Bioaccumulation of Cd, Pb and Zn in the edible and inedible tissues of three sturgeon species in the Iranian coastline of the Caspian Sea

Heavy metals bioaccumulation in free-ranging South American rattlesnakes (Crotalus durissus) in Southeastern Brazil

Anthropogenic activities are the main sources of soil, air, and water pollution by metals, including cadmium (Cd), lead (Pb), chromium (Cr), the metalloid arsenic (As), magnesium (Mg), zinc (Zn), and copper (Cu). The goal of this study was to assess the presence and concentration of toxic (As, Cd, Pb, and Cr) and essential metals (Mg, Zn, and Cu) in the liver and kidneys from 96 free-ranging rattlesnakes (Crotalus durissus) from Minas Gerais (Brazil). Bioaccumulation of Cd and Pb were significantly higher in males and heavier rattlesnakes (those with body weight above the average of the study population). Average ± standard deviations of Cd, Pb, Cr, Cu, Mg, Zn, and As in the general population (n = 96) were 3.19 ± 2.52; 5.98 ± 8.49; 0.66 ± 1.97; 3.27 ± 2.85; 776.14 ± 2982.92; 27.44 ± 29.55; and 0.32 ± 1.46; respectively. Bioaccumulation of some metals correlated positively with changes in hematologic and serum biochemical parameters. Results of this study were contrasted with previous studies assessing metal bioaccumulation in other species of terrestrial or aquatic snakes. Considering their position in the food chain and the broad range of bioaccumulation of both toxic and essential metals observed in this study, rattlesnakes may function as highly relevant biological sentinels for environmental pollution.

Microplastic Pollution in the Gastrointestinal Tract and Gills of Some Teleost and Sturgeon Fish from the Caspian Sea, Northern Iran

The increasing microplastic pollution in the marine environment has raised global concern. The main risk of microplastics in aquatic ecosystem is their bioaccumulation in aquatic organisms. A few studies have reported microplastic pollution in the digestive system of Caspian Sea fish species, but there is no research on sturgeon species, nor on fish gills. We investigated the occurrence of microplastics in the gastrointestinal tract (GIT) and gills of 62 specimens belonging to four species including three teleosts (Cyprinus carpio, Rutilus kutum, and Chelon aurata) and one sturgeon (Acipenser persicus, a valuable endangered species) from the Caspian Sea between January and March 2022. Fish tissues were removed, exposed for 24 h to 10% KOH, and then dried on filter paper. Particles were observed under a stereomicroscope and analyzed by Raman microspectrometry, scanning electron microscopy, and energy-dispersive spectroscopy. A total of 91 microplastics were detected in the GIT (average of 1.46 ± 1.17 items/individual) and 63 microplastics in the gills (average of 1.01 ± 0.62 items/individual). A significant correlation was not found between the number of microplastics found in both tissues and fish body length, body weight, GIT weight, and gill weight (p > 0.05), except between microplastics isolated from gills and gill weight in C. carpio (rs  = 0.707, p = 0.022). The abundance of microplastics in fish followed the order of A. persicus > C. aurata > R. kutum > C. carpio. The microplastics were in the size range of 45 to 5000 µm, with particles of 300 to 1000 µm being the most prevalent; 74.68% of the particles were shaped like fibers, 30.53% were red, and 70.6% were composed of nylon polymer. Environ Toxicol Chem 2023;42:2453-2465. © 2023 SETAC.

Heavy metal concentrations in Caspian pond turtle (Mauremys caspica) in Zarivar International Wetland, Kurdistan Province of Iran

In the present study, the cadmium, lead, and zinc levels in the blood and shell of Caspian pond turtles (Mauremys caspica) were investigated at five stations in Zarivar International Wetland in Kurdistan Province. All specimens were released at their capture locations within 2 h of capture. Water samples were collected at each station. Heavy metal concentrations were determined using an atomic absorption spectrometer. The mean cadmium, lead, and zinc concentrations were 0.04, 32.10, and 11.45 mg/l in blood samples; 1.82, 16.91, and 89.22 mg/l in shell samples; 0.005, 1.30, and 0.07 mg/l in water samples, respectively. In this study, the highest metal adsorption was zinc and was observed in shell. According to the results of this study, the shell of the Caspian Pond Turtle can be used to estimate the concentration of heavy metals. Our results suggest that Caspian pond turtle can be used as a biological indicator to estimate heavy metals.

Trace elements in the muscle tissue of Hemiculter leucisculus and Abramis brama orientalis from the Anzali International wetland, south-west of Caspian Sea: An exposure risk assessment

High levels of trace elements in aquatic environments can affect the quality of seafood. We analyzed the concentrations of As, Cd, Co, Hg, Mn, Ni and Pb, in the edible muscles of Hemiculter leucisculus and A. brama orientalis caught in four different areas of southwest of the Caspian Sea. We estimated the potential risks for human health deriving by the oral consumption of these two species, and the Target Hazard Quotient (THQ) according to the US-EPA approach. THQ by adults and children was always below 1 for all stations. The greater contribution was given by Co, followed by Cd, Hg, Pb, Ni, As and Mn. Total-THQ was 0.538 and 0.246 for children and adults, respectively. Trace elements detected by our study were not elevated, highlighting a positive picture of the studied area and a lower risk of developing chronic systemic effects deriving from the consumption of local fish products.

The Occurrence of Lead in Animal Source Foods in Iran in the 2010s Decade: A Systematic Review

Lead is a toxic, non-biodegradable, and accumulative heavy metal released into the environment by natural and anthropogenic activities. Despite health concerns due to the consumption of lead-contaminated foods, no systematic and comprehensive review studies have been published about the lead occurrence in animal source foods in Iran. The present study aimed to review the papers investigating the Pb contamination in animal-based food groups (including meat, fish, milk and dairy products, egg and honey) in Iran. A comprehensive search was performed with selected keywords in databases of Scopus, Web of science, and Magiran to find articles that had been published from January 2010 to December 2019. Of 371 identified articles on Pb contaminations in foods, 60 articles were selected using PRISMA. The lead concentrations were higher than the maximum recommended limits in 3 of 9 studies on meat and meat products, 12 of 26 studies on fish and canned fish, and 5 of 18 studies on milk and dairy products. However, the Pb contamination observed in studies on honey and egg was not comparable due to the lack of national and international standards. These results represent the importance of environmental monitoring and assessment for reducing exposure of animals to Pb, resulting in an improvement of food safety.

Bioaccumulation of heavy metals in fish species of Iran: a review

Accumulation of heavy metals (HMs) in fish tissues is an important factor in monitoring the health and safety of aquatic ecosystems. Furthermore, fish are important parts of aquatic food chains and play a significant role in human health. Considering the significant role of fish in the diet of humans and their ability to transfer and biomagnify HMs, it is necessary to determine and study these contaminants in fish tissues, especially in the edible parts of the fish. In addition to the other ecological and economic services of aquatic ecosystems, water bodies, especially the Persian Gulf in the south and the Caspian Sea in the north of Iran, are the main sources of seafood for people in nearby areas, as well as people living farther away who have gained access to seafood due to the extensive trade of aquatic organisms. This study provides an overview of the health conditions of the aquatic ecosystems in Iran by monitoring HM bioaccumulation in fish species. For this purpose, we reviewed, summarized, and evaluated papers published on HM concentrations in fish species from different aquatic ecosystems, including the Persian Gulf, the Caspian Sea, wetlands, rivers, qanats, water reservoirs, lakes, and dams, with emphasis on species habitats, feeding habits, and target organs in accumulation of HMs. Generally, the highest concentrations of HMs were observed in fishes collected from the Persian Gulf, followed by species from the Caspian Sea. Species inhabiting the lower zone of the water column and carnivorous and/or omnivorous species showed the highest levels of HMs. Moreover, liver was the main accumulator organ for HMs.

The concentration of the potentially toxic elements (PTEs) in the muscle of fishes collected from Caspian Sea: A health risk assessment study

In the present study, the concentration of (potentially toxic element) PTEs in the five fish species from the Caspian Sea (from five coastal areas) was measured and compared. The target hazard quotient (THQ) and total THQ (TTHQ) were calculated using Monte Carlo simulations to determine the non-carcinogenic risk in both children and adults consumers. The highest concentration of PTEs was associated with chromium (Cr) measured in Cyprinus carpio, sampled from Bandar Anzali (1.56 ± 0.14 μg/g dw), and the minimum PTEs level was nickel (Ni) in Vimba from Astara (0.02 ± 0.01 μg/g d w). The rank order for PTEs based on THQ was mercury (Hg) > cadmium (Cd) > lead (Pb)> Ni > tin (Sn) > Total Cr. For adults, the fishes rank order based on TTHQ was: Cyprinus carpio (3.268) > Chelon saliens (2.89) > Rutilus frisii kutum kanesky (2.28) > Oncorhynchus mykis (1.39) > Vimba (0.25); and for children was Cyprinus carpio (15.25) > Chelon saliens (13.47) > Rutilus frisii kutum kanesky (10.63) > Oncorhynchus mykis (6.48) > Vimba (1.16). Overall this study showed that the levels of PTEs in investigated fish species had a potential non-carcinogenic risk for both children and adults (TTHQ>1).

Potential mechanism of lead poisoning to the growth and development of ovarian follicle

With the rapid development of economic globalization and industrialization, lead (Pb), one of the most important heavy metals, has been used widely since antiquity for several purposes. In fact, its impact on the health of animals and humans is a significant public health risk all the time. Pb could be accumulated in the body for a long time, causing irreversible damage to the health of animals and humans, including hostile reproductive health. Up to now, although there are some published studies on impeding the normal development of ovarian folliculogenesis of female resulted from Pb exposure, with the damage of structure in uterine tissue, the imbalance of female menstrual status, and the change of hormone levels. The potential mechanism of Pb exposure on female reproduction system, however, remains enigmatic. How to alleviate the damage of Pb toxicity to reproductive function of female has become an urgent problem. Therefore, the aim of the present review is to discuss the information on the growth and development of ovarian follicle of mammalians and the potential toxic mechanism when exposed to Pb. The literatures were collected via various websites and consulting books, reports, etc. In summary, Pb impair folliculogenesis of mammalians, which may be related to the interference to the hypothalamic-pituitary-gonadal (HPG) axis and the production of reactive oxygen species (ROS), in turn impairs various molecules including proteins, lipids and DNA, as well as the disruption of the antioxidant defense system, ionic equilibrium and endoplasmic reticulum homeostasis.

Nitrogen and metal pollution in the southern Caspian Sea: a multiple approach to bioassessment

The Caspian Sea hosts areas of high ecological value as well as industrial, leisure, and agricultural activities that dump into the water body different kinds of pollutants. In this complex context, a proper description of the origin and potential sources of pollution is necessary to address management and mitigation actions aimed at preserving the quality of the water resource and the integrity of the ecosystems. Here, we aimed at detecting sources of both nitrogen inputs, by N stable isotope analysis of macroalgae, and metals in macroalgae and sediments in two highly anthropized coastal stretches at the Iranian side of the Caspian Sea. Sampling was done near the mouth of rivers and canals draining agricultural and urbanized areas. In the westernmost waters, facing a port city, low macroalgal δ¹⁵N signatures indicated industrial fertilizers as the principal source of pollution. By contrast, in the central coastal waters, facing touristic areas, the high macroalgal δ¹⁵N indicated N inputs from wastewaters. Here the lowest dissolved oxygen concentrations in waters were associated with excess dissolved inorganic nitrogen. Metal concentrations varied largely in the study areas and were lower in macroalgae than in sediments. Localized peaks of Pb and Zn in sediments were observed in the central coastal sites as probable byproducts of mining activity transported downstream. By contrast, Cr and Ni concentrations were high in all sampling sites, thus potentially representing hazardous elements for marine biota. Overall, macroalgal δ¹⁵N coupled with metal analysis in macroalgae and sediments was useful for identifying the main sources of pollution in these highly anthropized coastal areas. This double approach in comprehensive monitoring programs could thus effectively inform stakeholders on major environmental threats, allowing targeted management measures.

Use of 13C and 15N for the determination of the metal flux in the Caspian Sea fishes

Biomagnification of metals (Cd, Cr, Cu, Mn, Ni, Zn, Fe) was investigated in 14 species of Caspian Sea commercial fishes using ¹³C and ¹⁵N analyses to decode their trophic position (TP). The stable nitrogen isotope ratios varied among the Caspian Sea fish species from 8.7 to 13.8‰ while the stable carbon isotope ratios varied from -23.7 to -17.6‰. The TPs varied between 2.2 and 4.9. Clupeonella caspia had the lowest average TP, and Acipenseridae species (except Acipenser persicus) and Sander lucioperca had higher average TPs. Wide intra- and inter-specific differences were observed in metal concentrations. The stable isotope results were relatively coordinated with feeding behaviour of species. However, some exceptions were observed particularly in Alburnus chalcoides and S. lucioperca. By comparing logarithmic concentration of metals vs. TPs, no metal biomagnification was observed. The estimated daily intakes of metals were lower than the provisional tolerable daily intakes and, thus, these amounts do not pose any threat on human health.

Comparing dioxin-like polychlorinated biphenyls in most consumed fish species of the Caspian Sea

Among polychlorinated biphenyls (PCBs), dioxin-like PCBs (DL-PCBs) are of the most concern for human health. In this study, the levels of 12 DL-PCBs congeners were measured in 125 fish samples of the Caspian Sea, Iran. Five fish species (Oncorhynchus mykiss, Vimba vimba, Cyprinus carpio, Rutilus frisii kutum and Chelon saliens) were collected from 5 coastal cities of the Caspian Sea (25 samples per each city). Duncan's multi-scope test was used to compare the mean of DL-PCBs in different fish species and different cities. Probabilistic risk of exposure to DL-PCBs and sensitivity analysis were assessed using Monte Carlo simulation approach. The average (standard deviation) of DL-PCBs in fish samples ranged from 232 (16) to 1156 (14) pg/g lipids. The total maximum concentration was detected in Cyprinus carpio from Bandar Anzali, the minimum in Vimba vimba from Chalos. In all samples, non-carcinogenic risk of exposure to DL-PCBs was in safe level (Hazard Quotient < 1). In contrast, the lifetime cancer risk estimated for Bandar Anzali, Bandar Torkaman, and Rasht exceeded the threshold value of 1 × 10^-6 suggested by United States Environmental Protection Agency. Sensitivity analysis indicated that the concentration of DL-PCBs and exposure frequency were the most effective parameters in increasing carcinogenic risk.

Distribution pattern and pollution status by analysis of selected heavy metal amounts in coastal sediments from the southern Caspian Sea

Amounts of heavy metal elements (Zn, Cd, Pb, Cu, Ni, Co, Mn, and Fe) in surficial sediments at four regions (coastline, estuaries, rivers discharging into the sea, and Gorgan Bay) along the southern coastline of the Caspian Sea were investigated in summer 2015. Collected data was applied to appraise the sediment contamination degree and the origin of pollutants based on the Geo-accumulation Index. Pollution status was assessed via the Enrichment Factor (EF) and the Potential Ecological Risk Index (PERI, the Hakanson index). Heavy metal contents in sediments in mg g^-1 dw varied from 3000 to 39,500 for Fe, 166.66 to 2000 for Mn, 11 to 4198 for Zn, not detected (ND) to 822.83 for Pb, ND to 40.66 for Cd, 6.16 to 37.16 for Cu, 11.66 to 69 for Ni, and 6.33 to 33.00 for Co. Higher amounts of Cd, Pb, Cu, Mn, and Fe were determined in rivers discharging sediments into the sea. In Gorgan Bay, Zn, Ni, and Co were highest. Greater potential ecological risk levels were detected along the coastline as well as rivers discharging into the sea. Among heavy metals considered, Zn and Cd had the highest enrichment factors. The Geo-accumulation Index proved that the investigated region could be classified as Zn- and Cd-polluted area.

Heavy metals and arsenic content in water along the southern Caspian coasts in Iran

Due to the importance of pollution monitoring in marine ecosystems and lack of a coherent and systematic investigation of heavy metal ions along the southern shores of the Caspian Sea, in the present study, the amount of these metals and As ions in coastal waters along its 780-km-long coast in Iran have been studied. Heavy metals (cobalt, nickel, copper, zinc, cadmium, mercury, lead) and a poisonous metalloid (arsenic) were selected in 59 sampling stations and determined using differential pulse polarography method. The multivariate statistical tools were applied to describe and interpret the experimental data. The overall mean concentrations of studied metals (in microgram per liter; μg L^-1) in the samples were found in the order Zn (10.9) > Ni (7.4) > Cu (5.5) > Pb (1.9) > Hg (1.4) > As (1.3) > Co (1.1) > Cd (0.2). The results when compared with reported international standards confirmed that the sampled waters do contain some of these elements above the suggested maximum permissible limits. Hg and Cu were detected in 54.2 and 72.9% of the samples, almost all above the permissible limits. Ni, Zn, Pb, and Co were detected in 100, 96.6, 93.2, and 88.1%, respectively, while 8.5, 22.0, 3.4, and 1.7% were above the permissible limits. Cd and As were present in 61 and 93% of the samples, and their concentrations were higher than the rate presented by Russian System of Management Chemicals (RSMC). In addition, spatial distribution of heavy metal concentrations showed that Gorgan Bay is an ecosystem serving as a filter, trapping natural and anthropogenic materials that are brought from industrial, commercial, and urbanized areas. The multivariate data analysis reveals that Caspian Sea is contaminated by both anthropogenic as well as pedo-geochemical sources.

Comparative Study of Metal Accumulation in Three Fish Species (Silurus asotus, Cyprinus carpio, and Carassius auratus auratus) from the Jinsha and Tuo Rivers Located Upstream of the Yangtze River, China

The concentrations of lead, chromium, cadmium, arsenic, and mercury were analyzed in the muscle and liver (hepatopancreas) of three fish species (Silurus asotus, Cyprinus carpio, and Carassius auratus auratus) from the Jinsha and Tuo Rivers. The above mentioned metal concentrations in the muscles of the three fish species were below the permissible limits, indicating that these fishes are safe for human consumption. The concentration of mercury in the carnivorous fishes was higher than that in the omnivorous fishes. There was no significant difference in growth rate and the concentration of lead, chromium, cadmium, arsenic, and mercury among the fishes from Panzhihua and Fushun. In the two age groups, the concentration of mercury did not vary significantly with growth rate of fish. The relationship between heavy metal concentration and growth rate of fish varied with metal species, fish species, and fish tissue.

Tissue-Specific Antioxidative Responses and Cadmium Accumulation in Silurus meridionalis Under Chronic Waterborne Cadmium Exposure

In this study, the oxidative damage, antioxidative responses and cadmium (Cd) accumulation in juvenile Silurus meridionalis were studied, after S. meridionalis were exposed to 0 (control), 62.5, 125, 250 and 500 µg Cd/L for 56 days. Cd accumulation, malondialdehyde, superoxide dismutase (SOD), catalase, glutathione (GSH) and total antioxidant capacity (T-AOC) were determined in gill, liver, kidney and intestine tissues. The results showed that the Cd accumulation in S. meridionalis was dose-dependent and tissue-specific, with the highest Cd content in the kidney, followed by the liver, gill, and intestine. Waterborne Cd stress in S. meridionalis was expressed as tissue-specific oxidative damage and antioxidant responses in gill, liver, kidney and intestine tissues. Waterborne Cd exposure induced the most significant oxidative damage in the gill, followed by the liver and kidney, while the intestine showed no sensitivity to waterborne Cd exposure. The antioxidants, such as SOD in the liver, kidney and intestine, as well as T-AOC and GSH in the gill, liver and kidney, were sensitive to waterborne Cd exposure.

Health risk assessment of arsenic and heavy metals (Cd, Cu, Co, Pb, and Sn) through consumption of caviar of Acipenser persicus from Southern Caspian Sea

In the current study contents of As, Cd, Cu, Co, Pb, and Sn were determined in the caviar of Persian sturgeon collected from Southern Caspian Sea sampling site. After acid digestion of caviar specimens, the concentrations of elements determined using ICP-OES. The results showed that the mean concentrations (mg kg^-1) of elements in caviar samples were 0.01 for As, 0.05 for Cd, 1.42 for Cu, 0.01 for Co, 0.01 for Pb, and 0.28 for Sn and for all the elements are significantly lower than the adverse level for the human consumption. Also, health risk index (HRI) values were within the safe limits (HRI < 1). Therefore, there is no potential health risk to adults and children via consumption of caviar. Due to the discharge of hazardous chemicals into the marine ecosystems especially the Caspian Sea, residue analysis of pollutants in the sea foods is recommended.

Biochemical, Histopathological and Molecular Responses in Gills of Leuciscus cephalus Exposed to Metals

Gills are major targets for acute metal toxicity in fish, due to their permanent contact with aquatic pollutants. To assess the effects of metals on gills of the Leuciscus cephalus (chub), fish individuals were collected from two sites in the Tur River, Romania, in upstream (site 1) and downstream (site 2) of a metal pollution source. Quantitative and hyperspectral analyses showed that Zn, Sr, and Fe concentrations were significantly higher in gills from site 2 compared with site 1. Malondialdehyde and advanced oxidation protein products levels increased 17 and 28%, respectively, whereas reduced glutathione level diminished significantly in the gills of fish collected from site 2 compared to site 1. The activities of superoxide dismutase, catalase, and glutathione-S-transferase increased significantly at 41, 21, and 28%, respectively. Proliferating cell nuclear antigen (PCNA) protein levels, as well as the amount of DNA damage, were significantly increased for site 2 compared with site 1. The induced oxidative stress generated hyperplasia, hypertrophy, and inflammation in the epithelial cells and apoptosis. Hence, this could suggest that gill cells have tried to counteract the oxidative stress-induced DNA fragmentation by PCNA up-regulation, but the PCNA expression decreased on longer time due to the low level of GSH, resulting in apoptosis.

Potential health risk assessment of heavy metals via consumption of caviar of Persian sturgeon

Caviar may contain high levels of toxic metals. Therefore determination of health risk assessment of the heavy metals in this luxury product is vital. In this study, an Inductively Coupled Plasma-Optical Emission Spectrometer and a Direct Mercury Analyzer were used to assess the contents of elements in caviar of wild Persian sturgeon. The results showed that the contents of Ba, Cr, Fe, Hg, Mn and Zn (mgkg^-1) in caviar samples were 0.95, 0.27, 71.3, 1.44, 0.01 and 17.0, respectively. Also, Health Risk Index values were within the safe limits (HRI<1), and there is no potential health risk for adults and children via consumption of caviar. Finally, considering the contents of Fe and Hg were higher than Maximum Permissible Limits in the caviar samples related to the discharge of pollutants into the aquatic environment, monitoring of chemicals accumulation in the foodstuff is recommended.

Mercury, lead, and cadmium in tissues of the Caspian Pond Turtle (Mauremys caspica) from the southern basin of Caspian Sea

Concentrations of cadmium, lead, and mercury were measured in different tissues (liver, muscle, and shell) of 60 Caspian Pond Turtles collected from Tajan and Shiroud Rivers, southern basin of the Caspian Sea. Based on the results, different tissues showed different capacities for accumulating trace elements. The general trend of metals accumulation was: liver > shell > muscle. Results also showed that accumulation of these elements was not significantly different between sex and river in turtles (p > 0.05). Based on the results, Hg and Pb concentrations recorded in the present study were higher than some of the maximum concentration permissible. To our knowledge, this is the first report into heavy metal accumulation in tissues and organs of Caspian Pond Turtle from the southern basin of Caspian Sea. Further studies are needed to measure different heavy metals and trace metals in this valuable species.

Exposure of Persian sturgeon (Acipenser persicus) to cadmium results in biochemical, histological and transcriptional alterations

Sturgeon is one of the endangered families of fish in the Caspian Sea region, where there is up to 80% of their global caching. Unfortunately, in recent years, increase of pollutants has been resulted in their total population reduction. Due to their benthic nature, sturgeons are at great risk of exposing to contaminants such as cadmium. Despite their endangered status in the Caspian Sea, there are only a few studies on characterizing the relative sensitivity of sturgeons to cadmium. Adverse effects associated with pollution on angiogenesis are mediated by hypoxia inducing factor-1 (HIF-1) and vascular endothelial growth factor (VEGF). In this investigation, gene expression of two distinct HIFs-1, HIF-1α and HIF-2α, and VEGF was investigated at the mRNA transcript levels after exposure of Persian sturgeon (Acipenser persicus) to cadmium. VEGF, HIF-1α and HIF-2α expressions in treated Persian sturgeon were greater than controls. Significant increases (P<0.05) were also observed in cortisol and glucose levels compared to the control group especially in the fish exposed to higher cadmium concentration (800 μg/L). Plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactic acid dehydrogenase (LDH) levels were increased in the cadmium-exposed fish, although the observed increases were not significant between the control and 200 μg/L cadmium treatment at some sampling time points. Gill tissues also showed histopathological changes in the cadmium treatments. Overall, results indicated that cadmium resulted in some alterations in biochemical parameters, mRNA transcript level expression of two important angiogenesis related genes as well as histological alterations in Persian sturgeon.

Concentrations of trace elements in the kidney, liver, muscle, and skin of short sea snake (Lapemis curtus) from the Strait of Hormuz Persian Gulf

To our knowledge, this is the first report into trace elements accumulation in tissues of the short sea snake (Lapemis curtus). Lead (Pb), cadmium (Cd), copper (Cu), vanadium (V), nickel (Ni), and zinc (Zn) were determined in the kidney, liver, skin, and muscle tissues of short sea snake, L. curtus, from the Strait of Hormuz during October 2011. Skins generally displayed the lowest trace element burdens. Kidneys displayed the highest Pb, Cd, V, Ni, and Cu mean concentrations (0.89, 0.04, 1.66, 6.22, and 20.23 μg g(-1) dry weight, respectively), while muscle exhibited the highest Zn levels (493.32 μg g(-1) dry weight). Concentration ranges of the selected trace elements were compared with those reported in other studies. Data presented here may be considered as a baseline for further ecotoxicological studies in sea snakes.

Histopatological alterations and oxidative stress in liver and kidney of Leuciscus cephalus following exposure to heavy metals in the Tur River, North Western Romania

Pollution of the aquatic environment by heavy metals is a great concern worldwide. Freshwater fish ingests various metals through gills, skin or diet. Our aim was to investigate the oxidative stress and histopathological injuries induced by Fe, Cu, Zn, Pb, Cd in the liver and kidney of Leuciscus cephalus. Fish samples were collected from two sites in the Tur River, NW Romania, in upstream and downstream of a pollution source. Metals were differently distributed in the liver and kidney of fish. The highest concentrations of Fe, Cu and Pb were found in liver, whereas Zn and Cd concentrations were the highest in kidney in specimens collected from the downstream site. The histopathological changes were associated with metal bioaccumulation, being more severe in kidney than liver. Malondialdehyde (MDA) and advanced oxidation protein products (AOPP) increased significantly in the liver and kidney of fish from downstream site compared to upstream one, whereas reduced glutathione (GSH) decreased. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) increased significantly in livers, whereas SOD increased in kidney. Our study revealed that liver has a higher capacity and adaptability to counteract ROS compared to kidney. The more pronounced increase of hepatic SOD, CAT and GST activities is related milder structural changes observed in liver compared to kidney, where lesions were not reduced by antioxidant defense system.

Mapping differential elemental accumulation in fish tissues: assessment of metal and trace element concentrations in wels catfish (Silurus glanis) from the Danube River by ICP-MS

Studies of metal accumulation in fish are mainly focused on the muscle tissue, while the metal accumulation patterns in other tissues have been largely neglected. Muscle is not always a good indicator of the whole fish body contamination. Elemental accumulation in many fish tissues and organs and their potential use in monitoring programs have not received proper attention. In the present study, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn concentrations were assessed by inductively coupled plasma mass spectrometry (ICP-MS) in the following 14 tissues of the wels catfish (Silurus glanis) from the Danube River: muscle, gills, spleen, liver, kidneys, intestine, gizzard, heart, brain, gallbladder, swim bladder, vertebra, operculum, and gonads. A high level of differential elemental accumulation among the studied tissues was observed. The maximum overall metal accumulation was observed in the vertebra, followed by the kidneys and liver, with the metal pollution index (MPI) values of 0.26, 0.25, and 0.24, respectively. The minimum values were observed in the gallbladder, muscle, brain, and swim bladder, with MPI values of 0.03, 0.06, 0.07, and 0.09, respectively. Average metal concentrations in the fish muscle were below the maximum allowed concentrations for human consumption. The mean As, Cd, Pb, Cu, Fe, and Zn concentrations in the muscle were 0.028, 0.001, 0.001, 0.192, 3.966, and 3.969 μg/g wet weight, respectively. We believe that the presented findings could be of interest for the scientific community and freshwater ecosystem managers. There is a need for further research that would assess less studied tissues in different fish species.

Distribution and composition pattern of polycyclic aromatic hydrocarbons in different tissues of sturgeons collected from Iranian coastline of the Caspian Sea

The levels of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the liver, kidney, gills and muscle tissues of Persian sturgeon (Acipenser persicus; n=16), and Stellate sturgeon (Acipenser stellatus; n=7) collected from coastal waters of the South Caspian Sea from March and April 2011. The distribution and composition pattern of PAHs in the different tissues of sturgeons, and the effects of lipid content in sturgeon tissues and the octanol-water partition coefficient (Kow) of PAHs congeners on them were analyzed. The levels of total PAHs in the various tissues of Persian sturgeon and Stellate sturgeon ranged from 2.095 to 6.587 and 1.942 to 6.206 μg g(-1)dw, respectively. Stellate sturgeon showed significantly higher levels of heavy PAHs (⩾ 4-rings) than Persian sturgeon. The analysis has revealed a high degree of differential accumulation of the studied PAHs in the tissues of the both species. Low molecular weight PAHs predominated in the sturgeons, accounting for 81.89% of the total PAHs. Among the sixteen tested PAHs, naphthalene was the most dominant congener, followed by phenanthrene and fluorene. The PAHs levels and distribution in the tissues of sturgeons are dependent on both the Kow of PAH congeners and the lipid content in these tissues. There was a significant positive relationship (r=0.868, p<0.005) between lipid content and PAHs levels. The statistically significant negative relationships (p<0.01) were found between log Kow and log-transformed PAHs levels for muscle tissues of both sturgeon species.

Distribution patterns of PAHs in different tissues of annulated sea snake (Hydrophis cyanocinctus) and short sea snake (Lapemis curtus) from the Hara Protected Area on the North Coast of the Persian Gulf, Iran

The levels of 22 polycyclic aromatic hydrocarbons (PAHs) were determined in the skin, liver, kidney and muscle tissues of annulated sea snake (Hydrophis cyanocinctus), and short sea snake (Lapemis curtus) collected from the Hara Protected Area, Persian Gulf during October 2010. Low molecular weight (≤3-rings) had the highest levels in skin, while high molecular weight (≥4-rings) was highest in the kidney. The lowest levels of analyzed PAHs were found in muscle in the both species. H. cyanocinctus (59.37 ng g(-1) dw) revealed to be significantly more contaminated than L. curtus (50.51 ng g(-1) dw). Naphtalene was the PAH most frequently detected and at the highest level in the different tissues both species. Di- and tri-cyclic PAHs were predominant in both species suggesting petrogenic origin rather than pyrogenic sources of PAHs. The present study represents the first data of contamination by PAHs in sea snake from the Persian Gulf.

Assessment trace elements concentrations in tissues in Caspian Pond Turtle (Mauremys caspica) from Golestan province, Iran

Concentrations of cadmium, lead, zinc, and copper were measured in different organs and tissues of 15 Caspian Pond Turtle (Mauremys caspica) collected from Gharehsu River, Golestan province, Iran in June and July 2012. Mean concentrations (dry weight) of zinc and copper were 66.9 and 6.7µgg(-1) in liver, 147 and 3.4µgg(-1) in heart, 93.2 and 4.9µgg(-1) in shell, and finally 150.7 and 4.5µgg(-1) in muscle, respectively. Mean concentrations of cadmium and lead were 5.8 and 32.4µgg(-1) in liver, 2.9 and 20.9µgg(-1) in heart, 3.5 and 21.5µgg(-1) in shell, and finally 2.5 and 27.5µgg(-1) in muscle, respectively. On average, lead, cadmium, copper and zinc concentrations in the analyzed tissues were much higher than those reported in other freshwater turtle species. In particular, the mean concentrations of lead in liver and muscle of Caspian Pond Turtle was extremely high. To our knowledge, this is the first report into metal accumulation in tissues and organs of Caspian Pond Turtle from of the Gharehsu River in Golestan province, Iran.

Heavy metal bioaccumulation and risk assessment for wild and farmed beluga sturgeon caviar

Because of over-exploitation of sturgeon for caviar production, they have been listed worldwide in annex II of the Convention on International Trade in Endangered Species regulations; so caviar production using aquaculture is increasingly seen as a feasible way to reduce overfishing. The accumulation of the nonessential metals As, Ba, Cd, Hg, Pb, and Sn was determined in the caviar of farmed and wild Beluga sturgeon (Huso huso). The levels of As in both and Cd in wild samples were less than 0.01 mg kg(-1) wet weight, and the comparison for all of the metals studied did not show large fluctuations in metal concentrations between farmed and wild caviar samples. The average for each toxic metal was below the permissible limits proposed by the UK's Ministry of Agriculture, Fisheries and Foods (2000). The maximum allowable daily consumption rate of caviar was calculated; however, the health risks from caviar consumption are uncertain because the amount of caviar consumed by heavy users is not known.

Selected heavy metals analysis of Persian sturgeon's (Acipenser persicus) caviar from Southern Caspian Sea

The present research reports the heavy metal (Fe, Cr, Pb, As, and Co) contamination in caviar of Persian sturgeon (Acipenser persicus) caught from Southern Caspian Sea sampling site using ICP-OES. Heavy metal concentrations (microgram per gram, wet weight; means ± S.D.) in caviar samples were: Fe, 71.33 ± 0. 37; Cr, 0.27 ± 0.019; Pb, <0.01 ± 0.002; As, <0.01 ± 0.002; and Co, <0.01 ± 0.001, respectively. Comparative evaluation of these metals in different samples showed that except Fe, the average concentrations of Cr, Pb, As, and Co are significantly lower than adverse level for the species themselves and for human consumption when compared with FAO/WHO permissible limits. Therefore, their contribution to adverse health effects on human body can be considered as negligibly small.