Impacts of copper and lead exposure on prokaryotic communities from contaminated contrasted coastal seawaters: the influence of previous metal exposure

Abstract

Our understanding of environmental factors controlling prokaryotic community is largely hampered by the large environmental variability across spatial scales (e.g. trace metal contamination, nutrient enrichment and physicochemical variations) and the broad diversity of bacterial pre-exposure to environmental factors. In this article, we investigated the specific influence of copper (Cu) and lead (Pb) on prokaryotic communities from the uncontaminated site, using mesocosm experiments. In addition, we studied how pre-exposure (i.e. life history) affects communities, with reference to previous metal exposure on the response of three prokaryotic communities to similar Cu exposition. This study showed a stronger influence of Cu contamination than Pb contamination on prokaryotic diversity and structure. We identified 12 and 34 bacterial families and genera, respectively, contributing to the significant differences observed in community structure between control and spiked conditions. Taken altogether, our results point toward a combination of direct negative responses to Cu contamination and indirect responses mediated by interaction with phytoplankton. These identified responses were largely conditioned by the previous exposure of community to contaminants.

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

“…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).…”

“…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).…”

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)

“…Copper contamination from harbors has been proved to be highly toxic for planktonic microorganisms (Coclet et al, 2020(Coclet et al, , 2018. Lead (Pb) contamination is mostly archived in harbors sediment, often originating from older sources such as coal combustion, battery factories, metal smelting, leaded gasoline.…”

Seawater copper content controls biofilm bioaccumulation and microbial community on microplastics

“…Concentrations of TMs in Toulon-bay have been reported as being of the same order of magnitude or even higher than strongly impacted aquatic ecosystems (Pringault et al, 2012;Misson et al, 2016), with a decreasing gradient from the most anthropized parts to the open waters of the Mediterranean Sea. Along this gradient, bacterioplankton composition is shaped, including shifting the autotrophic community from picoeukaryote dominated community in the most contaminated parts to cyanobacteria (more representative of the open ocean) in less impacted areas (Coclet et al, 2018(Coclet et al, , 2019(Coclet et al, , 2020. Alongside TMs pollution, an important amount of MPs can be found in the surface water of Toulon bay, with an average of 32 800 MPs/km-2 (Tesan- Onrubia et al;2021).…”

“…The sampling locations were chosen based on the long-time monitoring of trace metals performed in the area, highlighting contrasted Cu concentrations in the considered locations (Tessier et al, 2011Coclet et al, 2018Coclet et al, , 2019Coclet et al, , 2020. Pt12 sampling station is located in the enclosed part of the bay of Toulon, near the main harbour, therefore submitted to important metallic inputs from the anthropogenic activities (Fig.…”