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Negative metal bioaccumulation impacts on systemic shark health and homeostatic balance
Abstract
Contamination by metals is among the most pervasive anthropogenic threats to the environment. Despite the ecological importance of marine apex predators, the potential negative impacts of metal bioaccumulation and biomagnification on the health of higher trophic level species remains unclear. To date, most toxicology studies in sharks have focused on measuring metal concentrations in muscle tissues associating human consumption and food safety, without further investigating potential impacts on shark health. To help address this knowledge gap, the present study evaluated metal concentrations in the gills, muscle, liver, and rectal gland of coastal sharks opportunistically sampled from Brazilian waters and tested for potential relationships between metal bio-accumulation and general shark health and homeostatic balance metrics. Results revealed high metal concentrations in all four tissue types, with levels varying in relation to size, sex, and life-stage. Metal concentrations were also associated with serum biomarkers (urea, lactate, ALT, triglycerides, alkaline phosphatase, and phosphorus) and body condition, suggesting potential negative impacts on organismal health.
... Fish are exposed to metals both from the dietary route and from the surrounding water column (Lee et al., 2019). Rubidium has several uses in the medical field, such as in positron emission tomographic (PET) imaging, epilepsy treatment, and the ultracentrifugal separation of nucleic acids and viruses, and is also employed in in fiber optic telecommunication systems, night-vision devices and photoelectric cells, among others (Butterman & Reese, 2003), Possible anthropogenic sources of Rb and Cs include coalburning and space rocket fuel (Campbell et al., 2005;Wosnick et al., 2021), as well as electronic waste (e-waste) disposed of incorrectly and inadequately recycled and processed (Huang et al., 2014), as it has been recently reported as present in high amounts in these electronic residues (Forti et al., 2020). Furthermore, it may also become bioavailable in the aquatic environment due to dredging activities, that restore ancient sedimentary characteristics or expose contaminated sediments to the water column (Mill-Homens, 2013). ...
... Thus, as stated by Hauser-Davis et al. (2021), establishing baseline elemental data is paramount in biomonitoring efforts, conservation measures and public health assessments. In this regard, concerning elasmobranchs, Rb data have only been reported for two arctic species, the Pacific sleeper shark, at 0.454 mg kg -1 w.w. in liver (n = 14) and the Greenland shark, at 0.38 mg kg -1 w.w. in liver (n = 24) (McMeans et al., 2007), and recently, nurse sharks (Ginglymostoma cirratum) from Northeastern Brazil (1.36 ± 0,64 mg kg -1 w.w. in muscle tissue) (Wosnick, 2021). ...
... Therefore, the seleniumdetoxification route, either through metal complexation and/or selenoprotein action (Tapieiro;Townsend & Tew, 2003;Yoneda & Suzuki, 1997) does not seem to be significant for Rb detoxification in this species, although further assessments in this regard are, of course, required. Interesting assessments would include metallothionein and reduced glutathione evaluations, as both are known detoxification routes for other metals and have been demonstrated as efficient excretion mechanisms in other elasmobranch species Walker et al., 2014;Wosnick et al., 2021). ...
Although pollution has been recently identified as a priority for elasmobranch conservation, metal contamination assessments in sharks and rays are still scarce, especially in southeastern Brazil. In this regard, rubidium (Rb) is a biomagnifying non-essential element determined in only two elasmobranch assessments to date. Therefore, the aim of this study was to obtain baseline Rb data and discuss the implications of Rb concentrations in the muscle and liver of the vulnerable Caribbean Sharpnose shark Rhizoprionodon porosus from Southeastern Brazil. Samples from 18 juvenile specimens were analyzed by inductively coupled plasma mass spectrometry following acid decomposition. When grouping males and females, muscle concentrations (1.117 ± 0.269 mg kg-1 w.w.) were significantly higher than liver (0.677 ± 0.146 mg kg-1 w.w.), indicating probable Rb bioaccumulation. Significant differences were observed between male and female liver and muscle Rb concentrations, both higher in muscle. Females also presented significantly higher liver concentrations. A negative correlation was observed between total length and liver Rb when grouping males and females, which may indicate the contaminant dilution effect, while a positive correlation was noted between total length and muscle Rb for males, indicating bioaccumulation processes. Significant ecological concerns regarding Rb contamination for this group are, therefore, noted, requiring further investigations.Keywords: Chondrichthyes, toxic elements, bioaccumulation, environmental pollution, Elasmobranchii.
... Fish are exposed to metals both from the dietary route and from the surrounding water column (Lee et al., 2019). Rubidium has several uses in the medical field, such as in positron emission tomographic (PET) imaging, epilepsy treatment, and the ultracentrifugal separation of nucleic acids and viruses, and is also employed in in fiber optic telecommunication systems, night-vision devices and photoelectric cells, among others (Butterman & Reese, 2003), Possible anthropogenic sources of Rb and Cs include coalburning and space rocket fuel (Campbell et al., 2005;Wosnick et al., 2021), as well as electronic waste (e-waste) disposed of incorrectly and inadequately recycled and processed (Huang et al., 2014), as it has been recently reported as present in high amounts in these electronic residues (Forti et al., 2020). Furthermore, it may also become bioavailable in the aquatic environment due to dredging activities, that restore ancient sedimentary characteristics or expose contaminated sediments to the water column (Mill-Homens, 2013). ...
... Thus, as stated by Hauser-Davis et al. (2021), establishing baseline elemental data is paramount in biomonitoring efforts, conservation measures and public health assessments. In this regard, concerning elasmobranchs, Rb data have only been reported for two arctic species, the Pacific sleeper shark, at 0.454 mg kg -1 w.w. in liver (n = 14) and the Greenland shark, at 0.38 mg kg -1 w.w. in liver (n = 24) (McMeans et al., 2007), and recently, nurse sharks (Ginglymostoma cirratum) from Northeastern Brazil (1.36 ± 0,64 mg kg -1 w.w. in muscle tissue) (Wosnick, 2021). ...
... Therefore, the seleniumdetoxification route, either through metal complexation and/or selenoprotein action (Tapieiro;Townsend & Tew, 2003;Yoneda & Suzuki, 1997) does not seem to be significant for Rb detoxification in this species, although further assessments in this regard are, of course, required. Interesting assessments would include metallothionein and reduced glutathione evaluations, as both are known detoxification routes for other metals and have been demonstrated as efficient excretion mechanisms in other elasmobranch species Walker et al., 2014;Wosnick et al., 2021). ...
Although pollution has been recently identified as a priority for elasmobranch conservation, metal contamination assessments in sharks and rays are still scarce, especially in southeastern Brazil. In this regard, rubidium (Rb) is a biomagnifying non-essential element determined in only two elasmobranch assessments to date. Therefore, the aim of this study was to obtain baseline Rb data and discuss the implications of Rb concentrations in the muscle and liver of the vulnerable Caribbean Sharpnose shark Rhizoprionodon porosus from Southeastern Brazil. Samples from 18 juvenile specimens were analyzed by inductively coupled plasma mass spectrometry following acid decomposition. When grouping males and females, muscle concentrations (1.117 ± 0.269 mg kg-1 w.w.) were significantly higher than liver (0.677 ± 0.146 mg kg-1 w.w.), indicating probable Rb bioaccumulation. Significant differences were observed between male and female liver and muscle Rb concentrations, both higher in muscle. Females also presented significantly higher liver concentrations. A negative correlation was observed between total length and liver Rb when grouping males and females, which may indicate the contaminant dilution effect, while a positive correlation
... In addition, the liver, a large organ and rich in lipids, provides a significant compartment of up to 20 % of the body mass for the accumulation of lipophilic pollutants and constitutes the main organ involved in the metal detoxification process (Cullen et al., 2019;Hauser-Davis et al., 2021). Thus, previous studies aimed to understand if the molecular effects of pollutants on these animals are still scarce, and usually, are aimed at the analysis of biochemical markers such as ethoxyresorufin-O-deethlyase (EROD), intracellular reactive oxygen species (ROS), glutathione S-transferase (GST), lactate dehydrogenase (LDH), metallothionein, and serum markers (Cullen et al., 2019;Wosnick et al., 2021a;Wosnick et al., 2021b;Hauser-Davis et al., 2021). ...
... Another problem related to continued exposure to metals is the bioaccumulation of pollutants in organisms. Previous studies indicate that the three species analyzed in this study demonstrate high potential for bioaccumulation (Shipley et al., 2021), with positive correlations observed between the accumulation of metals and the total length of individuals of G. cuvier (Wosnick et al., 2021b). In the present study, the positive relation observed between the length of individuals and the total genomic damage frequency for all sharks, especially N. brevirostris, suggests a bioaccumulation process. ...
... In this way, these individuals may present an increase in concentrations of metals and other compounds (such as surfactants) in the body, due to the consumption of more contaminated prey over time, as well as an increased time of exposure to environmental contamination (chronic exposure) (Chumchal and Hambright, 2009;Piraino and Taylor, 2009). The effects of theses exposure to pollutants may be reflected in the high frequency of cells with genomic damage observed in the evaluated sharks, in addition to effects observed in previous studies, such as the induction of DNA adducts, links between DNA molecules and metals or other pollutants, which are crucial factors in the development of cancer in fish and are linked to deficiencies in reproduction, development, and the reproductive immune system (Matsumoto et al., 2006), as well as disorders of the osmoregulatory system (De Boeck et al., 2007), oxidative stress (Wosnick et al., 2021a), changes in liver function (Wosnick et al., 2021b) and morphological abnormalities (Hauser-Davis et al., 2020) in elasmobranchs. ...
Elasmobranchs can bioaccumulate and biomagnify pollutants. However, few studies are directed to the effects of pollutants on the health of these animals, and in most cases, are limited to the analysis of biochemical markers. Thus, the incidence of genomic damage among shark species inhabiting a protected ocean island in the South Atlantic was investigated in association with the analysis of pollutants in seawater sample. High levels of genomic damage were identified, especially in Negaprion brevirostris and Galeocerdo cuvier, in addition to interspecific variations that may be related to characteristics such as animal size, metabolism and habits. High concentrations of Surfactants were observed in seawater sample, in addition to low concentrations of Cadmium, Lead, Copper, Chromium, Zinc, Manganese, and Mercury. The results evidenced the potential of shark species as a bioindicator of environmental quality and allowed assessing the anthropic impact on the archipelago, which currently drives its economy through tourism.
... Environmental pollution, in particular, may directly decrease organism resilience to other stressors, as it results in significantly decreased immune system responses in many vertebrates, including fish (Watts et al., 2001). In fact, in a study previously performed with sharks in the same region, including I. oxyrhynchus, results pointed to a negative metal bioaccumulation effect on their systemic health (Wosnick et al., 2021a) which, combined with fishing pressure, may explain the poor health status of the studied population. Thus, future studies on genetic structure, ecotoxicology, and molecular biology are necessary to better understand the underlying factors that are affecting the health and potentially the fitness of Daggernose sharks not only in the state of Maranhão, but among other fragmented populations. ...
... As phosphorus is a predominantly intracellular ion, increased extracellular concentrations indicate cell disruption, leading to excessive leakage (D'Arcy, 2019). In this context, as elasmobranch mortality due to fishing is mainly caused by flight or fight responses, biomarkers indicative of cell rupture/damage have been proven reliable (Wosnick et al., 2017;Wosnick et al., 2021a), always increasing circulating levels upon allostatic overload, as in the case of lactate. That being said, our results indicate that I. oxyrhynchus exhibits similar vulnerability to capture stress when compared to the well-known vulnerable hammerhead sharks, configuring another shark species heavily affected by fishing with little chances of post-release survival. ...
... Hepatic damage may also result in decreased environmental contaminant metabolization and subsequent excretion, as the liver is the main detoxifying organ in vertebrates (Yao et al., 2019). This, in turn, leads to higher circulating pollutant levels and significant deleterious physiological effects, including oxidative stress, altered hepatocellular lipid metabolism, citotoxicity and, potentially, genotoxicity which have been reported for many taxonomic groups (Hui et al., 2017;Gabriel et al., 2020;de Farias Araujo et al., 2022), including sharks (Hauser-Davis et al., 2021;Wosnick et al., 2021a), potentially affecting animal health conditions due to altered physiological, systemic and, ultimately, behavioral aspects (Wosnick et al., 2021b;Willmer et al., 2022;Wosnick et al., 2022). ...
The current Isogomphodon oxyrhynchus (Daggernose Shark) population status points to 99% losses in the last decade due to certain biological traits, site fidelity, and historical high representativeness as bycatch in artisanal fisheries. This species is listed as Critically Endangered (CR), both in the IUCN and the Brazilian Red Lists. Its vulnerability is so high that its recovery potential requires protection from ongoing fishing pressure.
In this context, this study aimed to evaluate the health status of Daggernose sharks and their ability to cope with allostatic overload in a comparative analysis with other Carcharhinid and Sphyrnid sharks. Sharks incidentally caught by the artisanal fleet in the state of Maranhão, on the Brazilian Amazon Coast, were sampled for blood, and serum was used to assess biochemical markers. The findings indicate significant differences in Daggernose Shark homeostatic capacity for ALP, ALT/GTP, creatinine, lactate, urea, total cholesterol, and triglycerides, pointing to lower health scores and recovery capacity when compared to other Carcharhiniformes inhabiting the same region.
It is possible that such vulnerability is a result of fisheries-induced evolution, leading to remaining populations with very low chances of fully recovering. Conservation planning is thus urgent, as current legislation based on fishing bans does very little for the species. International collaboration and longterm recovery measures are necessary, including the creation of MPAs specially designed for the species and captive maintenance aiming to monitor health status and carry out breeding attempts.
... Following their assimilation, cellular alterations, such as protein peroxidation and carbonylation and the production of reactive oxygen species may take place, the latter of which, when unbalanced, lead to oxidative stress, cell membrane damage and, consequently, cell death (Decataldo et al., 2004;Monteiro et al., 2020). In addition, the concentrations and activities of different proteins, enzymes, and metabolic products necessary for the proper functioning of metabolism and homeostatic balance may be affected, leading to physiological and systemic damage (Wosnick et al., 2021). Because of this, subcellular metal partitioning assessments are paramount to better understand metal accumulation and toxicity mechanisms (Vijver et al., 2004), in turn aiding in biomonitoring efforts and guide conservation actions. ...
... In fact, about 36% of all elasmobranchs are currently categorized as endangered by the International Union for the Conservation of Nature (IUCN) (IUCN, 2021) and 17.16% of these are classified as Data Deficient, indicating lack of minimal information for population assessment (Mace et al., 2008;Dulvy et al., 2014). Metal contamination in this group has been reported as resulting in compromised osmoregulatory capacity, acid-base balance, metabolic energy, and liver functioning (Wosnick et al., 2021), which, in turn, can cause reproductive, survival and, ultimately, ecological damage. Metal exposure also directly affects elasmobranch physical and health conditions, reflected, for example, in decreased body condition (Wosnick et al. al., 2021). ...
... Metal contamination in this group has been reported as resulting in compromised osmoregulatory capacity, acid-base balance, metabolic energy, and liver functioning (Wosnick et al., 2021), which, in turn, can cause reproductive, survival and, ultimately, ecological damage. Metal exposure also directly affects elasmobranch physical and health conditions, reflected, for example, in decreased body condition (Wosnick et al. al., 2021). Notably, elasmobranch sex and life stages can influence metal bioaccumulation patterns and their consequent systemic health effects (Wosnick et al., 2021;Amorim-Lopes et al., 2019). ...
This study comprises a novel report on subcellular metal partitioning and metallothionein (MT) metal detoxification efforts in lesser numbfish (Narcine brasiliensis) electric ray specimens, as well as the first assessment on MT contents in any ray electric organ. Individuals sampled from an area in Southeastern Brazil affected by the Mariana dam rupture disaster were assessed concerning subcellular metal partitioning and MT metal-detoxification in the liver, gonads, electric organ and muscle of both adults and embryos. Yolk was also assessed when available. Relative total and heat-stable (bioavailable) metal and metalloid comparisons between adults and embryos in different developmental stages demonstrates maternal transfer of both total and bioavailable metals and significant MT associations demonstrate the detoxification of As, Ag, Mn, Ni, Cd, Co, Cu, Se and V through this biochemical pathway. Our findings expand the lacking ecotoxicological assessments for this near-threatened species and indicates significant ecological concerns, warranting further biomonitoring efforts.
... The Complimentary Contributor Copy females, as they are related to lower body metrics (Wosnick et al. 2021). However, for males, higher concentrations of copper and iron are related to higher condition factors, indicating that the effects of accumulation may be sex-dependent in sharks. ...
... Boeck, Grosell, and Wood 2001;Grosell, Wood, and Walsh 2003), respiratory capacity (Eyckmans et al. 2013;Gudrun De Boeck, Grosell, and Wood 2001), acid-base balance (Wosnick et al. 2021;Gudrun De Boeck, Grosell, and Wood 2001) and energetic metabolism (Eyckmans et al. 2013;Wosnick et al. 2021). ...
... Boeck, Grosell, and Wood 2001;Grosell, Wood, and Walsh 2003), respiratory capacity (Eyckmans et al. 2013;Gudrun De Boeck, Grosell, and Wood 2001), acid-base balance (Wosnick et al. 2021;Gudrun De Boeck, Grosell, and Wood 2001) and energetic metabolism (Eyckmans et al. 2013;Wosnick et al. 2021). ...
During the months of January and November 2011 were captured eight dolphins (four females and four males) in Laguna de Terminos, Campeche, Mexico in order to take samples for health and for use with a satellite transceiver. Transmitters were used Wildlife Computers Company Model MK -10, specially designed to be placed in medium sized dolphin. It was tracking the movements of individuals over a period of two to four weeks showing a main mobility in the north-central part of the lagoon of terms and only a few males left the lagoon off the Gulf of Mexico for a short time. Seven of the eight subjects had adequate health status to the wild and only the longest female presented skin lesions caused by infectious agents (bacteria or viruses possibly), and several shark bite scars. It seems that neither the stress of capture and handling of animals led to abandon their usual areas. It was found that females use a larger area for their activities (of 260-340 km2), whereas in this area males ranged from 120 to 350 km2. The high site fidelity observed, showing that these individuals know the area they inhabit taking advantage of conditions Laguna de Terminos offers to meet their needs for food, shelter and reproduction. This is the first scientific catch of the species in the southern Gulf of Mexico to the use of satellite transmitters.
... The K is a valuable and simple tool which may indicate general fish health contaminant effects (Bervoets and Blust 2003;Linde-Arias et al. 2008), and has been reported as significantly correlated to metals, such as copper females, as they are related to lower body metrics (Wosnick et al. 2021). However, for males, higher concentrations of copper and iron are related to higher condition factors, indicating that the effects of accumulation may be sex-dependent in sharks. ...
... Although little is known about the physiological impacts of pollution on elasmobranchs, there is growing evidence of impairment for both organic and inorganic pollutants. Most studies have focused on the negative effects on osmoregulation processes (Kinne-Saffran and Kinne 2001; Gudrun De Boeck, Grosell, and Wood 2001;Grosell, Wood, and Walsh 2003), respiratory capacity (Eyckmans et al. 2013;Gudrun De Boeck, Grosell, and Wood 2001), acid-base balance (Wosnick et al. 2021;Gudrun De Boeck, Grosell, and Wood 2001) and energetic metabolism (Eyckmans et al. 2013;Wosnick et al. 2021). ...
... Although little is known about the physiological impacts of pollution on elasmobranchs, there is growing evidence of impairment for both organic and inorganic pollutants. Most studies have focused on the negative effects on osmoregulation processes (Kinne-Saffran and Kinne 2001; Gudrun De Boeck, Grosell, and Wood 2001;Grosell, Wood, and Walsh 2003), respiratory capacity (Eyckmans et al. 2013;Gudrun De Boeck, Grosell, and Wood 2001), acid-base balance (Wosnick et al. 2021;Gudrun De Boeck, Grosell, and Wood 2001) and energetic metabolism (Eyckmans et al. 2013;Wosnick et al. 2021). ...
Marine ecosystems in general, and coastal ecosystems in particular, suffer significant, diverse and, unfortunately, increasing, destructive impacts due to anthropogenic activities, including habitat devastation, biodiversity losses, and chemical contamination, resulting in severe ecological and human health effects. Elasmobranchs, comprising sharks and batoids (stingrays, skates, guitarfishes and sawfishes), in particular, play a key role in marine trophic network interactions, and threats to this group may lead to severe ecosystem imbalances. This group suffers several pressures, such as the finning market, meat consumption in developing countries, the sale of elasmobranch-derived products, climate change and chemical contamination, among others. Specifically concerning chemical contamination, several elasmobranch species occupy intermediate to high trophic levels, therefore becoming highly exposed to environmental contamination through the dietary route or through sediment association. This may result in both ecological effects, as several contaminants can affect elasmobranch physiology, resulting in decreased recruitment rates, reproductive failures and maternal contaminant transfer, and human health issues through elasmobranch meat consumption. Yet, interestingly, contamination assessments concerning this group and its implications, both ecological and human, are still scarce worldwide, albeit increasing in recent years. Taking this scenario into account, this chapter will discuss an integrated ecotoxicological view on elasmobranch conservation regarding chemical contamination, alongside potential ecological outcomes for this group and human impacts derived from elasmobranch consumption.
... The Complimentary Contributor Copy females, as they are related to lower body metrics (Wosnick et al. 2021). However, for males, higher concentrations of copper and iron are related to higher condition factors, indicating that the effects of accumulation may be sex-dependent in sharks. ...
... Boeck, Grosell, and Wood 2001;Grosell, Wood, and Walsh 2003), respiratory capacity (Eyckmans et al. 2013;Gudrun De Boeck, Grosell, and Wood 2001), acid-base balance (Wosnick et al. 2021;Gudrun De Boeck, Grosell, and Wood 2001) and energetic metabolism (Eyckmans et al. 2013;Wosnick et al. 2021). ...
... Boeck, Grosell, and Wood 2001;Grosell, Wood, and Walsh 2003), respiratory capacity (Eyckmans et al. 2013;Gudrun De Boeck, Grosell, and Wood 2001), acid-base balance (Wosnick et al. 2021;Gudrun De Boeck, Grosell, and Wood 2001) and energetic metabolism (Eyckmans et al. 2013;Wosnick et al. 2021). ...
... A growing concern about the negative effects of pollution in sharks is noted, as these animals are apex predators and, in addition to bioaccumulation concerns, certain elements also display the ability to biomagnify through the food chain, leading to risks concerning this group (Escobar-Sánchez et al., 2011;Olmedo et al., 2013;Matulik et al., 2017). Studies indicate that non-essential metallic elements displaying potential toxicity accumulate mainly in shark liver and muscle tissue (Terrazas-López et al., 2016), although other organs, such as gonads, gills, kidneys, rectal gland and brain, can also undergo bioaccumulation processes (Frías-Espericueta et al., 2014;Gilbert et al., 2015;Wosnick et al., 2021). ...
... Cadmium, mercury, and lead are noteworthy among contaminants with the potential to disrupt reproduction and, consequently, population recruitment in vertebrates (Kime, 1995;Massányi et al., 2020). These elements can also affect cardiac capacity, vascular dynamics (Evans and Weingarten, 1990;Wang et al., 1999), and regulatory processes associated to the homeostatic balance in sharks (Forrest et al., 1997;Kinne-Saffran and Kinne, 2001;Eyckmans et al., 2013;Wosnick et al., 2021). Furthermore, as some elements tend to biomagnify in higher trophic levels (Lozano-Bilbao et al., 2018;Tiktak et al., 2020), it is particularly interesting to assess their concentrations in the tissues of large-bodied sharks. ...
... An exploratory Principal Component Analysis was performed to first verify potential associations between the elements (i.e., Cd, Hg, Pb, Rb, and Se) and MT concentrations between both sampling seasons (rainy and dry), based on other assessments of this kind for different biota reported in the literature (De Boeck et al., 2003;O'Brien et al., 1995;Amiard et al., 2008;Subotić et al., 2013;Aru et al., 2016;Okay et al., 2016;Wosnick et al., 2021). The number of PCA factors were chosen based on Kaiser's rule, where the Principal Components (PCs) with the highest explanatory power display eigen values higher than 1 (Méndez et al., 1993). ...
It is widely recognized that apex predators, such as large sharks with highly migratory behavior, are particularly vulnerable to pollution, mainly due to biomagnification processes. However, in highly impacted areas, mesopredator sharks with resident behavior can be as vulnerable as apex sharks. In this context, this study evaluated cadmium (Cd), mercury (Hg), lead (Pb), and rubidium (Rb) concentrations, as well as the potentially protective effects of selenium (Se) and the behavior of two non-enzymatic biomarkers, metallothionein (MT) and reduced glutathione (GSH), employing the Atlantic nurse shark Ginglymostoma cirratum as a study model and compared the results with other resident benthic sharks, as well as highly mobile apex sharks. Muscle tissue samples from 28 nurse sharks opportunistically sampled from the Brazilian Amazon Coast were analyzed. Lower metal concentrations were observed for Pb, Rb and Se in the rainy season, while statistically significant correlations between metals were observed only between Hg and Cd and Pb and Se. Molar ratio calculations indicate potential protective Se effects against Pb, but not against Cd and Hg. No associations between MT and the determined metals were observed, indicating a lack of detoxification processes via the MT detoxification route. The same was noted for GSH, indicating no induction of this primary cellular antioxidant defense. Our results indicate that benthic/mesopredator sharks with resident behavior are, in fact, as impacted as highly mobile apex predators, with the traditional detoxification pathways seemingly inefficient for the investigated species. Moreover, considering the studied population and other literature data, pollution should be listed as a threat to the species in future risk assessments.
... The latter could account for the bioaccumulation of pollutants in its tissues over time, making it a useful bio-monitor for longer-term exposure to sea pollutants. One of the important parameters for choosing S. canicula as an indicator of pollutants [31][32][33] is that it is a hardy and resilient species that can tolerate a range of different environmental conditions. This means that it can be found in a range of different habitats and is less likely to be affected by natural fluctuations in the environment, making it easier to identify changes in pollutant levels [34]. ...
... However, in some cases, the concentration of heavy metals in the muscle tissue can also be high enough to make the consumption of shark meat potentially hazardous to humans. According to Wosnick et al. [32], S. canicula exposure to heavy metals could lead to alterations in hepatic markers with the bioaccumulation of Co, Fe, and Hg in the liver of sharks, in urea and lactate with the bioaccumulation of Fe and Hg in the gills. Moreover, in sharks, the rectal gland plays an important role in shark osmoregulation and associated homeostatic balance. ...
In this historical context, the Mediterranean Sea faces an increasing threat from emerging pollutants such as pharmaceuticals, personal care products, heavy metals, pesticides and microplastics, which pose a serious risk to the environment and human health. In this regard, aquatic invertebrates and fish are particularly vulnerable to the toxic effects of these pollutants, and several species have been identified as bio-indicators for their detection. Among these, bivalve molluscs and elasmobranchs are now widely used as bio-indicators to accurately assess the effects of contaminants. The study focuses on the catshark Scyliorhinus canicular and on the Mediterranean mussel Mytilus galloprovincialis. The first one is a useful indicator of localised contamination levels due to its exposure to pollutants that accumulate on the seabed. Moreover, it has a high trophic position and plays an important role in the Mediterranean Sea ecosystem. The bivalve mollusc Mytilus galloprovincialis, on the other hand, being a filter-feeding organism, can acquire and bioaccumulate foreign particles present in its environment. Additionally, because it is also a species of commercial interest, it has a direct impact on human health. In conclusion, the increasing presence of emerging pollutants in the Mediterranean Sea is a serious issue that requires immediate attention. Bivalve molluscs and elasmobranchs are two examples of bio-indicators that must be used to precisely determine the effects of these pollutants on the marine ecosystem and human health.
... The impacts of TMs on Chondrichthyan species were reported only in five studies (Pimienta et al., 2005;Wosnick et al., 2021aWosnick et al., , 2021bHauser-Davis et al., 2020b. Effects of TMs were measured using diverse biomarkers such as Metallothioneins (MTs) (Pimienta et al., 2005;Wosnick et al., 2021b;Hauser-Davis et al., 2022) and reduced glutathione (GSH) (Wosnick et al., 2021b), in muscle and liver, and serum biomarkers (urea, lactate, ALT, triglycerides, alkaline phosphatase, and phosphorus) in gills, liver, and rectal gland (Wosnick et al., 2021a). ...
... The impacts of TMs on Chondrichthyan species were reported only in five studies (Pimienta et al., 2005;Wosnick et al., 2021aWosnick et al., , 2021bHauser-Davis et al., 2020b. Effects of TMs were measured using diverse biomarkers such as Metallothioneins (MTs) (Pimienta et al., 2005;Wosnick et al., 2021b;Hauser-Davis et al., 2022) and reduced glutathione (GSH) (Wosnick et al., 2021b), in muscle and liver, and serum biomarkers (urea, lactate, ALT, triglycerides, alkaline phosphatase, and phosphorus) in gills, liver, and rectal gland (Wosnick et al., 2021a). Many authors provided a baseline for understanding the maternal offloading of trace metals in the sharks Rhizoprionodon lalandii, R. porosus, Mustelus higmani, Squalus albicaudus, and Pseudobatos horkelii, and in the ray Narcine brasiliensis (Amorim-Lopes et al., 2019Souza-Araujo et al., 2020;Hauser-Davis et al., 2020aMartins et al., 2022;Willmer et al., 2022). ...
This is the first research which extensively compiles all the available scientific literature on the presence of trace metals (TMs), persistent organic pollutants (POPs), and plastic debris in Chondrichthyan species inhabiting South America (including the Atlantic and Pacific Oceans), providing an insight into Chondrichthyans as bioindicators of pollutants as well as the impacts of pollutant exposure on the organisms. Seventy-three studies were published in South America between 1986 and 2022. While 68.5% focused on TMs, 17.8% on POPs, and 9.6% on plastic debris. Brazil and Argentina were at the top in terms of the number of publications; however, there is an absence of information regarding pollutants for Chondrichthyans in Venezuela, Guyana, and French Guiana. Of the 65 Chondrichthyan species reported, 98.5% belong to the Elasmobranch group, and 1.5% from the Holocephalans. Most studies focused on Chondrichthyans of economic importance, and the most analyzed organs were the muscle and liver. There is a lack of studies on Chondrichthyan species with low economic value and critical conservation status. Due to their ecological relevance, distribution, accessibility, high trophic position, capacity to accumulate high levels of pollutants, and the number of studies published, Prionace glauca and Mustelus schmitii seem to be adequate to serve as bioindicators. For TMs, POPs, and plastic debris there is a lack of studies focusing on the pollutant levels as well as their effect on Chondrichthyans. Future research reporting TMs, POPs, and plastic debris ocurrences in Chondrichthyan species are required in order to increase the scarce databases about pollutants in this group, with a clear need for further research on the responses of chondrichthyans to pollutants, as well as making inferences about the potential risks to the ecosystems and human health.
... In a recent study, Wosnick et al. (2021) undertook an assessment of the consequences stemming from exposure to various metallic elements among free-ranging sharks, adopting a multispecies approach within a globally significant hotspot for elasmobranch conservation. Detrimental physiological effects were evident, attributed to the assimilation of both essential and non-essential metallic elements within target organs. ...
Metal contamination poses a significant threat to elasmobranchs, underscoring the need for targeted conservation approaches. The critically endangered Brazilian guitarfish, Pseudobatos horkelii, confronts an array of challenges, notably overexploitation, putting its survival at risk. Our study investigated the potential toxicity arising from arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) contamination across various adult guitarfish tissues from southeastern Brazil. Serological stress indicators, nutritional metabolites, and creatinine, an organ function marker, were also assessed, and Selenium (Se) levels were also investigated for possible protective effects. Our investigation unveiled significant correlations between metal concentrations and the determined physiological markers, shedding light on potential adverse effects. Remarkably, six correlations were indicative of how Hg and Pb negatively impact hepatic metabolite assimilation, while As was shown to influence renal phosphorus dynamics, Cd to affect rectal gland phosphorus regulation, and Pb to influence creatinine production in muscle tissue. Furthermore, Se demonstrated protective properties against Cd, Hg, and Pb, suggesting a role in alleviating the toxicity of these elements. Despite probable protective Se influences, the detected elemental interactions still suggest potential for organ impairment. These findings gain heightened significance within the context of the cumulative stressors faced by the Brazilian guitarfish, with metal contamination exhibiting the capacity to erode this species resilience against both anthropogenic and environmental pressures, thereby disrupting systemic equilibrium and jeopardizing wild populations. By investigating the intricate balance between metal accumulation and physiological consequences, our study contributes with crucial insights into potential conservation strategy formulations towards pollution for this critically endangered elasmobranch species.
... Human-induced cryptic mortality or unnoticed health impairment in sharks may derive from several processes including fisheries discards (Campana et al., 2016;Binstock et al., 2023), habitat loss (Jennings et al., 2008), climate change (Rosa et al., 2014), and marine pollution (Alves et al., 2016;Wosnick et al., 2021). Since population assessments report many shark populations to be currently threatened at varying degrees (Dulvy et al., 2021), it is essential that both the magnitude and impacts of this type of adversity are suitably identified. ...
Plastic waste is currently a major threat to marine ecosystems, and the ever-growing production of plastic materials suggests that this scenario will not change soon. Understanding cryptic effects of plastic debris on keystone marine species is warranted to address ecosystem-level impacts caused by plastic pollution. This study reports on plastic entanglement in top predator tiger sharks, Galeocerdo cuvier, from the western South Atlantic Ocean. Circular plastic straps produced severe trauma in 3 % of all tiger sharks sampled and led to abnormal anatomical development, indicating worrisome incidence and consequences of plastic entanglement in this species. Removing the plastic strap from one shark which had been entangled for at least 9 months was probably the cause for the shark having experienced post-release mortality. This suggests that, in some circumstances, strap removal is not effective to promote the survival of entangled sharks. Eliminating the circular integrity of plastic materials at first use should contribute to mitigate some of the impacts of plastic pollution on marine megafauna since this shape might be determinant in the process of shark entanglement.
... MeHg concentration in Squalus sharks from Binuangeun was lower than in Brazil [21] and Southeast Australia [22]. Due to limited studies on S. hemipinis, mercury concentrations in these sharks compared to S. acanthias and S. albicaudus indicate the same habitat on the shelf and upper slopes of the ocean (from 0-600 m) [23]. Some studies have shown that several factors influence mercury accumulation in sharks, such as age, body length, habitat, sex and local pollution [24][25]. ...
This study analyzed MeHg in a fast, simple, low-waste, and accurate by using ultra-high liquid chromatography coupled with inductively coupled plasma mass spectrometry. Simple preparation by liquid extraction with sonication at room temperature was effective extract MeHg from Certified Reference Material (CRM) and shark meat samples. Effective MeHg separation was achieved in less than 300 s using a C18 Hypersil Gold analytical column with a mobile gradient phase of 0.5% (w/v) L-cysteine in 2% (v/v) HNO3 and 100% methanol. The MeHg was extracted from 100 mg of shark meat using 1 mL of 0.5% (w/v) L-cysteine in 2% (v/v) HNO3 and sonicated for 30 min. Analysis of certified reference material (DORM-4) showed values between the experimental and certified values. The observed limit of detection and quantification MeHg were 0.86 and 2.85 pg/L, respectively. This method was applied to measure MeHg in shark meat from Binuangeun areas. The MeHg concentration in Rhizoprionodon acutus was 0.22–0.63 mg/kg wet weight (w.w.), Squalus hemipinis 0.68–1.14 mg/kg w.w., and 0.29–1.22 mg/kg w.w. for Sphyrna lewini. This study provides a quick and easy method to evaluate MeHg in shark meat or other seafood products and applies to many samples in a single assay.
... The lack of data on the Chondrichthyes' transcriptomes is a combination of many factors, beginning with the logistics of RNA preservation that can be challenging and costly on field work [198]; chondrichthyes' meat presents a low commercial value (even though fin market is highly valuable) [199] which can lower the economic interest of preserving this class; and the difficulty of sampling these specimens [200] due to their biology and costs of marine expeditions. To tackle this, opportunistic sampling can be performed while on board of commercial or recreational fishing boats, as previously accomplished [201][202][203]. This can limit the experimental design due to the inconsistent sampling. ...
Chondrichthyes (including sharks, rays, and chimaeras) are a class of jawed cartilaginous fishes (with skeletons composed primarily of cartilage), with major relevance to the marine ecosystems and to humanity. However, cartilaginous fishes are facing various threatens, inflicting abrupt declines in their populations. Thus, critical assessment of available molecular genetic variation, particularly retrieved from Chondrichthyans' transcriptomic analyses, represents a major resource to foster genomics research in this ancient group of vertebrate species. Briefly, RNA-Seq involves the sequencing of RNA strands present on a target tissue, which can assist genome annotation and elucidate genetic features on species without a sequenced genome. The resulting information can unravel responses of an individual to environmental changes, evolutionary processes, and support the development of biomarkers. We scrutinized more than 800 RNA-Seq entries publicly available, and reviewed more than one decade of available transcriptomic knowledge in chondrichthyans. We conclude that chondrichthyans’ transcriptomics is a subject in early development, since not all the potential of this technology has been fully explored, namely their use to prospectively preserve these endangered species. Yet, the transcriptomic database provided findings on the vertebrates’ evolution, chondrichthyans’ physiology, morphology, and their biomedical potential, a trend likely to expand further in the future.
... Therefore, studies on the contamination of muscle tissue in fishes by metals have intensified. Determining levels in the edible portion is critical to protecting human health, as the consumption of contaminated fish is the primary transfer route to humans and poses serious a health problem for consumers (da Silva Rabitto et al., 2011;Franco-Fuentes et al., 2021;Gusso-Choueri et al., 2018;Kalantzi et al., 2019;Pérez-Domínguez et al., 2012;Rajeshkumar and Li, 2018;Renieri et al., 2019;Souza-Araujo et al., 2021;Sow et al., 2013;Tang et al., 2013;Töre et al., 2021;Varol and Sünbül, 2020;Wosnick et al., 2021). ...
The aim of the present study was to determine concentrations of cadmium, copper, chromium, manganese and iron in fishes in the São Marcos (SMB), São Jose (SJB) and Arraial (AB) Bays. Metal concentrations were determined using inductively coupled plasma optical emission spectrometry. Mean Cd and Cr levels were above the permissible limits set by different international or national guidelines in all three bays, whereas copper levels were well below the maximum acceptable limit. High concentrations of iron were found in all species analyzed, whereas high concentrations of manganese were found, especially in specimens caught in SJB. Spatial analysis indicated significant differences among the elements investigated. Copper was correlated more with SMB and AB as well as the species Macrodon ancylodon (carnivore) and Sciades herzbergii (omnivore). Cadmium and iron were strongly associated with AB and SJB, while manganese was only associated with SJB, mainly in carnivorous and herbivorous species.
... Nevertheless, the accumulation of trace elements has a negative effect on the health of elasmobranch species too (Depew et al., 2012;Bezerra et al., 2019;Merly et al., 2019;Tiktak et al., 2020;Wosnick et al., 2021). Few studies have evaluated the effects from the contamination of specific trace elements on elasmobranch species health, highlighting the provoked implications in osmoregulation (e.g. ...
Trace elements have the potential to bioaccumulate in marine organisms and to biomagnify towards the upper levels of marine trophic webs, resulting in a range of negative effects on organisms. Elasmobranchs are highly susceptible to bioaccumulation of trace metals, while their consumption by humans is increasing worldwide. Therefore, it is important to monitor the trace metal content in the edible tissues of elasmobranchs. This work reveals the content of 12 trace metals in the edible tissues of 10 elasmobranch species caught in Greek waters. Levels above the permissible limits for Hg and Pb were found in some species, while analysis of the lifetime consumption risk for adults and children using the Target Hazard Quotient (THQ), revealed a high risk for two of the most toxic substances on the priority list for substances, namely As and Hg. These are preliminary results, and further research is required to understand better the issue.
... In fact, the results indicate a moderate negative correlation between the CF and Ti at Rios das Ostras and Ni in Santos that may indicate potential foraging impairment reflected in sampled shark body condition. In this regard, a recent report has indicated differing condition factors directly associated to metals in elasmobranch organs (Wosnick et al., 2021), where higher Co, Ni and Cu concentrations were correlated with lower condition indices, and higher Cu and Fe concentrations were correlated with better body condition. However, since other sensory systems are also used to detect prey, further studies are needed to support this theory. ...
Metal contamination has never been assessed in Ampullae of Lorenzini. This study employed Rhizoprionodon lalandii, as an ecotoxicological model to investigate potential metal accumulation in Ampullae of Lorenzini jelly. No differences between sexes were observed regarding jelly metal concentrations at Rio das Ostras (RJ) or Santos (SP). Statistically significant correlations were noted between total lengths (TL) and condition factors and several metals at both sampling sites, demonstrating the potential for Chondrichthyan sensory capacity disruption and possible effects on foraging success. Maternal metal transfer to Ampullae jelly was confirmed. Rhizoprionodon lalandii is thus, a good model to assess Ampullae of Lorenzini contamination, as this electrosensory organ seems to be highly vulnerable to metal contamination.
... Complementary, an effort should be made to the development of biomarkers in tissues such as blood and skin, allowing non-lethal and even repeated-in-time samplings, along with techniques offering suitable information with small amounts of tissue. The reports of correlations between blood serum biomarkers and levels of contaminants in different tissues (e.g., Wosnick et al., 2021) are encouraging. Moreover, the field of "omic" techniques offers promising alternatives, with transcriptomics, proteomics, and metabolomics providing vast amounts of non-target information, allowing to observe effects throughout entire metabolic pathways, with very low sample requirements (Hampel et al., 2016). ...
Bioindicator species are increasingly valuable in environmental pollution monitoring, and elasmobranch species include many suitable candidates for that role. By measuring contaminants and employing biomarkers of effect in relevant elasmobranch species, scientists may gain important insights about the impacts of pollution in marine ecosystems. This review compiles biomarkers applied in elasmobranchs to assess the effect of pollutants (e.g., metals, persistent organic pollutants, and plastics), and the environmental changes induced by anthropogenic activities (e.g., shifts in marine temperature, pH, and oxygenation). Over 30 biomarkers measured in more than 12 species were examined, including biotransformation biomarkers (e.g., cytochrome P450 1A), oxidative stress-related biomarkers (e.g., superoxide anion, lipid peroxidation, catalase, and vitamins), stress proteins (e.g., heat shock protein 70), reproductive and endocrine biomarkers (e.g., vitellogenin), osmoregulation biomarkers (e.g., trimethylamine N-oxide, Na⁺/K⁺-ATPase, and plasma ions), energetic and neurotoxic biomarkers (e.g., lactate dehydrogenase, lactate, and cholinesterases), and histopathological and morphologic biomarkers (e.g., tissue lesions and gross indices).
... More specifically, incidental capture in fisheries targeting Scomberomorus brasiliensis Collette, Russo & Zavala-Camin, 1978, Cynoscion acoupa (Lacepède, 1801), and C. leiarchus (Cuvier, 1830 also impacted elasmobranch populations mainly due to the low selectivity of fishing apparatus and large volumes of neonates and juveniles caught . It was during this period that the Brazilian academic community established measures to deal with the reported declines, most of them resumed in the National Action Plan for the Conservation and Management of Elasmobranch stocks in Brazil (SBEEL 2005 In the last decade (2010 to 2020), new methodologies have emerged, with studies focused on spatial ecology , and the impacts of environmental pollution on BAC elasmobranchs (Chaves 2019, Wosnick et al. 2021a, Wosnick et al. 2021b. Social demands and food safety issues also stood out, with studies aiming to assess accidents with marine stingrays involving artisanal fishers (Dias et al. 2016, Carvalho et al. 2019) and the potential risks of shark meat consumption to human health (Souza-Araujo et al. 2021, with data collected in 2017). ...
Elasmobranchs exhibit the biggest population declines among vertebrates, being considered one of the groups with the highest risk of extinction. The Brazilian Amazon Coast (BAC) is considered a priority area for elasmobranch conservation, as many species are endemic to the region, and most of them are threatened with extinction. The present study made a scientometric analysis using the IRAMUTEQ method (Interface de R pour les Analyses Multidimensionnelles de Textes et de Questionnaires) to evaluate the trends of research with elasmobranchs in BAC in the last four decades. Ten research trends were identified, highlighting “Biodiversity”, “Reproduction”, “Trophic Ecology” and “Conservation”. However, most of the publications found are aimed at understanding the diversity and abundance of species in the region, with the number of studies focused on reproduction, feeding and other aspects of the biology and ecology of elasmobranchs in the BAC being less expressive. Although the research area “Conservation” stood out in the search, the amount of relevant information so that management and conservation measures can be implemented is still low. Lastly, despite following the global trend of studies with elasmobranchs between 2000 and 2010, investigations into the BAC need to advance, especially considering the poor level of basic information on most species (Biology and population dynamics) and the incomplete knowledge of specific composition of elasmobranch species in the entire area, aspects relevant to conservation and more applied studies that rely on more recent methodologies and technologies.
Sharks are particularly susceptible to bioaccumulation due to their life history characteristics and trophic position within marine ecosystems. Despite this, studies of bioaccumulation cover only a small proportion of extant species. In this study we report concentrations of trace elements and heavy metals in blood samples of S. lewini for the first time. We report high concentrations of several trace elements and heavy metals, with concentrations of some elements exceeding the limit determined safe for human consumption. High elemental concentrations may reflect biochemical differences between blood plasma and other tissues; however, they may also be symptomatic of high levels of exposure triggered by anthropogenic activities. We also provide evidence of elemental accumulation through ontogeny, the nature of which differs from that previously reported. Ultimately, this baseline study increases our understanding of interspecific and intraspecific variation in bioaccumulation and ecotoxicology in elasmobranchs which may prove important in ensuring adequate management.
Anthropogenic practices have increased metal contamination in marine ecosystems. Most sharks have long lifespans, occupy an important ecological position at the top of marine food webs, and can accumulate metals. However, reference levels of metal contaminants in the tissues of sharks, particularly, apex predators such as the white shark (Carcharodon carcharias), are lacking. In this study, concentrations of copper (Cu), cadmium (Cd), nickel (Ni), lead (Pb), silver (Ag), and zinc (Zn) were measured in the muscle tissue of white (n = 42) and tiger (Galeocerdo cuvier; n = 3) sharks. Metal exposure in various species, including sharks, has been correlated with increased oxidative stress. Therefore, the main objectives of this study were to assess metal accumulation and antioxidant enzyme activity (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)) in the muscle tissue of the population of white sharks and tiger sharks inhabiting the Western North Atlantic. The measured parameters were qualitatively compared between species. The small sample size of tiger sharks (collected from only one site) limited statistical analyses, therefore, white sharks were the primary focus of this study. Differences in tissue metal (Cu, Cd, Ni, and Zn) concentrations and antioxidant enzyme activities were detected based on collection site, with significant positive correlations between Cd and enzymes, SOD and CAT, and Zn and enzymes, SOD and GPx in C. carcharias. Differences in Ni concentration were detected based on sex, with females having higher Ni levels. Additionally, plasma osmolality was not correlated with tissue metal concentrations; however, osmolality decreased with increasing length in C. carcharias. This study is the first to report baseline levels of Cu, Zn, Cd, Ni, Ag, and Pb in muscle of North Atlantic white sharks and provides new insights into oxidative stress responses of these sensitive species to metal contaminants.
Apresentação dos resultados dos estudos e compilação dos dados relativos à biodiversidade da fauna maranhense voltados para a elaboração do zoneamento ecológico e econômico dos biomas Amazônia e Cerrado e Costeiro no Maranhão. São apresentadas uma série de sugestões de ação e manejo, inclusive com a proposta de criação da "Reserva da Biosfera Gurupi-Awá".
Marine pollution, due to the regular discharge of contaminants by various anthropogenic sources, is a growing problem that imposes detrimental influences on natural species. Sharks, because of a diet based on smaller polluted animals, are exposed to the risk of water contamination and the subsequent bioaccumulation and biomagnification. Trace elements are very diffuse water pollutants and able to induce oxidative stress in a variety of marine organisms. However, to date, studies on sharks are rather scarce and often limited to mercury. In this context, the present study aimed to analyze the accumulation of trace elements and their putative correlation with the onset of an oxidative status in the muscle of the lesser spotted dogfish Scyliorhinus canicula, from the Central Mediterranean Sea. Ecotoxicological analysis detected the presence of Pb, As, Cd, Mn, Zn, Ni, Cu, and Fe; no significant differences were observed between sexes, while a negative correlation was found between Pb and animal length. Analysis of oxidative stress markers showed either positive or negative correlation with respect to the presence of trace elements. Lipid peroxidation (TBARS) positively correlated with Zn, Ni, and Fe; SOD enzyme activity negatively correlated with Cu and Ni; LDH was negatively correlated with Fe and positively correlated with Pb. Moreover, positive correlations between the leukocyte count and Mn and Zn, as well as with LDH activity, were also observed. The data suggested that, in sharks, trace elements accumulation may affect oxidant and antioxidant processes with important outcomes for their physiology and health.
The tiger shark (Galeocerdo cuvier) has been relatively well assessed concerning biology and ecology aspects in both Atlantic and Pacific North America and in Caribbean waters. The amount of data in these regions has led to the species protection under capture quotas and with the creation of sanctuaries. The reality in developing countries, however, is the exact opposite, with scarce information on the species in the southern hemisphere, namely South American and African waters. In these regions, protection measures are insufficient, and studies on tiger shark biology and ecology are scarce, significantly hindering conservation and management efforts. Thus, the aim of this study was to compile scientific literature on the tiger shark in the South Atlantic and discuss the impact of these data (or lack thereof) distributed within a total of ten research categories for guiding management plans. In total, 41 scientific publications on different G. cuvier biology and ecology aspects were obtained. The most studied topics were Feeding Ecology (n = 12), followed by Human Interactions (n = 8), and Movements and Migration (n = 7). Northeastern Brazil (Southwest Atlantic) was the most researched area, probably due to the higher coastal abundance of tiger sharks in this area, alongside a high number of recorded attacks, justifying funding for studies in the region. No studies carried out in other South American or African countries were found. It is important to mention that even though some research topics are relatively well covered, a severe knowledge gap is noted for risk assessments and fisheries management, with a proposition for the implementation of sanctuaries noted. This is, however, particularly worrisome, as the South Atlantic is mostly unexplored in this regard for tiger sharks. It is also important to note how different the attention given to this species is in the North Atlantic when compared to the South region. Lastly, we highlight that the existence of sub-populations, the lack of migratory corridors geographically connecting distinct areas used by the species, and the lack of fisheries statistics on tiger shark landings, all increase the vulnerability of this species in the South Atlantic.
The bull shark (Carcharhinus leucas Valenciennes, 1839) is a large, primarily coastally distributed shark famous for its ability to penetrate far into freshwater bodies in tropical, subtropical, and warm-temperate climates. It is a cosmopolitan species with a geographical range that includes the coastlines of all major ocean basins (Atlantic Ocean, Indian Ocean, Pacific Ocean). As a consequence, freshwater occurrences of C. leucas are possible everywhere inside its geographic range. Carcharhinus leucas is a fully euryhaline, amphidromous species and possibly the widest-ranging of all freshwater tolerating elasmobranchs. This species is found not only in river systems with sea access that are not interrupted by human impediments but in hypersaline lakes as well. Rivers and estuaries are believed to be important nursery grounds for C. leucas, as suggested by observations of pregnant females in estuaries and neonates with umbilical scars in rivers and river mouths. Due to the physical capability of this species to enter riverine systems, the documentation of its occurrence in fresh and brackish water is essential for future conservation plans, fishery inspections, and scientific studies that focus on the link between low salinity habitats, shark nurseries, and feeding areas. The author’s review of the available literature on C. leucas revealed the absence of a comprehensive overview of fresh and brackish water localities (rivers and associated lakes, estuaries) with C. leucas
records. The purpose of this literature review is to provide a global list of rivers, river systems, lakes, estuaries, and lagoons with records and reports of this species, including a link to the used references as a base for regional, national, and international conservation strategies. Therefore, the objective of this work is to present lists of fresh and brackish water habitats with records of C. leucas as the result of an extensive literature review and analysis of databases. This survey also took into account estuaries and lagoons, regarding their function as important nursery grounds for C. leucas. The analysis of references included is not only from the scientific literature, but also includes semi-scientific references and the common press if reliable. The result of 415 global fresh and brackish water localities with evidence of C. leucas highlights the importance of these habitats for the reproduction of this species. Moreover, gaps in available distribution maps are critically discussed as well as interpretations and conclusions made regarding possible reasons for the distribution range of C. leucas, which can be interpreted as the result of geographic circumstances, but also as a result of the current state of knowledge about the distribution of this species. The results of the examination of available references were used to build a reliable and updated distribution map for C. leucas, which is also presented here.
Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goals: the Living Planet Index (a measure of changes in abundance aggregated from 57 abundance time-series datasets for 18 oceanic shark and ray species) and the Red List Index (a measure of change in extinction risk calculated for all 31 oceanic species of sharks and rays). We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure. This depletion has increased the global extinction risk to the point at which three-quarters of the species comprising this functionally important assemblage are threatened with extinction. Strict prohibitions and precautionary science-based catch limits are urgently needed to avert population collapse, avoid the disruption of ecological functions and promote species recovery.
As apex predators, blacktip sharks (Carcharhinus limbatus) are highly susceptible to biomagnified mercury (Hg) particularly in the Gulf of Mexico (GOM), which is known to contain fishes and invertebrates with elevated Hg levels. Blacktip sharks occur in the GOM year-round and are heavily fished both commercially and recreationally, but little is known about how Hg affects the species. In this study, blood, muscle, liver, and kidney samples were collected from neonatal (n = 57) and juvenile (n = 13) blacktip sharks in Charlotte Harbor, Florida. Hg concentrations in neonates and juveniles were found to be elevated in muscle (mean ± SE = 0.59 ± 0.23 mg kg−1), liver (0.39 ± 0.29 mg kg−1), kidney (0.56 ± 0.25 mg kg−1), and blood (0.059 ± 0.041 mg kg−1) compared to other local shark species and conspecifics from other areas. Blood plasma chemistry, hematology, and liver histology were evaluated to assess the relationship between Hg and tissue damage. Plasma chemistry parameters alanine aminotransferase (ALT) and phosphorus (PHOS) were not correlated with tissue Hg or liver condition index. Hematological effects were also not correlated with tissue Hg. However, melanomacrophage presence and lipid deposition, evaluated as part of histopathological analysis, were found to exhibit a statistically significant association with concentrations of Hg in tissue and ALT levels. These results suggest that Hg exposure potentially had a negative effect on the livers of the blacktip sharks evaluated in the present study.
Over the last century anthropogenic activities have rapidly increased the influx of metals and metalloids entering the marine environment, which can bioaccumulate and biomagnify in marine top consumers. This may elicit sublethal effects on target organisms and have broad implications for human seafood consumers. We provide the first assessment of metal (Cd, Pb, Cr, Mn, Co, Cu, Zn, As, Ag, and THg) and metalloid (As) concentrations in the muscle tissue of coastal sharks from The Bahamas. A total of 36 individual sharks from six species were evaluated, spanning two regions/study areas, with a focus on the Caribbean reef shark (Carcharhinus perezi), and to a lesser extent the tiger shark (Galeocerdo cuvier), due their high relative abundance and ecological significance throughout coastal Bahamian and regional ecosystems. Caribbean reef sharks exhibited some of the highest metal concentrations compared to five other species, and peaks in the concentrations of Pb, Cr, Cu, Zn, and Ag were observed as individuals reached sexual maturity. Observations were attributed to foraging on larger, more piscivorous prey, high longevity, as well a potential slowing rate of growth. We observed correlations between some metals, which are challenging to interpret but may be attributed to trophic level and ambient metal conditions. Our results provide the first account of metal concentrations in Bahamian sharks, suggesting individuals exhibit high concentrations which may potentially cause sublethal effects. Finally, these findings underscore the potential toxicity of shark meat and have significant implications for human consumers.
Sharpnose sharks Rhizoprionodon lalandii and R. porosus are frequently captured in fishing activities in Brazil and are significantly consumed by humans, especially in southeastern Brazil. Both species lack population data and suffer intense fishing pressures and habitat degradation, consequently hindering adequate management and conservation actions. In this context, this study aimed to assess mercury (Hg) contamination in R. lalandii, and R. porosus sampled off the coast of Rio de Janeiro, addressing both animal health and public health risks. Sharks were obtained from two artisanal fishing colonies in southeastern Brazil (Copacabana and Recreio dos Bandeirantes), located on the coastal zone adjacent to Guanabara Bay, one of the most important, productive, and contaminated estuaries in Brazil, and a further three artisanal fishing colonies from the Região dos Lagos area (Saquarema, Cabo Frio and Rio das Ostras). Hg concentrations in liver, muscle, and brain in R. lalandii (n ¼ 24) and R. porosus (n ¼ 20) specimens were determined by inductively coupled plasma mass spectrometry. A gravid female measuring 112 cm from Copacabana is the first record for an individual of this size for R. lalandii. No correlation between length and muscle Hg concentrations was observed, and no differences between Hg concentrations for muscle or liver were found between male and female juveniles from either Cabo Frio or Rio das Ostras. No differences in Hg loads were observed herein for both assessed species. Low Hg bioaccumulation in juveniles and nongravid female muscle tissue was noted compared to significantly higher Hg concentrations in gravid females. Hg was detected in all embryos, indicating potential maternal offloading. As Hg thresholds for sharks in particular have not yet been established, whether the Hg concentrations detected in brain pose neurotoxic risks for these animals is not known. Public health concerns concerning adult R. lalandii consumption from Copacabana, however, are significant.
Physiological adaptations have evolved to help sharks face rapid periods of feast. Tiger sharks are generalist apex predators that rely on a high-lipid/protein diet. To achieve a satisfactory nutritional condition, proper lipid absorption and hepatic storage are needed. Bile secretion in sharks is low and sporadic but increases during short periods of fasting. The present study describes a physiological impairment caused by bile accumulation in juvenile tiger sharks, possibly due to prolonged fasting. These evidences suggest that, even though sharks have adaptations that prevent them from dying from starvation, alarming physiological alterations might occur. Future studies are needed to assess how such a condition can affect wild populations, as well as possible sublethal consequences that could impact their long-term survival.
Dules auriga, a native Brazilian teleost, was applied as a sentinel species regarding metal contamination at Ilha Grande Bay, previously considered a reference site in Southeastern Brazil. Cytosolic (S50) and metallothionein-bound (HTS50) hepatic iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), cadmium (Cd), and silver (Ag) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), while metallothionein (MT) concentrations were determined by polarography. Ag concentrations in both cytosolic fractions were below the limit of detection. All other HTS50 metal contents were significantly lower than S50 contents. No significant associations were found for MT. Fe and Mn S50 were positively and moderately correlated to total length, as well as HTS50 Mn, while total weight was correlated to both Mn fractions, suggesting that environmental Mn and Fe concentrations may influence fish growth. A moderate correlation between the condition factor and the S50 Cu fraction was observed, also indicating that Cu may affect fish growth. Inter-element correlations were observed, including between Cd, a toxic element, and Mn and Zn, both essential elements. Calculated molar ratios indicate that both Mn and Zn are in molar excesses compared with Cd, corroborating literature assessments regarding protective Mn and Zn effects against Cd. Lack of MT correlations suggests that metal concentrations may not be high enough to reach an MT induction threshold and that MT variability is probably linked to environmental metal concentrations. Therefore, the increased environmental contaminant levels observed in the study area indicate the need for biomonitoring efforts aiming at the application of efficient mitigation measures.
Cobalt nanoparticles (Co-NPs) have been extensively used in clinical practices and medical diagnosis. In this study, the potential toxicity effects of Co-NPs with special emphasis over the biochemical enzyme activities, such as aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) in serum, liver, and kidney of Wistar rats were investigated. This toxicity measurement of nanomaterials can support the toxicological data. The biochemical enzymatic variations are powerful tools for the assessment of toxicity. ASAT and ALAT enzymes have been widely used to predict tissue-specific toxicities associated with xenobiotic. The biochemical changes induced by Co-NPs have significance in their toxicological studies because the alterations in biochemical parameters before clinical symptoms indicate either their toxicant safety or detrimental effect. Herein, Co-NPs with particle size <50 nm significantly activated ASAT and ALAT enzymes in the serum, liver, and kidney of rats at concentrationdependent order.
In Brazil, regulations for elasmobranch fishing are scarce, as well as insufficient monitoring and management. The first catch regulation for the group was published in 1998 (IBAMA No. 121/98). Despite the ban on finning, the legislation provides legal support for evisceration and decapitation prior to landing. Such practices have become particularly problematic for proper monitoring since decharacterization impairs the correct identification of species. In addition, processing is detrimental to research, as many studies rely on sampling of biological material (e.g., blood), posing an additional challenge for researchers using commercial fishing animals for scientific purposes. This study aimed to characterize the frequency of this practice in the fishing of elasmobranchs. The four years of monitoring show that landing patterns of gutted and beheaded animals are influenced by fishing conditions and the catch volumes of the day. We discuss the findings focusing on the need to revise the legal framework for the commercial landing of elasmobranchs and possible promising ways to address this challenge.
Shark meat is consumed as a food source worldwide, especially in Asian countries. However, since sharks are apex predators in the ocean food chain, they are prone to bioaccumulation of heavy metals. More than 100 million sharks are caught annually for human consumption, and the safety of shark meat cannot be overemphasized. Here, we examined heavy metal concentration in the muscle tissue of 6 shark species including 3 migratory species (Carcharhinus brachyurus, Carcharhinus obscurus, and Isurus oxyrinchus) and 3 local species (Triakis scyllium, Mustelus manazo, and Cephaloscyllium umbratile) from fish markets in Jeju Island, Republic of Korea. The concentrations of 11 heavy metals (Cr, Fe, Cu, Zn, As, Se, Cd, Sn, Sb, Pb, and Hg) and MeHg were analyzed. The result showed that the average concentrations of all metals, except for that of As, were below the regulatory maximum limits of many organizations, including the Codex standard. Hg and MeHg were significantly correlated with body length, body weight, and age, and the concentration of Hg was expected to exceed the limit in C. brachyurus with a body length or weight of over 130 cm or 25 kg, respectively. Our results indicate that shark meat can expose consumers to a high level of As and that copper sharks bigger than the predicted size should be avoided for excessive Hg. Considering these findings, a detailed guideline on consumption of meat of different shark species should be suggested based on further investigation. © 2019 Kim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Sharks are suffering from fishing industry pressure, mostly by human consumption of meat and fins, causing a great impact on its population. These top predators can bioaccumulate metals in its tissues, which brings risks to human health and indicates aquatic pollution. The objective of this work is to determine metallic trace elements as chromium, copper, zinc and aluminium in Prionace glauca, while studying the biological aspects such as fork length and approximate age to indicate if there is a metal accumulation in shark tissues evaluated. Nine specimens were obtained through commercial fishing in the Southeast and South regions of Brazil, using pelagic longline fishing. On arrival at the port, specimens were weighed and sexed in its commercial weight (headed, finned and gutted). About 100 g of muscular flesh from dorsal region between the dorsal and caudal fin was removed. Metal determination in muscle tissue (wet weight basis) was performed through acid digestion (mixture of HNO3 and H2O2). After the acid digestion, the metals concentration was determined by means of inductively coupled plasma optical emission spectrometry (ICP-OES). The results indicated that Prionace glauca capture during the winter in the Southeast-South regions of Brazil, consists mostly by small adult males. Copper, zinc and aluminium concentration was well below de maximum limits permitted by Brazilian and international agencies. Chromium average (0.14 mg/kg) was above the limits permitted by Brazilian legislation (0.10 mg/kg). A significant positive correlation was found between some metals (Al, Cr and Cu) and sharks fork length. These results corroborate the bioaccumulation of some metals in Prionace glauca, showing the need for more studies about metal determination in shark tissues.
Length, mass and girth relationships are presented for 112 juvenile white sharks (JWS) Carcharodon carcharias caught in the Southern California Bight (SCB) nursery area between June 2008 and August 2017. No difference was found between male and female JWS length–mass relationships, but data suggest that JWS in the SCB gain more mass per unit length for the juvenile size classes compared with other C. carcharias populations. Condition‐factor‐to‐liver‐mass and condition‐factor‐to‐liver‐lipid‐content relationships revealed that length and mass (i.e. condition factor) can be used as a non‐invasive proxy for body condition for juveniles of this species. The parameters estimated in this study are key information for population assessments of juvenile C. carcharias in the north‐east Pacific Ocean and will contribute to the conservation and management of this IUCN Red List Vulnerable species.
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Purpose of review:
To discuss the physiologic and pathologic effects of iron on men's reproductive health.
Recent findings:
Iron overload diseases are associated with hypogonadotropic hypogonadism, infertility, and sexual dysfunction in men. Recent findings have elucidated the roles by which iron may affect the male reproductive axis. Iron is requisite for life. Iron can also catalyze the production of reactive oxygen species. To maintain balance, the human body tightly regulates dietary iron absorption. Severe iron overload disorders-e.g., hereditary hemochromatosis and β-thalassemia-occur when these regulatory mechanisms are deficient. While iron is necessary, the male reproductive system is particularly sensitive to iron overload. Hypogonadotropic hypogonadism, infertility, and sexual dysfunction commonly occur if excess iron from iron overload disorders is not removed. The average male in the USA consumes significantly more iron than needed to replace daily losses. How this degree of iron loading may affect one's reproductive health remains less clear, but there is evidence it may have adverse effects.
The dogfish shark salt gland was predicted by Smith and discovered by Burger at the Mount Desert Island Biological Laboratory in Salisbury Cove, Maine. It is an epithelial organ in the intestine composed of tubules that serve a single function: the secretion of hypertonic NaCl. Many G protein receptors are present on the basolateral surface of these tubules, including stimulatory receptors for vasoactive intestinal peptide, adenosine A2, growth hormone releasing hormone, and inhibitory receptors for somatostatin and adenosine A1. An entirely different class of stimulatory receptors is present as C-type natriuretic peptide receptors. Each stimulatory receptor evokes powerful NaCl secretion. G protein receptors bind to Gαsto activate the catalytic unit of adenylate cyclase to form cyclic adenosine monophosphate (cAMP) and protein kinase A that phosphorylates the regulatory domain of cystic fibrosis transmembrane conductance regulator, opening the channel. The C-type natriuretic peptide receptor stimulates by activating guanylate cyclase and endogenous cyclic guanosine monophosphate which inhibits type 3 phosphodiesterase, the enzyme that breaks down cAMP, thereby elevating cAMP and activating the protein kinase A pathway.
Evaluating how predators metabolize energy is increasingly useful for conservation physiology, as it can provide information on their current nutritional condition. However, obtaining metabolic information from mobile marine predators is inherently challenging owing to their relative rarity, cryptic nature and often wide-ranging underwater movements. Here, we investigate aspects of energy metabolism in four free-ranging shark species (n = 281; blacktip, bull, nurse, and tiger) by measuring three metabolic parameters [plasma triglycerides (TAG), free fatty acids (FFA) and cholesterol (CHOL)] via non-lethal biopsy sampling. Plasma TAG, FFA and total CHOL concentrations (in millimoles per litre) varied inter-specifically and with season, year, and shark length varied within a species. The TAG were highest in the plasma of less active species (nurse and tiger sharks), whereas FFA were highest among species with relatively high energetic demands (blacktip and bull sharks), and CHOL concentrations were highest in bull sharks. Although temporal patterns in all metabolites were varied among species, there appeared to be peaks in the spring and summer, with ratios of TAG/CHOL (a proxy for condition) in all species displaying a notable peak in summer. These results provide baseline information of energy metabolism in large sharks and are an important step in understanding how the metabolic parameters can be assessed through non-lethal sampling in the future. In particular, this study emphasizes the importance of accounting for intra-specific and temporal variability in sampling designs seeking to monitor the nutritional condition and metabolic responses of shark populations. Cite as: Gallagher AJ, Skubel RA, Pethybridge HR, Hammerschlag N (2017) Energy metabolism in mobile, wild-sampled sharks inferred by plasma lipids. Conserv Physiol 5(1): cox002; doi:10.1093/conphys/cox002.
Sharks are very sensitive to stress and prone to a high mortality rate after capture. Since approximately 50 million of sharks are caught as bycatch every year, and current recommendations to reduce the impact of commercial fishing strongly support immediate release, it is imperative to better understand post-release mortality caused by the stress of capture and handling. Blood samples allow the assessment of stress levels which are valuable tools to reduce mortality in commercial, recreational and scientific fishing, being essential for the improvement in those conservation measures. Biochemical analyses are widely used for sharks as stress indicators, with secondary plasma parameters (lactate, glucose and ions) being the most often employed assays. However, it is virtually impossible to determine baseline plasma parameters in free-ranging sharks, since blood withdrawal involves animal capture and restrain, which are stressful procedures. This study aims at analyzing secondary parameters of five healthy tiger sharks captured with circular hooks and handlines in Fernando de Noronha (Northeastern Brazil) and comparing them with secondary parameters of three dead tiger sharks caught off Recife (also Northeastern Brazil). The results showed that the analysis of some plasma constituents in dead animals may be an efficient tool to assess stress and lethality. However, traditional parameters such as glucose and calcium, need to be used with caution. The results also demonstrated the extreme importance of urea and phosphorus for assessing stress response and mortality in tiger sharks, both parameters frequently neglected and of utmost importance for shark’s homeostasis.
Sharks have greater risk for bioaccumulation of marine toxins and mercury (Hg), because they are long-lived predators. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA), a ubiquitous cyanobacterial toxin linked to neurodegenerative diseases. Today, a significant number of shark species have found their way onto the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Many species of large sharks are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products. Recent studies suggest that the consumption of shark parts may be a route to human exposure of marine toxins. Here, we investigated BMAA and Hg concentrations in fins and muscles sampled in ten species of sharks from the South Atlantic and Pacific Oceans. BMAA was detected in all shark species with only seven of the 55 samples analyzed testing below the limit of detection of the assay. Hg concentrations measured in fins and muscle samples from the 10 species ranged from 0.05 to 13.23 ng/mg. These analytical test results suggest restricting human consumption of shark meat and fins due to the high frequency and co-occurrence of two synergistic environmental neurotoxic compounds.
Background:
Microwave is the most reliable sample digestion method. However, it requires expensive microwave digester automation and has relatively low productivity. In this study, three non-automated digestion methods, i.e. wet acid digestion using nitric acid (HNO3) and hydrogen peroxide (H2O2), wet acid digestion using HNO3, and dry washing, are compared in order to determine the best approach.
Methods:
Certified reference material IAEA-086 (International Atomic Energy Agency, Austria) and hair and nail samples from 20 female students of Universiti Kebangsaan Malaysia, aged 19 to 30 years, were collected and analysed using the three digestion methods.
Results:
For hair samples, analysis of variance of repeated measures showed significant differences in the level of all elements (P < 0.001) between the three methods. For nail samples, only the copper (Cu) level showed no significant difference (P = 0.100) between methods. Wet acid digestion using HNO3 and H2O2 showed the best within- and between-run relative standard deviation (RSD) values, with within-run RSD for all elements, except for selenium (Se), < 5%. The between-run precision ranges from 6.14% to 17.96% for hair and from 3.53% to 11.52% for nail samples. Wet acid digestion using HNO3 and H2O2 showed both good accuracy and precision for manganese (Mn) and magnesium (Mg), with percentage recoveries of 110% and 96.9%, respectively. All elements show higher method detection limit (MDL) values than the previous study: 0.05 μg/g Mg for wet acid digestion using HNO3, 0.02 μg/g Se for wet acid digestion using HNO3 and H2O2, and 0.2 μg/g Mg for dry ash method.
Conclusion:
Wet acid digestion using HNO3 and H2O2 proved to be the best method in terms of precision, accuracy, recovery, and MDL. However, only Mn and Mg showed adequate precision, accuracy, and percentage of recovery.
Background: Microwave is the most reliable sample digestion method. However, it requires expensive microwave digester automation and has relatively low productivity. In this study, three non-automated digestion methods, i.e. wet acid digestion using nitric acid (HNO3) and hydrogen peroxide (H2O2), wet acid digestion using HNO3, and dry washing, are compared in order to determine the best approach. Methods: Certified reference material IAEA-086 (International Atomic Energy Agency, Austria) and hair and nail samples from 20 female students of Universiti Kebangsaan Malaysia, aged 19 to 30 years, were collected and analysed using the three digestion methods. Results: For hair samples, analysis of variance of repeated measures showed significant differences in the level of all elements (P < 0.001) between the three methods. For nail samples, only the copper (Cu) level showed no significant difference (P = 0.100) between methods. Wet acid digestion using HNO3 and H2O2 showed the best within-and between-run relative standard deviation (RSD) values, with within-run RSD for all elements, except for selenium (Se), < 5%. The between-run precision ranges from 6.14% to 17.96% for hair and from 3.53% to 11.52% for nail samples. Wet acid digestion using HNO3 and H2O2 showed both good accuracy and precision for manganese (Mn) and magnesium (Mg), with percentage recoveries of 110% and 96.9%, respectively. All elements show higher method detection limit (MDL) values than the previous study: 0.05 µg/g Mg for wet acid digestion using HNO3, 0.02 µg/g Se for wet acid digestion using HNO3 and H2O2, and 0.2 µg/g Mg for dry ash method. Conclusion: Wet acid digestion using HNO3 and H2O2 proved to be the best method in terms of precision, accuracy, recovery, and MDL. However, only Mn and Mg showed adequate precision, accuracy, and percentage of recovery.
Metal pollution is a global problem in estuaries due to the legacy of historic contamination and currently increas- ing metal emissions. However, the establishment of water and sediment standards or management actions in brackish systems has been difficult because of the inherent transdisciplinary nature of estuarine processes. Ac- cording to the European Commission, integrative comprehension of fate and effects of contaminants in different compartments of these transitional environments (estuarine sediment, water, biota) is still required to better establish, assess and monitor the good ecological status targeted by the Water Framework Directive. Thus, the present study proposes a holistic overview and conceptual model for the environmental fate of metals and their toxicity effects on aquatic organisms in estuaries. This includes the analysis and integration of biogeochem- ical processes and parameters, metal chemistry and organism physiology. Sources of particulate and dissolved metal, hydrodynamics, water chemistry, and mechanisms of toxicity are discussed jointly in a multidisciplinary manner. It is also hypothesized how these different drivers of metal behaviour might interact and affect metal concentrations in diverse media, and the knowledge gaps and remaining research challenges are pointed. Ulti- mately, estuarine physicochemical gradients, biogeochemical processes, and organism physiology are jointly co- ordinating the fate and potential effects of metals in estuaries, and both realistic model approaches and attempts to postulate site-specific water criteria or water/sediment standards must consider such interdisciplinary
interactions.
We determined the Hg content of blood, placenta and umbilical cord of 20 pregnant females of the viviparous Pacific sharpnose shark, Rhizoprionodon longurio and of the livers of the embryos contained in their right and left uterus, aiming to provide information on the amount of this metal offloaded during pregnancy by the mother to the embryos. Hg content varied by close or higher than one order of magnitude in all tissues and showed the decreasing trend: maternal blood > umbilical cord > placenta > embryonic livers, with placenta and embryonic livers significantly lower than maternal blood. There were highly significant correlations (P < 0.001) between the Hg content of maternal blood, cord, and placenta. Those between embryonic livers and maternal blood, cord and placenta were not significant (P > 0.05). The results suggest transplacental Hg transfer and that the liver is not the main site of Hg accumulation.
Sharks are one of the most threatened groups of marine animals worldwide, mostly owing to overfishing and habitat degradation/loss. Although these cartilaginous fish have evolved to fill many ecological niches across a wide range of habitats, they have limited capability to rapidly adapt to human-induced changes in their environments. Contrary to global warming, ocean acidification was not considered as a direct climate-related threat to sharks. Here we show, for the first time, that an early ontogenetic acclimation process of a tropical shark (Chiloscyllium punctatum) to the projected scenarios of ocean acidification (ΔpH = 0.5) and warming (+4°C; 30°C) for 2100 elicited significant impairments on juvenile shark condition and survival. The mortality of shark embryos at the present-day thermal scenarios was 0% both at normocapnic and hypercapnic conditions. Yet routine metabolic rates (RMRs) were significantly affected by temperature, pH and embryonic stage. Immediately after hatching, the Fulton co
Animal condition typically reflects the accumulation of energy stores (e.g. fatty acids), which can influence an individual's decision to undertake challenging life-history events, such as migration and reproduction. Accordingly, researchers often use measures of animal body size and/or weight as an index of condition. However, values of condition, such as fatty acid levels, may not always reflect the physiological state of animals accurately. While the relationships between condition indi-ces and energy stores have been explored in some species (e.g. birds), they have yet to be examined in top predatory fishes, which often undertake extensive and energetically expensive migrations. We used an apex predatory shark (Galeocerdo cuvier, the tiger shark) as a model species to evaluate the relationship between triglycerides (energy metabolite) and a metric of overall body condition. We captured, blood sampled, measured and released 28 sharks (size range 125–303 cm pre-caudal length). In the laboratory, we assayed each plasma sample for triglyceride values. We detected a positive and significant relationship between condition and triglyceride values (P < 0.02). This result may have conservation implica-tions if the largest and highest-condition sharks are exploited in fisheries, because these individuals are likely to have the highest potential for successful reproduction. Our results suggest that researchers may use either plasma triglyceride val-ues or an appropriate measure of body condition for assessing health in large sharks. Cite as: Gallagher AJ, Wagner DN, Irschick DJ, Hammerschlag N (2014) Body condition predicts energy stores in apex predatory sharks. Conserv Physiol 2: doi:10.1093/conphys/cou022.
Alkaline phosphatase (ALP; E.C.3.I.3.1.) is an ubiquitous membrane-bound glycoprotein that catalyzes the hydrolysis of phosphate monoesters at basic pH values. Alkaline phosphatase is divided into four isozymes depending upon the site of tissue expression that are Intestinal ALP, Placental ALP, Germ cell ALP and tissue nonspecific alkaline phosphatase or liver/bone/kidney (L/B/K) ALP. The intestinal and placental ALP loci are located near the end of long arm of chromosome 2 and L/B/K ALP is located near the end of the short arm of chromosome 1. Although ALPs are present in many mammalian tissues and have been studied for the last several years still little is known about them. The bone isoenzyme may be involved in mammalian bone calcification and the intestinal isoenzyme is thought to play a role in the transport of phosphate into epithelial cells of the intestine. In this review, we tried to provide an overview about the various forms, structure and functions of alkaline phosphatase with special focus on liver/bone/kidney alkaline phosphatase.
Here, we evaluated the levels of As, Hg, Pb, and Cd in shark meat sold along the Amazon Coast of Brazil and used nitrogen stable isotope values to determine trophic position and to assess element biomagnification. From market samples, a total of 13 species were identified via molecular analysis, including those listed as endangered and vulnerable by the IUCN Red List. Arsenic was present in significantly higher concentrations than all other elements, followed by Hg, with the highest mean concentrations recorded in M. higmani (As: 19.46 ± 8.79 μg/g ww) and C. acronotus (Hg: 1.12 ± 0.68 μg/g ww). Lead and Cd were recorded at much lower levels in all species. The EWI of individual elements were above PTWI for all species when considering Hg, seven species for inor- ganic arsenic (iAs), and one species for Pb. The weekly consumption of 10 species should be reduced to less than 416.39 g, which is equivalent to the daily estimated fish consumption rate in the region. The mean (±SD) δ15N values of species ranged from 10.7 ± 0.51‰ in M. higmani to 14.2 ± 0.59‰ in C. porosus, indicating feeding over >1 trophic level. Arsenic was negatively correlated with δ15N values, while Hg was positively correlated indicating biodilution and biomagnification, respectively. Our results indicate that the sale and consumption of shark meat will expose consumers to potentially harmful levels of iAs and Hg, as well as contributing to the pop- ulation decline of species including those that are currently categorized as threatened.
Among environmental pollutants, metals and metalloids are of particular concern due to their potential toxic effects and the ability to bioaccumulate throughout the aquatic trophic web. However, the simple measurement of chemicals levels present in the environment is often not enough to reveal the actual adverse effects of the contamination, making it necessary to also assess the biological effects of contamination on living organisms, applying bioindicators and biomarker measurements. Mussels have been recognized as one of the best sentinel organisms regarding aquatic environments and have been increasingly used in many worldwide environmental monitoring programs. This chapter will discuss the role of several mussel species in environmental monitoring programs, with emphasis on metal contamination, including metal bioaccumulation and biomarker investigations. In addition, the fact that these organisms may be an important contaminant transfer link to the human population and pose important public health risks will also be discussed.
Essential trace elements play pivotal roles in numerous structural and catalytic functions of proteins. Adequate intake of essential trace elements from the daily diet is indispensable to the maintenance of health, and their deficiency leads to a variety of conditions. However, excessive amounts of these trace elements may be highly toxic, and in some cases, may cause damage by the production of harmful reactive oxygen species. Homeostatic dysregulation of their metabolism increases the risk of developing diseases. Specific transport proteins that facilitate influx or efflux of trace elements play key roles in maintaining the homeostasis. Recent elucidation of their crucial functions significantly facilitated our understanding of the molecular mechanisms of iron (Fe), copper (Cu), and zinc (Zn) absorption in the small intestine. This paper summarizes their absorption mechanisms, with a focus on indispensable functions of the molecules involved in it, and briefly discusses the mechanisms of homeostatic control of each element at the cellular and systemic levels.
Persian bamboo shark (Chiloscyllium arabicum) was collected from two sites of the Khozestan province, northern basin of Persian Gulf, with the aim to identify differences in metal concentrations between fishing areas as well as the risk for human health due to consumption of the selected species. We analyzed Zn, Cu, Pb, Hg, Cd and Ni in muscle and liver tissues of specimens from both areas of study using atomic adsorption spectrometry. Statistical elaborations revealed higher bioaccumulation of metals in livers than muscle as well as in the site of worthy of Musa as regards Zn, Pb and Ni than the site of worthy of Darvis, due to the more intensive anthropogenic input. The risk for consumers is low for the most of metals, with the exception of the THQ for Hg, which resulted next to the level of risk with high frequencies of consumption.
We analyzed Cd, Hg, Zn, Cu, Mn and Fe concentrations in liver samples from male and female star-spotted smooth-hounds at various life stages. Male sharks of this species are known to reach their maximum body length (BL) more quickly than females, while females are known to mature later and live longer than males. Hepatic Cd and Hg concentrations in males and females markedly increased after maturation, but these increases proceeded earlier in males than in females. Hepatic Zn and Cu concentrations decreased during the growth stage of males and females, and thereafter increased concomitantly with increases of Cd and Hg burdens, forming a U-shaped curve over their lifespan, and the BL at which the lowest concentrations of Zn and Cu were observed was smaller in males than in females. These gender-related differences in those metals could reflect the faster growth and earlier cessation of growth in males.
Copper (Cu) is an essential trace element required for the normal development of living organisms. Due to its redox potential, copper is a cofactor in many enzymes responsible for important processes in cells. Copper deficiency has a significant influence on the reduction or the total eradication of copper-dependent enzymes in the body, thereby inhibiting cell life processes. On the other hand, copper is a very reactive element and in its free state, it can trigger the production of large amounts of free radicals, which will consequently lead to the damage of proteins and DNA. Because of those reasons, living organisms have developed precise mechanisms regulating the concentration of copper in cells. Copper also plays a very important role in male fertility. It is an essential element for the production of male gametes. The significant role of copper is also described in the processes of cell division – mitotic and meiotic. Copper-dependent enzymes such as ceruloplasmin, superoxide dismutase SOD1 and SOD3, group of metallothionein and cytochrome c oxidase are present at all stages of gametogenesis as well as in the somatic cells of the testis and in the somatic cells of epididymis. Substantial amounts of copper can also be found in liquids associated with sperm in the epididymis and prostate. Copper also affects the integral androgen distribution in terms of fertility on the line hypothalamic-pituitary-testis. Both copper increase and deficiency leads to a significant reduction in male fertility, which spans the entire spectrum of abnormalities at the sperm level, male gonad, production of hormones and distribution of micronutrients such as zinc and iron. Nowadays, the effects of copper on gametes production have become more important and are connected with the increasing levels of pollution with heavy metals in environment.
Bilirubin had been studied since the eighteenth century because assessment of serum bilirubin concentration is important in the diagnosis and prognosis of patients with liver disorders. All prognostic scores for liver diseases include bilirubin in their calculations, and some studies have shown that bilirubin is an independent biomarker of mortality risk. We know that a high total bilirubin level is an indicator of disease, but nowadays there is evidence indicating the association of a low level with increased risk of diseases, for example, cancer or cardiovascular disorders. Bilirubin is a potential biomarker because its concentration is associated with mortality and may also be associated with the prevention of disease. This chapter will review the usefulness of bilirubin as a marker in liver diseases and their possible use to assess outcomes and risk of other non-liver diseases.
The phrase "limit of detection" sounds so simple, yet it leads to one of the biggest, murkiest, most frustrating swamps in the statistical literature. All the organizations in all the towns in all the world took it upon themselves to define, redefine, and re-re-redefine the phrase. This resulted in hundreds of definitions for "limit of detection.".
Bilirubin had been studied since the eighteenth century because assessment of serum bilirubin concentration is important in the diagnosis and prognosis of patients with liver disorders. All prognostic scores for liver diseases include bilirubin in their calculations, and some studies have shown that bilirubin is an independent biomarker of mortality risk. We know that a high total bilirubin level is an indicator of disease, but nowadays there is evidence indicating the association of a low level with increased risk of diseases, for example, cancer or cardiovascular disorders. Bilirubin is a potential biomarker because its concentration is associated with mortality and may also be associated with the prevention of disease. This chapter will review the usefulness of bilirubin as a marker in liver diseases and their possible use to assess outcomes and risk of other non-liver diseases.
Marine ecosystems are constantly being threatened by contaminants produced by human activities. There is an urge to better understand their impacts on marine organisms and develop reliable tools for biomonitoring studies, while also assessing their potential impacts on human health. Given their position on top of food webs, sharks are particularly susceptible to bioaccumulation, making them potential sentinel species of marine contamination. The main objective of this study was to find suitable biomarkers for future marine pollution biomonitoring studies by correlating biochemical responses with tissue contaminant body burden in blue sharks (Prionace glauca), a species heavily caught and consumed by humans, while also addressing their general health. The chemical contaminants analysed comprised different persistent organic pollutants (POPs) families from polychlorinated compounds to brominated flame retardants (BFRs) and perfluorinated compounds (PFCs) and different trace and heavy metals. Concentrations of some contaminants in sharks' tissues were found to be above the legally allowed limits for human consumption. A canonical correspondence analysis (CCA) was performed and some strong associations were found between biochemical responses and contaminants' accumulation levels. DNA damage and lipid peroxidation levels, as well as the inhibition of the antioxidant enzyme glutathione peroxidase, were the main effects and consequences of contamination. The impact of contamination on these vital macromolecules underlines the suboptimal conditions of the sampled P. glauca, which can ultimately lead to the degradation of core ecological aspects, such as swimming, feeding, and reproduction. It can be concluded that P. glauca demonstrates great potential to be used as environmental sentinel and suitable biomarker candidates were identified in this work. Moreover, this study also highlights the risks that the consumption of blue shark derived products can pose to human health, which is of upmost interest as the sampled organisms were still juveniles and already presented values above regulatory limits.
Chronic exposure impacts of waterborne and dietary nickel (Ni) and cobalt (Co) on the growth performance of juvenile major carps viz.Catla catla, Labeo rohita and Cirrhina mrigala were studied under static water bioassay. Fish growth was monitored in terms of wet weight and fork length increments, condition factor, feed intake and feed conversion efficiency (FCE). All the three treated fish species showed exploratory behavior during first few hours of both waterborne and dietary exposure of metals. However, these responses were more pronounced in the fish exposed to waterborne than that of dietary metals. Theexposure of both Ni and Co caused significant effects on weight and fork length increments, feed intake and FCE of all the three fish species. Exposure of waterborne metals caused significantly lower weight and fork length gains to all the three fish species, while feed intake, FCE and condition factor were significantly better due to dietary treatments. All the three control fish species exhibited significantly higher feed intakes that resulted into significantly better FCE than the fish either exposed to waterborne or dietary metals. Dietary exposure of both Ni and Co increased the feed intake by the fish thatshowed positive relationship with its growth, while waterborne exposureof both metals resulted into significant loss of apatite to cause significant reduction in growth of all the three fish species. L. rohitashowed significantly higher sensitivity to metallic toxicity as evident from its lower weight increment than C. mrigala, while the difference between C. catla and L. rohita was non-significant. The conditionfactor and feed intake of all the three fish species did not change significantly due to the toxicity of both waterborne and dietary exposure of metals. The response of three fish species towards FCE fluctuated significantly that followed the order: C. mrigala > L. rohita > C.catla.
Despite their long evolutionary history (400 million years; Grogan and Lund 2004), elasmobranchs are now facing new substantial anthropogenic threats, including habitat degradation and fisheries interactions, which cause acute and chronic stress that may exceed stress levels typically imposed by natural events (e.g., seasonal habitat changes, predator avoidance). Although the physiological stress response of teleosts has been studied for decades (e.g., Adams 1990a), much of this work has centered on salmonids due to the ease of maintaining and manipulating these fishes in captivity as well as the economic interests of the aquaculture industry and the recreational fishing sector. The global expansion of both commercial and recreational fisheries coupled with the mandated release of captured fish due to bag limits, quotas, and minimum sizes, prompted the expansion of stress studies beyond freshwater teleosts to their marine counterparts. However, studies of elasmobranch stress physiology have lagged far behind despite the rapid proliferation of directed fisheries for, and a significant increase in the incidental capture of, these species over the last two decades (NMFS 2008) and the possibility that modifications to coastal habitats, which are important to many elasmobranch species, could increase stress.
The rectal gland of elasmobranchs secretes large quantities of electrolytes and is of primary importance in the osmoregulatory mechanisms of these animals (Burger and Hess, 1960; Burger, 1962). Analogously, various organs of other vertebrates are also known to be involved in salt secretion (Schmidt-Nielsen, 1965; Bonting, 1970; Bentley, 1971). In general, active ion transport is the basis of this phenomenon; in any case, it requires the presence of structural devices, morphologically and chemically well defined, and of metabolic capabilities which, taken singly, are not specific, but collectively are consistent with active ion transport and salt secretion.
This chapter explores the physiology of freshwater, marine, and euryhaline elasmobranchs. In seawater, the blood of elasmobranchs is slightly hyperosmotic and the need for water balance is limited. Salt balance is handled partly by a rectal gland that removes salt from the plasma and secretes it into the rectum for elimination. In freshwater this gland is non-functional, and salt balance is handled by gill uptake mechanisms and kidney retention. A significant portion of plasma and cellular osmolarity in seawater is comprised of organic solutes, e.g. urea. The small number of freshwater and euryhaline elasmobranch species may be explained by several factors, including: the osmoregulatory system (rectal gland cannot reverse its function in freshwater); temperature (freshwater distribution limited to warmer latitudes), reproductive and sensory limitations (reduced electroreception in freshwater); and the use of urea as the main organic osmolyte in seawater (may be limiting in freshwater). Further studies of euryhaline elasmobranch physiology and biochemistry are needed to fully understand the scarcity of these species.
Current theories of vertebrate evolution suggest that primitive fish-like vertebrates originally evolved in a freshwater habitat and that the appearance of marine forms resulted from a subsequent reinvasion of the sea. It appears that such a reinvasion followed two basic patterns — whilst the bony fish retained a relatively low osmotic concentration of their body fluids and developed in the sea as hypo-osmotic regulators, the early cartilagenous fish elevated the osmotic concentration of their body fluids so as to become isosmotic, or slightly hyperosmotic, to their marine environment. The elevation of body fluid osmotic concentration in the latter group was mainly achieved, however, not by large increases in inorganic ion concentrations, but by the accumulation and retention of certain organic nitrogenous compounds, such as urea and trimethylamine oxide (TMAO). The net result of this early divergence in osmoregulatory strategy means that the two major groups of marine fish, the teleosts and the elasmobranchs, are fundamentally different in their osmotic status, although they do both face broadly similar problems of ionic balance. For elasmobranchs, the basic problems of hydromineral regulation therefore centre on the retention of urea and related compounds, and the elimination of excess ions. This latter process involves an unusual organ, the salt-secreting rectal gland, which has attracted considerable interest, originally as an extremely rich source of the enzyme Na-K-ATPase (Hokin et al. 1973), and more recently as a model system for a particularly widespread, and medically highly important, transport process — the secondary active transport of chloride.
A B S T R A C T This study is designed to investigate the hepatotoxic effect of copper sulphate and cobalt chloride, which are used as feed additives. One hundred rats classified to five groups. First group used as control; second and third groups were given 1/10 and 1/5 LD 50 of CuSo 4 respectively, fourth and fifth groups were given 1/10 and 1/5 LD 50 of CoCl 2 respectively (orally via stomach tube). Body weight was measured weekly. Serum samples used for detection of liver functions. Liver tissue was homogenized for detection of oxidative stress (Reduced glutathione (GSH), Glutathione-s-transferase (GST) and maloneldehyde MDA)). Histopathological examination was performed in liver tissue. Results showed increase level of serum Alanine aminotransferase (ALT), Aspartat aminotransferase (AST), alkaline phosphatase (AP), gamma glutamyl transferase (GGT) and MDA. Decrease level of GSH and GST was detected. It can be concluded that ingestion of copper and cobalt in high doses has hepatotoxic effect on albino rats.
As large long-lived predators, sharks are particularly vulnerable to exposure to methylmercury biomagnified through the marine food web. Accordingly, nonlethal means were used to collect tissues for determining mercury (Hg) concentrations and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) from a total of 69 sharks, comprising 7 species, caught off Southwest Florida from May 2010 through June 2013. Species included blacknose (Carcharhinus acronotus), blacktip (C. limbatus), bull (C. leucas), great hammerhead (Sphyrna mokarran), lemon (Negaprion brevirostris), sharpnose (Rhizoprionodon terraenovae), and tiger sharks (Galeocerdo cuvier). The sharks contained Hg concentrations in their muscle tissues ranging from 0.19 mg/kg (wet-weight basis) in a tiger shark to 4.52 mg/kg in a blacktip shark. Individual differences in total length and δ(13)C explained much of the intraspecific variation in Hg concentrations in blacknose, blacktip, and sharpnose sharks, but similar patterns were not evident for Hg and δ(15)N. Interspecific differences in Hg concentration were evident with greater concentrations in slower-growing, mature blacktip sharks and lower concentrations in faster-growing, young tiger sharks than other species. These results are consistent with previous studies reporting age-dependent growth rate can be an important determinant of intraspecific and interspecific patterns in Hg accumulation. The Hg concentrations observed in these sharks, in particular the blacktip shark, also suggested that Hg may pose a threat to shark health and fitness.