Brief presentation

Despite the fact that rocky seabed is characterized by an extraordinary biodiversity, the quantitative studies of this type of sediment are still limited in number. This can be explained by the fact that remote sampling using different types of trawls, dredges and grabs, are inappropriate to sample hard substrates. Difficulties arise in collecting all organisms inhabiting cavities and fissures of rocks and stones and in extrapolating the number of collected organisms per square metre, taking into account that this type of sediment is extremely rugged in structure and whose surface is hard to estimate. The only method for quantitative study of organisms from rocky substrate is that of underwater visual census and in situ sampling using SCUBA (Self Contained Underwater Breathing Apparatus).

The importance of the direct observations relies on the fact that there is no need to collect samples when the knowledge of the diver is sufficient for de visu identification of benthic species, at least for fishes and epibenthic macrofauna. Thus, the visual techniques, which include also the scientific photography and video recording, present the main advantage to not to disturb the biotope nor the communities studies. These methods are non-destructive, they are strongly indicated in case of the study of rare or threatened species or in case of Marine Protected Areas (MAP). Thus, to assure a complete image about the biodiversity of rocky substrate it is necessary to complete direct observations with in situ sampling of organisms.

This study, apart the updating of the species inventory, will allow us to estimate the abundance and biomass achieved by organisms which inhabit hard substrate of Romanian Black Sea coast. This will permit to enlarge our knowledge on the distributional patterns, the dynamics and biological productivity of this type of substrate. The results obtained will serve as a database for future research and for establishment of an integrated ecological monitoring at the regional and/or national level.