Geodiversidade e comunidades bentônicas da plataforma continental leste do Ceará: indicadores e linha de base ambiental para a sustentabilidade da economia azul

Abstract

The Eastern Continental Shelf of Ceará (PCLC) has enormous potential for offshore wind energy generation. In addition, it has bioclastic sediments that have been of interest to several industrial sectors due to the high concentration of carbonate minerals. Despite previous knowledge about the sedimentary facies of this region, it lacks information about its benthic assemblage, which is a significant scientific gap, especially when related to environmental indicators and ecological characteristics. Thus, this study aimed to map the biotic components, focusing on benthic foraminifera, of the surface sediments of the PCLC and correlate them with marine geodiversity in order to characterize the ecology of this environment and produce a new and essential baseline for environmental monitoring studies. For such purposes, data from remote sensing, bathymetry and sediment samples were used. Sedimentological analysis identified bryozoans (35.5%), calcareous algae (27%), foraminifera (12.3%), molluscs (12%), cnidarians (4%), echinoderms (3.9%), porifera (3.5%) and arthropods (1.7%) as the main biotic components. Principal component analyses revealed positive correlations between calcareous algae, porifera and cnidarians with depths of 20 - 40 m, zones of transverse dunes and reef constructions, and the bioclastic sand facies. Arthropods were associated with depths of 40-60 m and the biolithoclastic sand facies, while echinoderms and molluscs predominate in shallower regions (0 - 20 m), associated with suspended sediment zones and the bioclastic gravel and bioclastic sand with gravel facies. Regarding benthic foraminifera, 14 epifaunal and 6 infaunal genera were identified. Most samples showed moderate diversity and there was an absence of extremely dominant species. The Shannon-Wiener diversity, Uniformity and Dominance indices suggest that the water condition in the PCLC is favourable for foraminiferal habitat. This work proves the relationship between geodiversity and biotic components of the study area, showing that abiotic factors influence the distribution of the biocenosis. The balanced distribution of foraminifera reflects a stable benthic community, typical of well-oxygenated and oligotrophic environments. This knowledge is particularly important to assess possible environmental changes and support management strategies, subsidizing the sustainable development of the PCLC within the scope of the Blue Economy.