Ingestion of inorganic mercury by juvenile black tiger prawns (Penaeus monodon) alters biochemical markers

Acetylcholinesterase activity in muscle tissue of Norway lobster Nephrops norvegicus: Importance of body size, season, sex and naturally occurring metals

The aim of the present study was to determine the levels of acetylcholinesterase (AChE) activity in the tail muscle tissue of wild populations of Nephrops norvegicus from the Northern Adriatic, and correlate it to body size, seasons, sex and the content of mercury, arsenic, cadmium, lead and copper. The animals of both sexes were collected in spring and autumn from two relatively distant fishing grounds. A marked variability of muscle AChE activity was found (0.49 to 11.22 nmol/min/mg prot.), displaying the opposite seasonal trend between two sampling sites. Small, but significant negative correlation has been found between AChE activity and carapace length (rs = - 0.35, p < 0.05). Data reported here provide an essential baseline for future studies of neurotoxicity in crustaceans. The study highlights the necessity for continuous monitoring of potentially toxic metals in edible marine species to avoid possible repercussions of seafood consumption on human health.

Assessment of mercury distribution and bioavailability from informal coastal cinnabar mining - Risk to the marine environment

Coastal cinnabar mining commenced in 2010 around Luhu on Seram (Ceram) Island, Indonesia. This study investigates the ore characteristics and environmental distribution and bioavailability of mercury in coastal sediments from eight sites adjacent to, and north and south of the mining area. Sediment and ore samples were digested using 1:3 HNO3:HCl for total extractable metal determination and separate samples were extracted with 1.0 HCl for bioavailable metals (Hg, Cu, Zn, Cr, Ni and Pb). Analysis was completed using inductively coupled plasma-mass spectrometry. Ore defined by miners as 'first class ore' was around 50 % cinnabar. Mercury concentrations were extremely elevated in near coastal sediments (up to 2796 mg/kg) with bioavailable concentrations exceeding 450 mg/kg. Marine sediments elevated in mercury extend to the north and south of the coastal mine site and cover in excess of 14 km. Total organic carbon in marine sediments was relatively low (predominately <0.6 %) suggesting mercury methylation will likely be slow, however, inorganic mercury is a known toxicant. Other metals of environmental concern (Cu, Zn, Cr, Ni and Pb) in sediments were not strongly associated with the mining operations, rather were elevated around coastal villages, but not at concentrations that raise immediate concerns.

The environmental remediation capacity of Ulva lactuca: the potential of macroalgae to reduce the threats caused by Titanium in marine invertebrate species

As a result of the wide use of Titanium (Ti) compounds in various products, Ti and Ti nanoparticles (nTi) are released into aquatic environments, inducing varying degrees of toxicity on aquatic fauna. Ulva lactuca, green macroalgae commonly found in coastal areas, has been extensively studied due to its worldwide distribution and capacity to accumulate trace elements under toxic conditions, which makes it a good universal sorbent. The present study aimed to establish the remediation properties of U. lactuca by evaluating the toxicity of Ti and nTi in bivalves, in the presence and absence of algae. Using the bivalve species Mytilus galloprovincialis, Ti toxicity was evaluated by assessing changes in mussel's metabolic capacity and oxidative status. Results evidenced cellular damage in M. galloprovincialis exposed to Ti and nTi. This was a result of the inactivation of antioxidant defences. The presence of U. lactuca limited cellular damage, however, this was not a result of the previously demonstrated bioremediation capacity, as no accumulation of Ti was verified in algal tissues. As a metabolic depression was verified for mussels exposed to Ti/nTi in the presence of algae, we hypothesise that U. lactuca may have been responsible for changes to the water quality which induced this response.

Metals and oxidative stress in aquatic decapod crustaceans: A review with special reference to shrimp and crabs

The objective of this review is to synthetize knowledge of the relationship between metals and oxidative stress in aquatic crustaceans (mainly shrimp and crabs) to analyze antioxidant responses when organisms are exposed to metals because the direct metal binding to the active site of enzymes inactivates most of the antioxidant systems. This study reviewed over 150 works, which evidenced that: (i) antioxidant defense strategies used by aquatic decapod crustaceans vary among species; (ii) antioxidant enzymes could be induced or inhibited by metals depending on species, concentration, and exposure time; and (iii) some antioxidant enzymes, as superoxide dismutase increase their activity in low metal levels and time exposures, but their activities are inhibited with higher metal concentrations and exposure time.

Acute toxicity, accumulation and sublethal effects of four neonicotinoids on juvenile Black Tiger Shrimp (Penaeus monodon)

Neonicotinoid pesticides have been detected in aquatic habitats, and exposure may impact the health of aquatic organisms such as commercially-important crustaceans. Black Tiger Shrimp (Penaeus monodon) is a broadly distributed and high-value shrimp species that rely on estuaries for early life stages. Differences in the acute toxicity and accumulation of different neonicotinoids in tissues of commercial crustaceans have not been widely investigated. This study compared acute toxicity, uptake, and depuration of four neonicotinoids; thiamethoxam, clothianidin, acetamiprid, and imidacloprid, on juvenile P. monodon and their effects on enzyme biomarkers. Acute toxicity (48-h LC₅₀) was determined as 190 μg L^-1 (clothianidin), 390 μg L^-1 (thiamethoxam), 408 μg L^-1 (imidacloprid), and >500 μg L^-1(acetamiprid). To assess uptake and elimination, shrimp were exposed to a fixed 5 μg L^-1 water concentration for eight days (uptake) or four days of exposure followed by four days of depuration (elimination). Neonicotinoid water and tissue concentrations were measured by liquid chromatography-mass spectrometry following solid-phase extraction and QuEChER extraction respectively. The lower toxicity associated with acetamiprid could be associated with lower accumulation in the tissue, with concentrations remaining below 0.01 μg g^-1. The activity of acetylcholinesterase, catalase and glutathione S-transferase in abdominal tissues was determined by spectrophotometric assay, with significant sublethal effects detected for all four neonicotinoids. Depuration reduced the tissue concentration of the active ingredient and reduced the activity of oxidative stress enzymes. Given acetamiprid showed no acute toxicity and reduced impact on the enzymatic activity of P. monodon, it may be an appropriate alternative to other neonicotinoids in shrimp producing areas.