Arsenic in marine mammals, seabirds, and sea turtles

Heavy metals and metalloid levels in the tissues of yellow-legged gulls (Larus michahellis) from Spain: sex, age, and geographical location differences

In the present study, mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se), and arsenic (As) were measured in liver, kidney, and feathers of adult, juvenile, and chick seagulls (Larus michahellis) collected from the northwest of Spain. Age, sex, and the geographical location of samples were considered variables that can influence metal bioaccumulation, for which concentrations were determined by means of ICP-MS. The mean concentrations (dry weight) found in seagulls were 7.01 ± 0.37 mg Hg/kg, 22.82 ± 2.83 mg Cd/kg, 7.36 ± 1.36 mg Pb/kg, 18.64 ± 0.63 mg Se/kg, and 10.64 ± 0.59 mg As/kg. Regarding the different factors analyzed, Hg was the only metal showing sex-related differences, being significantly higher (p < 0.05) the concentrations found in feathers of males (1.26 ± 0.12 mg/kg) than those in females (0.99 ± 0.11 mg/kg). A highly significant (p < 0.01) increase in levels of some metals was found in liver related to the increase of age: Hg (adults (A) 3.33 ± 0.22 mg/kg vs chicks (C) 1.76 ± 0.28 mg/kg), Cd (A 4.74 ± 0.62 mg/kg vs C 1.79 ± 0.2), Pb (A 0.65 ± 0.12 mg/kg vs juveniles 0.4 ± 0.11 mg/kg), and Se (A 7.56 ± 0.43 mg/kg vs C 5.24 ± 0.53 mg/kg). Positive correlations between Cd-Hg and Se-Hg were found in liver (p < 0.001), kidney (p < 0.001), and feathers (p < 0.05 and p < 0.001, respectively). The associations found may reflect antagonistic interactions between Se and Cd on Hg toxicity. The results suggest that L. michahellis can reveal local contamination around the foraging and breeding sites and can be a very useful monitoring instrument for assessing heavy metal contamination and sentinel species of environmental health.

EVALUATION OF TRACE ELEMENT CONCENTRATIONS IN THE SERUM AND VIBRISSAE OF PERUVIAN PINNIPEDS (ARCTOCEPHALUS AUSTRALIS AND OTARIA BYRONIA)

Concentrations of 15 trace elements (aluminum, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, tin, vanadium, and zinc) were determined in vibrissae (whiskers) and serum of two sympatric pinniped species, the Peruvian fur seal population (PFS; Arctocephalus australis Peruvian subpopulation) and South American sea lion (SASL; Otaria byronia) at Punta San Juan, Peru during 2011-19 sampling events. Element concentrations were 2-20 times higher in vibrissae than in serum. Vibrissae and serum concentrations of several elements, including aluminum, arsenic, and lead, suggest that environmental contaminants may affect the health of pinnipeds at Punta San Juan. Although toxicity thresholds are unknown in pinnipeds, high concentrations of some elements (especially aluminum, arsenic, and lead) may have adverse impacts on their health such as immunosuppression and impaired reproduction. Arsenic was the only element that increased in mean vibrissae concentration throughout the study period. Female SASL vibrissae contained a mean arsenic concentration three times higher than the male SASL vibrissae mean arsenic concentration, and twice as high as the arsenic mean for all PFS vibrissae. The mean male SASL vibrissae cadmium concentration was five times higher than the vibrissae cadmium mean for both PFS males and females and nearly three times higher than the vibrissae cadmium mean for SASL females. Serum concentrations of aluminum, arsenic, copper, and manganese were significantly higher during moderate to extreme El Niño years compared to La Niña years. With stronger and more frequent El Niño-Southern Oscillation events predicted in the future, it is vital to understand how these trace elements may affect pinniped population health.

Total Arsenic Concentrations in Sea Turtle Tissues from the Mediterranean Coast of Spain

In this work we studied total arsenic concentrations in liver, muscle and kidney of 49 individuals of two sea turtle species (loggerhead sea turtles, n = 45; leatherback turtles, n = 4) stranded in Murcia (South-eastern Spain) coastline between 2009 and 2018. In accordance with the literature, muscle was the tissue with the highest concentrations in both species, followed by liver and kidney. Although differences in arsenic concentrations were not statistically significant between the study species, loggerhead sea turtles showed concentrations two or three times higher than those of leatherback turtles, which we attribute to differences on feeding behavior and habitat preferences. Arsenic concentrations in turtles from this area increase evidence of western Mediterranean Sea as a hotspot for metal pollution. Based on the scarce existing knowledge on arsenic toxicity in sea turtles, those levels found in our study are below those responsible for liver damage.

Evidence of Low-Habitat Contamination Using Feathers of Three Heron Species as a Biomonitor of Inorganic Elemental Pollution

The concentration of 12 elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) has been investigated in the feathers of three species of Ardeidae, namely the Grey Heron Ardea cinerea, the Little Egret Egretta garzetta, and the Cattle Egret Bubulcus ibis, all breeding at a colony located in the southern Padana Plain (NW Italy). This study is a first step for an evaluation of possible direct effects of these elements on chicks' survival and growth rate. Fe, Zn, Cu, and Mn were in the range 7-69 mg Kg-1, while lower levels of Pb, Ni, As, and Se (0.27-1.45 mg Kg-1) were measured. Co, Cd, and Cr were close to the method detection limits (MDLs) in all the species. The measured concentrations of the most abundant trace elements, such as Zn and Cu, seem to reflect the geochemical pattern of the background (running water and soil), while Hg concentration is lower and it appears to be biomagnified, particularly in Grey Heron feathers. Its concentration is higher in adults than in chicks, and it differs among the three species, as it is closely related to the fish-based dietary pattern. The measured trace elements' concentrations are below the threshold levels in all the heron species, and consequently, harmful and acute effects on the local population are unlikely; the conservation status of herons populations in northern Italy is probably more affected by other factors, such as climate changes, altered aquatic environment, and, consequently, food quality.

Environmental impact and recovery of the Bohai Sea following the 2011 oil spill

The 2011 spill at platforms B and C of the Penglai 19-3 oil field in the Bohai Sea has been the worst oil spill accident in China. To assess long-term effects, a comprehensive monitoring program of chemical and biological variables (within a 2.2 km radius of the spill site) was conducted five years after the spill. Comparison of nutrient, Chl-a and oil concentrations in seawater, TOC, PAHs, heavy metals concentrations within the sediments, and the abundance and biomass of macrobenthic organisms to values obtained before and after the oil spill in previous studies indicate habitat recovery has occurred within the Bohai Sea following the episodic oil release. Observed elevated oil concentration in the water column and higher concentrations of two heavy metals, five PAHs, TOC, TOC/TN and lower values of δ¹³C, together with a reduction in macrobenthic biomass in near-field samples, suggest the influence of contaminants from chronic releases of oil and operational waste discharges within the vicinity of the oil platforms.

Effects of Formalin Fixation on Trace Element Concentrations in Bottlenose Dolphin (Tursiops truncatus) Tissues

Odontocetes are considered ideal sentinel species to monitor environmental trace element concentrations. Although frozen tissues are preferable for trace element analysis, formalin-fixed tissues are often the only samples available; however, it is uncertain whether formalin fixation alters tissue trace element concentrations. To explore whether formalin-fixed tissues could be utilized for toxicology studies, concentrations of 14 trace elements (arsenic [As], cadmium, cobalt, chromium, copper, iron, mercury, manganese, nickel, lead, selenium, tin, vanadium, and zinc [Zn]) were measured in frozen and formalin-fixed bottlenose dolphin (Tursiops truncatus) tissues following short-term (6 wk; tissues: blubber, liver, and lung) and long-term preservation (3-7 yr; tissues: blubber, brain, kidney, liver, lung, and skin) using inductively coupled plasma mass spectrometry. Following both short-term and long-term preservation, there were significant differences in tissue trace element concentrations between preservation methods. Some trace elements were found in greater concentrations in frozen tissues compared with formalin-fixed tissues, suggesting leaching (e.g., mean As concentrations were between 1.4 and 7.6 times greater in frozen tissues). In contrast, other trace elements were found in greater concentrations in formalin-fixed tissues compared with frozen tissues, suggesting contamination (e.g., mean Zn concentrations were up to 8.7 times higher in some formalin-fixed tissues). Our results suggest that it may be possible to account for the effects of formalin fixation for some trace elements, but leaching and contamination should be carefully considered. Environ Toxicol Chem 2020;39:1149-1164. © 2020 SETAC.

A Systematic Review on Arsenic Bio-Availability in Human and Animals: Special Focus on the Rice-Human System

The present systematic review synthesizes the diverse documentation of research on the occurrence of arsenic in soil-water systems and the human and animal bio-availability scenarios related to food chain contamination by arsenic. Humans and animals may drink arsenic-contaminated groundwater in addition to consuming foods that have been grown in arsenic-contaminated groundwater and soils. Rice grain is a potential arsenic carrier and the staple food in many parts of the world, particularly in Southeast Asian countries. Data have been summarized from 183 articles describing different aspects of arsenic flow in the food chain, that is, the soil-water-rice-human system and the water-crops-animals system and the bio-availability of arsenic to humans and animals. The phyto-availability of arsenic depends on the physicochemical and biological conditions of soil and water. In humans, the bio-accessibility of inorganic arsenic is 63-99%. Arsenic is more bio-available from rice than from other foods: different food materials differ in bio-accessible potential. Additionally, the review identifies trends in research on arsenic contamination and food chain flow considering arsenic species, toxicity assessment, and bio-accessibility studies. This systematic review provides a comprehensive assessment of the documented evidence to be used to guide future research on arsenic availability for the rice plant and subsequent availability to humans from cooked rice that can determine arsenic toxicity. The review also highlights how the focus of research on arsenic as a pollutant has changed in the past decades.

Elucidating temporal trends in trace element exposure of green turtles (Chelonia mydas) using the toxicokinetic differences of blood and scute samples

Blood is considered a suitable biomonitoring matrix for evaluating relatively recent exposure to environmental contaminants since abrupt changes in exposure regimes are rapidly reflected in blood. On the other hand, keratinized tissues, such as turtle scutes, are known to integrate trace element exposure over relatively long time periods. This study aimed to test the use of the differences in blood and scute to inform on the historical trace element exposure of green turtles. We propose a blood-scute kinetic model to predict how an increase in exposure would affect the concentrations in these two matrices over time. We then tested the relationship between blood and scute concentrations for 19 trace elements in two green turtle populations presumed to experience relatively constant exposure conditions. Significant log-log and linear correlations were observed between blood and scute concentrations for Co, As, Mo, Sb, and Cd. We then analysed blood-scute ratios in turtles from two coastal sites with known elevated exposure to various trace elements from previous studies. Deviations from the steady-state were clearly evident in these coastal turtles (for Co and Cd) and were consistent with the model prediction of changes in exposure. These field data provide evidence that blood-scute ratios can provide a valuable tool for examining the historical trace element exposure of turtles. We further present a method by which the general model may be refined and validated, by using data from individual turtles that had been recaptured across multiple years. Although the timeframe and number of recaptured samples available for this study were limited, the temporal changes in blood-scute ratios in these animals were generally consistent with those suggested by the model. Thus, the ratio between paired blood and scute trace element concentrations could be used to establish a temporal exposure index in turtles.

Mercury (Hg), Lead (Pb), Cadmium (Cd), Selenium (Se), and Arsenic (As) in Liver, Kidney, and Feathers of Gulls: A Review

Mercury (Hg), lead (Pb), cadmium (Cd), selenium (Se), and arsenic (As) are metals or metalloids of high concern because of their effects on the environment and, specially, their potential toxicity on the animals inhabiting there. Due to their relevance, these elements have been object of several biomonitoring studies in different animal species around the world. Birds are widespread and, as species, are able to supply specific and relevant information about the regions where they live, being useful as bioindicators, as long as they are not birds with a strong migratory character. The main goal of this review is to summarize data collected from different studies using seabirds, paying special attention to gulls, in order to be helpful for coming studies and regulatory affairs.Several tissues have been used to evaluate Hg, Cd, Pb, Se, and As concentrations in seabirds, being focused the present review in those analyzing the liver, kidneys, and feathers. The most frequently analyzed tissue for Hg was the liver, followed by feathers, and finally kidney. For Cd levels, most of the studies were carried out in the liver, followed by feathers and kidneys. Pb, Se, and As levels were determined to a lesser extent. Feathers should be taken carefully as indicator of accumulation of pollutants, since procedure during analysis may lead to controversial results.Some authors reported that interspecific differences in the exposure of elements are determined by multiple factors, including properties of the contaminant, species, feeding habits, migratory status, sex, and age.The present review provides a comprehensive overview of the analyzed elements' occurrence in different species of seabirds, including gulls. Therefore, it can be a useful database providing for Hg, Pb, Cd, Se, and As levels in different tissues of seabirds.

Contamination Status of Seven Elements in Hooded Cranes Wintering in South-West Kyushu, Japan: Comparison with Red-Crowned Cranes in Hokkaido, Japan

The hooded crane is designated as an endangered species. The cranes breed primarily in wetlands in southeast Russia and China in summer. Most of the hooded crane population winters in the Izumi plain in Japan. It is difficult to know the contamination status of their habitat because of their vast breeding area. We determined the levels of Cd, Pb, As, (total) Hg, Se, Zn, and Cu in the liver, kidney, and muscle of hooded cranes that were found dead in Izumi in the periods 2003-2006 and 2014-2015 compared with the levels in red-crowned cranes in Hokkaido, Japan, as the only cranes in which these elements had been studied extensively. There were no notable differences between levels of the seven elements in the two periods. Overall, tissue levels of the elements examined in hooded cranes were comparable to those in red-crowned cranes except for Hg and Se. Tissue levels of Hg and Se were clearly lower in hooded cranes than in red-crowned cranes that were found dead from 2000. One lead poisoning case was confirmed. The results suggest that Hooded cranes wintering in Izumi are not extensively contaminated with the seven elements examined.

New Sulfur-Containing Polyarsenicals from the New Caledonian Sponge Echinochalina bargibanti

Arsenicin A (C₃H₆As₄O₃) was isolated from the New Caledonian poecilosclerid sponge Echinochalina bargibanti, and described as the first natural organic polyarsenic compound. Further bioguided fractionation of the extracts of this sponge led us to isolate the first sulfur-containing organic polyarsenicals ever found in Nature. These metabolites, called arsenicin B and arsenicin C, are built on a noradamantane-type framework that is characterized by an unusual As⁻As bonding. Extensive NMR measurements, in combination with mass spectra, enabled the assignment of the structure for arsenicin B (C₃H₆As₄S₂) as 2. The scarcity of arsenicin C and its intrinsic chemical instability only allowed the collection of partial spectral data, which prevented the full structural definition. After the extensive computational testing of several putative structures, structure 3 was inferred for arsenicin C (C₃H₆As₄OS) by comparing the experimental and density functional theory (DFT)-calculated ¹H and ¹³C NMR spectra. Finally, the absolute configurations of 2 and 3 were determined with a combined use of experimental and time-dependent (TD)-DFT calculated electronic circular dichroism (ECD) spectra and observed specific rotations. These findings pose great challenges for the investigation of the biosynthesis of these metabolites and the cycle of arsenic in Nature. Arsenicins B and C showed strong antimicrobial activities, especially against S. aureus, which is comparable to the reference compound gentamycin.

Tissue partition and risk assessments of trace elements in Indo-Pacific Finless Porpoises (Neophocaena phocaenoides) from the Pearl River Estuary coast, China

Throughout the last few decades, an increased number of stranded marine mammals, particularly the Indo-Pacific Finless Porpoises (Neophocaena phocaenoides), were observed in the Pearl River Estuary (PRE). As long-lived, apex predators vulnerable to bioaccumulation of contaminants, the tissue residue levels and health risk of trace elements (TEs) in N. phocaenoides from the PRE have been little studied. Eleven typical TEs distributed in skin, liver and kidney tissues were investigated from 25 specimens stranded along the PRE from 2007 to 2015 in the present study. It revealed that most TEs were highly accumulated in internal organs (liver and kidney), except for Zn with high residue levels in external skin. Compared with the TEs in prey items, the residue levels of Hg, Se, Zn, Cu, Cd and Cr in N. phocaenoides increased 4-618 times, indicating a potentially significant biomagnification. Sex-related differences of TE accumulation were not obvious, except for renal Mn, in which the females showed lower mean concentrations than males. Significantly positive correlations between body length and TE levels were found for Hg, Se and Cd. Results of the calculated risk quotients (RQ) suggested that the risks to N. phocaenoides from consumption of prey items were generally low, but further attentions should be paid to Cd, Cr, Cu, Hg and As due to the elevated RQ values. The concentrations of Hg, Cd and Se in the epidermis were positively correlated with the levels found in internal organs. Our investigation provides evidence to support the use of skin as one biomonitoring approach on Hg, Cd and Se contamination of internal tissues in this species.

Trace element concentrations in muscle tissue of milk shark, (Rhizoprionodon acutus) from the Persian Gulf

We analyze the heavy metals concentrations in muscle samples of milk shark (Rhizoprionodon acutus) from Persian Gulf. The metals distribution was Zn > Cu > Pb > Cd > Hg. No statistical differences were observed among size or weight by sex (p < 0.05). Metals concentrations in the population de R. acutus from Larak and Lavan islands are homogeneous along the coastal study area. Our study suggest that the results reflect the natural contents of trace metals in this species, and the health risk associated to milk shark consumption in Persian Gulf is relatively low.

Trace Element Contamination in Tissues of Four Bird Species from the Rift Valley Region, Ethiopia

Concentrations of ten trace elements (Hg, As, Cd, Pb, Co, Cr, Cu, Ni, Se and Zn) were determined in different tissues (liver, kidney, muscle, heart and brain) of African sacred ibis (Threskiornis aethiopicus), Hamerkop (Scopus umbretta), marabou stork (Leptoptilos crumeniferus) and great white pelican (Pelecanus onocrotalus) inhabiting the Ethiopian Rift Valley region. There were differences in trace element patterns among the bird species. Significantly (p < 0.05) higher concentrations of Cd (5.53 µg/g dw ± 2.94) in kidney and Hg (0.75 µg/g ww ± 0.30) in liver were observed in the great white pelican compared to the other species, and liver concentrations of these two elements showed positive correlations with trophic level. Concentrations of toxic elements (As, Cd, Pb and Hg) in liver were below their respective toxicological thresholds, indicating that the data may provide baseline information for future studies.

Trace Element Concentrations in Relation to the Trophic Behaviour of Endangered Ivory Gulls (Pagophila eburnea) During Their Stay at a Breeding Site in Svalbard

The ivory gull is a high-Arctic species considered endangered in most parts of its breeding range. Ivory gulls must cope with both the reduction of sea ice cover triggered by climate change and increasing contaminant loads due to changes in global contaminant pathways. The objective of this study was to assess the concentration of 14 essential and nonessential trace elements at four colonies of ivory gulls breeding on Barentsøya, Svalbard, and the relationship between contaminant exposure and the diet of individuals. Contaminants and stable isotopes (δ¹⁵N, δ¹³C) were determined in blood (red blood cells and whole blood), and feathers of ivory gulls collected over several years. The most quantitatively abundant nonessential trace element found in the ivory gull was mercury (Hg). Selenium (Se) was present in substantial surplus compared with Hg, which would imply relative protection against Hg toxic effects but raises concern about Se potential toxicity. Moreover, other elements were detected, such as silver, arsenic, cadmium, and lead, which would warrant monitoring because of the potential additive/synergetic effects of these compounds. This study demonstrated individual differences in trophic behaviour that triggered discrepancies in Hg concentrations, highlighting the potential biomagnifying ability of this metal in the ivory gull's food web. Results highlighted the mixing of birds coming from different geographical areas on Barentsøya.

Arsenobetaine: the ongoing mystery

Arsenobetaine (AsB) is a non-toxic organoarsenical identified as a major arsenic species in marine animals and a number of terrestrial mushrooms. Since its first identification nearly 40 years ago, numerous studies investigating the biosynthesis and function of AsB have been carried out, although molecular mechanisms have not been fully elucidated. Where and how is AsB formed? Why do marine animals acquire high concentrations of AsB? This review briefly summarizes the current progress of AsB research toward understanding its origin, function and the putative pathways for its biosynthesis. This paper also suggests potential future studies in the attempt to solve the AsB mystery.

Trace elements in striped dolphins (Stenella coeruleoalba) from the Eastern Mediterranean: A 10-years perspective

Concentrations of Hg, Se, Cd, Cu, Zn, Fe, Mn and As, in kidney, liver, muscle and blubber from 7 specimens of Stenella coeruleoalba, stranded along the Israeli Mediterranean coast (IMC) from 2006 to 2011 (2011-series) were determined and compared to previous data on S. coeruleoalba from the IMC (2001-series). No differences were observed in essential and toxic elements concentrations, between the two series, except for hepatic Mn which was higher in the latter. Hg/Se molar ratios in blubber, kidney and liver increased linearly with log Hg concentrations, while muscle was more heterogenic in this respect. Means (±SD) of hepatic Hg concentrations (134±89 and 181±200mgkg(-1), from the 2011 and 2001 series, respectively) were similar to that found in 2007-2009 specimens from Spain, possibly reflecting the relatively high natural background levels of mercury in the Mediterranean Sea.

Trace element concentrations in harvested auks from Newfoundland: Toxicological risk of a traditional hunt

Common (Uria aalge) and Thick-billed Murres (Uria lomvia) are apex predators in the North Atlantic Ocean, and are also subject to a traditional hunt in Newfoundland and Labrador during the winter months, along with small numbers of illegally harvested Razorbills (Alca torda). Because of their high trophic position, auks are at risk from high contaminant burdens that bioaccumulate and biomagnify, and could therefore pose a toxicological risk to human consumers. We analysed trace element concentrations from breast muscle of 51 auks collected off Newfoundland in the 2011-2012 hunting season. There were few differences in contaminant concentrations among species. In total, 14 (27%) exceeded Health Canada or international guidelines for arsenic, lead, or cadmium; none exceeded guidelines for mercury. Cadmium concentrations >0.05μg/g have persisted in Newfoundland murres for the last 25 years. We urge the integration of this consumptive harvest for high-trophic marine predators into periodic human health risk assessments.

Investigation of trophic level and niche partitioning of 7 cetacean species by stable isotopes, and cadmium and arsenic tissue concentrations in the western Pacific Ocean

A total of 24 stranded or bycatch cetaceans, including Balaenoptera omurai, Lagenodelphis hosei, Kogia sima, Stenella attenuata, Grampus griseus, Neophocaena phocaenoides, and Sousa chinensis, were collected from 2001 to 2011 in Taiwan. Using the muscular δ(13)C and δ(15)N data, three ecological groups were identified as the oceanic baleen whale, the neritic, and the coastal toothed whale groups, coinciding with their taxonomy, feeding habits and geographical distribution. A horizontal inshore to offshore distribution was found for the sympatric neritic toothed dolphins, G. griseus, K. sima, S. attenuata, and L. hosei in the outermost offshore waters, accompanying their growth. For the first time we identify Taiwan's Chinese white dolphin, S. chinensis, as an exclusive fish eater. Cd and As bioaccumulated in the G. griseus, L. hosei and S. attenuata increase as they grow. Prey-derived As- and Cd-induced health threats were found in L. hosei, and G. griseus.

Trace elements in blood of sea turtles Lepidochelys olivacea in the Gulf of California, Mexico

This study determined the concentrations of heavy metals in blood collected from Pacific Ridley sea turtles (Lepidochelys olivacea) inhabiting the coast of Guasave, Mexico, in the Gulf of California. The highest reported metal concentration in blood was Zn, followed by Se. Of nonessential toxic metals, As was reported in higher percentage compared to Cd. The concentrations of metals detected were present as follows: Zn > Se > Mn > As > Ni > Cd > Cu. Cd concentration in blood is higher in our population in comparison with other populations of L. olivacea, and even higher in other species of sea turtles. Our study reinforces the usefulness of blood for the monitoring of the levels of contaminating elements, and is easily accessible and nonlethal for sea turtles.

Global assessment of arsenic pollution using sperm whales (Physeter macrocephalus) as an emerging aquatic model organism

Arsenic is an oceanic pollutant of global concern due to its toxicity, ability to bioaccumulate and continued input into the environment by anthropogenic activities. The sperm whale (Physeter macrocephalus) is an emerging aquatic model for both human disease and ocean health having global distribution and high trophic level. The aim of this study was to establish global and regional baselines of total arsenic concentrations using free-ranging sperm whales. Skin biopsies (n=342) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age in males. Arsenic was detectable in 99% of samples with a global mean of 1.9μg/g ww ranging from 0.1 to 15.6μg/g ww. Previous work in toothed whale skin found mean concentrations 3 fold lower with 0.6μg/g ww. A significant gender-related effect was found with males having higher mean arsenic concentrations than females. There was no significant age-related effect between adult and subadult males. Arsenic concentrations in sloughed skin samples were similar to levels in skin biopsies indicating that arsenic excretion can occur by skin sloughing. Regional mean concentrations were highest in the Maldives, Seychelles and Sri Lanka with 3.5, 2.5, and 2.4μg/g ww, respectively, raising concern for arsenic pollution in the Indian Ocean. Literature suggests that arsenic exposure is emitted from natural sources and the heavy use of arsenic-containing pesticides and herbicides in this region. These data suggest that research is needed in determining the extent and source of arsenic pollution in the Indian Ocean.

Levels and chemical speciation of arsenic in representative biota and sediments of a tropical mangrove wetland, India

The general concern for arsenic in the marine environment is associated with its wide distribution and potential toxicity. In the present work, concentrations and chemical speciation of arsenic were characterized in sediments and representative biota from the Indian Sundarban, the largest continuous mangrove tract formed at the mouth of the Hugli (Ganges) River estuary, northeastern part of the Bay of Bengal. Analyzed organisms included both shellfish (Macoma birmanica, Sanguinolaria acuminata and Meretrix meretrix) and finfish (Liza parsia, Liza tade, Harpodon nehereus and Eleutheronema tetradactylum). Arsenic concentrations in sediments did not exceed 4 μg g(-1) dry weight with the contribution of inorganic molecules (arsenate and arsenite) ranging from 61.7 to 81.3%. Total As (TAs) concentrations varied from less than 2 to 16 μg g(-1) in tissues of bivalves; the more elevated As accumulation was observed in gills and the mantle probably due to ion exchange properties of the mucous layer covering these organs, whereas adductor muscle and the podium showed limited values. Distribution of various arsenic compounds followed a quite similar trend in bivalve tissues; arsenobetaine (AsB) was the most dominant form followed by compounds such as dimethylarsinate (DMA), trimethyl arsine-oxide (TMAO), tetramethyl arsonium (TETRA) and arsenocholine (AsC), while inorganic arsenic (IAs) represented a minor constituent (0.2 to 6.9%). Among the fish, detritivorous/herbivorous species (L. parsia and L. tade) exhibited TAs concentrations of 10.8 and 9.71 μg g(-1) dry wt with a prevalence of AsB (52-67%) and TETRA (26-35%); higher concentrations of TAs were measured in the two carnivorous species (20.62 and 19.67 μg g(-1) dry wt, in H. nehereus and E. tetradactylum respectively) mostly as AsB (63.3-72.3%) and AsC (17.5-28.6%). The obtained results can be considered as baseline levels for arsenic in the investigated area, confirming the predominance of organoarsenicals in marine organisms compared to more toxic inorganic compounds. Considering the ecological importance of this ecosystem and the increasing anthropogenic impact, the distribution of arsenic through the food chain should be continuously monitored, using organisms of different feeding guilds as indicators.

Evidence of species-specific detoxification processes for trace elements in shorebirds

This study investigated sub-lethal effects and detoxification processes activated in free-ranging Red Knots (RKs) (Calidris canutus) from the Pertuis Charentais on the Atlantic coast of France, and compared the results with previous data obtained on another shorebird species, the Black-tailed Godwit (Limosa limosa). The concentrations of 13 trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn) were assessed in the liver, kidneys, muscle and feathers. Stable isotope analyses of carbon and nitrogen were carried out to determine whether differences in diet explained variations in elemental uptake. The mRNA expression of relevant genes (cytochrome c oxidase 1, acetyl-CoA carboxylase, Cu/Zn and Mn superoxide dismutase, catalase, metallothionein, malic enzyme), antioxidant enzyme activities (catalase, glutathione peroxidase (GPx), superoxide dismutase), and metallothionein (MT) levels were investigated to shed light on trace element detoxification and toxic effects. Although Red Knots were characterized by elevated As and Se concentrations which were potentially toxic, most elements were usually below toxicity threshold levels. The results strongly suggested a dietary specialization of Red Knots, with individuals feeding on higher trophic status prey experiencing higher As, Hg and Se burdens. Red Knots and Godwits also showed discrepancies in elemental accumulation and detoxification processes. Higher As and Se concentrations in Red Knots enhanced catalase gene expression and enzyme activity, while Godwits had higher Ag, Cu, Fe and Zn levels and showed higher MT production and GPx activity. The results strongly suggest that detoxification pathways are essentially trace element- and species-specific.

Insight on trace element detoxification in the Black-tailed Godwit (Limosa limosa) through genetic, enzymatic and metallothionein analyses

Trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn) were investigated in the liver, kidneys, muscle and feathers of 31 black-tailed godwits (Limosa limosa) accidentally killed during catches by mist net in the Pertuis Charentais, Atlantic coast of France. Analyses of carbon and nitrogen stable isotope ratios were carried out in liver, muscle and feathers in order to elucidate dietary patterns and to determine whether differences in diet explained the variation in elemental uptake. This study also aimed to have a preliminary assessment of sub-lethal effects triggered by trace elements through the investigation of gene expressions by quantitative real-time PCR, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase), and metallothionein (MT) levels. The results showed that Cr and Ni concentrations in tissues of adults were lower than in juveniles in part because adults may have eliminated these trace elements through moulting. Except for Cd and Ni, trace element concentrations were negatively correlated to the body mass of godwits. Ag, As, Hg and Se concentrations were positively linked with the trophic position of birds. The diet could be considered as a fundamental route of exposure for these elements demonstrating therefore the qualitative linkage between dietary habits of godwits and their contaminant concentrations. Our results strongly suggest that even though trace element concentrations were mostly below toxicity threshold level, the elevated concentrations of As, Ag, Cd, Cu, Fe and Se may however trigger sub-lethal effects. Trace elements appear to enhance expression of genes involved in oxidative stress defence, which indicates the production of reactive oxygen species. Moreover, birds with the highest concentrations appeared to have an increased mitochondrial metabolism suggesting that the fight against trace element toxicity requires additional energetic needs notably to produce detoxification mechanisms such as metallothioneins.

Trace element concentrations in feathers of flesh-footed Shearwaters (Puffinus carneipes) from across their breeding range

Seabirds are convenient indicators of contamination of the marine environment because feathers can be sampled non-destructively, and a great deal is known about their ecology. Flesh-footed Shearwaters (Puffinus carneipes) are of conservation concern in Australia and New Zealand, partly because ingestion of marine debris may be reducing breeding success at their largest colony. Because marine plastics accumulate contaminants in the ocean environment, an assessment of metal and metalloid contaminants was initiated. We sampled feathers from Kauwahaia (n = 18) and Lady Alice Island, New Zealand (n = 30), Lord Howe Island (n = 24) and Western Australia (n = 33) during the 2008 austral summer, making this the most complete assessment of metal and metalloid contamination of any shearwater. We found colony differences in all elements except lead and thallium. Samples from Western Australia had higher silver, aluminium, cadmium, and copper concentrations, while shearwaters from Lord Howe Island (eastern Australia) had elevated concentrations of mercury (mean ± S.D., 11221 ± 5612 ppb). We conclude that mercury, and potentially arsenic and cadmium represent toxicological concerns for this declining species.

Characteristics and nutritional and cardiovascular-health properties of seaweeds

While marine algae have traditionally formed part of the Oriental diet, their major use in Western countries has been in the phytocolloid industry. Only a few coastal communities outside Asia have customarily used seaweeds as components of special dishes. Of late, however, seaweeds have gained importance as foodstuffs in Western countries and most recently as components of functional foods because of their high dietary fiber, mineral, vitamin, and phytochemical content, low energy levels, and high concentrations of certain polyunsaturated fatty acids. The present paper reviews the available data for some of the components of the major edible algae and studies several factors that can affect their physiochemical properties (e.g., hydration, water and oil-holding capacity, fermentability, binding capacity, etc.) and, in turn, their nutritional importance. The effects of marine alga consumption on growth and body weight, mineral availability, lipid metabolism, blood pressure, and antioxidant properties are reviewed, together with preliminary data on the effects of some functional foods containing seaweeds on lipid metabolism and gene expression of enzymes engaged in antioxidant protection. This review concludes with some remarks regarding the danger of the improper use of seaweeds in herbal medications. In addition, as the properties of algae are highly dependent on their individual composition, any generalization regarding these properties may be considered misleading and scientifically inappropriate.