Benthic fluxes of oxygen and nutrients under the influence of macrobenthic fauna on the periphery of the intermittently hypoxic zone in the Baltic Sea

Role of Macrofaunal Communities in the Vistula River Plume, the Baltic Sea—Bioturbation and Bioirrigation Potential

“…The present study revealed the presence of 23 taxa of the benthic macrofauna in the study area. The results were similar to those obtained during other macrozoobenthos studies conducted in the Vistula estuary [39,41,72,73]. The greatest diversity of benthic organisms was observed in the coastal zone, where the density was dominated by P. ulvae, a gastropod species typical of the coastal zone in the Baltic Sea, while in the deeper zones the species composition of the benthic community shifted and the abundance was dominated by P. elegans and M. balthica, species also common in the Baltic Sea.…”

“…Coastal areas, such as estuaries, lagoons and bays, are dynamic environments with gradients of freshwater and seawater flows, representing transition zones between land and sea [3,59,60]. Gradients in physicochemical parameters of bottom water and surface sediments are typical for the Gulf of Gda ńsk [41,42,61] [this research]. As the depth of the basin increases, salinity increases, DO decreases, while the proportion of the finest fraction, organic matter content and hydrogen sulfide concentration increases.…”

“…In the case of benthic communities inhabiting the seabed of the Gulf of Gda ńsk, the factors that had the greatest impact on biomass structure, macrofauna burial depth and indices of bioturbation and bioirrigation potential were conditions such as salinity and oxygen concentration in the water above the bottom, and factors strongly related to these, such as sediment conditions. It is known that as oxygen conditions in the water above the seabed deteriorate, the concentration of toxic hydrogen sulfide in the sediments increases [41,[69][70][71].…”

“…A few studies on the role of macrofauna carried out in the Gulf of Gda ńsk have addressed the bioturbation potential index (BP C ) or nutrient fluxes between water and sediments [39][40][41][42]. Studies on the functioning of marine ecosystems in the Gulf of Gda ńsk in recent years have also considered the influence of organic matter on the structure and functioning of trophic networks [43] and how organic matter is transformed by organisms [44].…”

“…There are also few published studies on the distribution of organisms in the sediment. They mostly contain information on the depth of occurrence of individual macrofauna and meiofauna taxa [45][46][47][48], but only single studies addressed entire benthic communities [40,41,49].…”