Studied Fish Species Research Articles

Bioaccumulation of Some Heavy Metals in Some Organs of Three Selected Fish of Commercial Importance from Niger River, Onitsha Shelf, Anambra State, Nigeria

The present study reports the bioaccumulation of cadmium (Cd), zinc (Zn), lead (Pb) and mercury (Hg) in the gills, muscles and intestine of Tilapia zillii, Malapterurus electricus and Clarias gariepinus sampled from fishermen at Niger River, Onitsha shelf. Heavy metals in gills, muscles and intestine of fishes was investigated using Varian AA240 Atomic Absorption Spectrophotometer. Mean cadmium concentration in the fish organs was highest (0.068 ± 0.02 mg/kg) in the gills and lowest (0.040 ± 0.01 mg/kg) in the muscles. The descending order of mean cadmium concentration in the organs is gills > intestine > muscles. T. zillii and C. gariepinus had the maximum and minimum mean cadmium concentration of 0.087 ± 0.04 mg/kg and 0.043 ± 0.01 mg/kg, respectively. Cadmium concentration in the fish organs were lower than the FAO/WHO standard for seafood, thus the fishes with this levels of heavy metals are safe for human consumption. The mean concentration of zinc in the organs of the studied fish species was highest (8.180 ± 3.508 mg/kg) in intestine and lowest (4.176 ± 1.091 mg/ kg) in the muscles. The descending order was intestine > gills > muscles. Mean zinc concentration was maximum (8.848 ± 3.39 mg/kg) in T. zillii and minimum (5.084 ± 1.17 mg/kg) in M. electricus. These values were below the FAO/WHO recommended standard limit of zinc (10–20 mg/kg) in fish samples. Lead and mercury were not detected in any of the fish. The result obtained in this study, revealed that Niger River is contaminated to varying levels by zinc and cadmium. Control measures recommended include public enlightenment on the need to desist from anthropogenic activities that could lead to water pollution.

Levels of pesticide residues in water, sediment, and fish samples collected from Nile River in Cairo, Egypt

Pesticides constitute one of the major sources of environmental hazards to human and animals as they concentrate in the food chain. Organochlorine, organophosphorus, and carbamate pesticides were investigated using water, sediment, and fish (Clarias gariepinus, Oreochromis niloticus, and Tilapia zillii) muscle samples of the Nile River in Cairo region (Egypt). Pesticide residues were analyzed seasonally using gas chromatography. The results showed that the average total pesticide residue in sediment was higher (63.5 ± 36.2 ppb) than that in water samples (45.1 ± 35.0 ppb). High levels of total pesticide residues in water and sediment samples were detected in autumn (73.57 ± 62.97 and 103.03 ± 16.05 ppb, respectively), which may be attributed to the increase in suspended matter (low flood) and high application of pesticides during that season. Pesticide residue in tissue samples of C. gariepinus amounted to 49.1 ± 17.8 ppb followed by T. zillii (48.3 ± 18.9 ppb) and O. niloticus (45.6 ± 28.7 ppb). The relatively high levels of total pesticide residue on C. gariepinus tissue may be explained by the nature of catfish habits and feeding. The estimated pesticide residual concentrations in fish samples did not exceed the maximum residue limits. Health risk estimation revealed that all tested pesticides in the studied fish species had no potential for systemic toxicity to consumers, but regular monitoring is recommended to control the levels of pesticide residues in the Nile River ecosystem.

Trace elements in marine organisms of Magdalena Bay, Pacific Coast of Mexico: Bioaccumulation in a pristine environment.

Trace element (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, As, Hg) concentrations were assessed in marine organisms (n = 52) sampled from the Magdalena Bay lagoon complex in Baja California Sur, Mexico, a pristine marine environment. The overall trend of metal concentrations (dry weight) in the organisms was found to be Fe > Zn > Cd > Cu > Mn > Pb > As > Hg > Ni > Cr > Co. Bivalve mollusks (53.83mgkg-1) contained twofold higher levels of metals than the finfishes (20.77mgkg-1). Calculated BioConcentration Factor(BCF) values showed that dissolved Mn is readily bioavailable to the organisms, whereas Biota Sediment Accumulation Factor(BSAF) indicated high values for Zn, Cu and Cd. Cd and As levels were observed to be increasing with the trophic levels. Toxic elements, namely Pb, Cd and As in the studied fish species were found to be higher than the values recommended for human seafood consumption. The study provides a comprehensive baseline report on trace element bioaccumulation in several marine organisms that will aid in developing effective conservation strategies of the highly biodiverse lagoon complex.

Brain as a target organ of climate events: Environmental induced biochemical changes in three marine fish species

The present study aims to examine physiological and biochemical response of three commercial fish species (Dicentrarchus labrax; Platichthys flesus and Solea solea), over contrasting environmental dynamics: an extremely dry (2012) and flood (2014) years, in a shallow temperate southern European estuary, the Mondego Estuary (Portugal). Physiological and biochemical biomarkers were evaluated by a principal component analysis (PCA), which allowed to conclude that severe climatic events affected the set of fish species analyzed, revealing two distinct annual brain antioxidant responses. The drought episode affected the physiological state of the organisms, as well as increased brain antioxidant potential, strongly associated with fluctuations in environmental drivers (salinity and dissolved oxygen), however, ROS have not been effectively neutralized by antioxidant defence system causing lipid peroxidation. During flood episode was stated a general depletion of the antioxidant potential in the analyzed fish species, affected by interactions with chemical compounds, increased by a combination of high precipitation and associated runoff, probably, increasing nutrient and contaminant load at the Mondego estuary. Nevertheless, lipid peroxidation remained low, related to the action of non-enzymatic antioxidants, since that the studied fish species had optimal physiological status and high nutritive reserves. According to the present work we consider that brain enzymatic depletion may be organ-specific, looking to the greater vulnerability of brain's proteins to degradation compared to lipids. The role of enzymatic mobilization on fish brains is not extensively yet known, but our results suggest that brain seems to be metabolic sensitive to salinity and dissolved oxygen fluctuations. This is the first approach made to evaluate the physiological and biochemical responses of the brain of aquatic organisms’ to extreme climatic events and to establish reference values to determine the effects of extreme climate events to aquatic species.

Genome-Scale Association Study of Abnormal Scale Pattern in Yellow River Carp Identified Previously Known Causative Gene in European Mirror Carp.

Common carp (Cyprinus carpio) is one of the most widely studied fish species due to its great economic value and strong environmental adaptability. Scattered scale, a typical phenotype of the mirror carp that is derived from Europe, has never been observed in the Yellow River carp previously. We recently identified approximately one fourth of the F1 progenies displaying scattered scale in a full-sib Yellow River carp family in our breeding program, despite both parents that showed wild type with normal scale patterns. This family provides us unique materials to investigate the genetic basis underlying the abnormal scale mutant in Yellow River carp population. Genome-wide association study (GWAS) and association mapping were performed based on genome-wide single nucleotide polymorphisms (SNP) genotyped with common carp 250K SNP genotyping array in 82 samples of the Yellow River carp family. We identified a 1.4Mb genome region that was significantly associated with abnormal scattered scale patterns. We further identified a deletion mutation in fibroblast growth factor receptor 1 a1 (fgfr1a1) gene within this genome region. Amplification and sequencing analysis of this gene revealed a 311-bp deletion in intron 10 and exon 11, which proved that fgfr1a1 could be the causal gene responsible for abnormal scattered scale in the Yellow River carp family. Since similar fragment mutation with 306-bp and 310-bp deletions had been previously reported as causal mutation of scattered scale patterns in the mirror carp, we speculate that either the deletion mutation was introduced from Europe-derived mirror carp or the deletion independently occurred in the mutation hotspot in fgfr1a1 gene. The results provided insights into the genetic basis of scale pattern mutant in Yellow River carp population, which would help us to eliminate the recessive allele of the abnormal scale patterns in Yellow River carp population by molecular marker-assisted breeding.

Metal concentrations and risk assessment in water, sediment and economic fish species with various habitat preferences and trophic guilds from Lake Caizi, Southeast China

Despite the potential emissions of heavy metal pollution in Lake Caizi due to extensive agriculture, urban growth and fishing activities, the risk posed by metal concentrations to aquatic environments and human populations has not yet been studied. In this study we compared the concentrations of Hg, As, Pb, Cd, Cr, Cu and Zn in water, sediment, and economic fish species with different habitat preferences and trophic guilds across important fishery areas in Lake Caizi, located on the northern shore of the Yangtze River, Southeast China. The concentrations of Cr in water were found approximately 6 times higher than the safety thresholds established by international legislation. Cr, Zn, As and Cd concentrations in sediments surpassed the background values for Yangtze River basin in Anhui Province. However, all the studied fish species in Lake Caizi had metal concentrations lower than legislation thresholds established by China and international organizations. Heavy metal concentrations were found to be significantly higher in demersal (inhabiting near the sediments) and piscivorous (possessing higher trophic level) fishes than in pelagic/benthopelagic (inhabiting the upper and lower water column) and herbivorous/planktivorous (possessing lower trophic level) fishes. Our finding demonstrated that the metal concentrations in fishes are simultaneously influenced by the habitat and bio-accumulation through the food chain. According to target hazard quotient (THQ) calculations for heavy metal contents in the muscles of fish species, all the determined heavy metals gave THQ values lower than 1, suggesting the inexistence of health risks from the intake of fishes from Lake Caizi.

Element contents in commercial fish species from the Croatian market

Concentrations of toxic (Al, As, Cd, Cr, Hg, Mn, Ni, Pb) and essential elements (Cu, Fe, Zn) were measured in 11 fish species purchased from supermarkets located in different Croatian cities. Mean element concentrations in fishes ranged: mg kg−1: Al 0.13–3.5, As 0.52–3.4, Cu 0.24–0.88, Fe 2.0–19, Mn 0.095–1.6, Zn 3.4–18; μg kg−1: Cd 0.61–123, Cr 5.0–41, Hg 17–130, Pb 2.0–59, Ni 5.5–51. The highest mean concentrations of elements were found in fishes: Al in cod; Cd in bluefin tuna; Cr in rainbow trout; Hg in European sea bass; Pb in canned sardine; As, Cu, Fe, Mn, Ni and Zn in sardine. Significant differences in the concentrations of all elements measured were found between fish species. Mean Cd levels of 123 μg kg−1 for bluefin tuna exceeded the European Commision limit of 100 μg kg−1. An estimation of the dietary intake of elements associated with the consumption of the studied fish species, and its comparison with the toxicological reference values is provided. The obtained results suggest a strong reason for public concern with regard to exposure to As and Hg for consumers who often consume certain types of fishes.

Heavy metal contamination and health risk assessment in three commercial fish species in the Persian Gulf

Five heavy metals/metalloids and related potential health risks were investigated in three commercially important fish species (Anodontostoma chacunda, Belangerii, and Cynoglossurs arel) in Musa Estuary and Mahshahr Harbour of the Persian Gulf. A total of 116 fish samples were collected, and their liver and muscle organs were separately analyzed using ICP-MS. Results revealed that studied metals concentrations (with some exceptions) varied among sampling stations, fish species and their organs. Human health risk is evaluated using different indices. The results indicated that arsenic and mercury are the most hazardous elements. Estimated daily intake (EDI) for the metals exceeded the provisional tolerable daily intake (PTDI) for all studied fish species. Also, target risk (TR) of arsenic indicated that consumption over a long period of time may result in a carcinogenic effect. The results are expected to create awareness among the public on the safety of consuming food products grown in particular areas.

Range expansion of rotan Perccottus glenii, sunbleak Leucaspius delineatus, and bleak Alburnus alburnus in the Ob River basin

The ranges of three alien fish species (rotan Perccottus glenii, sunbleak Leucaspius delineatus, and bleak Alburnus alburnus) in the Ob River basin, West Siberia, have expanded. Our data prove the expansion of rotan and sunbleak ranges to the north. In particular, for the first time, populations of rotan are reported from the lower section of the Ob. We also present new data about range expansion of the studied fish species southward. All three species have probably reached the southern limits of their possible distribution in the Upper Ob system, entering the potamon/rhithron transition zone, because the species under study prefer lowland waters. The spatio-temporal dynamics of their expansion reveals the role of the Ob River as the main invasion corridor, enhancing their distribution mostly in meridional direction. In the system of the Upper Ob, rotan and sunbleak were found by us in isolated ponds and lakes, as well as in floodplain systems. This is in agreement with the concept of two invasion vectors: the translocation of fish by humans between water bodies and self-distribution along the river courses.

Inter Simple Sequence Repeat (ISSR) and Cytogenetic Analysis of Three Fish Species of Family Osphronemidae

The ISSR-PCR and karyological analysis methods are successfully used to detect the genetic variations between the different species of fishes, especially these belonging to the same family. The aim of this study was to determine the karyotypes and molecular genetic variations of three species of family Osphronemidae, Trichogaster trichopterus, Trichogaster leeri and Colisa laliaby using ISSR-PCR and chromosomal analysis. Samples were collected from ornamental fish farms in Egypt. The diploid chromosome numbers and Fundamental numbers for species under study were 2n = 46 and FN = 46, 2n = 46 and FN = 46, 2n = 46 and FN = 70 respectively, the first two species have same karyotype but the third species was different. The ISSR-PCR analysis was carried out using ten primers. All primers were successfully amplified on the genomic DNA extracted from all studied fish species. These findings indicate that ISSR-PCR and cytogenetic analysis are very useful in determination of genetic molecular variations and relationship degree between the species which belong to same family.

ОСОБЕННОСТИ СВОБОДНОРАДИКАЛЬНЫХ ПРОЦЕССОВ В ОРГАНИЗМЕ НЕКОТОРЫХ ВИДОВ ХИЩНЫХ РЫБ В РАЗЛИЧНЫЕ СЕЗОНЫ ГОДА

The authors of the article have studied the content of the elements of anti-oxidant system (malondialdehyde, catalase, selenium) in tissues of the internal organs (gills, intestine, muscles, liver, swimbladder, scales) in some species of predatory fish (pike Esox lucius (L., 1758), perch Perca fluviatilis (L., 1758), pike-perch Sander lucioperca (L., 1758), catfish Silurus glanis ) widespread in the basin of the Volga river in the Saratov region. The lowest concentration of malondialdehyde in organisms of the studied fish species is observed in fall and winter; the highest - in spring and summer. Catalase activity in gills tissue of a pike raised in 11.8%, cat-fish - 9.1%, pike-perch - 7.5%, perch - 7.8%. In fall (compared to winter) enzyme activity lowering in gonads of pike-perch makes 16.3%, in gonads of perch - 14.4%. In other tissues there were not observed any evident changes of catalase activity. Fish species under consideration are listed according to the average value of selenium concentration in organisms, µg/g: pike (0.208) > catfish (0.207) > pike-perch (0.196) > perch (0.178). According to the average value of the selenium accumulation in the body in different season all the studied species can be placed in the following order, µg/g: winter-pike (0.132) > pike-perch (0.136) > perch and catfish (0.142); spring - pike-perch (0.190) > perch (0.191) > pike (0.208) > catfish (0.209); summer - perch (0.186) > pike-perch (0.190) > catfish and pike (0.203); autumn - perch (0.193) > pike-perch (0.268) > > catfish (0.274) > pike (0.289).

Concentration and Human Health Implications of Trace Metals in Fish of Economic Importance in Lagos Lagoon, Nigeria.

Background.The most significant sources of food-borne diseases are microbiological and chemical hazards. The health risk due to consumption of food from aquatic ecosystems contaminated with hazardous chemicals including metals has increased globally, especially in developing countries like Nigeria.Objectives.The concentration and human health implications of trace metals in fish of economic importance in Lagos lagoon were investigated by determining the degree of contamination with heavy metals of selected fish from Lagos lagoon and assessing the possible health risks associated with fish consumption.Methods.Fish of economic importance including Caranx hippos, Chrysichthys nigrodigitatus, Elops lacerta, Galeoides decadactylus, Ilisha africana, Liza falcipinnis, Lutjanus goreensis, Mugil cephalus, Pseudotolithus senegalensis, Sarotherodon spp, Sphyraena spp, and Tilapia spp were bought from fishermen fishing in Lagos lagoon. The fish tissue samples were digested and analyzed in five replicates for heavy metals (lead, cadmium, iron, manganese and zinc) using a Varian AA600 atomic absorption spectrometer.Results.There were considerable variations in the concentrations of heavy metals among different species. The twelve fish species collected from Lagos lagoon were found to contain various concentrations of heavy metals and the levels of accumulation of these heavy metals varied across different species. Lead, cadmium, and manganese were present in all the studied fish species at higher concentrations than the maximum allowable concentrations in fish recommended by the Food and Agricultural Organization (FAO) and World Health Organization (WHO). The target hazard quotient (THQ) estimated for individual heavy metals through consumption of different fish species was less than 1 for all individual heavy metal in all the fish species.Conclusions.Controls on the dumping of wastes in the lagoon are needed, along with regular monitoring. Currently, no potential non-carcinogenic health risks from ingestion of a single heavy metal through consumption of these fish species was found.

Quantitative contribution of primary food sources for a mangrove food web in Setiu lagoon from East coast of Peninsular Malaysia, stable isotopic ([formula omitted] and [formula omitted]) approach

Applying stable isotopes to explore insight into the food web structure in marine ecology have been increasing recently. Tropical mangrove forest, one of the vital marine habitats, has been received intensive attentions in the field. However, there is still controversy about the important roles of primary carbon sources provide to consumers in the ecosystem. In this study, stable isotopic (13C and 15N) ratios were used to determine food web and to estimate quantitative contributions of primary carbon sources for invertebrates and four fish species in the tropical mangrove from Setiu lagoon, Malaysia using the Bayesian mixing model (SIAR). The primary nutrient sources showed δ13C values ranging from −18.7 to −31.1‰ and δ15N from 2.5 to 3.8‰. The wide range of the isotopic composition of consumers (−26.1 to −18.4‰ and 4.3 to 10.2‰ for δ13C and δ15N, respectively) indicated that a variety of carbon sources provided to the intertidal mangrove food webs. Mixing model outputs indicated that mangrove-derived carbon was important food sources for gastropod, Littoraria carinifera, Neritina violacea, N. coromandeliana, N. cornucopia, Cerithdea quadrata, and sesarmid crab, while the benthic microalgae (BMA) mainly fueled to Cerithidea djadjariensis, Cerithium coralium, fiddler crab and the crenate crab Thalamita crenata. Two Scylla species relied largely on BMA and SOMs. Bivalve species mainly assimilated phytoplankton-derived carbon, however, the difference of stable carbon isotope ratios among these bivalve species might relate to feeding selectivity or a small portion of BMA contributed to their diets. The model also resulted that BMA and seston sources might be important to the studied fish species rather than mangrove-derived carbon sources. However, further studies are needed to elucidate insight into the fish food web, and to determine whether there is ecological connectivity between habitats inside and outside of the lagoon.

ROLE OF HEAVY METALS BIOACCUMULATION ON SOME PHYSIOLOGICAL AND HISTOPATHOLOGICAL CHANGES IN THE CULTURED OREOCHROMIS NILOTICUS AND MUGIL CEPHALUS AT EL-FAYOUM GOVERNORATE, EGYPT

As the world population increase, the demand for high protein foods would gradually rise. Heavy metals are natural trace components of the aquatic environment, but their levels have been increased due to industrial wastes, geochemical structure, agricultural and mining activities. The absorption and accumulation of different pollutants vary among different biological systems. Therefore, the present study aims to high lighten the impact of the bioaccumulation of heavy metals in different organs of fish and the factors affecting their dissemination. It is also concerned with the study of some physiological and biochemical parameters of the two studied fish species and their ability to resist stressors. This is confirmed by histopathological investigation on the diagnosis of fish diseases caused by the heavy metals. Bioaccumulation of heavy metals in fish tissues led to histopathological alterations in liver and kidneys of both fish species collected from the studied fish farms that irrigated with agricultural drainage water (El-Berka and El-Wadi).These alterations didn’t occur in case of Demo fish farm that irrigated with fresh water of Bahr Yousef (branch of the river Nile). Data representing the hematological parameters of both fish species collected from Demo fish farm showed blood picture values within normal ranges. However, there was a highly significant decrease in values of erythrocytes count, hemoglobin content and hematocrit value for both studied fish species collected from the other studied fish farms (El-Berka and El-Wadi). This decrease was accompanied by an increase in mean corpuscular volume as a case of macrocytic anemia in case of Oreochromis niloticus and microcytic anemia in case of Mugil cephalus. The present results revealed that there were highly significant differences in the other blood indices and blood leucocytes of each species individually collected from the different studied fish farms. The results declared highly significant differences in serum glucose, total protein, creatinine, and uric acid concentrations, in addition to ASAT and ALAT activities for each species in the studied fish farms that resemble different aquatic habitats.

Accumulation of heavy metals and human health risk assessment via the consumption of freshwater fish Mastacembelus armatus inhabiting, thermal power plant effluent loaded canal.

Bioaccumulation of six heavy metals (Mn, Fe, Co, Ni, Cu, Zn) in the muscle of highly consumed fish species (Mastacembelus armatus) were measured using atomic absorption spectrometer. Fe (213.29 mg/kg dry weight) concentration was the most, followed by Zn (186.19 mg/kg dry weight), Ni (58.98 mg/kg dry weight), Cu (41.36 mg/kg dry weight), Co (9.06 mg/kg dry weight) and Mn (9.03 mg/kg dry weight). Estimated daily intake of heavy metals was calculated by mean fish consumption rate 19.5 × 10−3 kg/day, on the basis of a calculation of the amount of fish consumed by adult individuals (male and female). The studied fish species pose non carcinogenic risk for Co and Ni [target hazard quotient (THQ) > 1] only. Hazard index (HI) was high. Carcinogenic risk (TR) posed by this fish for male and female was 3.43 × 10−3 and 3.91 × 10−3, respectively for Ni (the carcinogenic potency slope factor was available for Ni only). The study is an alert indicating that inhabitants who consume these fishes (particularly females) were at risk of Co and Ni toxicity. In India recommended guidelines have yet not been established for these heavy metals, which is essential for setting of toxicological standards.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2471-3) contains supplementary material, which is available to authorized users.

Metazoan parasites of deep-sea fishes from the South Eastern Pacific: Exploring the role of ecology and host phylogeny

We studied the parasite fauna of five deep-sea fish species (>1000m depth), Three members of Macrouridae (Macrourus holotrachys, Coryphaenoides ariommus and Coelorhynchus sp.), the Morid Antimora rostrata and the Synaphobranchidae Diaptobranchus capensis caught as by-catch of the Patagonian toothfish (Dissostichus eleginoides) from central and northern Chile at depths between 1000 and 2000m. The parasite fauna of M. holotrachys was the most diverse, with 32 species (The higher reported for Macrourus spp.) and the lower occur in the basketwork eel D. capensis (one species). Trophically transmitted parasites, mainly Digenea and Nematoda explain 59.1% of the total number of species obtained (44 species) and the 81.1% of the 1020 specimens collected. Similarity analysis based on prevalence as well as a Correspondence analysis shows that higher similitude in parasite fauna occurs in members of Macrouridae. The importance of diet and phylogeny is discussed as forces behind the characteristics of the endoparasite and ectoparasite communities found in the studied fish species.

Dietary preference and digestive physiology of plankti-benthivorous fishes inhabiting mudflats of Indian Sundarban estuaries

In this study, the digestive physiology of 12 plankti-benthivorous species as functional analogues from intertidal mudflats of Indian Sundarbans was carried out in order to find out whether diet or phylogeny played a larger role in influencing digestive enzyme activity. Upon analysis of prey preferences, they were categorized into different trophic subgroups. Two dendrograms, one based on prey diversity and other on digestive enzymes of studied fish species were constructed through cluster analysis. These dendrograms were compared again with the phylogenetic tree constructed on the basis of the taxonomic positions. The specific nature of the enzymes in two plankti-detritivorous fishes appeared to possess a specific feeding behaviour and dietary preference though no clear predominance among digestive enzymes was observed. However, regardless of different feeding habits, four gobiid species showed similarity in their overall digestive enzyme patterns and clustered together. Despite mixed results, it can be ...

Consumption of the invasive New Zealand mud snail (Potamopyrgus antipodarum) by benthivorous predators in temperate lakes: a case study from Lithuania

Introduced species interact both directly and indirectly with native species. Of particular interest from the fisheries management point of view is how the invasive New Zealand mud snail, Potamopyrgus antipodarum, can alter the diet of fish and crayfish. If the snail is somewhat resistant to predation, it cannot be easily included into predators’ diet. We examine the direct interactions between the introduced P. antipodarum and benthivorous predators local to temperate lakes through laboratory experiments and field surveys. Field survey showed that P. antipodarum dominated in the macroinvertebrate communities of the studied lakes. Feeding experiments indicated low consumption of P. antipodarum by most of its potential predators. Field diet survey showed that the main fish species did not significantly consume P. antipodarum. Moreover, it was ascertained that this snail can survive passing through the gastrointestinal tract of most studied fish species. Consequently, as local fish do not consume P. antipodarum, a part of lake primary production becomes locked in lower trophic levels. Therefore, there is a legitimate concern that the invasion of this snail may reduce the direct flow of primary production towards higher trophic levels in temperate lakes.

Quality Attributes of the Most Common Consumed Fresh Fish in Saudi Arabia

Although fish is an important food as a source of high biological value of protein and polyunsaturated fatty acids such as EPA and DHA, fish is a fast perishable food because of the high water activity and the high enzymatic activity in fish viscera. The main target of this study was to evaluate some sensory and chemical attributes of fresh fish samples from the Central Fish Market of Makkah, Saudi Arabia. However, 33 fresh fish samples of 11 species were randomly purchased from the Central Fish Market, El-Kaakia, Makkah, Saudi Arabia during spring 2015. These species are commonly consumed by the local population in Saudi Arabia. Sensory evaluation by quality index method and some chemical analysis such as biogenic amines were done. The obtained results showed that there were significant differences between all studied fish species in pH and TVN value at <i>P>0.05</i>. However, there were no any significant differences in case of fish quality%. It could be noticed that there were 8 samples from 33 samples exceeded pH value of 6.80, represented 24.24% of all samples, and there were 3 samples exceeded TVN value of 30mg/100g, represented 9.09% of all samples. As for quality %, there were 4 samples from 33 samples below 50%, represented 12.12% of all samples. Meanwhile, histamine content of studied fish samples ranged from 0.66±0.33 mg/100g in rusty parrot fish to 17.21±2.85 mg/100g in grey mullet. Eleven fish samples exceeded the permissible limit of tyramine represented 33.33%. The statistical analysis showed that there were no significant differences between all studied fish samples in tyramine and phenethylamine content at <i>P>0.05</i> with F value of 0.89 and 0.68, respectively. It is recommended to carry out the same study on other central fish markets such as Jeddah, Riyadh and Dammam. Consequently, a complete quality assurance system must be planned to be applied in any central fish market in Saudi Arabia. It should be considered some criteria such as refrigerated cars, sun protected receiving area, fish layer thickness, ice/fish ratio, using of fine ice, using of salty ice and mechanical refrigeration.

Quantification of X. laevis vitellogenin by liquid chromatography tandem mass spectrometry

Over the last several decades, there has been an increase in public awareness and regulatory activity in regard to the presence of emerging contaminants in the environment that may have the potential to interact with the endocrine system of exposed wildlife. Alterations in vitellogenin (VTG), a high density yolk precursor protein, can indicate endocrine activity in oviparous species, including many fish and amphibians. While various methodologies and experiments have been performed to characterize baseline VTG concentrations among commonly studied fish species, fewer methodologies for accurately quantifying amphibian VTG are available. Since there is relatively little information available on background VTG levels in male and female frogs, the present investigation set out to quantify baseline levels of VTG in juvenile as well as adult male and female African clawed frogs (Xenopus laevis) using a newly developed liquid chromatography tandem mass spectrometry method. This new methodology for quantifying VTG in X. laevis frog blood plasma can be applied in mechanistic and toxicity studies with X. laevis to better characterize potential endocrine modes of action.