Tolerance measurement and histopathological observations on the gills of Mystus M. vittatus under the toxic stress of the fertilizer NPK

The tolerance level of the fertilizer NPK for the freshwater siluroid Mystus M. vittatus (BL .) and histopathological changes in the gill of this fish against two concentrations of NPK were investigated. It was found that at 400 ppm (24 h) mortality in the fish started, and at 700 ppm (96 h) all the fish died. Hence the concentration of NPK at 400 ppm was taken as an experimental concentration for this fish. Curling towards the upperside in the secondary lamellae resulting in the joining with each other and profuse mucus secretion and subsequent death of 40% of the fish (96 h) were observed. At 700 ppm (96 h) NPK, which is far higher than the highest tolerance limit of the fish, all the fish died. Profuse mucus secretion, formation of subepithelial spaces, sloughing of epithelial layer, leaving only the rows of pilaster cells, resulting in the death of the fish, were observed. The mortality of the fish was due to asphyxiation and damage in the gill tissues resulting in the alteration in the respiratory and osmoregulatory metabolism.     

Impaired Functions in Nile Tilapia,Oreochromis niloticus (Linnaeus, 1757), from Polluted Waters

Oreochromis niloticus is an endemic species in the River Nile and represents the main object of fishery in the Nile Delta Lakes of which Lake Maryût is the smallest and most polluted. Due to current pollution problems, fish production in the lake greatly declined. Besides fish biology, this study considered a wide array of water databases in selected sites along the lake. Hydrologic and biologic data were compared to that of a reference fish hatchery. Water concentrations of ammonia, manganese, nickel, cadmium, lead and mercury proved hazardous to fish, whereas chromium, copper, iron, zinc, pH, alkalinity, hardness, phosphate, nitrate, and nitrite always fell within acceptable levels. Physiologic evaluation of O. niloticus pointed out improper growth, protein inadequacy, and functional impairment in fish inhabiting polluted sites, in particular the lake main basin. These were reflected by data of specific formulae as RNA/DNA and the relative RNA content (r) in cells of the liver and gill arches as well as by the relative mobilization of serum protein fractions. It seems, however, that growth competence is additionally affected by the stress impact exerted upon fish by massive population numbers in some cramped commercial ponds.     

Acute toxicity of cadmium to Channa punctatus (BLOCH)

Effects of acute cadmium poisoning on survival, its residual values and histopathology in certain organs of a freshwater airbreathing fish, Channa punctatus (BLOCH ) were investigated. The threshold concentration, MATC and LC₅₀ values obtained from 96 h static bioassay, revealed that Channa is more susceptible to cadmium ions at higher temperature. The atomic absorption spectrophotometric determination of cadmium residues differed significantly in organs of specimens having survived and died after 96 h of exposure. The gill accumulate the highest amount of cadmium, the liver accumulated a slightly smaller amount than the gill, while the kidney accumulated the least. The histopathological lesions subjected to sublethal (5.2 mg/l Cd) and lethal (8.4 mg/l Cd) concentrations of cadmium were: detachment and rupture of lamellar epithelium, collapse of pillar cells and hypertrophy in mucus producing gland cells in the gill; vacuolization and coagulative necrosis in hepatic cells of the liver; and expansion, necrosis and accumulation of cellular debris in renal tubules of the kidney. The probable causes for death of fish due to cadmium ions have been discussed.     

Cytopathological Studies Resulting in Cadmium Bioassay with Heteropneustes fossilis (Bloch)

Histopathological changes in various cellular constituents of gill, liver and kidney were studied in Heteropneustes fossilis (Bloch) after treatment with cadmium. The changes included fusion, vacuolization, necrosis, hypertrophy and formation of cellular debris in the gill; swellings in nuclei, vacuolization, necrosis and coagulation of cytoplasm in the liver; expansion of renal tubules and formation of cellular debris in the kidney. The changes in the tissue architecture have been discussed in reference to fish mortality.     

Biochemical and Physiological Responses in Atlantic Salmon (Salmo salar) Following Dietary Exposure to Copper and Cadmium

Three experiments were conducted with Atlantic salmon (Salmo salar) to assess the effects of dietary exposure to copper and cadmium. The results presented here provide an overview, details of each experiment will be published in full elsewhere. In the first experiment, salmon parr exposed for four weeks to 35 and 700 mg Cu kg⁻¹ diet had significantly elevated intestinal copper concentrations, cell proliferation (PCNA) and apoptosis rates compared to control fish. No differences were observed in gill or plasma copper concentrations among the groups. In contrast to the controls, the Cu exposed groups did not grow significantly during the exposure period. The second experiment (three months exposure) was conducted to assess the effects of dietary copper (control, 35, 500, 700, 900 or 1750 mg Cu kg⁻¹ diet) on growth and feed utilization in salmon fingerlings. Growth was significantly reduced after three months exposure to dietary Cu concentrations above 500 mg kg⁻¹. Similarly, copper body burdens were significantly higher in fish exposed to elevated dietary copper concentrations (above 35 mg Cu kg⁻¹ diet). In the third experiment, salmon parr were exposed to one of six dietary cadmium concentrations (0, 0.5, 5, 25, 125 or 250 mg Cd kg⁻¹ diet) for four months. Cadmium accumulated in the liver>intestine>gills of exposed fish. Rates of apoptosis and cell proliferation in the intestine increased following exposure to dietary cadmium. Exposure to elevated concentrations of dietary cadmium had no effect on growth in salmon parr. Results from these studies indicate that cellular biomarkers have potential as early warning signs of negative effects on the overall fitness of an organism.     

Study of the Interaction Mechanism in the Biosorption of Copper(II) Ions onto Posidonia oceanica and Peat

A systematic approach was used to characterize the biosorption of copper(II) onto two biosorbents, Posidonia oceanica and peat, focusing on the interaction mechanisms, the copper(II) sorption–desorption process and the thermal behavior of the biosorbents. Sorption isotherms at pH 4–6 were obtained and the experimental data were fitted to the Langmuir model with a maximum uptake (q_max) at pH 6 of 85.78 and 49.69 mg g^?1, for P. oceanica and peat, respectively. A sequential desorption (SD) with water, Ca(NO₃)₂, and EDTA was applied to copper‐saturated biosorbents. Around 65–70% copper(II) were desorbed with EDTA, indicating that this heavy metal was strongly bound. The reversibility of copper(II) sorption was obtained by desorption with HCl and SD. Fourier transform IR spectroscopy (FTIR) analysis detected the presence of peaks associated with OH groups in aromatic and aliphatic structures, CH, CH₂, and CH₃ in aliphatic structures, COO^? and COOH groups and unsaturated aromatic structures on the surface of both biosorbents, as well as peaks corresponding to Si? O groups on the surface of peat. The results of SEM‐EDX and FTIR analysis of copper‐saturated samples demonstrated that ion exchange was one of the mechanisms involved in copper(II) retention. Thermal analysis of biosorbent samples showed that copper(II) sorption–desorption processes affected the thermal stability of the biosorbents.     

太湖不同生态型湖区湖鲚(Coilia ectenes taihuensis)食物组成及其季节变化

利用单船表层单囊拖网于2013年2 12月分别在太湖不同生态型湖区(敞水湖区和草型湖区)采集湖鲚(Coilia ectenes taihuensis)样品,同时用刺网补充大个体样品.通过胃含物鉴定,分析湖鲚饵料生物的种类及数量季节和湖区间差异,同时测定湖鲚摄食率、肥满度和食物选择系数等.结果显示,湖鲚主要食物为浮游枝角类和桡足类,此外,水生昆虫、轮虫和小型鱼虾也是湖鲚的重要食物来源.湖鲚食物组成季节变化明显,冬季以桡足类的哲水蚤(Calanus spp.)、剑水蚤(Cyclops spp.)为主,夏、秋季则以枝角类的象鼻溞(Bosmina spp.)、裸腹溞(Moina spp.)和盘肠溞(Chydorus spp.)为主.不同湖区湖鲚食物种类差异明显,草型湖区水生昆虫、鱼虾较敞水湖区多,桡足类较敞水湖区少.不同湖区间湖鲚食物数量差异明显,敞水湖区湖鲚平均食物数量为788.98±262.4 ind./尾,而草型湖区仅为298.85±71.1 ind./尾.湖鲚主动摄食大型枝角类,如僧帽溞(Daphnia cucullata)、低额溞(Simocephalus spp.)和大型溞(Daphnia magna),选择指数(Ii)介于0.59~1.00之间.小型裸腹溞(Moina spp.)也是湖鲚主动选择的食物(0.62Ii0.95),但湖鲚对桡足类选择性较低,这可能与桡足类较强的逃避能力有关.湖鲚对食物选择性的季节变化明显,如冬季回避透明薄皮溞(Leptodora kindti),而夏季则主动选择,但不同湖区湖鲚对食物的选择差别较小.本研究结果有利于从食物网层面剖析湖鲚种群增长原因,进而通过生物操纵理论对湖鲚种群进行控制,最终为形成合理的湖泊渔业结构和湖泊环境修复提供科学依据.     

The Toxic Effects of Mercury Ions on a Freshwater Teleost,Puntius sophore (HAMILTON), as assessed by Bioassay and Histopathological Indices

Puntius sophore (HAMILTON ) were exposed to several concentrations of mercury up to 10 d under static bioassay conditions. Abnormal behaviour in fish were increase in swimming activity, absence of shoaling behaviour, surfacing, loss of equilibrium and death. The body and gills of dead and living fish in the higher mercury concentrations are covered by coagulated mucus. The 96 h and 240 h LC₅₀ values and their 95% confidence limits were 0.145 (0.133 … 0.165); 0.065 (0.057 … 0.072) mg/l of Hg, respectively. The F-ratios are significant at the 1% level of significance and thus indicate that the per cent mortality caused by mercury is distributed in a heterogeneous manner while there is no significant overall difference between the replications. The histopathological assessment of the gill was also carried out. In the control fish, gills are characterized by thin secondary gill lamellae and epithelial layer closely associated with the basement membrane. Several histopathological changes were observed in the gill, including the swelling in secondary gill lamellae, nuclei increases in size and number, and degeneration of epithelial layer.     

Water Quality Estimation Based on Histological Investigations of Fish: Case Study of Kenozero Lake

Specific hydrological and hydrochemical conditions in Kenozero Lake have led to changes in the morphology of fishes at a cellular level. The abnormalities in the function of the respiratory, digestive, and excretory systems were recorded. The degree of pathology depended on the ecological features of the fish. The pathological changes were most pronounced in the gills of the fish species (orfe, perch, and roach) characterized by active mode of life and sensible to oxygen deficiency. The changes in the epithelium of gill filaments had a compensatory significance and were aimed at increasing the area of the functional surface of the gills under the conditions of hypoxia.     

太湖贡湖湾鲚(Coilia ectenes taihuensis Yen et Lin)食物组成的季节变化

鲚(Coilia ectenes taihuensis Yen et Lin)是太湖主要的鱼类之一,其产量随水体富营养化程度的加重呈上升趋势.本研究于2009年4-12月用刺网(a=10 mm)在太湖贡湖湾采集了鲚,分析了其胃含物中食物组成的季节变化以及鲚对食物种类的选择性.结果表明,鲚在各月中主要以浮游动物为食,同时也摄食幼鱼、幼虾和水生昆虫等.鲚的食物组成具有明显季节变化,4月份以桡足类为食,其中桡足幼体、汤匙华哲水蚤(Sinocalanus dorrii Brehm)和剑水蚤(Cyclops spp.)所占的平均个数百分比相当;6、8和10月份主要以枝角类为食,其中6月以裸腹溞(Moina spp.)为主,而8和10月以象鼻溞(Bosmina spp.)为主.食物选择性方面,鲚对大型浮游动物表现出主动选择;当环境中出现溞(Daphnia spp.)和透明薄皮溞(Leptodora kindti Focke)时,鲚对它们表现出很强的选择性摄食,但透明薄皮溞只出现在6月鱼类食物中;个体较小的裸腹溞也是鲚主动选择的重要食物,在整个调查期间鲚对裸腹溞都表现出较高的主动选择性;象鼻溞虽然在各月份食物中的出现率最高,但除10月份鲚对其表现出主动选择外,其它月份表现为主动回避或随机选择.本研究结果有助于我们了解鲚对浮游动物群落影响的季节变化,为制定合理的湖泊与渔业管理方案提供依据.     

Evaluation of the Relative Resistance of Twelve Species of Fish in Toxicity Bioassays with Electroplating Waste

The present paper deals with the evaluation of the relative resistance of 12 species of fish in static toxicity bioassay tests of electroplating waste. The electroplating waste is highly toxic as it contains several toxic metals like copper, nickel, cadmium, zinc, lead and chromium alongwith cyanides, acids and alkalies. On the basis of TL₅₀, the fish Clarias batrachus ist the most resistant fish and Labeo rohita the most sensitive. The relative resistance of the fish is in the decreasing order: Clarias batrachus, Saccobranchus fossilis, Ophiocephalus gachua, Ophiocephalus punctatus, Puntius stigma, Puntius sophore, Mystus vittatus, Cyprinus carpio, Colisa fasciatus, Notopterus notopterus, Cirrhina mrigala and Labeo rohita.     

Quantifying the environmental impacts of artisanal fishing gear on Kenya's coral reef ecosystems

The environmental impacts of artisanal fishing gear on coral reef ecosystems were studied in the multi-gear fishery of southern Kenya to evaluate which types of gear have the greatest impact on coral reef biodiversity. The gear types studied were large and small traps, gill nets, beach seines, hand lines and spear guns. Levels of coral damage, proportion of juvenile fish and discards, size and maturity stage at first capture were quantified and compared amongst the gear types. Results indicate that fishers using beach seines, spears and gill nets cause the most direct physical damage to corals. Spear fishers showed the highest number of contacts to live corals per unit catch followed by fishers using gill nets (12.6 ± 1.8 and 5.9 ± 2.0 coral contacts per kg fish caught per trip respectively). Apart from discarding 6.5% of their daily catch in the sea, as it was too small, beach seine fishers also landed the highest percentage of juvenile fish (68.4 ± 15.7%), a proportion significantly higher (p < 0.001) than in any other gear. The size and maturity stage at first capture for 150 of 195 species caught by all gear types was well below the lengths at which they mature. For example, 100% of Lethrinus xanthochilus, 99% of Lethrinus nebulosus and 94% of Lethrinus harak caught were juveniles. Across all gear types, 50.1 ± 22.7% of the catch consisted of juvenile fish, indicating serious growth overfishing. Field assessment of levels of coral density showed that fishing grounds where beach seines were still in use had a significantly lower density than where beach seining was not used. This correlation is likely to arise in part because seines cannot be used in the most coral rich areas, and in part because coral loss is a consequence of seine use. On a per gear basis therefore, beach seines had the most impact on coral reef biodiversity. This study emphasizes the need to enforce restrictions on destructive gear and mesh sizes.     

Seasonal changes of the gill epithelia of Arctic char (Salvelinus alpinus) from a high mountain lake

The gill structure of Arctic char from a low ionic (1-2 7mol Cl^-) high mountain lake (2344 m above sea level) showed distinct seasonal changes. From spring to early winter chloride cells (responsible for ion uptake) were numerous, and during summer gill epithelia were highly hypertrophic resulting in a thick blood-to-water barrier. This gill morphology is typical for fish from soft water habitats and reflects osmoregulatory responses. In mid-winter, however, both chloride cell numbers and epithelia thickness were reduced and comparable to the situation in freshwater with high ionic contents. This pattern correlated with seasonal fluctuations of water chemistry. The most significant correlation was found with CO₂ which accumulated under the ice cover, reaching a tenfold oversatturation. The concentration of Ca, Na, and Cl varied only by a factor of two or less and the correlation with the epithelial thickness was much weaker.     

The effect of copper-treated net pens on farmed salmon (Salmo salar) and other marine organisms and sediments

Samples of Atlantic salmon (Salmo salar), saithe (Pollacius virens), blue mussel (Mytilus edulis), brown seaweed (Ascophyllum nodosum) and sediment were collected from six different fish farms. Five of the farms used net pens treated with copper-containing coatings, whereas one farm did not use copper-containing coating (this was used as a reference location). Samples of muscle, liver and gills of Atlantic salmon and saithe, blue mussel and brown seaweed were freeze dried, homogenised, wet digested and analysed for copper by flame atomic absorption spectrometry. The results showed no significant differences in copper concentrations among the samples from the different locations. The copper contents of some of the samples appeared to be in the upper part of the normal concentration range. From a nutritional point of view, the use of copper-coatings on net pens did not affect the quality of the seafood products either within, or around the net pen.     

Toxicity of Copper and Cadmium to Heteropneustes fossilis (BLOCH)

Static bioassay tests were conducted to determine the acute toxic effects of copper, cadmium and their mixtures on Heteropneustes fossilis in two different seasons. Median lethal concentrations (24, 48, 72 and 96 h LC50) revealed that copper is more toxic to fish even at very low concentrations in comparison to cadmium, tested separately or in combination with cadmium. The data indicate that the level of tolerance of the fish to metallic ions tested was temperature specific. Generally, fishes were found to be more susceptible to metallic ions at higher temperatures as revealed by the threshold concentration, MATC and LC50 values. The behavioural changes of the test fishes were also observed in reference to different concentrations of the metallic ions and temperatures.     

南京玄武湖鱼类暴发性死亡原因分析

南京玄武湖近年来死鱼事件频发,对该湖水生生态系统的长期监测结果表明,湖水富营养化和沉积物污染十分严重。但生礅毒理学研究表明,湖水和沉积物等对鱼类尚未见有急性毒性作用,根据玄武湖鱼类死亡症状,从玄下湖鱼体上分离到一种致力极强的鱼类病原菌－－嗜水气单胞菌,研究了该病原菌的至病特性,并系统地分析了水质主要污染指标,水体富化,藻类种群动态,沉积的污染及其氧化还原层等多种因素对玄武涌鱼类暴发性死亡的发生和流     

Environmental stochasticity promotes copper bioaccumulation and bioenergetic response in tilapia

Environmental change not only undergoes in mean environmental conditions but also in their degree of stochasticity. Changes in waterborne metal variability are often associated with altered disturbance regimes and temporal patterns of source availability. Here copper (Cu) was used as an example because Cu sulfate (CuSO₄) has been extensively used as a chemical tool to exterminate phytoplankton for controlling skin lesions and gill disease of fish in aquatic ecosystems. This study showed that increased variability of waterborne Cu concentrations strongly promotes a key process of biokinetics, bioaccumulation. In experimental tilapia populations, the mean growth cost coefficient in pulsed Cu exposures was 7 % lower than the control group. On the other hand, the double-pulse, constant low, and single-pulse scenarios had similar effect on biomass change (2.2–2.4 %). The greatest biomass change (~10 %) occurred where Cu concentrations were gradually increasing over time or at a constant high rate. Most importantly, this study demonstrated that chronic exposure of tilapia to a low Cu concentration rate that approximated a single large pulse of field-realistic levels damaged bioenergetic mechanisms and increased energy acquisition. This study also showed that interactions across multiple pulsed or fluctuating Cu exposures were involved in accumulation changes that could also be achieved by controlling pulse timing and duration. It can be concluded that increased metal variability can promote biokinetic and bioenergetic responses in fish; and that changes in environmental variability may interact with other global change processes and thereby substantially accelerate change in aquatic ecosystems.     

Effects of Copper Sulphate on the Free Amino Acids of Channa punctatus (BLOCH).

The free amino acids of the liver and muscle of C. punctatus exposed to 1 ppm of copper sulphate solution up to 84 days were investigated. Few amino acids, notably cystine and tryptophan, disappeared and few new amino acids appeared. These changes in the free amino acids may be due to toxic effects of copper sulphate leading to rancidity in the fish.     

In situ biomonitoring of caged, juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Lower Duwamish Waterway

Contaminated sediments may have wide-ranging impacts on human and ecological health. A series of in situ caged exposure studies using juvenile Chinook salmon was conducted in the Lower Duwamish Waterway (LDW). Chemical analysis of sediment, water, and fish tissue were completed. Additionally, in 2004, DNA adducts in hepatic and gill tissues were measured. Gills contained significantly higher DNA adducts at stations B2 and B4, prompting further analysis of gills in 2006 and 2007. Fluorescent aromatic compounds (FACs) in bile, and CYP1A1 in hepatic tissue were also measured during 2006 and 2007, respectively. FACs in field-caged fish were comparable or significantly higher than wild-caught fish LDW fish and significantly higher than lab fish after only 8-10 days, demonstrating the equivalency of exposure to that of migrating salmon. Furthermore, selected biomarkers appear to be capable of detecting spikes in contamination between sampling years, emphasizing the need for multiple year data collection.     

The distribution of short-chain halogenated aliphatic hydrocarbons in some marine organisms

A number of halogenated aliphatic hydrocarbons have been determined in the various organs of three species of molluscs and five species of fish. In general, the compounds were only slightly enriched (2–25 times) on a dry weight basis relative to their seawater concentrations. The usual order of enrichment was found to be brain > gill > liver > muscle. Methyl iodide was found to be the compound most strongly concentrated.