Benthic Microbial Community Structure across the Adriatic Sea: Role of Terrigenous Inputs and Human Impacts
Giovannelli; D.; Selci; M.; Spagnoli; F.; Tramontana; M.; Droghini; E.; Dinelli; E.; Annibaldi A.; Manini; E.;
Flowing rivers represent the first vector of transport of sediments into the marine environment. With them, huge quantities of substances like nutrients, organic matter (DOC and POM) and chemical compounds are transferred. All these spread along the marine coastal system, where under different depositional systems they can interact with benthic communities causing ecological shifts in their structure. To assess the influence of different depositional environments, trophic resources and possible contamination by human activities on the large-scale distribution of prokaryotes, we investigated the variability of benthic prokaryotic communities (Bacteria and Archaea) in the surface sediments of the Middle and Southern Adriatic Sea, along the Italian coast. Results show that the trophic status analyzed through biochemical investigations is typical of eutrophic environments. This was also confirmed from the prokaryotic diversity found, suggesting a strong role of the prokaryotic community in organic matter cycling. To understand which factors affected the prokaryotic abundance and distribution and the organic matter load, the large-scale microbial diversity dataset was correlated to different metadata and geochemical data. Linear relationships between variables were present only for limited range of values. A non-linear combination of Al2O3 and Fe2O3 concentrations in the sediments, grain size distribution and distance from the coastline were identified through General Additive Models analysis as the major factors explaining the variation in the prokaryotic distribution in the surface sediment. These variables were associated in Adriatic sediments with the Alpine and Apennines river inputs, and strongly correlated with the presence of deposits from the Po river, which suggest a strong influence in controlling the characteristics of the sediments, and the distribution of both trophic resources and prokaryotic abundances. These observations implicate a strong influence of the function performed at the interface between water and sediments for the flux of nutrient to the entire benthic community.
2019 - Abstract in atti di convegno
AGU, Fall Meeting 2019, San Francisco, 9-13/12/2019
Keywords: Adriatic Sea, biogeochemistry