variables and diversity indices showed a common trend with both sampling devices across the salinity gradient, but were also highly variable within each lagoon. The results indicated that the assemblages inhabiting the superficial sediment and colonizing litter detritus in transitional waters were distinct, but also highlighted the heterogeneity among these ecosystems.