Journal articles on the topic 'Freshwater invertebrates Effects of water pollution on'

The pollution of aquatic ecosystems by pharmaceuticals is presently recognized as a serious threat. The drug residues may contaminate surface waters via sewage discharges as well as improper disposal of industrial waste. Very few studies focused on the effects of drug pollutants on behaviour of invertebrates. In this study the effects of ibuprofen and venlafaxine on activity of the Unio tumidus were studied. Changes in behaviours were analysed at concentrations corresponding to wastewater discharges (3.4, 6.8 and 13.6 μgL−1). At dosage of 3.4 μgL−1, ibuprofen affected the activity time and shell opening level. The reduction in activity was particularly evident during the first few days. The same dose of venlafaxine caused hyperactivity of bivalves during the first few days of exposition. The highest doses (13.6 μgL−1) same drugs promoted reduction of activity and shell opening level. Moreover, exposure to these drugs resulted in the reduced water filtering time and hence its purification. The Unio tumidus reaction may indicate negative reaction of other aquatic species to the tested drugs.

The use of pesticides in agricultural systems may have deleterious effects on surrounding environments. Aquatic systems are no exception and are increasingly polluted through the leaching of pesticides from agricultural activities. However, the pesticide pollution effects on key aquatic species have not been studied in many regions. In southern Africa, increasing pesticide use associated with macadamia tree Macadamia integrifolia farming presents a growing risk to surrounding aquatic ecosystems. This study assessed behavioural responses of an important and widely-distributed freshwater fish, Mozambique tilapia Oreochromis mossambicus, following exposure to three commonly used macadamia pesticides (i.e., Karate Zeon 10 CS, Mulan 20 SP, Pyrinex 250 CS) at different concentrations (0.7–200 µL, 0.3–1000 mg, and 0.7–8750 µL, respectively) over 24 h. Behavioural responses, i.e., swimming erratically, surfacing, vertical positioning, loss of equilibrium, being motionless and mortality were observed after pesticides exposure. Lethal dose 50 (LD50) values of Karate Zeon 10 CS, Mulan 20 SP and Pyrinex 250 CS were 2.1 µL (per water litre dilution—WLD), 5.2 mg (WLD) and 21.5 µL (WLD), respectively. These concentrations are therefore expressed as a maximal threshold usage in the environment around macadamia farms and a minimum distance of the plantations to water systems should be considered. Further studies should examine effects on other fish species and aquatic invertebrates to inform on pesticide pollution threats and mitigation plans for the region.

Benthic macroinvertebrates are widely used as indicators of the health of freshwater ecosystems, responding both to water quality and to the hydromorphological integrity. In urban streams, evaluations can be tricky for the synergistic effects of multiple stressors and confounding factors. In these situations, the most broadly used multimetric indices can be used to assess the overall damage to the invertebrate community and, thus, the overall anthropogenic pressure, but they do not allow to understand the specific causal effects. Particularly, habitat loss due to morphological alterations can be difficult to evaluate, especially due to the often concurrent disturbance caused by water pollution. We used a multivariate approach to focus on the characteristics of the streams and rivers in an urban district and to define which macroinvertebrate metrics should be used to assess the influence of the different kinds of alteration in a severely damaged environment. Some metrics enabling the assessment of habitat loss (ratio of oligochaeta, ratio of filterers) were identified. These metrics may help to raise a better awareness in the evaluation of river restoration success and, thus, in the support of decision-making processes.

Stream ecosystems provide invaluable ecosystem services but are highly impacted ecosystems in need of water quality monitoring for habitat change impacts. Freshwater macroinvertebrate (FWI) assemblages have been shown to be good indicators of water quality and are known to be vulnerable to land-use land cover (LULC) and other habitat changes. The goal of this case study was to use an existing dominant LULC analysis in the Neponset River watershed, Massachusetts, USA, as LULC sampling treatment groups to deliberately capture the influence of these LULC effects on meso-scale habitat quality, FWI assemblages, and FWI water quality indices at eight sampling reaches. To achieve this goal, we collected physical habitat measurements and FWI samples in the summers of 2010 and 2012 at eight reach-scale stations spread across four previously determined LULC sub-watershed types (forest, residential, industrial, and golf) in the watershed. We expected that LULC change would influence the habitat quality, which would influence the FWI assemblage water quality scores and composition. We also expected that the water quality at these LULC sub-watershed types would be reflected in the FWI assemblage composition. We identified five major findings from our study. Our first finding was that the habitat quality in the Neponset River watershed was somewhat degraded relative to pristine conditions. Our second finding was that our habitat characterization analysis reflected some separation of our reach-scale macrohabitat types at land-use land-cover treatment stations with some correlations with microhabitat variables. Our third finding was that the water quality base on FWI assemblages was generally degraded in reference to pristine conditions. Our fourth finding was that, contrary to our expectations, there was no significant correlation between our reach-scale EPA habitat quality scores and FWI water quality scores. Our fifth finding was that our FWI assemblage NMS showed separation of land-use land-cover sampling stations and that that low pollution-tolerant taxa dominated some of our LULC sampling treatment stations and influenced NMS groupings.

ABSTRACT A research project was commissioned by the American Petroleum Institute (API) to summarize information on freshwater spill environmental effects. While threats to migrating fish stocks or aquatic mammals may be primary concerns following an ocean spill, adverse effects to benthic invertebrates, reptiles, amphibians, waterfowl, fish hatcheries, shoreline vegetation, or public drinking water intakes may be the focus of a freshwater event. Environmental effects from spilled petroleum constituents and whole oils are discussed. Research needs are identified.

Coal mining and extraction of methane from coal beds generate effluent with elevated salinity or major ion concentrations. If discharged to freshwater systems, these effluents may have adverse environmental effects. There is a growing body of work on freshwater invertebrates that indicates variation in the proportion of major ions can be more important than salinity when determining toxicity. However, it is not known if saline toxicity in a subset of species is representative of toxicity across all freshwater invertebrates. If patterns derived from a subset of species are representative of all freshwater invertebrates, then we would expect a correlation in the relative sensitivity of these species to multiple saline waters. Here, we determine if there is a correlation between the acute (96 h) lethal toxicity in freshwater invertebrates to synthetic marine salts (SMS) and sodium bicarbonate (NaHCO 3 ) added to dechlorinated Sydney tap water. NaHCO 3 is a major component of many coal bed effluents. However, most salinization in Australia exhibits ionic composition similar to seawater, which has very little HCO 3 − . Across all eight species tested, NaHCO 3 was 2–50 times more toxic than SMS. We also observed strong correlations in the acute toxicity of seven of the tested species to SMS and NaHCO 3 . The strongest relationship (LC50 r 2 = 0.906) was dependent on the exclusion of one species, Paratya australiensis (Decopoda: Atyidae), which was the most sensitive species tested to NaHCO 3 , but the second-most tolerant of SMS. We conclude that differences in the toxicity of different proportions of major ions can be similar across a wide range of species. Therefore, a small subset of the invertebrate community can be representative of the whole. However, there are some species, which based on the species tested in the current study appear to be a minority, that respond differently to saline effluent and need to be considered separately. We discuss the implications of this study for the management of saline coal bed waters. This article is part of the theme issue ‘Salt in freshwaters: causes, ecological consequences and future prospects'.

Cadmium is a nonessential element that can be toxic and carcinogenic. On a global scale, the ratio anthropogenic to natural emissions of cadmium is approximately 7:1. Sources of cadmium for freshwater and salt water include atmospheric deposition, direct and via runoff, as well as direct discharges into water or watersheds. Thirty percent of the atmospheric emissions fall onto water. In freshwater, the cadmium ion is the predominant dissolved form, while in seawater, chloride dominates. Much of the cadmium added to aquatic systems accumulates in sediments where it presents a risk to benthic biota and under certain conditions may reenter the water column. The cadmium ion is the most bioavailable to aquatic biota; factors affecting availability include salinity, dissolved organic matter, and hydrogen ion concentration, which affect the chemical forms of cadmium. Hydrogen and other ions, most notably calcium, also affect cadmium uptake and toxicity, through competition and physiological effects. The concentrations of cadmium that result in acute or chronic toxicity vary over several orders of magnitude, with certain freshwater fish and invertebrates being the most sensitive. Long-term field experiments and chronic toxicity tests on invertebrates suggest that the present Canadian guideline of 200 ng Cd∙L−1 for the protection of freshwater biota may be too high. Aquatic animals and plants, like most organisms, produce metal binding proteins, called metallothioneins, in response to cadmium. Some species or varieties within a species of aquatic biota are tolerant to cadmium. The relationship between cadmium tolerance and metallothionein is still incompletely resolved.Key words: cadmium, seawater, freshwater, availability, toxicity, metallothionein, tolerance, food chain.

Salts of marine origin, predominantly consisting of Na+ and Cl− ions, are dominant in most Australian inland saline waters. The proportions of other ions, Ca2+, Mg2+, SO42–, HCO3− and CO32–, in the water may influence salinity tolerance of freshwater organisms and thus the effect of increasing salinity may vary with difference in ionic proportions. We exposed freshwater invertebrates to different concentrations of four ionic compositions and compared them with commercial sea salt (Ocean Nature). They were: synthetic Ocean Nature (ONS) and three saline water types (ONS but without: SO42–, HCO3− and CO32– (S1); Ca2+, HCO3− and CO32– (S2); and Ca2+ and Mg2+ (S3)), which are considered to be the predominant saline water types in south-eastern Australia and the Western Australian wheatbelt. The 96-h LC50 values for the five media were determined for six invertebrate species and sub-lethal responses were observed for two species. There were no differences between responses of invertebrates to various ionic compositions in acute toxicity tests. However, in prolonged sub-lethal tests, animals reacted differently to the various ionic compositions. The greatest effect was observed in water types lacking Ca, for which plausible physiological mechanisms exist. Variation in ionic proportions should be taken into account when considering sub-lethal effects of salinity on freshwater invertebrates.

Agriculture disrupts all freshwater systems hugely from their pristine states. The former reductionist concept of pollution was of examining individual effects of particular substances on individual taxa or sub-communities in freshwater systems, an essentially ecotoxicological concept. It is now less useful than a more holistic approach that treats the impacts on the system as a whole and includes physical impacts such as drainage and physical modification of river channels and modification of the catchment as well as nutrient, particulate and biocide pollution. The European Water Framework Directive implicitly recognizes this in requiring restoration of water bodies to ‘good ecological quality’, which is defined as only slightly different from pristine state. The implications for the management of agriculture are far more profound than is currently widely realized.

Pentachlorophenol is used as an industrial wood preservative for utility poles, crossarms, fence posts, and other purposes (79%);for NaPCP (12%); and miscellaneous, including mill uses, consumer wood preserving formulations and herbicide intermediate (9%) (CMR, 1980). As a wood preservative, pentachlorophenol acts as both a fungicide and insecticide (Freiter, 1978). The miscellaneous mill uses primarily involve the application of pentachlorophenol as a slime reducer in paper and pulp milling and may constitute ∼6% of the total annual consumption of pentachlorophenol (Crosby et al., 1981). Sodium pentachlorophenate (NaPCP) is also used as an antifungal and antibacterial agent (Freiter, 1978). Pentachlorophenol also is used as a general herbicide (Martin and Worthing, 1977). Photolysis and microbial degradation are the important chemical removal mechanisms for pentachlorophenol in water. In surface waters, pentachlorophenol photolyzes rapidly (ECETOC, 1984; Wong and Crosby. 1981; Zepp et al., 1984); however, the photolytic rate decreases as the depth in water increases (Pignatello et al., 1983). Pentachlorophenol is readily biodegradable in the presence of accli-mated microorganisms; however, biodegradation in natural waters requires the presence of microbes that can become acclimated. A natural river water that had been receiving domestic and industrial effluents significantly biodegraded pentachlorophenol after a 15-day lag period, while an unpolluted natural river water was unable to biodegrade the compound (Banerjee et al., 1984). Even though pentachlorophenol is in ionized form in natural waters, sorption to organic particulate matter and sediments can occur (Schellenberg et al., 1984), with desorption contributing as a continuing source of pollution in a contaminated environment (Pierce and Victor, 1978). Experimentally determined BCFs have shown that pentachlorophenol can significantly accumulate in aquatic organisms (Gluth et al., 1985; Butte et al., 1985; Statham et al., 1976; Veith et al., 1979a,b; Ernst and Weber, 1978), which is consistent with its widespread detection in fish and other organisms. Direct photolysis may be an important environmental sink for pen tachlorophenol present in the atmosphere. The detection of pen tachlorophenol in snow and rain water (Paasivirta et al., 1985; Bevenue et al., 1972) suggests that removal from air by dissolution is possible. Soil degradation studies indicate that pentachlorophenol is biodegrad able; microbial decomposition is an important and potentially domin ant removal mechanism in soil (Baker et al., 1980; Baker and Mayfield, 1980; Edgehill and Finn, 1983; Kirsch and Etzel, 1973; Ahlborg and Thunberg, 1980). The degree to which pentachlorophenol leaches in soil is dependent on the type of soil. In soils of neutral pH, leaching may be significant, but in acidic soils, adsorption to soil generally increases (Callahan et al. , 1979; Sanborn et al. , 1977). The ionized form of pentachlorophenol may be susceptible to adsorption in some soils (Schellenberg et al., 1984). In laboratory soils, pen tachlorophenol decomposes faster in soils of high organic content as compared with low organic content, and faster when moisture content is high and the temperature is conducive to microbial activity. Half- lives are usually ∼2-4 weeks (Crosby et al., 1981). Monitoring studies have confirmed the widespread occurrence of pentachlorophenol in surface waters, groundwater, drinking water and industrial effluents (see Table 2). The U.S. EPA's National Urban Runoff Program and National Organic Monitoring Survey reported frequent detections in storm water runoff and public water supplies (Cole et al., 1984; Mello, 1978). Primary sources by which pen tachlorophenol may be emitted to environmental waters may be through its use in wood preservation and the associated effluents and its pesticidal applications. Pentachlorophenol can be emitted to the atmosphere by evaporation from treated wood or water surfaces, by releases from cooling towers using pentachlorophenol biocides or by incineration of treated wood (Skow et al., 1980; Crosby et al., 1981). Pentachlorophenol has been detected in ambient atmospheres (Caut reels et al., 1977), in snow and rain water (Paasivirta et al,. 1985; Bevenue et al., 1972) and in emissions from hazardous waste incinera tion (Oberg et al., 1985). The U.S. Food and Drug Administration's Total Diet Study (conducted between 1964 and 1977) found pen tachlorophenol residues in 91/4428 ready-to-eat food composites (See Tables 4 and 5). The average American dietary intake of pen tachlorophenol during 1965-1969 was estimated to range from <0.001-0.006 mg/day (Duggan and Corneliussen, 1972). The most likely source of pentachlorophenol contamination in many food prod ucts may be the exposure of the food to pentachlorophenol-treated wood materials such as storage containers (Dougherty, 1978). Acute toxicity data indicated that salmonids are more sensitive to the toxic effects of pentachlorophenol than other fish species, with LC50 values of 34-128 μ g/l for salmonids and 60-600 μ g/l for other species. More recent data showed that carp larvae, bluegills, channel catfish and knifefish also had LC50 values < 100 μ gl (see Table 10). The most sensitive marine fishes were pinfish larvae, the goby, Gobius minutus, and eggs and larvae of the flounder, Pleuronectes platessa, all with LC50 values <100 μ g/l (Adema and Vink, 1981). The most sensitive freshwater invertebrate species were the chironomid, Chironomus gr. thummi (Slooff, 1983) and the snail, Lymnaea luteola (Gupta et al., 1984). The most sensitive marine invertebrates were the Eastern oyster (Borthwick and Schimmel, 1978), larvae of the crusta ceans, Crangon crangon and Palaemon elegans (VanDijk et al. , 1977), and the copepod, Pseudodiaptomus coronatus (Hauch et al., 1980), all with LC50 values <200 μ g/l. In chronic toxicity tests, the lowest concentration reported to cause adverse effects was 1.8 μ g/l (NaPCP), which inhibited growth of sockeye salmon (Webb and Brett, 1973). The marine species tested displayed similar thresholds for chronic toxicity. Both acute and chronic toxicity increased at lower pH, probably because a lower pH favors the un-ionized form of pentachlorophenol, which is taken up more readily and is therefore more toxic than ionized pentachlorophenol (Kobayashi and Kishino, 1980; Spehar et al., 1985). Data concerning the effects of pentachlorophenol on aquatic plants were highly variable. Therefore, it was difficult to draw conclusions from these data. Pentachlorophenol did not appear to bioaccumulate in aquatic or ganisms to very high concentrations. BCFs for pentachlorophenol were <1000 for most species tested. The highest BCF was 3830 for the polychaete, Lanice conchilega (Ernst, 1979). Some species appear to have an inducible pentachlorophenol-detoxification mechanism, as evidenced in several experiments in which pentachlorophenol tissue levels peaked in 4-8 days and declined thereafter despite continued exposure (Pruitt et al., 1977; Trujillo et al., 1982). A study by Niimi and Cho (1983) indicated that uptake of waterborne pentachlorophenol from gills was much greater than uptake from food, indicating that bioconcentration of pentachlorophenol through the food chain is unlikely. Biomonitoring data of Lake Ontario fishes showed that similar pentachlorophenol levels were found in predators andforage species. Studies with experimental ecosystems have indicated that ecological effects may occur at pentachlorophenol levels as low as those causing chronic toxicity in sensitive species in single-species tests. The lowest concentration that caused adverse effects in these studies was 15.8 μ g/l, which caused a reduction in numbers of individuals and species in a marine benthic community (Tagatz et al., 1978). Pentachlorophenol is readily absorbed from the gastrointestinal tract of rats, mice, monkeys and humans (Braun et al. , 1977, 1978; Ahlborg et al., 1974; Braun and Sauerhoff, 1976). Peak plasma concentrations are reached within 12-24 hours after oral administration to monkeys (Braun and Sauerhoff, 1976), but 4-6 hours after oral administration to rats (Braun et al., 1977). After oral administration, the highest concentration of radioactivity was found in the liver and gastrointesti nal tract of monkeys (Braun et al., 1977). In rats and mice, tet rachlorohydroquinone was identified in the urine (Jakobson and Yllner, 1971; Braun et al., 1977; Ahlborg et al., 1974) as well as unmetabolized pentachlorophenol and glucuronide-conjugated pen tachlorophenol. Although Ahlborg et al. (1974) reported that oxidative dechlorination of pentachlorophenol occurs in humans, as evidenced by the presence of tetrachlorohydroquinone in the urine of workers occupationally exposed (probably by inhalation), analysis of human urine after ingestion of pentachlorophenol revealed the presence of conjugated pentachlorophenol and unmetabolized pentachlorophenol (Braun et al., 1978). The primary route of excretion after oral administrtation of all species studied is in the urine (Braun et al. , 1977, 1978; Ahlborg et al., 1974; Larsen et al., 1972; Braun and Sauerhoff, 1976). Although urinary excretion followed second-order kinetics in rats (Larsen et al., 1972; Braun et al., 1977) except in females receiving a single high dose (100 mg/kg) of pentachlorophenol, urinary excretion of pentachlorophenol in humans and monkeys followed first-order kinetics (Braun and Sauerhoff, 1976; Braun et al., 1978). Enterohepatic circulation played an importation role in the pharmacokinetics of pen tachlorophenol. The half-life of pentachlorophenol in the plasma is longer in female rats and monkeys than it is in male rats and monkeys (Braun et al. , 1978; Braun and Sauerhoff, 1976). Because many preparations of pentachlorophenol are contaminated with small but measurable amounts of highly toxic substances, such as dibenzodioxins, special attention must be paid to the composition of the pentachlorophenol solution tested. In studies where technical and purified pentachlorophenol have been evaluated (Schwetz et al., 1974; Goldstein et al., 1977; Kimbrough and Linder, 1978; Knudsen et al., 1974; Johnson et al., 1973; Kerkvliet et al., 1982), only the results of the experiments using purified pentachlorophenol were reported in detail. Oral exposure to pentachlorophenol was not carcinogenic in mice (BRL, 1968; Innes et al., 1969) or rats (Schwetz et al., 1977), regardless of the composition of the pentachlorophenol solution tested. Although there are a few studies that suggest pentachlorophenol may be mutagenic in B. subtilis (Waters et al., 1982; Shirasu, 1976), in yeast, Saccharomyces cerevisiae (Fahrig et al., 1977) and in mice, as evidenced by the coat-color spot test (Fahrig et al., 1977), no evidence of mutagenicity was reported in S. typhimurium (Anderson et al. , 1972; Simmon et al., 1977; Lemma and Ames, 1975; Moriya et al. , 1983; Waters et al., 1982; Buselmaier et al., 1973) or in E. coli (Simmon et al., 1977; Fahrig, 1974; Moriya et al., 1983; Waters et al., 1982) with or without metabolic activation. Three teratogenicitylreproductive toxicity studies (Schwetz et al., 1974, 1977; Courtney et al., 1976) indicate that pentachlorophenol is fetotoxic in rats at oral dose levels ≥5 mg/kg/day. At the highest dose tested (500 ppm) in a fourth teratogenicity/reproductive toxicity study (Exon and Koller, 1982), there was a statistically nonsignificant decrease in litter size. The lowest dose tested (5 mg/kg/day) by Schwetz et al. (1977) was the lowest dose at which any evidence offetotoxicity, as indicated by delayed ossification, was observed. No adverse fetal or reproductive effects were reported at ≤3 mg/kg/day (Schwetz et al., 1977; Exon and Koller, 1982). In subchronic and chronic toxicity studies, adverse effects occurred primarily in the liver (Kerkvliet et al., 1982; Johnson et al., 1973; Knudsen et al. , 1974; Goldstein et al. , 1977; Kimbrough and Linder, 1978; Schwetz et al., 1977), the kidney (Johnson et al., 1973; Kimbrough and Linder, 1978; Schwetz et al., 1977) and the immune system (Kerkvliet et al., 1982). Knudsen et al. (1974) reported increased liver weights in female rats and centrilobu lar vacuolization in male rats exposed to diets containing ≧50 ppm commercial pentachlorophenol, which contained 282 ppm dioxins. In the remaining studies, increased liver weight (Johnson et al., 1973) and increased pigmentation of hepatocytes (Schwetz et al., 1977) were observed at oral doses of≥10 mg/kg/day (∼90%), and SGPT levels significantly increased in rats ingesting 30 mg/kg/day pentachloro phenol (∼90%) for 2 years (Schwetz et al., 1977). Increased kidney weight unaccompanied by renal histopathology was reported in rats exposed to dietary concentration ≧20 ppm of pentachlorophenol (>99%) for 8 months (Kimbrough and Linder, 1978) and in rats ingesting 30 mg/kg/day (∼90%) for 90 days (Johnson et al., 1973). Increased pigmentation of the renal tubular epithelial cells was re ported in rats ingesting 10 or 30 mg/kg/day pentachlorophenol for 2 years (Schwetz et al., 1977). Although decreased immunocompetence was reported in mice exposed to dietary levels of 50 or 500 ppm of pentachlorophenol (>99%) for 34 weeks (Kerkvliet et al., 1982), the decrease was statistically significant only at the higher dose. An ADI of 0.03 mg/kg/day or 2.1 mg/day for a 70 kg human was derivedfrom the NOAEL of 3 mg/kg/day in rats in the chronic dietary study by Schwetz et al. (1977). An uncertainty factor of 100 was used. An RQ of 100 was derived based on the fetotoxic effects of pen tachlorophenol in rats in the study by Schwetz et al. (1974). Based on guidelines for carcinogen risk assessment (U.S. EPA, 1984b) and inadequate evidence for animal carcinogenicity or absence of human cancer data, pentachlorophenol is classified as Group D, meaning that it is not classified as a human carcinogen.

From 1985 to 1987, long-term and more or less permanent effects of discharges from combined or separate sewer systems on communities of sessile diatoms and macro-invertebrates in receiving waters have been studied. Sessile diatoms and/or macro-invertebrates have been investigated on 46 locations, spread all over The Netherlands. The results were related to the type of sewer system, the discharges, and the characteristics of the receiving water, and compared with results from sample(s) taken from a corresponding water not influenced by sewer overflows, the reference water. In general, communities of sessile diatoms and macro-invertebrates indicate a more severe organic pollution and disturbance of receiving waters compared with reference waters. In the immediate vicinity of the overflows these communities were more disturbed than at some distance. In small ditches, effects were more pronounced compared with large waterbodies and waters with a constant flow regime. Finally, effects of combined sewer overflows were more pronounced than effects of discharges from separate sewer systems, except for locations in industrial areas.

This research draws together data on the secondary production of 164 invertebrate populations in 51 lakes to test the hypothesis that the annual production of aquatic invertebrate populations is significantly correlated with the mean annual population biomass, individual body mass, and ambient temperature. Further analyses examine the effects of water chemistry, trophic status, and lake morphometry. Mean annual biomass, individual body mass, and the mean annual water temperature accounted for 79% of the variance in the logarithm of annual secondary production. In contrast to the findings of previous studies, the ratio of mean annual production to mean annual biomass [Formula: see text] varied systematically with population biomass. No significant difference was found between the secondary production of littoral and open water invertebrate populations. Analyses also suggest that zoobenthic and zooplanktonic populations of similar biomass, body mass, and temperature have similar rates of secondary productivity. Analyses demonstrate that the total phosphorus concentration in the water column, and other trophic indicators were positively correlated with secondary production. The pH, lake depth, thermocline depth, drainage area, and the water turnover rate were also found to be correlated with the secondary productivity of natural populations of lentic invertebrates.

Abstract This study evaluates the suitability of using Hyalella azteca as a predictor of the risk that tributyltin (TBT) poses to freshwater invertebrates by comparing the toxicity and bioaccumulation of TBT in H. azteca to five species: Hexagenia limbata, Physella gyrina, Tubifex tubifex, Chironomus riparius and Daphnia magna. Young from each species were added to aquaria containing sediment spiked with TBT concentrations of 0, 28.6, 258 and 1900 ng Sn/g dry weight. Chironomus riparius data could not be quantified reliably due to poor control survival. Bioaccumulation of TBT in the five remaining species was similar at sediment concentrations of 258 ng Sn/g, and the bioaccumulation relationships of P. gyrina and H. azteca were virtually identical. No toxicity was evident in any test species at body concentrations of 1100 to 1800 ng Sn/g. Body concentrations of 4000 to 6000 ng Sn/g were associated with significant (p &lt; 0.05) mortality in H. limbata, P. gyrina, T. tubifex and D. magna, but not in H. azteca. However, bioaccumulation of TBT in H. azteca was comparable and can be used in predicting the effects of environmental TBT concentrations on these four species of freshwater invertebrates.

Abstract This study evaluates the suitability of using Hyalella azteca as a predictor of the risk that tributyltin (TBT) poses to freshwater invertebrates by comparing the toxicity and bioaccumulation of TBT in H. azteca to five species: Hexagenia limbata, Physella gyrina, Tubifex tubifex, Chironomus riparius and Daphnia magna. Young from each species were added to aquaria containing sediment spiked with TBT concentrations of 0,28.6, 258 and 1900 ng Sn/g dry weight. Chironomus riparius data could not be quantified reliably due to poor control survival. Bioaccumulation of TBT in the five remaining species was similar at sediment concentrations of 258 ng Sn/g, and the bioaccumulation relationships of P. gyrina and H. azteca were virtually identical. No toxicity was evident in any test species at body concentrations of 1100 to 1800 ng Sn/g. Body concentrations of 4000 to 6000 ng Sn/g were associated with significant (p &lt; 0.05) mortality in H. limbata, P. gyrina, T. tubifex and D. magna, but not in H. azteca. However, bioaccumulation of TBT in H. azteca was comparable and can be used in predicting the effects of environmental TBT concentrations on these four species of freshwater invertebrates.

Abstract In Canada, the Metal Mining Effluent Regulation is a mechanism developed from the Fisheries Act (R.S., c. F-14, s.1) under which the effects of mine effluent on fish and fish habitat (i.e., benthic invertebrate communities) is determined by Environmental Effects Monitoring (EEM) studies. The Metal Mining EEM (MM EEM) program proceeds in a tiered manner, commencing with determining whether an effect is present and continuing with determining extent, magnitude and cause of the effect. The benthic invertebrate monitoring component of the MM EEM program includes consideration of study design elements such as confounding factors, monitoring frequency, statistical study design, appropriate community endpoints and standardized approaches to site descriptions, field and laboratory methods and data interpretation. We present the approaches and rationale recently adopted for the benthic component of Canada's Metal Mining EEM program. A primary objective of this program was to outline a consistent national program that was scientifically defensible and that would produce the necessary information to evaluate the effectiveness of current pollution regulations.

Abstract The toxicity of tributyltin (TBT) in sediment in fresh water was determined using spiked sediment bioassays for four benthic invertebrates, (the oligochaete worm Tubifex tubifex, the chironomid Chironomus riparius, the amphipod Hyalella azteca, and the mayfly Hexagenia). Although there was some degradation of spiked TBT into dibutyltin (DBT) and monobutyltin (MBT) in the sediment-water mixtures during the equilibration phase before toxicity testing, the contribution of these degradation products to the observed toxicity was assumed to be minimal based on evidence that TBT is up to orders of magnitude more toxic to many aquatic organisms than its degradation products. The results of this work indicated that Hexagenia was the most sensitive benthic organism to TBT of the four organisms tested (by factors up to about 7), with an IC50 (growth) value for TBT of 0.6 µg Sn/g dry weight. This value is about six times greater than mean concentrations of TBT observed in sediment in fresh water in surveys conducted across Canada before and after the regulation of antifouling uses of TBT in 1989. However, maximum TBT concentrations in sediment before and after regulation exceeded the IC50 (growth) value for Hexagenia, and were close to the lower limits of toxicity ranges for H. azteca and T. tubifex (cocoons/adult and young/adult). Consequently, at the time of surveys before and after the TBT regulation there was potential for adverse effects of TBT in some sediments to some freshwater benthic species.

End-of-life tires are utilized for various purposes, including sports pitches and playground surfaces. However, several substances used at the manufacture of tires can be a source of concerns related to human health or environment’s adverse effects. In this context, it is necessary to map whether this approach has the desired effect in a broader relation. While the negative effects on human health were investigated thoroughly and legislation is currently being revisited, the impact on aquatic or soil organisms has not been sufficiently studied. The present study deals with the exposure of freshwater and soil organisms to rubber crumb using the analysis of heavy metal and polycyclic aromatic hydrocarbon concentrations. The obtained results refer to substantial concerns related to freshwater contamination specifically, since the increased concentrations of zinc (7 mg·L−1) and polycyclic aromatic hydrocarbons (58 mg·kg−1) inhibit the growth of freshwater organisms, Desmodesmus subspicatus, and Lemna minor in particular. The performed test with soil organisms points to substantial concerns associated with the mortality of earthworms as well. The acquired knowledge can be perceived as a roadmap to a consistent approach in the implementation of the circular economy, which brings with it a number of so far insufficiently described problems.

Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach.

Individual growth rates of the freshwater amphipod Hyalella azteca (Saussure) were measured in the littoral zone oftwo small oligotrophic Ontario lakes and in growth experiments over a natural temperature gradient (10, 15, 20, and 238C).Field observations showed that a temperature of 208C is important for both the induction and termination of reproductiveresting stages in H. azteca. Growth rates were more affected by temperature in small than in large individuals. Growthparameters are related to rearing temperature by linear regressions, which can be used as a simple model for bioenergeticscalculations in crustaceans. A negative relationship between water temperature and maximum size attained by the amphipodswas found. The largest adults were absent in studied populations when summer temperatures were high, and this phenomenon,which has also been observed in other aquatic invertebrates, was bioenergetically determined. Energy-budget estimationsshowed negative net growth efficiency (K2) in the largest adults at temperatures above 208C. The relationship between K2andtemperature showed a dome-shaped pattern, K2values for larger amphipods being maximal at lower temperatures. Seasonalmigrations of adult H. azteca from shallow littoral to deeper cold habitats, observed in lakes during the warmest periods, appearto be temperature-induced and bioenergetically advantageous, despite probable increases in predation risk experienced inspatially simple deep-water habitats.

Vibrios are ubiquitous bacteria in aquatic systems, especially marine ones, and belong to the Gammaproteobacteria class, the most diverse class of Gram-negative bacteria. The main objective of this review is to update the information regarding the ecology of Vibrio species, and contribute to the discussion of their potential risk in a changing environment. As heterotrophic organisms, Vibrio spp. live freely in aquatic environments, from marine depths to the surface of the water column, and frequently may be associated with micro- and macroalgae, invertebrates, and vertebrates such as fish, or live in symbiosis. Some Vibrio spp. are pathogenic to humans and animals, and there is evidence that infections caused by vibrios are increasing in the world. This rise may be related to global changes in human behavior (increases in tourism, maritime traffic, consumption of seafood, aquaculture production, water demand, pollution), and temperature. Most likely in the future, Vibrio spp. in water and in seafood will be monitored in order to safeguard human and animal health. Regulators of the microbiological quality of water (marine and freshwater) and food for human and animal consumption, professionals involved in marine and freshwater production chains, consumers and users of aquatic resources, and health professionals will be challenged to anticipate and mitigate new risks.

Abstract Nowadays, pollution has become a serious problem with the development of industry and the exploitation of the earth’s resources. Acid rain and lake acidification caused by pollutants such as sulfur dioxide and nitric oxide has caused serious effects in many places. Nowadays people do not know the ecological influence of acidification, how to detect it and how it recovers. This paper examines the effects of acid rain on fish, plants and microorganisms in freshwater lakes, as well as how to detect acid rain and how to manage and recover from it. The results are not always clear, but there is a lot of evidence that acidification is changing lakes in many aspects, whether living or non-living things, small or widespread factors, acidified freshwater is no longer what it used to be. By examining those problems, people can protect the environment more effectively. Reducing the occurrence of acid rain and the damage it causes in the future. The significance of this paper is analyzing the ecological influence of acid rain, studying and discussing the negative impact on species, and giving some solutions for people, governments and companies for acidification. Furthermore, lake water self-cleaning is also considered in the solution as well. Acid rain causes acidification of the soil, which has a negative impact on agriculture. And it also damages the breeding environment of animals, reducing their reproductive success. For example, fish, microorganisms, and plants can be negatively affected by acidification of the lake water, even leading to extinction.

The increasing application of nanoparticles both in industries and in agricultural fields has led to its accumulation in the aquatic ecosystem through water run-off. Insights into the validity of safer nanoparticles such as gold and chitosan are fairly established. However, its effect on aquatic invertebrates has been less studied. The present study was aimed to study effects of chitosan reduced gold nanoparticles (CRGNPs) during green fluorescent protein (GFP) encoding plasmid delivery in giant freshwater prawn, macrobrachium rosenbergii. The mean particle size and zeta potential CRGNPs was 33.7 nm and 24.79 mV respectively. Prawn juveniles were exposed to nanoparticles concentrations (10 µg/L, 20 µg/L) of CRGNPs by immersion treatment for a period of 36 hours. GFP was ubiquitously expressed in muscle tissues of prawns. The comet assay indicated dose dependent genotoxicity of CRGNPs in gill, pleopod and muscle tissues which was in conformity with its bioaccumulation pattern in vivo. The highest bioaccumulation of CRGNPs was found in Gills, followed by pleopods and least in muscles. Hence, the toxicological potential of CRGNPs to the environment cannot be denied and demands more research on the particular aspect. The doses standardized in the present study would be helpful in safer nano-gene delivery in aquatic invertebrates and development of transgenics employing less cost.

Freshwater ecosystems are affected by anthropogenic alterations. Different studies have extensively studied the concentrations of metals, nutrients, and water quality as measurements of pollution in freshwater ecosystems. However, few studies have been able to link these pollutants to bioindicators as a risk assessment tool. This study aimed to examine the potential of two bioindicators, plant ecotoxicological assays and sediment bacterial taxonomic diversity, in ecological risk assessment for six freshwater constructed wetlands in a rapidly urbanizing watershed with diverse land uses. Sediment samples were collected summer, 2015 and 2017, and late summer and early fall in 2016 to conduct plant ecotoxicological assays based on plant (Lepidium, Sinapis and Sorghum) growth inhibition and identify bacterial taxonomical diversity by the 16S rRNA gene sequences. Concentrations of metals such as lead (Pb) and mercury (Hg) (using XRF), and nutrients such as nitrate and phosphate (using HACH DR 2800TM spectrophotometer) were measured in sediment and water samples respectively. Analyses of response patterns revealed that plant and bacterial bioindicators were highly responsive to variation in the concentrations of these pollutants. Hence, this opens up the scope of using these bioindicators for ecological risk assessment in constructed freshwater wetland ecosystems within urbanizing watersheds.

The excessive worldwide production of plastic materials results in omnipresent microplastic pollution. Scientific studies dealing with the impacts of microplastics on aquatic ecosystems focus mainly on the marine environment, documenting the effect on the functional traits of various organisms. Polystyrene, one of the most commonly used plastics, has become a widely used model in this respect. In our study, freshwater shrimps (Neocardina heteropoda) were exposed to virgin polystyrene particles (size 0.5 mm; nominal concentration 8 mgL−1), and their behavioral and physiological responses were compared to control shrimp. The exposed shrimps exhibited modified activity patterns (greater speeds, accelerations and distances moved), accompanied by a lowered standard metabolic rate (SMR). The observed effects differed in their progression from the 7th to 14th day of exposure, from undetectable changes (distance, SMR) to significant differences (speed, acceleration). Significant differences were also detected in the behavioral syndromes expressed by the exposed and controlled shrimps, indicating that the microplastics influence not only the particular traits, but also their functional relationships. As such, our study contributes to the integration of behavioral ecotoxicology in risk assessment, documenting the adverse performance of freshwater invertebrates exposed to microplastics with the potential to transpose the problem to higher levels of the food web.

AbstractThe toxicity of endocrinologically active pharmaceuticals finasteride (FIN) and melengestrol acetate (MGA) was assessed in freshwater mussels, including acute (48 h) aqueous tests with glochidia from Lampsilis siliquoidea, sub-chronic (14 days) sediment tests with gravid female Lampsilis fasciola, and chronic (28 days) sediment tests with juvenile L. siliquoidea, and in chronic (42 days) sediment tests with the amphipod Hyalella azteca and the mayfly Hexagenia spp. Finasteride was not toxic in acute aqueous tests with L. siliquoidea glochidia (up to 23 mg/L), whereas significant toxicity to survival and burial ability was detected in chronic sediment tests with juvenile L. siliquoidea (chronic value (ChV, the geometric mean of LOEC and NOEC) = 58 mg/kg (1 mg/L)). Amphipods (survival, growth, reproduction, and sex ratio) and mayflies (growth) were similarly sensitive (ChV = 58 mg/kg (1 mg/L)). Melengestrol acetate was acutely toxic to L. siliquoidea glochidia at 4 mg/L in aqueous tests; in sediment tests, mayflies were the most sensitive species, with significant growth effects observed at 37 mg/kg (0.25 mg/L) (ChV = 21 mg/kg (0.1 mg/L)). Exposure to sublethal concentrations of FIN and MGA had no effect on the (luring and filtering) behaviour of gravid L. fasciola, or the viability of their brooding glochidia. Based on the limited number of measured environmental concentrations of both chemicals, and their projected concentrations, no direct effects are expected by these compounds individually on the invertebrates tested. However, organisms are exposed to contaminant mixtures in the aquatic environment, and thus, the effects of FIN and MGA as components of these mixtures require further investigation.

Human presence at water bodies can have a range of ecological impacts, creating trade-offs between recreation as an ecosystem service and conservation. Conservation policies could be improved by relying on robust knowledge about the relative ecological impacts of water-based recreation. We present the first global synthesis on recreation ecology in aquatic ecosystems, differentiating the ecological impacts of shore use, (shoreline) angling, swimming and boating. Impacts were assessed at three levels of biological organization (individuals, populations and communities) for several taxa. We screened over 13 000 articles and identified 94 suitable studies that met the inclusion criteria, providing 701 effect sizes. Impacts of boating and shore use resulted in consistently negative, significant ecological impacts across all levels of biological organization. The results were less consistent for angling and swimming. The strongest negative effects were observed in invertebrates and plants. Recreational impacts on birds were most pronounced at the individual level, but not significant at the community level. Due to publication bias and knowledge gaps, generalizations of the ecological impacts of aquatic recreation are challenging. Impacts depend less on the form of recreation. Thus, selectively constraining specific types of recreation may have little conservation value, as long as other forms of water-based recreation continue.

Plastic has become a “hot topic” for aquatic ecosystems’ conservation together with other issues such as climate change and biodiversity loss. Indeed, plastics may detrimentally affect habitats and biota. Small plastics, called microplastics, are more easily taken up by freshwater organisms, causing negative effects on growth, reproduction, predatory performance, etc. Since available information on microplastics in freshwater are fragmentary, the aim of this review is twofold: (i) to show, analyse, and discuss data on the microplastics concentration in freshwater and (ii) to provide the main polymers contaminating freshwater for management planning. A bibliographic search collected 158 studies since 2012, providing the scientific community with one of the largest data sets on microplastics in freshwater. Contamination is reported in all continents except Antarctica, but a lack of information is still present. Lentic waters are generally more contaminated than lotic waters, and waters are less contaminated than sediments, suggested to be sinks. The main contaminating polymers are polypropylene and polyethylene for sediment and water, while polyethylene and polyethylene terephthalate are mainly found in biota. Future research is encouraged (1) to achieve a standardised protocol for monitoring, (2) to identify sources and transport routes (including primary or secondary origin), and (3) to investigate trophic transfer, especially from benthic invertebrates.

Tropical freshwater wetlands are subject to multiple stressors but there is little information on which stressors cause wetland degradation. Increased turbidity is considered a major cause of degradation, but the effects of introduced fish are often overlooked. Tilapia are frequently introduced in tropical regions, especially species in the genus Oreochromis, and the ecological effects of introducing tilapia are poorly studied. We used enclosure experiments in a shallow lake in Madagascar to assess the effects of tilapia and turbidity on macrophytes and benthic invertebrates, and to test management interventions designed to increase both. Tilapia at high and low stocking densities had negative effects on survival of Charophyte algae and water lilies, but no direct effect on benthic invertebrate abundance or diversity. Invertebrate abundance was highest on submerged Charophytes, so herbivory by tilapia indirectly affected invertebrates. Turbidity affected Charophyte survival, and abundance and diversity of non-Dipteran insects. As a complication, tilapia may increase turbidity by re-suspending the lake sediment. Our results suggest that herbivory by tilapia is a plausible cause of the removal of macrophytes from the lake and an impediment to their re-establishment. Tilapia are widely introduced in tropical areas as a food resource. Our results demonstrate serious consequences to these introductions.

Microplastic pollution has increased rapidly over recent decades and accepted as an emerging thread. However, the effects and dimensions of microplastic pollution on aquatic ecosystems have not been fully understood yet. Most of these few studies have been carried out in marine ecosystems and the number of studies on freshwater are very limited. In this study, microplastic (<5 mm) pollution level of surface water samples taken from Cevdet Pond (Yozgat/Turkey) was investigated. Water samples (150 L) were taken from 5 stations and microplastic particles were extracted via density separation method. Random particles were examined both visually and spectrophotometrically (µ-Raman). According to station averages, there were 233 microplastic particles in 1 m3 of the pond water. Highest number of MP particles observed in 100-250 µm (56%) size class. Most abundant microplastic type and colour are fiber (91%) and blue (36%) respectively. Polypropylene (50%) and polyethylene (40%) were the most abundant type of polymers according to µ-Raman analysis. The presence of microplastic pollution in an area where human impact is relatively low, indicates the prevalence of microplastic pollution in freshwater ecosystems.

Trophic cascades, or indirect effects of predators on non-adjacent lower trophic levels, are a classic phenomenon in ecology, and are thought to be strongest in aquatic ecosystems. Most research on freshwater trophic cascades focused on temperate lakes, where fish are present and where Daphnia frequently dominate the zooplankton community. These studies identified that Daphnia often play a key role in facilitating trophic cascades by linking fish to algae with strong food web interactions. However, Daphnia are rare or absent in most tropical and subtropical lowland freshwaters, and fish are absent from small and temporary water bodies, where invertebrates fill the role of top predator. While invertebrate predators are ubiquitous in freshwater systems, most have received little attention in food web research. Therefore, we aimed to test whether trophic cascades are possible in small warmwater ponds where Daphnia are absent and small invertebrates are the top predators. We collected naturally occurring plankton communities from small fishless water bodies in central Texas and propagated them in replicate pond mesocosms. We removed zooplankton from some mesocosms, left the plankton community intact in others, and added one of two densities of the predaceous insect Neoplea striola to others. Following an incubation period, we then compared biomasses of plankton groups to assess food web effects between the trophic levels, including whether Neoplea caused a trophic cascade by reducing zooplankton. The zooplankton community became dominated by copepods which prefer large phytoplankton and exhibit a fast escape response. Perhaps due to these qualities of the copepods and perhaps due to other reasons such as high turbidity impairing predation, no evidence for food web effects were found other than somewhat weak evidence for zooplankton reducing large phytoplankton. More research is needed to understand the behavior and ecology of Neoplea, but trophic cascades may generally be weak or absent in fishless low latitude lowland water bodies where Daphnia are rare.