Bioaccumulation and depuration of chromium in the selected organs and whole body tissues of freshwater fish Cirrhinus mrigala individually and in binary solutions with nickel

Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful effects on human health and other organisms in the environment. Most of the studies dealing with toxic effects of metals deal with single metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also the ＂critical＂ organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C. mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats.

BIODIVERSITY AND CONSERVATION OF FRESHWATER FISH IN HONG KONG, CHINA

We surveyed the distribution, composition and diversity of freshwater fish in Hong Kong, China from 2002 to 2004. Sites surveyed were mainly streams, marshes and estuaries. There are ponds for aquaculture and reservoirs in Hong Kong but no large natural water bodies. From the 220 sites surveyed, 114 species of 37 families were found. Gobiidae (with 24 species) and Cyprinidae (21 species) were the dominant families. This survey has increased the number of freshwater fish species recorded in Hong Kong to 167. Among these, 71 (42.5%) are primary freshwater fish, 44 are brackish and 46 are vagrants. The remaining 6 species are diadromous. In Hong Kong, freshwater fish are conserved by a combination of measures. About 38% of Hong Kong’s land area is designated as country parks and/or special areas, and is managed for nature conservation and educational purposes. In addition, another 5% of land area is zoned for conservation in the statutory land use zoning system to protect them from development and incompatible land uses. Major development projects have to go through the statutory environmental impact assessment process to ensure that they will not have adverse impact as far as practicable. There are conservation action plans for important species. For example, captive-bred individuals of the endemic Hong Kong Paradise Fish Macropodus hongkongensis have been released to suitable and secure sites inside country parks and their populations are regularly monitored. Other measures such as wetland creation, restoration and enhancement programmes are also implemented for freshwater fish conservation.

Strategic Conception for Sustainable Development of Massive Freshwater Fish in China

[ Objective] To propose strategic conception for sustainable development of massive freshwater fish in China. [ Method] The current development status of massive freshwater fish industry in China was analyzed. On this basis, strategic conception for sustainable development of massive freshwater fish in China was proposed. [Remlt] In order to solve the present problems in the massive freshwater fish industry in China, basic strategies were proposed to develop the massive freshwater fish industry in China. The fishery resources should be capitalized to promote sustainable development of resources. Consumer demand of end-market should be used to drive stable development of the whole industry chain. Consumer demand should be guided to enhance the industrial market position. Processing and distribution channels should be constructed to promote sustainable development of seed and farming industries. Consumer demand at different levels should be used to promote multi-level multi-media health culture. Brand building and operating should be performed to enhance the competitive position of the industry in international and domestic markets. [ Condusion] The study has great theoretical and practical significance for promoting development of the massive freshwater fish industry in China.

Estimation of Mercury Intake from Consumption of Fish and Seafood in Russia

Data on the mercury concentration in freshwater and marine fish and seafood on the territory of Russia are presented. The level and pattern of the fish and seafood consumption in various regions of Russia are found from the analysis of open statistics. Regions with the maximum and minimum consumption of fish products are established. Mercury intake from these products in a human organism is calculated. It is shown that at the current level and pattern of the diet in Russia fish cannot be a source of high mercury concentrations in a human organism.

Whole Chia Flour as Yield Enhancer, Potential Antioxidant and Input of n-3 Fatty Acid in a Meat Product

In this paper, the effect of the addition of whole chia flour and water at cooked fish burgers on yield, water and fat retention, n-3 fatty acids content and oxidative stability were studied. The results showed that 94% of yield, 92% of water retention and 97% of fat retention were achieved with the addition of 5.92 g of whole chia flour and 15 g of water per 100 g of burger. The n-3 fatty content increased from 704.57 ± 21.66 mg to 1551.71 ± 47.71 mg/100g of cooked burger when the chia flour was added, enhancing nutritional quality indices of lipid. A good oxidative stability, with minimum formation of conjugated dienes, hydroperoxides and thiobarbituric acid reactive substances during 30 days frozen storage was obtained too, probably due to the presence of polyphenolic compounds with antiradical activity and reducing power in the fibrous fraction of the flour chia. The results from the present study highlight remarkable technological applications of whole chia flour as food ingredient in the design of healthier fish meat commodities.

Arsenic speciation in freshwater fish:challenges and research needs

Food and water are the main sources of human exposure to arsenic.It is important to determine arsenic species in food because the toxicities of arsenic vary greatly with its chemical speciation.Extensive research has focused on high concentrations of arsenic species in marine organisms.The concentrations of arsenic species in freshwater fish are much lower,and their determination presents analytical challenges.In this review,we summarize the current state of knowledge on arsenic speciation in freshwater fish and discuss challenges and research needs.Fish samples are typically homogenized,and arsenic species are extracted using water/methanol with the assistance of sonication and enzyme treatment.Arsenic species in the extracts are commonly separated using high-performance liquid chromatography(HPLC)and detected using inductively coupled plasma mass spectrometry(ICPMS).Electrospray ionization tandem mass spectrometry,used in combination with HPLC and ICPMS,provides complementary information for the identification and characterization of arsenic species.The methods and perspectives discussed in this review,covering sample preparation,chromatography separation,and mass spectrometry detection,are directed to arsenic speciation in freshwater fish and applicable to studies of other food items.Despite progress made in arsenic speciation analysis,a large fraction of the total arsenic in freshwater fish remains unidentified.It is challenging to identify and quantify arsenic species present in complex sample matrices at very low concentrations.Further research is needed to improve the extraction efficiency,chromatographic resolution,detection sensitivity,and characterization capability.

Genetic diversity and population structure of Prochilodus costatus and Prochilodus argenteus preceding dam construction in the Paraopeba River,Sao Francisco River Basin,Minas Gerais,Brazil

Curimat?-pioa (Prochilodus costatus) and curimat?-pacu (Prochilodus argenteus) are migratory fish species endemic to the S?o Francisco River Basin in Brazil. Both species play important roles in local fisheries and ecology in the Paraopeba River. A dam was recently constructed on this river and to help in the development and conservation programs, we characterized the genetic variation of both species before dam construction. Complex hypervariable repeats micro-satellite was used to asses genetic variation for both species within and between the five collection sites in order to detect population substructuring. Nucleotide substitutions and insertion/deletion polymorphisms (indels) resulted in 35 P. costatus haplotypes (sample size = 89) and 22 P. argenteus haplotypes (sample size = 32). Significant genetic diversity and population differentiation was detected between five sampling sites for both species. Therefore, each of the five sites should be regarded as a group comprising significant genetic differences in species conservation and maintenance plans. Comparing these results to genetic diversity measures after dam construction will be critical for future management in this region.

The dynamic changes of arsenic biotransformation and bioaccumulation in muscle of freshwater food fish crucian carp during chronic dietborne exposure

Dietary uptake is the major way that inorganic arsenic(iAs)enters into benthic fish;however,the metabolic process of dietborne i As in fish muscle following chronic exposure remains unclear.This was a 40-day study on chronic dietborne i As[arsenite(AsⅢ)and arsenate(AsⅤ)]exposure in the benthic freshwater food fish,the crucian carp(Carassius auratus),which determined the temporal profiles of iAs metabolism and toxicokinetics during exposure.We found that an adaptive response occurred in the fish body after iAs dietary exposure,which was associated with decreased As accumulation and increased As transformation into a non-toxic As form(arsenobetaine).The bioavailability of dietary AsⅢwas lower than that of AsⅤ,probably because AsⅢhas a lower ability to pass through fish tissues.Dietary AsⅤexhibited a high potential for transformation into AsⅢspecies,which then accumulated in fish muscle.The largely produced AsⅢconsidered more toxic at the earlier stage of AsⅤexposure should attract sufficient attention to human exposure assessment.Therefore,the pristine As species and exposure duration had significant effects on As bioaccumulation and biotransformation in fish.The behavior determined for dietborne arsenic in food fish is crucial for not only arsenic ecotoxicology but also food safety.

Sequence analysis and typing of Saprolegnia strains isolated from freshwater fish from Southern Chinese regions

Saprolegniasis,caused by Saprolegnia infection,is one of the most common diseases in freshwater fish.Our study aimed to determine the epidemiological characteristics of saprolegniasis in Chinese regions of high incidence.Saprolegnia were isolated and identified by morphological and molecular methods targeting the internal transcribed spacer(ITS)ribosomal DNA(rDNA)and building neighbor-joining(NJ)and maximum parsimony(MP)phylogenetic trees.The ITS sequences of eight isolated strains were compared with GenBank sequences and all strains fell into three clades:CLADE1(02,LP,04 and 14),CLADE2(S1),and CLADE3(CP,S2,L5 and the reference ATCC200013).Isolates 02 and LP shared 80%sequence similarity with S.diclina,S.longicaulis,S.ferax,S.mixta,and S.anomalies.Further,isolates 04 and 14 shared 80%similarity with S.bulbosa and S.oliviae.Finally,extremely high ITS sequence similarities were identified between isolates S1 and S.australis(100%);CP and S.hypogyna(96%);and S2,L5,ATCC200013 and S.salmonis(98%).This research provides insights into the identification,prevention and control of saprolegniasis pathogens and the potential development of effective drugs.

Helminth parasites of freshwater fishes from Cuatro Ciénegas,Coahuila,in the Chihuahuan Desert of Mexico:inventory and biogeographical implications

As part of an ongoing inventory of the helminth parasites of freshwater fishes in Mexico, 570 individual fish were collected between Apr 2008 and Oct 2011 in 26 localities along the Cuatro Ciénegas region in Coahui­la State, northern Mexico. Seventeen species of hosts, mostly corresponding to Nearctic freshwater elements, were studied. A total of 8324 individual worms were collected during this survey, representing 25 species of helminths, of which 9 were digeneans, 3 monogeneans, 3 acanthocephalans, 9 nematodes and 1 cestode. Most of the records in this checklist represent new host or locality records. The information provided in this checklist may be helpful for our understanding of the biodiversity and historical biogeography of this host-parasite sys­tem, because in the Cuatro Ciénegas region occur a Nearctic freshwater fish fauna, along with Neotropical and endemic elements, and from a biogeographical point of view, this may represent a transitional area.

The effects of two free-floating plants (Eichhornia crassipes and Pistia stratiotes) on the burrow morphology and water quality characteristics of pond loach (Misgurnus anguillicaudatus) habitat

Loach exhibit conspicuous drilling behaviors in the mud of shallow waters,yet their burrow morphology and the factors affecting this behavior have received little attention.We characterized the burrow morphology and water quality of the pond loach Misgurnus anguillicaudatus in three scenarios:in tanks without plants,tanks with the free-floating plant water hyacinth Eichhornia crassipes,and tanks with water lettuce Pistia stratiotes.Water hyacinth effectively removed water TN,COD,NO3-N and NH4-N,and water lettuce removed water TP and NH4-N.Water hyacinth and water lettuce markedly reduced water turbidity and DO,increased TOC and EC.Water hyacinth purified water more effectively than water lettuce,providing a suitable habitat for loach feeding,living and burrowing.The burrow structures were V-shaped,Y-shaped,inverted L-shaped,or complicated dendritic networks composed of multiple V shapes.The hyacinth treatment was characterized by the greatest burrow volume,length,depth,and structural complexity,but the opening size was reduced by dense root mat coverage.Burrows in the water lettuce treatment were characterized by intermediate volume,length,branches and sinuosity,but they had the largest opening and pit size.The control treatment had a flat bottom with the smallest,shortest burrows.This study indicates that free-floating plants improve habitat suitability and change burrow morphology and may be used to improve loach breeding methods。

Behavioral type,in interaction with body size,affects the recapture rate of brown trout Salmo trutta juveniles in their nursery stream

Movement activity levels of wild animals often differ consistently among individuals,reflecting different behavioral types.Previous studies have shown that laboratory-scored activity can predict several ecologically relevant characteristics.In an experiment on wild brown trout Salmo trutta,spanning from June to October,we investigated how spring swimming activity,measured in a standardized laboratory test,related to relative recapture probability in autumn.Based on laboratory activity scores,individuals clustered into 2 groups,which showed contrasting patterns in the size-dependency of their recapture probability.Size had a slightly positive effect on recapture probability for passive fish but a clear negative effect on active fish.Our results show that the population structure in a cohort,in terms of relative proportions of behavioral types in different size classes,can vary over time.The results of this study could depend on either selective mortality or migration.However,selective disappearance of individuals with specific phenotypes,regardless of the mechanism,will have implications for trout population management,such as stocking efficiency of hatchery fish with high growth rates or maintenance of fishways past migration barriers.

Marked elevation of serum alpha-fetoprotein following Clonorchis sinensis infection: A rare case report

Clonorchiasis,also known as the liver fluke disease,is caused by eating raw freshwater fish or shrimps that contain Clonorchis sinensis cyst larvae,which mainly involves the hepatobiliary system.Chronic abdominal pain and distention,loss of appetite,and hepatomegaly are the most common clinical manifestation.Persistent infection with Clonorchis sinensis would result in chronic inflammation,epithelial hyperplasia,and periductal fibrosis and even progress to cholangiocarcinoma.Nevertheless,the majority of the infected people are asymptomatic or mildly symptomatic,contributing to its high misdiagnosis rate.Alpha-fetoprotein(AFP)is a well-known biomarker for hepatocellular carcinoma(HCC).A high level of AFP can also be caused by several benign diseases,causing confusion and influ-encing treatment decisions.So far,clonorchiasis with a markedly elevated level of AFP has been rarely reported.We present a case of clonorchiasis with a high level of AFP in a 52-year-old man.We hope to raise clinical awareness of this food-borne disease.Clonorchiasis should be considered in patients with extremely high levels of AFP,excluding HCC and germ cell tumors,especially if the patient has a history of ingesting raw freshwater fish or shrimps.