BUSCADOR RECOLECTA

Gabon_dryad_fish_data Data description: Date – MM/DD/YYYY ; Reef – Gabon ; STATION – Rig1……Rig10 ; Latitude – Decimal degrees, WGS 1984 ; Longitude - Decimal degrees, WGS 1984 ; Depth_m- depth in meters ; Depth_stratum - DIVER – AMF = Alan Friedlander ; TRANSECT = A, B, C, D ; Taxon – lowest possible scientific name ; num_m^2 – numerical abundance in number per meter squared ; g_m^2 – biomass in grams per meter squared, The marine biodiversity of Gabon, West Africa has not been well studied and is largely unknown. Our examination of marine communities associated with oil platforms in Gabon is the first scientific investigation of these structures and highlights the unique ecosystems associated with them. A number of species previously unknown to Gabonese waters were recorded during our surveys on these platforms. Clear distinctions in benthic communities were observed between older, larger platforms in the north and newer platforms to the south or closer to shore. The former were dominated by a solitary cup coral, Tubastraea sp., whereas the latter were dominated by the barnacle Megabalanus tintinnabulum, but with more diverse benthic assemblages compared to the northerly platforms. Previous work documented the presence of limited zooxanthellated scleractinian corals on natural rocky substrate in Gabon but none were recorded on platforms. Total estimated fish biomass on these platforms exceeded one ton at some locations and was dominated by barracuda (Sphyraena spp.), jacks (Carangids), and rainbow runner (Elagatis bipinnulata). Thirty-four percent of fish species observed on these platforms are new records for Gabon and 6% are new to tropical West Africa. Fish assemblages closely associated with platforms had distinct amphi-Atlantic affinities and platforms likely extend the distribution of these species into coastal West Africa. At least one potential invasive species, the snowflake coral (Carijoa riisei), was observed on the platforms. Oil platforms may act as stepping stones, increasing regional biodiversity and production but they may also be vectors for invasive species. Gabon is a world leader in terrestrial conservation with a network of protected areas covering >10% of the country. Oil exploration and biodiversity conservation currently co-exist in terrestrial and freshwater ecosystems in Gabon. Efforts to increase marine protection in Gabon may benefit by including oil platforms in the marine protected area design process., Peer reviewed

Survey results and feeding experiment data All fish and benthos (algae and invertebrate) survey data and results from feeding assays. All data collected in the field. data_Verges_Tomas_etalJEcol.xlsx, A striking example of climate-mediated range shifts in marine systems is the intrusion of tropical species into temperate areas worldwide, but we know very little about the ecological consequences of these range expansions. In the Mediterranean Sea, the range expansion of tropical rabbitfishes that first entered the basin via the Suez Canal provides a good example of how tropical herbivorous fish can impact the structure of rocky bottoms in temperate seas. Two species of rabbitfishes have now become a dominant component of total fish biomass in the southernmost part of the eastern Mediterranean. Experimental evidence shows these species can profoundly transform benthic communities, turning algal forests into ‘barrens’, but the specific mechanisms that facilitate this shift have not been established. We surveyed ~1000 km of coastline in the eastern Mediterranean and identified two clearly distinct areas, a warmer group of regions with abundant tropical rabbitfish and a colder group of regions where these consumers were absent/ extremely rare. In regions with abundant rabbitfish, canopy algae were 65% less abundant, there was a 60% reduction of overall benthic biomass (algae and invertebrates) and a 40% decrease in total species richness. Video-recorded feeding experiments showed that the extensive barrens characteristic of regions with abundant rabbitfish were not due to greater rates of herbivory by these tropical consumers, but rather by functional differences among the herbivores. Temperate herbivorous fish displayed the greatest macroalgae consumption rates overall, but they fed exclusively on established adult macroalgae. In contrast, in regions with abundant rabbitfishes, these consumers fed complementarily on both established macroalgae and on the epilithic algal matrix, which typically contains macroalgal recruits. Synthesis: Range-shifting tropical rabbitfish can severely reduce the biomass and biodiversity of temperate reefs at a scale of hundreds of kilometres. A shift from macroalgal dominance to barrens is mediated by the addition of functionally diverse herbivores that characterise tropical reefs. This work highlights the importance of assessing the functional traits of range-shifting species to determine potential mechanisms of impact on ecological communities., Peer reviewed