Toxic pollution and parasitism in freshwater fish

As aquatic habitats throughout the world are increasingly contaminated with toxic chemicals, toxicologist strive to determine what impact these substances will have an biological systems. So far, the effects of this type of pollution on fish parasites has received little attention, despite their important status as determinants of fish health. Robert Poulin discusses the many ways in which toxic pollution may affect infections of metazoan parasites in freshwater fish. Effects on fish immunity, parasites survival and intermediate host populations are not independent, and currently the outcome of toxic pollution and parasitism in fish is impossible to predict. Future research will have to answer several questions if we are to understand and forecast pollution-mediated changes in parasitism, an urgent challenge for ecotoxicologists and fish parasitologists alike.     

Bacterial pollution indicators in the intestinal tract of freshwater fish

A study was made of the occurrence, distribution, and persistence of coliforms, fecal coliforms, and fecal streptococci in the intestinal tract of freshwater fish. A total of 132 fish representing 14 different species were used in various phases of these experiments. Examination of the intestinal contents of 78 fish from moderately polluted sections of the Little Miami River indicated that fecal coliform densities were lowest in bluegills (less than 20 per gram) and highest in catfish (1,090,000 per gram). Levels of fecal streptococci for these two species were 220 and 240,000 per gram, respectively. The occurrence of fecal coliforms in fish caught in this stream reflected the warm-blooded-animal-pollution level of the water. All fish used in this phase of the study were caught during July, August, and September when the water temperatures were between 13 and 18 C. The fate of fecal coliforms and Streptococcus faecalis in the fish intestine indicated that these organisms can probably survive and multiply when fish and water temperatures are 20 C or higher, but only when the organisms are retained in the gut for periods beyond 24 hr. Based on the biochemical reactions for 3,877 coliform strains isolated from 132 freshwater fish of 14 different species, 91.4% of all strains were composed of five IMViC types. In a similar study of the biochemical reactions of 850 streptococci isolated from the intestinal tract of 55 freshwater fish, the predominant strains included S. faecalis and various closely associated biotypes. No consistently recurring pattern for either coliforms or streptococci could be developed to identify species of fish investigated. The composition of the intestinal flora is, however, related in varying degree to the level of contamination of water and food in the environment.     

Lysosomal perturbations in fish liver as indicators for toxic effects of environmental pollution

• 1.1. Lysomones play a key role in liver injury in fish caused by organic and inorganic xenobiotics. The lysosomal stability test was transferred to fish liver with the aim of testing responsive and practicable methods for biological-effects monitoring.
• 2.2. A two-step response of lysosomes in fish liver could be discerned, reflected by the activity (number and size of lysosomes) and the injury (membrane destabilisation) of the lysosomal detoxifying system.
• 3.3. Significant differences, with respect to lysosomal enlargement, membrane stability and pathological lipid accumulation, were found along a pollution gradient throughout the year.
• 4.4. The lysosomal tests clearly reflect the breakdown of the adaptive capacity of the fish liver to toxic injury. Therefore, a test battery measuring lysosomal perturbations should be recommended for the biological-effects monitoring.

     

Lysosomal perturbations in fish liver as indicators for toxic effects of environmental pollution.

1. Lysomones play a key role in liver injury in fish caused by organic and inorganic xenobiotics. The lysosomal stability test was transferred to fish liver with the aim of testing responsive and practicable methods for biological-effects monitoring. 2. A two-step response of lysosomes in fish liver could be discerned, reflected by the activity (number and size of lysosomes) and the injury (membrane destabilisation) of the lysosomal detoxifying system. 3. Significant differences, with respect to lysosomal enlargement, membrane stability and pathological lipid accumulation, were found along a pollution gradient throughout the year. 4. The lysosomal tests clearly reflect the breakdown of the adaptive capacity of the fish liver to toxic injury. Therefore, a test battery measuring lysosomal perturbations should be recommended for the biological-effects monitoring.     

Soil macroinvertebrates as indicators of pollution by heavy metals

A broad range of soil pollutants were found to decrease with distance from a zinc smelter from 35,000 to 77, 8270 to 40 and from 190 to less than 1 ppm for zinc, lead and cadmium, respectively. Along this gradient, observed species richness of soil macro-organisms seemed to be more affected by the land-use type than by soil pollution--minimum in crops (21), maximum in woody sites (126). IndVal index allowed isolation of 21 indicator species from the 339 morphospecies identified. Most of these indicator species were characteristic of the unpolluted sites: only two diplopods and one gastropod from polluted poplar plantations, and none from the most polluted site. Since soil invertebrates respond to different environmental factors, including direct effect of heavy metals, we suggest there may be some confounding factors generating spurious relationships between the values of species as bioindicators and the pollution status they are supposed to indicate.     

Strontium-calcium concentration ratios in fish otoliths as environmental indicators

• 1.1. External and internal examinations of otoliths in fishes for macrostructure and microstructure has demonstated yearly, daily and population rhythmic patterns.
• 2.2. Chemical analyses (atomic absorption) of otolith carbonate from reared Fundulus heteroclitus for strontium-calcium concentration ratios demonstrated changes in chemistry related to temperature.
• 3.3. Microprobe analyses made it feasible to interpret almost daily changes in temperature to provide the temperature history of an individual fish.
• 4.4. A combination of microprobe analyses and daily increment analyses of otoliths can provide a life history profile for individual fish and can provide information on the environmental history of each fish.
• 5.5. Such information is vital to our understanding of the processes underlying recruitment and growth rates, and would make it possible to link growth and mortality rates to environmental occurrences.

     

The use of grasses as indicators of environmental pollution

Summary An exploratory examination of the use of rye grass as an indicator of environmental accumulation of minor elements confirmed that natural grass is contaminated by soil or airborne dust, and that this contamination cannot be washed off sampled grass with water without also removing elements from within the leaves, to an extent that varies with the age and/or environment of the grass. This reduces the suitability of natural grasses as indicators of pollution, and alternative procedures are required and proposed.     

Microorganisms resistant to heavy metals and toxic chemicals as indicators of environmental pollution and their use in bioremediation

Microorganisms present in water samples from various industrial effluents were analysed for their resistance to lead, chromium, and cadmium. The ability of these microorganisms to grow on or metabolize toxic hydrocarbons and pesticides was also checked. Microorganisms in samples from the steel and tanning industries were generally resistant to metal ions but were not capable of metabolizing toxic hydrocarbons. Conversely, microorganisms found in samples of pesticide and from the chemical industry were capable of metabolizing hydrocarbons and pesticides but were not much resistant to metal ions. Microorganisms from effluents of the paint industry and urban wastes were resistant to lead. A correlation between the population of microorganisms and the type of pollution was observed. Indigenous microorganism could be regarded as indicators of pollution and be used in various operations to resist, process, metabolize, and detoxify toxic industrial wastes.     

DNA adducts in marine and freshwater fish as biomarkers of environmental contamination

The analysis of DNA modifications in aquatic animals may serve as a sensitive marker of exposure to genotoxic contaminants. This is of importance in assessing water quality regarding pollution with genotoxic compounds, food safety analysing edible aquatic animals and in terms of ecotoxicology. Covalent modification of DNA is considered a crucial event in chemical carcinogenesis and thus may be considered a biomarker of an early genotoxic effect. Measuring DNA adducts is unique in that these lesions may be considered a biomarker of both exposure and effect. A number of studies have described the analysis of the DNA isolated from the liver of both freshwater and marine fish. Considerable levels of DNA adducts have been observed in some animals from contaminated lakes or rivers. Low levels were observed in DNA from the liver of marine fish. The background levels of DNA adducts have to be determined in animals from appropriate uncontaminated control sites that are matched for species, gender, age and season of the year. It is of crucial importance to consider the species analysed since there have been reports of the non responsiveness of some species.     

DNA adducts in marine and freshwater fish as biomarkers of environmental contamination

The analysis of DNA modifications in aquatic animals may serve as a sensitive marker of exposure to genotoxic contaminants. This is of importance in assessing water quality regarding pollution with genotoxic compounds, food safety analysing edible aquatic animals and in terms of ecotoxicology. Covalent modification of DNA is considered a crucial event in chemical carcinogenesis and thus may be considered a biomarker of an early genotoxic effect. Measuring DNA adducts is unique in that these lesions may be considered a biomarker of both exposure and effect. A number of studies have described the analysis of the DNA isolated from the liver of both freshwater and marine fish. Considerable levels of DNA adducts have been observed in some animals from contaminated lakes or rivers. Low levels were observed in DNA from the liver of marine fish. The background levels of DNA adducts have to be determined in animals from appropriate uncontaminated control sites that are matched for species, gender, age and season of the year. It is of crucial importance to consider the species analysed since there have been reports of the non responsiveness of some species.     

Gill surface area of water-breathing freshwater fish

Summary To provide a hitherto lacking review which focuses on gill surface area of freshwater fish, we collected and analysed morphometric data from the literature. The scaling exponent of gill area ranges from 0.36 to 1.13, with a mean value of 0.76. The absolute values for the largest gill areas are about 5 times as high as those of the smallest. This range resembles that of marine fish, if specially adapted steady swimmers, such as tunnies and some sharks, are excluded. Generally it appears that the gill areas of freshwater fish are smaller than those of comparable marine species. To establish whether a relationship exists between gill area and swimming activity or oxygen content of water, the activity of each species and the oxygen content of its habitat were estimated and checked against the gill area. ANOVA revealed that activity explains the presence of the smallest gill areas only, while oxygen content does not correlate with gill area at all. The morphometric variables determining gill area (total length of filaments, average lamellar density, average lamellar area) are highly correlated; total gill area correlates mainly with lamellar density and to a lesser degree with filament length; lamellar area varies independently. Different populations of the same species exhibit striking differences with respect to gill areas, total length of filaments, average lamellar density and average lamellar area. These differences point to a substantial morphological plasticity of the gill system.     

Histological changes in fish hepatopancreas and kidney as indicators of environmental quality in tropical bays

Environmental Biology of Fishes - Biomarkers are used to assess health conditions of organisms and consequently to indicate environmental hazard, being important tools to address the effects of...     

Lichens as air pollution indicators in the metropolitan area of San José, Costa Rica

Lichens were used as air pollution indicators in the metropolitan area of San José, Costa Rica. Transplants showed a positive correlation between the percentage of dead cells in the thallus and the ketone soluble substances deposited on it. Those parts of the city where pollution is greatest (industrial areas and heavy traffic) were also the ones where lichens suffered the most, and in some extreme cases the thallus died after 8 months of exposure. Besides this transplant experiment, the coverage of Parmelia lichens on the bark of several tree species was determined in some areas of the city. The results of these observations suggest that the city of San José has three different kinds of air environment in relation to lichen survival: normal, transitional and desertic, as reported for other cities of the world. The most frequent air pollutants in San José are: CO, CO2, C2H5OH, Cl2, HCl, H2S, H3PO4, H2CrO4, NO, NH3, NH4 Cl, SO2 and Zn.     

Fish eco-genotoxicology: Comet and micronucleus assay in fish erythrocytes as in situ biomarker of freshwater pollution

Owing to white meat production Labeo rohita have vast economic importance, but its population has been reduced drastically in River Chenab due to pollution. Atomic absorption spectrophotometry showed a merciless toxicity level of Cd, Cu, Mn, Zn, Pb, Cr, Sn and Hg. Comet assay results indicated significant (p?<?.05) DNA fragmentation in Labeo rohita as 42.21?±?2.06%, 31.26?±?2.41% and 21.84?±?2.21% DNA in comet tail, tail moment as 17.71?±?1.79, 10.30?±?1.78 and 7.81?±?1.56, olive moment as 13.58?±?1.306, 8.10?±?1.04 and 5.88?±?0.06, respectively, from three different polluted sites on the river. Micronucleus assay showed similar findings of single micronucleus induction (MN) as 50.00?±?6.30‰, double MN 14.40?±?2.56‰, while nuclear abnormalities (NA) were found as 150.00?±?2.92‰. These higher frequencies of MN induction and NA were found to be the cause of reduction of 96% of the population of this fish species in an experimental area of the River Chenab. This fish species has been found near extinction through the length of the river Chenab and few specimens in rainy seasons if restored by flood, may die in sugarcane mill season. Due to sweeping extinction Labeo rohita showed the highest sensitivity for pollution and could be used as bioindicator and DNA fragmentation in this column feeder fish species as a biomarker of the pollution load in freshwater bodies.     

Benthic freshwater cyanobacteria as indicators of anthropogenic pressures

Freshwater cyanobacteria are hardly used as biological indicators of anthropogenic pressures, possibly for two main reasons: (a) their response to anthropogenic pressures is often poorly known; (b) reliably identifying cyanobacteria species is a challenge for technicians and researchers. We assessed the usefulness of cyanobacteria species as biological indicators of two human stressors: the high orthophosphate input from urban wastewaters; the high nitrate concentration produced by agricultural land use. We analysed variation in benthic cyanobacterial assemblages at 85 sites in South-Central Spain as a response to eight environmental variables: pH, conductivity, temperature, altitude, nitrate, orthophosphate, irrigation land use and non-irrigation land use.Results revealed that conductivity was the main environmental factor that contributed to differences between assemblages. Orthophosphate was more influential for community composition than nitrate. Changes in species composition related to human pressures suggested that some cyanobacteria species (e.g. Nostoc verrucosum, Phormidium autumnale, Plectonema tomasinianum, Rivularia haematites, Tolypothrix distorta) could be useful tools for the bioindication of anthropogenic pressures; while others species provide more information about natural physicochemical reference conditions (Nostoc caeruleum, Phormidium fonticola). Further research into cyanobacteria and macroalgae assemblages in different impacted scenarios could help improve macrophyte indices.     

Artificial mussels as indicators of metal pollution in freshwater systems: A field evaluation in the Koekemoer Spruit,South Africa

There has been a recent increase in water quality problems in South Africa. The monitoring of water resources is important for the continued management of water resources. The use of artificial mussels (AMs) as passive sampling devices in the monitoring of metals within a freshwater system was evaluated in a recent field study. Correlation testing was conducted between the AMs and Melanoides tuberculata for As, Cd, Cr, Co, Cu, Pb, Mn, Ni, U, V and Zn. It was found that a positive significant correlation exists between AMs and M. tuberculata with regards to As, U, and Co accumulations. The trend of metal accumulation between AMs and M. tuberculata were found to be similar for all of the metals tested. Site 2 which is located close to a gold mine, was found to have the highest metal concentrations in this study. This study confirms the hypothesis that AMs can be used as a useful tool for monitoring metals in freshwater.     

Monitoring of trace metals in tissues of Wallago attu (lanchi) from the Indus River as an indicator of environmental pollution

We aimed to assess the bioaccumulation of selected four trace metals (Cd, Ni, Zn and Co) in four tissues (muscles, skin, gills and liver) of a freshwater fish Wallago attu (lanchi) from three different sites (upstream, middle stream and downstream) of the Indus River in Mianwali district of Pakistan. Heavy metal contents in water samples and from different selected tissues of fish were examined by using flame atomic absorption spectrometry. The data were statistically compared to study the effects of the site and fish organs and their interaction on the bioaccumulation pattern of these metals at P < 0.05. In W. attu the level of cadmium ranged from 0.004 to 0.24; nickel 0.003–0.708; cobalt 0.002–0.768 and zinc 47.4–1147.5 μg/g wet weight. The magnitude of metal bioaccumulation in different organs of fish species had the following order gills > liver > skin > muscle. The order of bioaccumulation of these metals was Ni < Zn < Co < Cd. Heavy metal concentrations were increased during the dry season as compared to the wet season. The results of this study indicate that freshwater fish produced and marketed in Mianwali have concentrations below the standards of FEPA/WHO for these toxic metals.