Liver Tissues Of Fish Research Articles

Effect of prebiotics on the growth performance, haematological, biochemical, and histological parameters of African catfish (Clariasgariepinus) in recirculating aquaculture system

In this study, African catfish (Clarias gariepinus) was investigated under controlled conditions in recirculating aquaculture system (RAS). The experiment tested the effects of three different dietary prebiotics (FOS: fructooligosaccharide, GOS: galactooligosaccharide, and MOS: mannanoligosaccharide) in two levels (1 g/kg and 2 g/kg) and a control diet on the growth performance, survival rate, haematological and biochemical parameters, and small intestinal and liver histology of the African catfish. Better growth results were obtained in MOS (2 g/kg) supplementation, and there was a statistical difference (P < 0.05) between the MOS (2 g/kg) and the control group. Haematological parameters (erythrocyte sedimentation rate, red blood cell, white blood cell, lymphocyte, neutrophil, and glucose) were similar among all groups (P > 0.05) while some (alanine aminotransferase, aspartate aminotransferase enzymes, and monocyte) were significantly different (P < 0.05). The MOS (2 g/kg) group had longer villi length values than the control group. There was no difference among the groups in terms of small intestine histomorphology and liver tissues in fish. According to the results of this experiment, it can be said that MOS addition has a positive effect on growth parameters and could improve health conditions in Clarias gariepinus culture.

Bioaccumulation of metal in liver tissue of fish in response to water toxicity of the Araguari-Amazon River, Brazil.

This study aimed to determine the concentration of metals in the water and in the liver tissue of fish (Anodus orinocensis, Hemiodus unimaculatus, Curimata vittata, and Plagioscion squamosissimus) in the lower Araguari River. Steps were also taken to estimate any difference in metal bioaccumulation in the liver of fish species at different trophic levels, determine any correlations between metals found in hepatic tissue of fish species relative to that found in river water, and evaluate the bioaccumulation factor. The metals analyzed in the water in the lower Araguari River (Cd, Pb, Fe, Hg, Cu, and Zn) exceeded the limits considered safe for aquatic life. We found a significant difference only in the bioaccumulation of Pb between A. orinocensis and C. vittata (F = 4.65, p = 0.005) and Cr between A. orinocensis and H. unimaculatus (F = 3.12, p = 0.03). Species of distinct trophic levels showed differences in metal concentration in liver. Cd and Cu showed bioaccumulation factor above 100, especially Cu with a relatively high value, for all fish species. The bioaccumulation of metals in the liver of fish species showed a positive correlation with the metals detected in the water of the Araguari River. In this sense, the lower course of the Araguari River is undergoing some type of environmental stress, making this study of additional valuable in diagnosing environmental quality pursuant to the development of environmental monitoring projects in order to guarantee the safety and maintenance of aquatic life.

Polyunsaturated fatty acids in fish tissues more closely resemble algal than terrestrial diet sources

The River Continuum Concept implies that consumers in headwater streams have greater dietary access to terrestrial basal resources, but recent studies have highlighted the dietary importance of high-quality algae. Algae provide consumers with physiologically important omega-3 (n-3) polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA). However, terrestrial plants and most benthic stream algae lack the long-chain (LC) n-3 PUFA docosahexaenoic acid (DHA, 22:6n-3), which is essential for neural development in fish and other vertebrates. We sampled subalpine streams to investigate how the PUFA composition of neural (brain and eyes), muscle, and liver tissues of freshwater fish is related to their potential diets (macroinvertebrates, epilithon, fresh and conditioned terrestrial leaves). The PUFA composition of consumers was more similar to epilithon than to terrestrial leaves. Storage lipids of eyes most closely resembled dietary PUFA (aquatic invertebrates and algae). However, DHA and arachidonic acid (ARA, 20:4n-6) were not directly available in the diet but abundant in organs. This implies that algal PUFA were selectively retained or were produced internally via enzymatic PUFA conversion by aquatic consumers. This field study demonstrates the nutritional importance of algal PUFA for neural organs in aquatic consumers of headwater regions.

Biomarker responses of Nile tilapia towards wastewater effluents exposure

Due to the limited water resources for fish culturing, fish farming using wastewater has been adopted in many countries. Therefore, fish are in continuous exposure to these pollutants. Considering fish, a bio-indicator model to monitor the aquatic pollution, this study was undertaken to evaluate a general fish health indicators at the cellular and molecular levels in cultured Nile tilapia (Oreochromis niloticus) using wastewater effluents as their primary water source over three sites known for their industrial pollution as highly polluted sites (S1), moderately polluted (S2) and a putative control deemed low in contaminants (reference site, RS). The impact of wastewater was assessed in Nile tilapia and results revealed a significant increase in innate immune, oxidant/antioxidant parameters and serum biochemical parameters; mostly in fish captured from (S1) than others. Liver tumour necrosis factor-α (TNF-α) and interleukin-8 (IL-8) mRNA levels were significantly increased in fish from contaminated sites compared with those from the unpolluted site. Phenolic compounds were detected in water and liver tissue of fish captured from the highly polluted site. The principal component analysis (PCA) score plots for these parameters revealed that the groupings were based on high percentage of the explained variance in all cases (60% for control, 60% for site 1 and 40% for site 2). The current findings suggested a correlation between biomarkers response and wastewater exposure as stressors. Besides, the assessed multiple general health indicators give potential insights for Nile tilapia adaptive pattern and monitoring of pollution of freshwater ecosystems.

Effects of dietary proline on swim bladder collagen synthesis and its possible regulation by the TGF‐β/Smad pathway in spotted drum, Nibea diacanthus

Swim bladder is an ideal source of collagen production in fish for improved human health. Proline (Pro) is the main proteinogenic amino acid needed for collagen production. However, the effects of Pro supplementation on the swim bladder collagen synthesis have rarely been evaluated in fish. We determined the effects of dietary Pro supplementation on swim bladder collagen synthesis and its possible signalling pathway in spotted drum, Nibea diacanthus. A total of 450 N. diacanthus (100 ± 3.05 g) were randomly assigned into six treatments and fed with diets supplemented with different levels of Pro (0, 2.5, 5, 7.5, 10 and 12.5 g/kg of dry diet, hereafter P0, P1, P2, P3, P4 and P5, respectively) for 8 weeks. At the end, we evaluated collagen synthesis in swim bladder and the expression of genes related to TGF-β/Smad pathway in the fish. Dietary Pro levels increased significantly the contents of crude protein, total collagen (TC) and the levels of some amino acids in swim bladder than the control diet (p < .05). The optimum amount of dietary Pro inclusion in diets for swim bladder collagen synthesis in N. diacanthus was 7.6 and 7.5 g/kg based on crude protein and TC in swim bladder, respectively. Dietary Pro levels increased significantly the proline 4-hydroxylase (P4H) content in fish serum, swim bladder, muscle and liver tissues than control (p < .05). The relative expression of collagen type I alpha 1 (COL1A1), alpha 2 (COL1A2) and mothers against decapentaplegic homolog 2 (Smad2) genes in liver and swim bladder initially increased significantly as the concentration of Pro and later decreased (p < .05). Similarly, the relative expression of transforming growth factor beta (TGF-β), P4Ha2 and P4Ha3 genes in the swim bladder increased significantly as dietary Pro levels increased (p < .05). Using K-means clustering analysis, dietary proline partly promoted collagen accumulation in swim bladder through upregulation of Smad2 and TGF-βRT genes. Taken together, Pro affected the collagen metabolism in swim bladder, probably by regulating the TGF-β/Smad pathway, most likely via transient overexpression of Smad2 gene.

Comparison of the metal concentrations in muscle and liver tissues of fishes from the Erren River, Southwestern Taiwan, after the restoration in 2000

Metal concentrations in the muscle and liver tissues of fishes from the Erren River in southwestern Taiwan were analyzed to evaluate the pollution status after the completion of the restoration plan in 2000. It was the first time the tissue concentrations of 4 important elements, i.e. Fe, Mn, As and Hg, were reported in fishes from this area. Samples were collected in January 2002 at the junction of the Erren River and the Sanyegong River, the most polluted section of the river. Five fish species, Megalops cyprinoids (Indo-Pacific tarpon), Chanos chanos (milkfish), Liza macrolepis (large-scaled mullet), Mugil cephalus (striped mullet) and Orechromis sp. (tilapia) were collected. A total of 91 fishes were dissected and the muscle and liver tissues taken for analysis of seven metals, Fe, Zn, Cu, Mn, As, Hg and Cd, on a wet weight basis (mg/kg). Among them, Fe and Zn were the highest, followed by Cu, Mn and As, while the Hg and Cd concentrations were the lowest. Except for As and Hg, which showed higher concentrations in the muscle tissues than in the livers, the remaining elements showed higher concentrations in livers. Significant species differences were found in all elements and tissues. The highest concentrations of Fe, Zn, Cu and Mn in muscles were found in tilapia (4.04), striped mullet (4.38), large-scaled mullet (0.20) and milkfish (0.534), respectively. The highest concentrations of As and Hg were found in striped mullet (1.59) and Indo-Pacific tarpon (0.081), respectively. The highest concentrations of Fe (3122), Hg (0.045) and Cd (0.123) were found in livers of large-scaled mullet, while striped mullet had the highest concentration of Zn (77.6), Cu (78.2) and As (2.39). The level of Mn in tilapia was 1.32 mg/kg. The Zn, Cu and Cd concentrations of the muscles and livers were mostly 7-50% lower than the levels reported on the same species of the same tissue before the restoration indicating the improvement on the metal pollution status. The heavy metal concentrations in this area were similar to various uncontaminated areas around Taiwan and all were within the food standard levels of the FDA and NHMRC.

Heavy rainfall provokes anticoagulant rodenticides' release from baited sewer systems and outdoor surfaces into receiving streams

Prevalent findings of anticoagulant rodenticide (AR) residues in liver tissue of freshwater fish recently emphasized the existence of aquatic exposure pathways. Thus, a comprehensive wastewater treatment plant and surface water monitoring campaign was conducted at two urban catchments in Germany in 2018 and 2019 to investigate potential emission sources of ARs into the aquatic environment. Over several months, the occurrence and fate of all eight ARs authorized in the European Union as well as two pharmaceutical anticoagulants was monitored in a variety of aqueous, solid, and biological environmental matrices during and after widespread sewer baiting with AR-containing bait. As a result, sewer baiting in combined sewer systems, besides outdoor rodent control at the surface, was identified as a substantial contributor of these biocidal active ingredients in the aquatic environment. In conjunction with heavy or prolonged precipitation during bait application in combined sewer systems, a direct link between sewer baiting and AR residues in wastewater treatment plant influent, effluent, and the liver of freshwater fish was established. Moreover, study results confirmed insufficient removal of anticoagulants during conventional wastewater treatment and thus indirect exposure of aquatic organisms in receiving streams via tertiary treated effluents and combined sewer overflows. Nevertheless, further research is required to determine the ecological implications and risks for aquatic organisms as well as fish-eating predators from chronic AR exposure at environmentally relevant concentrations.

Methylmercury bioaccumulation among different food chain levels in the EEZ of Qatar (Arabian Gulf)

Methylmercury (MeHg) concentrations in three different species from different trophic levels with different amounts of Hg exposures were determined for the first time in the EEZ of Qatar. Sampling was conducted during autumn 2017 in two nearshore (Palm Tree and Al-Besheriya Islands) and two offshore locations (Sherawoo and Ishat Islands). Fish muscle and liver tissues were analyzed according to the US Environmental Protection Agency Method 1630. The lowest mean MeHg concentration was found to be 42.3 ppb wet weight in the lower trophic level fish Gerres oyena due to small fish size and trophic level; whereas, the highest MeHg concentration was found in higher trophic level sharks Rhizoprionodon oligolinx and Chiloscyllium arabicum with mean wet weight concentrations of 712 ppb and 166 ppb, respectively. Linear relationships were found between fish body size (weight, length, age) and MeHg concentrations. MeHg bioaccumulation was found to be higher in liver than in muscle tissue; however, there was no significant difference in tissue MeHg accumulation as well as, the concentrations between the four locations. The present study concludes that MeHg in most of the fish tissues is within the allowable limits and pose no threat to public health. Only the higher trophic level shark Rhizoprionodon oligolinx was found to have a MeHg concentration higher than the US EPA advisory level of 0.3 ppm. However, consumers should still be encouraged to eat smaller sized younger fish from lower trophic levels, which would be safer than larger older species from higher trophic levels.

The effective adsorbent capacity of rice husk to iron and aluminum oxides nanoparticles using Oreochromis niloticus as a bioindicator: biochemical and oxidative stress biomarkers.

Metal oxide nanoparticles (NPs) have different industrial applications so it is unavoidable that NPs products could find their way into aquatic habitats. Therefore, toxic NPs must be treated sufficiently to reach the standard values before their discharge into the aquatic ecosystems. Our study aimed to investigate the adsorptive capacity of rice husk to iron and aluminum oxides from water and reducing their potential toxic effects. Fish were classified into eight groups for 7days: Fe2O3 NPs (10mg/l)-exposed group; Al2O3 NPs (10mg/l)-exposed group; combined group (same concentrations of Fe2O3 and Al2O3NPs), and control group (dechlorinated water). The other four groups were the same as the above groups but with 50mg/l rice husk in each group. Compared with control groups, our results showed a significant (p < 0.05) increase in plasma total proteins, globulin, glucose, liver enzymes, and kidney function biomarkers (creatinine and uric acid). While the recorded albumin and total lipids were significantly decreased. The oxidative biomarkers in liver and gill tissues of NPs-exposed fish showed significant (p < 0.05) reduction in glutathione-reduced content and elevation in thiobarbituric acid reactive substances, glutathione peroxidase, catalase, and superoxide dismutase. Based on our results, Fe2O3 NPs were more toxic than Al2O3 NPs. The combined doses of both NPs showed more or less toxicity compared to single doses. Therefore, this point needs more studies to show the mode of interaction. Finally, rice husk was a good adsorber to both NPs as it could improve the biochemical and antioxidant status of the studied fish.

Poikilocytosis and tissue damage as negative impacts of tramadol on juvenile of Tilapia (Oreochromis niloticus)

Pharmaceuticals residue was detected in the water bodies as a consequence of the incomplete treatment. Recently, the side impacts of that residue on aquatic creatures have received a considerable attention. However, there is insufficient information about the effect of the most consumed narcotic drug (tramadol) on fish as an aquatic model. Thus, this study aims at investigating the poikilocytosis and tissue damage in Oreochromis niloticus after the exposure to 100 and 200 mg/L of tramadol hydrochloride. Three groups of fish were used; one as a control group, and the other two groups were exposed to 100 mg/L and 200 mg/L of tramadol hydrochloride respectively for 25 days. Exposure to tramadol caused a significant increase in the percentage of poikilocytosis compared to the control group. Poikilocytosis included tear-drop cell, spindle-shaped cell, sickle cell, schistocyte, blebbed cell, acanthocyte, eccentric nucleus, amoebocyte, dividing cell, and crenated cell. Moreover, liver tissue in fish exposed to tramadol showed degeneration and vacuolization of hepatocytes and atrophy of pancreatic acini as signs of histopathological alterations. Histopathological changes of brain showed severe gliosis, dark neurons, and vacuolization in fish exposed to tramadol compared to control fish. Gills tissue showed erosion, epithelial lifting, and secondary lamellae shrinking in fish exposed to tramadol compared to control fish. In conclusion, tramadol induced histopathological changes in liver, brain, and gills of Oreochromis niloticus as well as poikilocytosis were indicated clearly. Therefore, tramadol leakage to waters should be avoided to preserve aquatic creatures.

Isolation, identification and pathogenicity of Proteus vulgaris from moribund common carp (Cyprinus carpio) farmed in China

Common carp (Cyprinus carpio) is one of the most important aquaculture species in the world. In recent years, several outbreaks of unknown etiology has caused huge economic losses in common carp culture. To determine the death cause of common carp in Chongqing, China, we isolated potential pathogens from the infected common carp. The isolated bacteria (CQC01) recovered from moribund common carp was identified as Proteus vulgaris based on biochemical characterization and 16S rDNA sequence analysis. The pathogenicity of CQC01 was determined by artificial infection. Common carp experimentally infected with CQC01 showed the same symptoms as the naturally infected fish, including swelling on the anus, congestion on the eyelids, fins and abdominal muscle. At 6 h post infection (hpi), malondialdehyde (MDA), catalase (CAT), alanine aminotransferase (ALT), alkaline phosphatase (AKP), and lysozyme (LYZ) level in serum of fish infected with high concentration of CQC01 (109 CFU/mL) were significantly increased, but superoxide dismutase (SOD) activity was significantly decreased; whereas, liver tissue of infected fish showed immunological and oxidative stress. The histopathology of the challenged fish showed pathological lesions on hepatopancreas, kidney, spleen and muscle, suggesting CQC01 infection caused great damage to fish. Antimicrobial susceptibility test showed that the strain CQC01 was not resistant to most of antibiotics. Narrow-spectrum antibiotics were recommended for the control of strain CQC01. This study highlights the incrimination of P. vulgaris in the disease outbreak of cultured common carp for the first time. These findings provide guidance for the prevention and control of Proteus related diseases.

Comparative Study on Diet Added with Organic and Inorganic Selenium Forms Provided to Carps Exposed to Fipronil Insecticide

Carps belonging to species Cyprinus carpio (carp) were fed on organic and inorganic selenium forms for 60 days to enable evaluating the biochemical profile of tissues exposed to fipronil (FPN) insecticide. Diphenyl diselenide [(PhSe)2] (3.0 mg/kg) and sodium selenite (Na2SeO3) (0.75 mg/kg) were used as organic and inorganic selenium forms, respectively. Overall, the adopted organic and inorganic selenium forms were similarly capable of reestablishing oxidant and antioxidant stress parameters close to control levels. Fish exposed to fipronil have shown decreased acetylcholinesterase (AChE) activity in brain and muscle tissues. Brain tissues of fish supplemented with Na2SeO3 or (PhSe)2 diets presented reestablished AChE levels in comparison to those of fish fed on standard diet. Liver tissues of fish fed on standard diet presented decreased δ-ALA-D activity after their exposure to FPN, whereas diets added with two selenium forms were efficient in reestablishing the levels of standard diets. Therefore, (PhSe)2 and Na2SeO3 have potential to be used as supplementation factors in diets to feed C. carpio.

Specific pathogens and microbial abundance within liver and kidney tissues of wild marine fish from the Eastern Mediterranean Sea.

SummaryThis study is an initial description and discussion of the kidney and liver microbial communities of five common fish species sampled from four sites along the Eastern Mediterranean Sea shoreline. The goals of the present study were to establish a baseline dataset of microbial communities associated with the tissues of wild marine fish, in order to examine species‐specific microbial characteristics and to screen for candidate pathogens. This issue is especially relevant due to the development of mariculture farms and the possible transmission of pathogens from wild to farmed fish and vice versa. Although fish were apparently healthy, 16S rRNA NGS screening identified three potential fish bacterial pathogens: Photobacterium damselae, Vibrio harveyi and Streptococcus iniae. Based on the distribution patterns and relative abundance, 16 samples were classified as potential pathogenic bacteria‐infected samples (PPBIS). Hence, PPBIS prevalence was significantly higher in kidneys than in liver samples and variation was found between the fish species. Significant differences were observed between fish species, organs and sites, indicating the importance of the environmental conditions on the fish microbiome. We applied a consistent sampling and analytical method for monitoring in long‐term surveys which may be incorporated within other marine fish pathogens surveys around the world.

Partial and total replacement of fish oil with fatty acid ethyl esters in the starter diets of rainbow trout (Oncorhynchus mykiss)

Fatty acid ethyl esters (FAEE) are a potential alternative to fish oil as a source of polyunsaturated fatty acids in fish feeds. This investigation examined the growth performance, lipid composition, and intestinal and liver histology of rainbow trout (Oncorhynchus mykiss) fed experimental starter diets with graded levels of FAEE and fish oil. Five experimental diets were formulated with 20% total lipid content and 0%, 25%, 50%, 75%, and 100% replacement of Alaskan Pollock oil with FAEE oil, and they were formulated with analogous fatty acid levels. The five diets used defatted fish meal as the primary protein source, and a sixth diet was included that used full-fat fish meal and extracted fish oil. Triplicate groups of rainbow trout (144 ± 20 mg initial weight) were fed experimental diets for 62 days on a restricted feeding regime (4–5.5% biomass/day). The group fed the full-fat fish meal diet had faster growth and a lower feed conversion ratio than the defatted fish meal diet groups after 31 and 62 days of feeding. The growth rate and feed conversion ratios of fish were significantly different between the FAEE-containing diet groups in the first 31 days of feeding, but were not significant from 32 to 62 days of feeding. Fatty acid analysis showed similarity between the fatty acid profiles in experimental diets and in fish muscle and liver tissues at the end of the experiment (all groups mean weight ~3.6 g/fish). Satiation feed intake for a single day was measured at 31 days of feeding, and feed intake was higher in the 100% FAEE diet than the control (8.3 ± 1.1% vs 6.4 ± 0.3% daily satiation ratio). This result suggests that FAEE has a positive effect on voluntary feed intake. Histological analysis of posterior intestine enterocytes and hepatocytes showed a significant reduction in lipid vacuole size in the 100% FAEE group, relative to the defatted and full-fat fish meal control groups. These results suggest that rainbow trout had utilized diet with ≥50% FAEE less efficiently in the first feeding phase, likely due to reduced fatty acid absorption, but that these trends were diminished as fish grew to a larger size.

P.586 Comorbid depression in patients with schizophrenia: does it have an impact on their neurocognitive functioning?

Historically, the European Atlantic is probably the most important oil-spill hotspot worldwide. One of the most recent accidents occurred in 2002 when the oil-tanker Prestige sank over the Galician Bank causing two major oil-spills followed by several small leaks until March 2003. This resulted in contamination of virtually all types of marine habitat. Considering that parasites have proved to be good effect and accumulation bioindicators, the present study addresses the medium-term changes in trace element content after the Prestige oil-spill in a model host-parasite system, the bogue, Boops boops (Sparidae) and the isopod Ceratothoa oestroides. To our knowledge, this study is the first to address trace element concentrations in natural fish and parasite populations associated with the effects of an oil-spill. We observed that both test organisms examined, the host and the parasite, indicate a detectable change in the relative composition of trace element concentrations before and after the Prestige oil-spill. Multivariate analyses also indicated a differential response of the different tissues to the temporal sampling sequence. However, analyses of both host and parasite tissues supported the pattern of a gradual temporal transition to a state of relative trace element content distinctly departing from the pre-spill situation. Moreover, the parasite-host element accumulation ratios better depicted this temporal pattern. Additionally, changes in V concentrations in fish liver tissues and Ni concentrations in the parasite tissues suggest that this host-parasite system may be a useful tool to assess these two element contaminations linked to heavy fuel oil-spill.

The ameliorative role of geranium (Pelargonium graveolens) essential oil against hepato-renal toxicity, immunosuppression, and oxidative stress of profenofos in common carp, Cyprinus carpio (L.)

The present study investigated the possible effect of profenofos (PFF) on hepato-renal functions, non specific-immunity, and oxidants/antioxidants status in common carp, Cyprinus carpio (L.), and the supportive role of geranium (Pelargonium graveolens) essential oil (GEO). A static 96-h acute toxicity test was performed to determine the 96-h LC50 of PFF in common carp fingerlings and it was found to be 47.46 μg L−1 calculated by Finney probit analysis. One hundred and twenty fish were randomly allocated into four groups in triplicate. The first served as control and second groups were fed on basal diets that were enriched with 0.0 and 400 mg kg−1 of diet GEO, respectively without PFF exposure. The third and fourth groups were fed on the same diets and in addition, were exposed to 1/10 of the 96 h-LC50 of PFF (4.74 μg L−1), respectively for 60 days. The results revealed that the PFF exposure induced marked increases in the levels of serum alanine and aspartate aminotransferases (ALT and AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine, urea, cholesterol, triglycerides (TG), and malondialdehyde (MDA). Meanwhile, the serum total protein (TP), globulins, glucose, lysozyme activity, complement3 (C3), nitric oxide (NO), and hepatic antioxidant enzyme activities as well as the reduced glutathione (GSH) content were markedly declined in the PFF-exposed fish compared to the control group. Additionally, vacuolation, pyknosis, and degeneration of hepatocytes and epithelial cells of renal tubules with mononuclear cell infiltration were observed. A strong caspase-3 and weak BCL-2 immunohisto-reactivity in the liver and kidney tissues of PFF-exposed fish were noted respective to the control. Interestingly, GEO supplementation improved these variables with nearly restoring to control values with improving the histological architecture of liver and kidney tissues. The apoptotic condition of the examined tissues was markedly restricted in the combination group than PFF-exposed group. These results concluded that GEO has ameliorative influence against toxic impacts of PFF on hepato-renal functions, immunological parameters, and oxidative stress in common carp, and therefore, maybe a valuable candidate as a dietary supplement in aquaculture.

Occurrence, origin and health risk of arsenic and potentially toxic elements (PTEs) in sediments and fish tissues from the geothermal area of the Khiav River, Ardebil Province (NW Iran)

In this study contamination, ecological and health risk of potentially toxic elements (As, Cr, Cu, Ni, Pb and Zn) were investigated in 22 surface sediments, 3 water and 8 fish (muscle and liver tissues) samples of the Khiav River. Results showed that mean concentration of As, Cr, Cu, Ni and Zn in sediments, and As in water samples are higher than local background and standard values. Moderate to significant enrichment of As in river and very high enrichment in sediments of pollution hotspots were observed, while Zn, Cr, Cu, Ni and Pb showed low to moderate enrichment. Based on mean probable effect level (PEL) quotient, river and hotspot sediments were classified as slightly toxic and heavily toxic, respectively. Potential ecological risk index (PER) indicated low risk and high risk for river sediments and pollution hotspots, respectively. Based on factor analysis, Moiel iron mine and geothermal/hot springs are the main sources of Cr, Zn, Pb and As. Limonite as a secondary mineral accumulated As from hydrothermal or geothermal sources. Concentrations of As, Cr and Pb in fish muscle samples are higher than liver, while higher Cu, Ni and Zn concentrations observed in liver of fish samples. The Mann-Whitney U test revealed significant differences in As, Cu and Zn concentrations between different organs. The average target hazard quotient (THQ) in fish muscle followed the order of As > Cr > Cu > Pb > Zn > Ni, and hazard index (HI) values indicate an alarm for public health concern. Consumption of these fish can cause carcinogenic and non-carcinogenic effects for local people and consumers in long term.

Occurrence of organochlorine compounds in fish from freshwater environments of the central Andes, Argentina.

The Central Andes region is considered an area of high environmental relevance in South America and it is rich in glaciers, which are the main fresh water sources and reservoirs of the region. The presence of organochlorine compounds (OCs) is an environmental threat due to their persistence and adverse effects on wildlife and humans. The levels of OCs, such as chlordane compounds (CHLs), dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs), were determined in muscle and liver tissues of fish and in sediments collected from different sites of the central Andes: the Mendoza River and the Yaucha River (rainbow trout: Oncorhynchus mykiss) and Carrizal Dam (silverside: Odontesthes bonariensis). Regardless of studied site and fish tissue, the general OC trend was: DDTs > PCBs > HCHs > CHLs > HCB. The results showed clear geographic distribution patterns for DDTs. Among the sampling sites, silverside fish showed the highest average load of DDTs (614 and 867 ng g-1 lw in muscle and liver tissues, respectively). Based on the biota-sediment bioaccumulation factor (BSAF), both rainbow trout and silverside fish showed comparable capability to accumulate p,p'-DDT in their tissues. Intraspecific correlational analysis showed that CB-138 in muscle and p,p'-DDT in liver were clearly correlated with the lipid content in silverside specimens, which highlights the relevance of taking into account the fat content and the type of target tissues.

Chronic exposure of Oreochromis niloticus to sub-lethal copper concentrations: Effects on growth, antioxidant, non-enzymatic antioxidant, oxidative stress and non-specific immune responses

BackgroundTrace elements of copper (Cu) are one of the main forms of ecological noxious waste in freshwater systems that affect the survival and development of organisms. The objective of the current study was to investigate the effects of chronic exposure to Cu on the growth, oxidative stress, immune and biochemical response in the Nile tilapia, Oreochromis niloticus. MethodsThree groups of O. niloticus were tested as follows; the first group was used as the control (not treated with Cu in water), while the 2nd and 3rd groups were exposed to (low) 40 μg L−1 and (high) 400 μg L−1 concentrations of Cu added to water, respectively. The duration of the experiment, which was conducted in triplicate, was 60 d. End points were evaluated on days 30 and 60. Following 30 d and 60 d of exposure to Cu, the fish were removed from experimental tanks to determine growth. Consequently, blood samples were collected from caudal veins at the end of the trial period (30 d and 60 d) and serum was separated to evaluate different immunological parameters, such as lysozymes (LYZ), respiratory burst activity (RBA) and myeloperoxidase (MPO). Gill and liver tissues were collected for evaluation of Cu and certain biochemical parameters as follows: antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST); non-enzymatic antioxidants such as glutathione (GSH) and metallothionein (MT), and oxidative stress indicators such as malondialdehyde (MDA) and protein carbonyl (PCO). The results pertaining to treatments and the control were compared using two-way ANOVA and Tukey’s HSD test. The level of significance was set at P ≤ 0.05. Data were expressed as mean ± SD. ResultsChronic exposure to Cu did not induce any mortality in fish during the test period. However, following exposure to Cu, growth of fish in the exposed groups was affected more than that in the control group (unexposed to Cu). In addition, accumulation of Cu in the liver tissue was higher than that in the gill tissues of fish exposed to Cu, compared to that in the control. Gill and liver tissues of Cu-exposed fish showed a significant (P ≤ 0.05) reduction in the activities of the antioxidant enzymes, SOD, CAT, GPx, and GST, compared to those of unexposed fish. Non-enzymatic antioxidants, GSH and MT, in gill and liver tissues were significantly increased (P ≤ 0.05) in fish exposed to both concentrations of Cu, compared to those in unexposed fish. Oxidative stress indicators, MDA and PCO in gills and liver of Cu-exposed fish was significantly (P ≤ 0.05) at both tested concentrations, when compared to control group. Non-specific immune response of LYZ, RBA, and MPO activity in serum decreased significantly (P ≤ 0.05) in Cu-exposed fish, compared with that of unexposed fish. ConclusionOverall, the present results highlighted that chronic exposure to Cu ions may exert a strong effect on the antioxidant and immune responses of O. niloticus. Changes in antioxidant enzymes, oxidative stress effects and immune parameters during post-chronic metal exposure may indicate the potential of these parameters as biomarkers of metal toxicity in aquatic ecosystems.

Medium-term dynamics of element concentrations in a sparid fish and its isopod parasite after the Prestige oil-spill: Shifting baselines?

Historically, the European Atlantic is probably the most important oil-spill hotspot worldwide. One of the most recent accidents occurred in 2002 when the oil-tanker Prestige sank over the Galician Bank causing two major oil-spills followed by several small leaks until March 2003. This resulted in contamination of virtually all types of marine habitat. Considering that parasites have proved to be good effect and accumulation bioindicators, the present study addresses the medium-term changes in trace element content after the Prestige oil-spill in a model host-parasite system, the bogue, Boops boops (Sparidae) and the isopod Ceratothoa oestroides. To our knowledge, this study is the first to address trace element concentrations in natural fish and parasite populations associated with the effects of an oil-spill. We observed that both test organisms examined, the host and the parasite, indicate a detectable change in the relative composition of trace element concentrations before and after the Prestige oil-spill. Multivariate analyses also indicated a differential response of the different tissues to the temporal sampling sequence. However, analyses of both host and parasite tissues supported the pattern of a gradual temporal transition to a state of relative trace element content distinctly departing from the pre-spill situation. Moreover, the parasite-host element accumulation ratios better depicted this temporal pattern. Additionally, changes in V concentrations in fish liver tissues and Ni concentrations in the parasite tissues suggest that this host-parasite system may be a useful tool to assess these two element contaminations linked to heavy fuel oil-spill.