Heavy metal bioconcentration factors in the burrowing crab Neohelice granulata of a temperate ecosystem in South America: Bahía Blanca estuary, Argentina

Use of the gonadal structures of the mangrove crab Ucides cordatus as a biomarker for environmental contamination by metals

This study investigates the concentration of metals in the different developmental phases of the gonads of Ucides cordatus from mangrove areas of Vila do Bacuriteua on the Bragança Peninsula, Caeté-Taperaçu Marine Extractive Reserve, state of Pará, on the Brazilian Amazon coast. Elemental analysis was determined by inductively coupled plasma optical emission spectrometry (ECP-OES). Metal concentration in males ranged from Cd = 0.04 to Cu = 2.27 mg kg-1 ww in the Developing and Developed gonadal stages, respectively. In females it was from Cd = 0.11 to Cu = 8.43 mg kg-1 ww only in the Developed stage). The elements Cr and Pb, for both sexes, presented concentrations above the limits allowed by the Brazilian regulatory body and only Pb by the international agencies, revealing a higher degree of contamination of these metals in the gonads of the mangrove crabs. Increasing mangrove crab consumption amplifies the risks of metal contamination among the human population and may cause public health problems.

Occurrence and Health Risk Assessment of Heavy Metals in the Blue Land Crab (Cardisoma guanhumi) from a Tropical Mangrove Swamp

Coastal ecosystems in the Caribbean are vulnerable to pollution from land-based activities with possible impacts to human health. Ten heavy metals in the blue land crab, Cardisoma guanhumi, harvested from the Caroni Swamp, Trinidad, were investigated in the wet and dry seasons. Metal concentrations (µg g^-1 dry weight) in crab tissue were: As (0.15-6.46), Ba (0.69-19.64), Cd (< 0.001-3.36), Cr (0.63-3.64), Cu (26.64-120.31), Hg (0.09-1.83), Ni (1.21-9.33), Se (0.19-1.55), V (0.16-0.69) and Zn (121.06-494.3). There were seasonal differences in the concentration of some heavy metals and, Cu and Zn exceeded the local maximum permissible levels for fish and shellfish at several sites in either one or both seasons. Health risk assessment based on estimated daily intake, target hazard quotient and hazard index revealed that Cardisoma guanhumi harvested from the Caroni Swamp, does not pose a health risk to consumers.

Disposition of trace elements in the mangrove ecosystem and their effects on Ucides cordatus (Linnaeus, 1763) (Crustacea, Decapoda)

The tropical mangrove at the Estação Ecológica do Lameirão (Southeastern Brazil), an ecosystem of high socio-economic value, receives a large load of pollutants from domestic, industrial, and agricultural sources. Samples of interstitial water, sediments, and crustacean specimens were collected at different periods and regions throughout the study area to measure the concentrations of copper (Cu), cadmium (Cd), lead (Pb), and tin (Sn) along the mangrove, as well as the bioaccumulation behavior in the crab Ucides cordatus. Subsequently, we correlated the accumulation of metals in U. cordatus with the concentrations of metals in the environment and physicochemical and climatic factors. Furthermore, we compared the bioconcentration factors (BFCs) of trace elements with the concentration levels obtained from the mangrove sediment. The fluctuation of rain and tide throughout the study period caused oscillations in the concentrations of trace elements. This condition induced bioconcentration records (BFC > 1), influencing the bioaccumulation trend in U. cordatus. We also identified that the lowest metal concentration values in the sediment were close to the river, indicating that the rivers cause a dilution effect. Finally, we found that the hepatopancreas had the highest levels of bioaccumulated heavy metals, explained by its detoxifying ability. In females of U. cordatus, we found a slightly lower accumulation of trace elements when compared to males, possibly related to the high rate of ecdysis in females. Ucides cordatus is a species widely used for human consumption. Our results show that the mangrove environment influences the concentration of trace elements in this organism, which the authorities should consider in mapping safer fishing areas.

Water, sediments and fishes: First multi compartment assessment of metal pollution in a coastal environment from the SW Atlantic

This is an integrated assessment of the distribution of Cd, Cr, Hg and Pb in dissolved water, sediments and muscle fish tissues (Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti and Ramnogaster arcuata) from the Bahía Blanca estuary, Argentina. Within the water fraction (μg L^-1), Hg and Pb concentrations ranged from below the limit of detection (<LOD) to 0.53 and 54, respectively. For Cd and Cr, values varied from 0.060 to 0.56 and from 1.6 to 18, respectively. In the sediment fraction (μg g^-1) values ranged from <LOD to 0.21 and 0.47 for Cd and Hg, respectively, from 11 to 18 for Cr and from 5.1 to 10 for Pb. Metals in fish muscle tissues (μg g^-1) ranged from <LOD to 2.8, 0.53 and 0.52 for Cr, Hg and Pb, respectively. All Cd values were <LOD. This marine environment is potentially vulnerable to anthropogenic pollution since dissolved Cr, Hg and Pb values exceeded established environmental quality guidelines. Moreover, the sediment pollution indices indicated a deterioration of the estuarine environment, with Cr and Pb associated to anthropogenic impacts, whereas Hg could be occasionally associated with adverse biological effects. The biota to water accumulation factor (BWAF) reflected that fish species showed potential to accumulate Cr (BWAF: 73-510) and, especially, Hg (BWAF: 1000-8000). The high biota to sediment accumulation factor found for Hg (up to 9.8) indicated that fish species behaved as macro or micro concentrators. These results highlights the importance of a multi compartment approach in pollution assessment, with implicances for future works.

Assessment of toxicity and environmental behavior of chiral ethiprole and its metabolites using zebrafish model

Ethiprole is effective against a wide range of insects and has been used throughout the world. In this work, the toxicity, bioaccumulation and elimination of ethiprole and its main metabolites (ethiprole sulfone (M1), ethiprole sulfide (M2), ethiprole amide (M3), ethiprole sulfone amide (M4) and desethylsulfinyl ethiprole (M5)) in zebrafish Danio rerio were investigated at enantiomeric level. Rac-ethiprole showed high toxicity (96 h LC₅₀ = 708 μg L^-1) and M2 was six times more toxic than ethiprole (111 μg L^-1). Enantioselective toxicity was observed, with the S-ethiprole (924 μg L^-1) being more toxic than R-ethiprole (2195 μg·L^-1). Rac-ethiprole and M2 could induce oxidative stress in the liver of adult zebrafish and developmental toxicity in zebrafish embryos. Zebrafish were exposed to 100 μg L^-1 rac-/R-/S-ethiprole and the bioaccumulation was monitored during a 21 d period followed by a 7 d metabolism. The bioconcentration factor (BCF) of rac-ethiprole was 17, and the half-lives of rac-ethiprole and metabolites varied between 0.44 and 2.99 d. R-ethiprole was preferentially accumulated and metabolized in zebrafish. Besides, the metabolic pathways of R- and S-ethiprole were found to be different. This study indicated assessment of metabolites and enantioselectivity should be taken into consideration in evaluating environmental risks of ethiprole.

Soil metal pollution assessment in Sarcocornia salt marshes in a South American estuary

Soil metal pollution in two Sarcocornia salt marshes within the Bahía Blanca estuary (Argentina, South America) was evaluated through pseudo-total and bioavailable metal levels and pollution indexes. Soil conditions were also studied. The pseudo-total metal concentrations were similar in both salt marshes and followed the same decreasing order: Fe > Zn > Cu > Cr > Ni > Pb > Cd. Bioavailable metals presented different patterns between salt marshes. The percentages of the bioavailable fraction varied between 28 and 80%, being higher than 60% for Cu, Zn and Pb. Organic matter ruled the distribution of all metals, except Pb. Using shale average concentration as background level, indexes did not show pollution nor enrichment, whereas using as background levels local values, anthropogenic enrichment was found for all metals and most metals showed moderate metal pollution. Our results showed that bioavailable metals levels and indexes using local background values provide an adequate assessment of metal pollution in salt marsh soils.

First approaches to the depuration process of trace metals in the burrowing crab Neohelice granulata from a temperate wetland in South America: Bahía Blanca estuary, Argentina

Trace metal contamination is among the major concerns of stakeholders due to its potential adverse effects on biota and humans, even at low concentrations. Few studies have recently focused on the ability of organisms to depurate trace metals from different tissues. Therefore, we carried out this study to evaluate the bioconcentration of trace metals (Cd, Zn, Pb, Ni, Mn, Fe, Cr, Cu) and the depuration process of these pollutants in two tissues (soft tissue and carapace) in an estuarine benthic crab model, Neohelice granulata. The results indicate that Cu and Zn were the highest bioconcentrated metals in crab tissues, while other metals, such as Pb and Cr, were found in sediments but were not bioconcentrated. On the other hand, Cd was found in crabs but not in sediments. The depuration indicates a total decline in Ni and a significant decrease in Cu and Fe in the soft tissues after the experiment. However, the concentration of the trace metals in the carapace before and after the depuration did not show any significant variation except in the Mn, in which the levels decreased significantly at the end of the depuration. Thus, we recommend continuing to explore metal detoxification in bioindicator species, such as N. granulata, in order to understand the efficiency of the mechanisms of depuration of trace metals.

Uptake and detoxification of trace metals in estuarine crabs: insights into the role of metallothioneins

The detoxification process of trace metals in the estuarine burrowing crab Neohelice granulata, after previously being exposed to anthropogenic pressures in the field, is described for the first time. The objectives of this study were (a) to assess the metal content (Cd, Cu, Pb, Zn, Mn, Ni, Cr, Fe) in the sediments and the uptake of these elements in the hepatopancreas of N. granulata; (b) to quantify trace metal concentrations in the hepatopancreas before and after the detoxification experiment; and (c) to relate this information to metallothionein (MT) induction or reversibility. The detoxification assay was performed for 25 days with artificial seawater under controlled conditions in a culture chamber. The results showed higher uptake and bioaccumulation of Zn and Cu from the sediments, and the hepatopancreas exhibited increased levels of Zn and lower concentrations of the rest of the metals and MTs after the assay, mainly Fe and Mn that were significantly lower. We conclude that trace metals could be translocated to and accumulated in the hepatopancreas, the main metabolic organ, and then eliminated under controlled conditions with corresponding reversibility of MTs. Graphical abstract.

A baseline study of microplastics in the burrowing crab (Neohelice granulata) from a temperate southwestern Atlantic estuary

Growing evidence has demonstrated that microplastics (MPs) are available for a wide range of marine organisms, with filter-feeding bivalves and crabs being especially vulnerable. The crab Neohelice granulata is considered a key and structuring species in the Bahía Blanca Estuary (BBE) (SW Atlantic) and its ecological role makes this species especially vulnerable to several pollutants. In this study, male specimens of N. granulata and water samples were collected at three sites in the BBE for the presence of MPs. Different types of MPs were found in all the crabs and the water column samples, although the most frequent were fibers <500-1500 μm, mainly blue. This is the first study to identify MPs in the gills and digestive tract of N. granulata. Moreover, gills presented higher total abundances of MPs than the digestive tract, which suggests that in this case the main uptake of MPs would be by adherence to the gills.