Long-term monitoring emphasizes impacts of the dredging on dissolved Cu and Pb contamination along with ultraplankton distribution and structure in Toulon Bay (NW Mediterranean Sea, France)

Abstract

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Trace Metal Contamination Impacts Predicted Functions More Than Structure of Marine Prokaryotic Biofilm Communities in an Anthropized Coastal Area

“…Taken together, our results suggest that surrounding superficial sediments could possibly serve as a direct source for the colonization of nearby immersed substrates by opportunistic microorganisms at the sediment/water interface, as already reported for freshwater ecosystems (Battin et al, 2001). This process could happen with sediment resuspension during storm events or human activities, such as dredging operations, which are numerous in Toulon Bay (Layglon et al, 2020). Investigating the benthic compartment of the Toulon Bay appears necessary to shed the light on the role of both benthic communities and sediment contamination on biofilm formation and establishment in a multi-contaminated ecosystem.…”

“…Overall, abiotic variables were stable through the one-month experiment in June 2015, and no significant differences between surface and bottom seawater were observed. However, we found that TM concentrations exhibited strong north-south decreasing gradients, as previously observed punctually, monthly, or pluri-annually in Toulon Bay (Coclet et al, 2018(Coclet et al, , 2019(Coclet et al, , 2020Layglon et al, 2020), allowing us to specifically address the potential effect of TM on the structure and functions of prokaryotic biofilm communities. The high contamination levels of localized areas indicated significant anthropogenic inputs that could be attributed to numerous recent (e.g., large boat traffic, harbor activities, antifouling coatings, sediment remobilization) (Turner, 2010;Layglon et al, 2020), and historical events (2nd World War) (Tessier et al, 2011).…”

“…Thus, TM concentrations in Mediterranean coastal surface waters, mainly due to atmospheric inputs, are higher than those, for example, in Atlantic Ocean (Heimbürger et al, 2011;Cossa et al, 2020). Rather than the atmospheric pathway, TM seawater contamination of the semi-enclosed Toulon Bay (Mediterranean Sea, France) is primarily caused by urban and industrial wastes (Levin et al, 2001;Oursel et al, 2013), antifouling coatings (Turner, 2010), fuel consumption (Callender, 2003), and sediment resuspension (Dang et al, 2015;Layglon et al, 2020). Then, seawater of the Toulon Bay is characterized by high levels of anthropogenic (Cd, Pb, and Zn) and intermediate (i.e., both anthropogenic and natural origins) (Cu and Ni) TMs (Jean et al, 2012;Coclet et al, 2018Coclet et al, , 2019Coclet et al, , 2020Layglon et al, 2020), which can be 100-fold above geochemical background levels of the Mediterranean Sea (Morley et al, 1997), and by far, upper than most of Mediterranean coastal zones (Cossa et al, 2020).…”

Quantification of Microplastics in North-Western Mediterranean Harbors: Seasonality and Biofilm-related Metallic Contaminants

“…Hence, trace metals associated to MPs can be released or ingested by organisms, affecting remote food webs [35,59,60]. Concerning the bay of Toulon, various studies [18,61] have highlighted the presence of strong wind between 25% and 30% of the time, in a direction flushing away the waters from the harbor to the open sea [18]. Elsewhere, in the bay of Genova, during summer, the dominant south eastern winds divide the eastern port entrance in two opposite current directions flowing outwards in the south and inwards in the north.…”

Quantification of Microplastics in North-Western Mediterranean Harbors: Seasonality and Biofilm-Related Metallic Contaminants

“…Hence, trace metals associated with MPs can be released or ingested by organisms, affecting remote food webs [21,61,62]. Concerning the bay of Toulon, various studies [18,63] have highlighted the presence of strong wind between 25% and 30% of the time, in a direction flushing away the waters from the harbor to the open sea [18]. Elsewhere, in the bay of Genova, during summer, the dominant south eastern winds divide the eastern port entrance in two opposite current Inorganic contaminants extracted from biofilm showed higher average concentrations in microplastics than macroplastics, with a significant difference for Pb, Fe, Cu and V (Table S3).…”