Massive use of pesticides in conventional agriculture leads to accumulation in soil of complex mixtures, triggering questions about their potential ecotoxicological risk. This study assessed cropland soils containing pesticide mixtures sampled from conventional and organic farming systems at La Cage and Mons, France. The conventional agricultural field soils contained more pesticide residues (11 and 17 versus 3 and 11, respectively) and at higher concentrations than soils from organic fields (mean 6.6 and 10.5 versus 0.2 and 0.6 μg kg⁻¹, respectively), including systemic insecticides belonging to neonicotinoids, carbamate herbicides and broad-spectrum fungicides mostly from the azole family. A risk quotient (RQᵢ) approach evaluated the toxicity of the pesticide mixtures in soil, assuming concentration addition. Based on measured concentrations, both conventional agricultural soils posed high risks to soil invertebrates, especially due to the presence of epoxiconazole and imidacloprid, whereas soils under organic farming showed negligible to medium risk. To confirm the outcome of the risk assessment, toxicity of the soils was determined in bioassays following standardized test guidelines with seven representative non-target invertebrates: earthworms (Eisenia andrei, Lumbricus rubellus, Aporrectodea caliginosa), enchytraeids (Enchytraeus crypticus), Collembola (Folsomia candida), oribatid mites (Oppia nitens), and snails (Cantareus aspersus). Collembola and enchytraeid survival and reproduction and land snail growth were significantly lower in soils from conventional compared to organic agriculture. The earthworms displayed different responses: L. rubellus showed higher mortality on soils from conventional agriculture and large body mass loss in all field soils, E. andrei showed considerable mass loss and strongly reduced reproduction, and A. caliginosa showed significantly reduced acetylcholinesterase activity in soils from conventional agriculture. The oribatid mites did not show consistent differences between organic and conventional farming soils. These results highlight that conventional agricultural practices pose a high risk for soil invertebrates and may threaten soil functionality, likely due to additive or synergistic “cocktail effects”.

In this study, we determined the concentrations of Cu, Zn, Ni, Cd, Pb and As and their subcellular distributions within the tissues of mussels (Bathymodiolus marisindicus) and snails (Gigantopelta aegis) from two hydrothermal vent regions, i.e., Tiancheng and Longqi, at Southwest Indian Ridge. Mussels collected from the two venting regions showed comparable concentrations for Ni and Pb, but Cu, Zn, Cd and As concentrations were significantly different in mussel gills between the two vent regions. Similar ranges of metal concentrations were found in the snails as those in the mussels, but most of the metals were mainly accumulated in the viscera, except for Ni. Similar subcellular partitioning of Cu, Zn and Cd was documented in different mussel tissues, with cellular debris (50%) being the predominant fraction, followed by equivalent values in other fractions. Lead was distributed in both cellular debris and metal-rich granules (MRG) fraction, whereas Ni was predominantly distributed in MRG (90%). Arsenic was mainly partitioned in cellular debris and metallothionein-like protein. However, deep-sea snails displayed elevated subcellular partitioning of Cu in the organelles (up to 60%) and may be more susceptible to Cu stress than the mussels. Our results demonstrated the metal-specificity of detoxification strategies in these deep-sea hydrothermal vent mollusks, and the mussels may be more adaptable to high metal exposures than the snails at hydrothermal vent.

Akanda National Park (ANP) is composed of mangrove ecosystems bordering Libreville, Gabon's capital. The contamination of aquatic resources from the ANP by persistent organic pollutants (POPs) and trace metals (TMs) was never evaluated. To provide a basis for their monitoring in the ANP, five species (two fish, two mollusks, and one crustacean) were analyzed from three sampling sites in 2017. Contamination levels for POPs and TMs were below maximum acceptable limits for seafood, including Cd and Pb. No DDT was found in any sample. Inter-specific differences were more obvious than the differences among sites, although the results may be biased by an unbalanced sampling design. The oyster Crassostrea gasar was the most contaminated species, making this species a good candidate to assess environmental contamination in the area. The studied species also contained essential elements, such as Fe, Zn and Mn at interesting levels in a nutritional point of view.

Distribution and behavior of many trace elements in the aquatic environment has been well characterized, but little is known about silver (Ag) concentrations in coastal waters, even though this element ranks among the most toxic to marine invertebrates (Calabrese et al., 1977 ; Fisher and Hook, 1997 ; Webb and Wood, 1998). Studies conducted by Flegal et al. (1995), River-Duarte et al. (1999), and Ndung'u et al. (2001), provided the first valuable data on Ag distribution in the oceanic environment, indicating that this element is found in very low concentrations in the dissolved phase. However, although silver concentrations in coastal waters do not reach the nanomolar range (Smith and Flegal, 1993 ; Squire et al., 2002), formation of a stable chloro complex enhances bioavailability and toxicity to biota (Luoma et al., 1995). Experimental studies have shown that Ag is toxic to some living organisms at environmentally realistic levels (Bryan and Langston, 1992). Silver found in the aquatic environment mainly originates in effluents from sewage treatment plants (Rozan and Hunter, 2001). Silver can therefore be used as a tracer of wastewater discharges in coastal waters (Martin et al., 1988 ; Sañudo-Wilhelmy and Flegal, 1992), for instance through the use of sentinel organisms, which concentrate bioavailable contaminants in their tissues (Stephenson and Leonard, 1994 ; Jiann and Presley, 1997 ; Riedel et al., 1998 ; Muñoz-Barbosa et al., 2000). This study concerns biological monitoring as a means of providing a synoptic view of silver contamination in French coastal waters. The National Network for the Observation of Marine Environment Quality (RNO, the French Mussel-Watch) which has been regularly measuring concentrations of various chemical contaminants in oyster and mussel tissues for 25 years (Claisse, 1989), has been monitoring silver levels since 2003. This valuable database including data collected at 80 sampling sites distributed along the French coasts (Fig. 1), is used as a reference to provide the spatial distribution of a given contaminant (Chiffoleau and Bonneau, 1994), identify trends of contamination/decontamination (Chiffoleau et al., 2001), and detect peak concentrations due to accidental events (Chiffoleau et al., 2004). Mussels (Mytilus edulis and Mytilus galloprovincialis) and oysters (Crassostrea gigas) are collected twice a year in February and November. Sample collection (size of samples, size of animals) and treatment (cleaning, depuration, removal of soft parts from the shells, draining, homogenization, and freeze-drying) are performed according to the OSPAR Convention guidelines and the method described by Claisse (1989).

Studies have shown that shell morphology and enzymatic activities in mollusks are affected by contaminants exposure. However, the correlation between enzymatic activities and the biomineralization process are not fully understood. The present study used a transplant bioassay and field sampling to evaluate shell measurements and the activities of carbonic anhydrase, Ca²⁺-ATPase, and Mg²⁺-ATPase in Lottia subrugosa sampled in Brazilian sites under different contamination levels. Results showed that, in general, shells from the reference site (Palmas) were more rounded than the ones from the contaminated site (Balsa). Effects in enzymatic activities in specimens from transplant bioassay were attributed to the known high contaminant levels present at Balsa. While the lack of enzymatic activity alterations during field sampling was attributed to physiological adaptation to contaminants exposure. Enzymatic activities were not correlated to shell biometric parameters in field sampling, indicating that these enzymes were not related to shell alterations detected in the present study.

Arsenic is the most toxic element for humans. Presenting naturally in aquatic ecosystems and due to anthropogenic action, this semi-metal transfers to shellfish through the food chain. This systematic review aims to explain the dynamic of arsenic in the marine aquatic system, investigating factors that affect its bioaccumulation. A total of 64 articles were considered from three databases. The key abiotic factor influencing the presence of arsenic in shellfish is anthropogenic contamination, followed by geographic location. The crucial biotic factor is the genetics of each species of shellfish, including their diet habits, habitat close to the sediment, metabolic abilities, physiological activities of organisms, and metal levels in their habitats and food. Finally, arsenic presents an affinity for specific tissues in shellfish. Despite containing mostly less toxic organic arsenic, shellfish are a relevant source of arsenic in the human diet.

Metals are non-degradable in the aquatic environment and play a vital role in estuarine biogeochemistry but could also be detrimental to associated biota. A comparative evaluation of the trace metal concentrations (Fe, Mn, Zn, Cu, Ni, and Co) was carried out in the Zuari estuary, Goa during the post-monsoon season of 2013 at six locations, each representing three mangrove and three mudflat regions. In addition, fractionation of trace metals in sediments was performed to provide information on the mobility, distribution, bioavailability and toxicity. Special attention was paid to the marine mollusks viz. bivalves and gastropods that are extensively used as bio-indicators in coastal pollution. Considering the percentage of metals in the sequentially extracted fractions, the order of mobility from most to least bioavailable forms was Mn > Zn > Cu > Ni > Co > Fe. Mn maintained high bioavailability (average around 60%) in Fe–Mn oxide and carbonate bound forms indicating that Mn is readily available for biota uptake. The bioavailability of Fe was on an average of around 6% whereas other metals like Cu, Zn, Ni and Co were around 19% to 34%. When the bioavailable values were compared with standard Screening Quick Reference Table (SQUIRT), Zn showed higher toxicity level and bioavailability in the lower estuary. On the basis of calculated Bio Sediment Accumulation Factors (BSAF's), overall trend in bioaccumulation was in the order of Cu > Zn > Mn > Ni > Co > Fe. Metal Pollution Index (MPI) computed was higher for gastropods than bivalves.

In order to infer changes in sediments and mollusk assemblages for the last century, we used biogeochemical data from two 210Pb dated cores collected in Sagua La Grande estuary, Cuban Archipelago. We found evidences of cumulative anthropogenic disturbance during the last century, causing considerable depletion of mollusk assemblage diversity and enhancement of the dominance of deposit feeding species. The sequence of impacts assessed was i) eutrophication due to nutrient releases from urban settlements, ii) habitat alteration due to water channeling and damming, and iii) mercury pollution. These successive impacts caused a steady diversity depletion from ca. 70 mollusk species in 1900 to less than five in 2010. Only two species persisted in the estuary: Nuculana acuta and Finella dubia. Hurricanes did not impact the molluscan fauna in the long term. The effects of the anthropogenic impacts suggest that the resilience of this estuarine system is compromised.

Anthropogenic CO2 emissions are rapidly changing seawater temperature, pH and carbonate chemistry. This study compares the embryonic development under high pCO2 conditions across the south-north distribution range of the marine clam Limecola balthica in NW Europe. The combined effects of elevated temperature and reduced pH on hatching success and size varied strongly between the three studied populations, with the Gulf of Finland population appearing most endangered under the conditions predicted to occur by 2100. These results demonstrate that the assessment of marine faunal population persistence to future climatic conditions needs to consider the interactive effects of co-occurring physico-chemical alterations in seawater within the local context that determines population fitness, adaptation potential and the system resilience to environmental change.

Numerous countries have been confronted with infectious diseases in mariculture activities, including fungi infections, although reports in scallops are scarce. Thus, this study aimed to investigate the occurrence of filamentous fungi in Nodipecten nodosus specimens from three marine farms in Southeastern Brazil. Eight fungi genera were observed in the branchial arches, intestine and muscle tissue of the scallop specimens. These include potentially toxin-producing species, such as Aspergillus, Penicillium and Fusarium. Their presence may lead to potential public health concerns, since all sampling sites showed the presence of fungi in all scallop organs, with special concern regarding edible muscle tissue. A significant number of species was observed at one of the study areas, which could indicate a previously unknown source of contamination, since increases in fungi species richness in polluted coastal waters have been reported. This is also, to the best of our knowledge, the first report of Pestalotiopsis in shellfish.