The effects of parasite exposure on mortality from aquatic contaminants, carbaryl and elevated salinity, in a freshwater crustacean

2020 ◽  
Vol 42 (3) ◽  
pp. 394-397
Author(s):  
Juliana K Ilmain ◽  
Catherine L Searle

Abstract Freshwater pollution is a major global concern. Common methods for determining the effects of contaminants on freshwater organisms involve short-term laboratory experiments with otherwise healthy organisms. However, in natural systems, organisms are commonly exposed to parasites, which could alter their ability to survive exposure to aquatic contamination. We used a freshwater crustacean (Daphnia dentifera) to quantify the effects of parasite exposure on mortality from two common freshwater contaminants (elevated salinity [NaCl] and carbaryl). In our salinity trial, both parasite exposure and elevated salinity reduced survival in an additive manner. In our carbaryl trial, exposure to carbaryl reduced survival and we found a less-than-additive (i.e. antagonistic) interaction between carbaryl and the parasite; the parasite only reduced survival in the control (no carbaryl) treatments. Our results demonstrate that parasites and contaminants can jointly affect mortality in aquatic organisms in an additive or less-than-additive manner.

2008 ◽  
Vol 4 (4) ◽  
pp. 392-394 ◽  
Author(s):  
Zoe E Squires ◽  
Paul C.E Bailey ◽  
Richard D Reina ◽  
Bob B.M Wong

Human-induced environmental change is occurring at an unprecedented rate and scale. Many freshwater habitats, in particular, have been degraded as a result of increased salinity. Little is known about the effects of anthropogenic salinization on freshwater organisms, especially at sublethal concentrations, where subtle behavioural changes can have potentially drastic fitness consequences. Using a species of Australian frog ( Litoria ewingii ), we experimentally examined the effects of salinization on tadpole behaviour and their vulnerability to a predatory dragonfly nymph ( Hemianax papuensis ). We found that tadpoles exposed to an ecologically relevant concentration of salt (15% seawater, SW) were less active than those in our freshwater control (0.4% SW). Tadpoles in elevated salinity also experienced a higher risk of predation, even though the strike rate of the predator did not differ between salt and freshwater treatments. In a separate experiment testing the burst-speed performance of tadpoles, we found that tadpoles in saltwater were slower than those in freshwater. Thus, it would appear that salt compromised the anti-predator response of tadpoles and made them more susceptible to being captured. Our results demonstrate that environmentally relevant concentrations of aquatic contaminants can, even at sublethal levels, severely undermine the fitness of exposed organisms.


2021 ◽  
Vol 8 ◽  
Author(s):  
Elio de Almeida Borghezan ◽  
Tiago Henrique da Silva Pires ◽  
Takehide Ikeda ◽  
Jansen Zuanon ◽  
Shiro Kohshima

The Amazon has the highest richness of freshwater organisms in the world, which has led to a multitude of hypotheses on the mechanisms that generated this biodiversity. However, most of these hypotheses focus on the spatial distance of populations, a framework that fails to provide an explicit mechanism of speciation. Ecological conditions in Amazon freshwaters can be strikingly distinct, as it has been recognized since Alfred Russel Wallace’s categorization into black, white, and blue (= clear) waters. Water types reflect differences in turbidity, dissolved organic matter, electrical conductivity, pH, amount of nutrients and lighting environment, characteristics that directly affect the sensory abilities of aquatic organisms. Since natural selection drives evolution of sensory systems to function optimally according to environmental conditions, the sensory systems of Amazon freshwater organisms are expected to vary according to their environment. When differences in sensory systems affect chances of interbreeding between populations, local adaptations may result in speciation. Here, we briefly present the limnologic characteristics of Amazonian water types and how they are expected to influence photo-, chemical-, mechano-, and electro-reception of aquatic organisms, focusing on fish. We put forward that the effect of different water types on the adaptation of sensory systems is an important mechanism that contributed to the evolution of fish diversity. We point toward underexplored research perspectives on how divergent selection may act on sensory systems and thus contribute to the origin and maintenance of the biodiversity of Amazon aquatic environments.


Author(s):  
Hamidreza Sadegh ◽  
Gomaa A. M. Ali ◽  
Hamid Jafari Nia ◽  
Zahra Mahmoodi

With the development of dyeing, textile, leather, paper, and other chemical industries, an increasing amount of dye wastewater containing refractory organic dyes is discharged. Undoubtedly, much high content dye wastewater will lead to serious environmental issues such as color pollution, light penetration interference, and virulence to aquatic organisms, even endanger human health. Therefore, it is an imminent problem and has become a global concern to degrade dye wastewater efficiently. So far, many techniques have been used to degrade dyeing wastewater, such as chemical degradation, biological degradation, photochemical degradation, coagulation, membrane filtration, and combined methods. These methods have certain impacts on the degradation of dye wastewater, but usually with slow degradation rate, complex and high operation costs, as well as easily causing secondary pollution. The adsorption process is a simple, effective, and low-cost way to remove dyes.


2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Qi Wang ◽  
Yalin Du ◽  
Fuhong Sun ◽  
Xinmiao Deng ◽  
Hong Chang

Due to the persistence and the high toxicity of metals to many aquatic organisms, metals in aquatic ecosystems have attracted considerable attention. The objective of the present study was to rank metals in Lake Taihu based on the threat they pose to aquatic organisms. The method involved the assessment of the risks of metals to native aquatic organisms and the potential influence of concentration distributions. Both quotient and probabilistic methods were used to rank the risks of arsenic, cadmium, chromium, copper (Cu), mercury, manganese, nickel (Ni), lead, and zinc (Zn). Based on the probabilistic method, Cu, Ni, and Zn were the metals of great concern, with Cu posing the highest risk.


Author(s):  
John P. Sumpter

Tens of thousands of man-made chemicals are in everyday use in developed countries. A high proportion of these, or their transformation products, probably reach the aquatic environment. A considerable amount is known about the environmental concentrations of some of these chemicals (such as metals), especially the regulated ones, but little or nothing is known about the majority. In densely populated countries, most or all rivers will receive both diffuse (e.g. agricultural runoff) and point source (e.g. sewage treatment plant effluent) inputs, and hence be contaminated with complex, ill-defined mixtures of chemicals. Most freshwater organisms will be exposed, to varying degrees, to this contamination. The number of species exposed is in the thousands, and quite possibly tens of thousands. Little is known about whether or not these species are adversely affected by the chemicals present in their environment. Often it is not even known what species are present, let alone whether they are affected by the chemicals present. In a few high-profile cases (e.g. tributyl tin causing imposex in molluscs and oestrogens ‘feminizing’ male fish), chemicals have undoubtedly adversely affected aquatic species, occasionally leading to population crashes. Whether or not other chemicals are affecting less visible species (such as most invertebrates) is largely unknown. It is possible that only very few chemicals in the freshwater environment are adversely affecting wildlife, but it is equally possible that some effects of chemicals are, as yet, undiscovered (and may remain so). Nor it is clear which chemicals may pose the greatest risk to aquatic organisms. All these uncertainties leave much to chance, yet designing a regulatory system that would better protect aquatic organisms from chemicals is difficult. A more flexible and intelligent strategy may improve the current situation. Finally, the risk due to chemicals is put into context with the many other threats, such as alien species and new diseases that undoubtedly can pose significant risks to aquatic ecosystems.


2021 ◽  
Vol 56 (4) ◽  
pp. 710-720
Author(s):  
Carla Juliana Nin ◽  
Suzelei Rodgher

Ecosystems are subject to various stress factors, such as temperature rises due to climate changes and metal disposal. Thermal stress can amplify or mask the effects of metals on aquatic organisms. This study aims to carry out a systematic review on the effects of temperature rises due to climate changes on the toxicity of metals for freshwater organisms. Searches were made in different electronic databases and article selection was based on the following inclusion criteria: concordance with the question of a systematic review; publication in English, Spanish, and Portuguese between 1960 and 2020; and the use of standard methodology. Forty-three articles were included, which were classified with respect to the year and country of publication, test-organisms and metals studied, temperatures tested, and the effects observed. In 80% of the studies analyzed, a temperature rise was responsible for increasing the toxicity of metals for the aquatic organisms. The temperatures studied contemplated the temperature rise predicted by the Intergovernmental Panel for Climate Change at the end of the 21st century. Brazil stood out among the countries for having the greatest number of research studies in this area, although there is still the need for an increase in studies in tropical climate regions. Based on the literature review, it was shown that the metals most studied were copper and cadmium and the test-organisms most used in the research projects were fish. The information obtained from ecotoxicological studies is essential to predict the effects and prevent the risks associated with the metal contamination of aquatic ecosystems due to climate changes.


2021 ◽  
Author(s):  
Nalissa Farrah Khan

The increasing demand of alternative energy sources has created interest in biodiesel and biodiesel blends; biodiesel is promoted as a diesel substitute. Like diesel spills, biodiesel spills can have deleterious effects on aquatic environments. The effect of neat biodiesel, biodiesel blends and diesel on O. mykiss and D. magna was evaluated using acute toxicity testing. Static non-renewable bioassays of freshwater organisms containing B100, B50, B20, B5 and conventional diesel fuel were used to compare the acute effects of biodiesel to diesel. Mortality was the significant endpoint measurement in this study; percent mortality and lethal concentration (LC50) at different exposure times were determined from the acute toxicity tests performed. Trials were considered valid if the controls exhibited more than 90% survival. Based on percent mortality and LC50 values, a toxicity ranking of fuels was developed. The results of the definitive tests indicated that diesel is more toxic than neat biodiesel or biodiesel blends. This approach can provide insights into the lethality of biodiesel spills in the aquatic environment.


Parasitology ◽  
2019 ◽  
Vol 147 (2) ◽  
pp. 182-193
Author(s):  
Olwyn C. Friesen ◽  
Sarah Goellner ◽  
Robert Poulin ◽  
Clément Lagrue

AbstractParasites directly and indirectly influence the important interactions among hosts such as competition and predation through modifications of behaviour, reproduction and survival. Such impacts can affect local biodiversity, relative abundance of host species and structuring of communities and ecosystems. Despite having a firm theoretical basis for the potential effects of parasites on ecosystems, there is a scarcity of experimental data to validate these hypotheses, making our inferences about this topic more circumstantial. To quantitatively test parasites' role in structuring host communities, we set up a controlled, multigenerational mesocosm experiment involving four sympatric freshwater crustacean species that share up to four parasite species. Mesocosms were assigned to either of two different treatments, low or high parasite exposure. We found that the trematode Maritrema poulini differentially influenced the population dynamics of these hosts. For example, survival and recruitment of the amphipod Paracalliope fluviatilis were dramatically reduced compared to other host species, suggesting that parasites may affect their long-term persistence in the community. Relative abundances of crustacean species were influenced by parasites, demonstrating their role in host community structure. As parasites are ubiquitous across all communities and ecosystems, we suggest that the asymmetrical effects we observed are likely widespread structuring forces.


2020 ◽  
Vol 94 ◽  
Author(s):  
D. Milotic ◽  
M. Milotic ◽  
J. Koprivnikar

Abstract Many temperate freshwater habitats are at risk for contamination by run-off associated with the application of road de-icing salts. Elevated salinity can have various detrimental effects on freshwater organisms, including greater susceptibility to infection by parasites and pathogens. However, to better understand the net effects of road salt exposure on host–parasite dynamics, it is necessary to consider the impacts on free-living parasite infectious stages, such as the motile aquatic cercariae of trematodes. Here, we examined the longevity and activity of cercariae from four different freshwater trematodes (Ribeiroia ondatrae, Echinostoma sp., Cephalogonimus sp. and an unidentified strigeid-type) that were exposed to road salt at five different environmentally relevant concentrations (160, 360, 560, 760 and 960 mg/ml of sodium chloride). Exposure to road salt had minimal detrimental effects, with cercariae activity and survival often greatest at intermediate concentrations. Only the cercariae of Cephalogonimus sp. showed reduced longevity at the highest salt concentration, with those of both R. ondatrae and the unidentified strigeid-type exhibiting diminished activity, indicating interspecific variation in response. Importantly, cercariae seem to be relatively unaffected by salt concentrations known to increase infection susceptibility in some of their hosts. More studies will be needed to examine this potential dichotomy in road salt effects between hosts and trematodes, including influences on parasite infectivity.


Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 66
Author(s):  
Tatiana Andreani ◽  
Verónica Nogueira ◽  
Ana Gavina ◽  
Saul Fernandes ◽  
José Luís Rodrigues ◽  
...  

The aim of the present study was to investigate the eco-cytotoxicity of several forms of nanomaterials (NM), such as nano-CuO, nano-TiO2, nano-SiO2 and nano-ZnO, on different aquatic species (Raphidocelis subcapitata, Daphnia magna and Lemna minor) following standard protocols and on human cell lines (Caco-2, SV-80, HepG2 and HaCaT). Predicted no-effect concentrations (PNEC) or hazard concentrations for 5% of the species (HC5) were also estimated based on the compilation of data available in the literature. Most of the NM agglomerated strongly in the selected culture media. For the ecotoxicity assays, nano-CuO and nano-ZnO even in particle agglomeration state were the most toxic NM to the freshwater organisms compared to nano-TiO2 and nano-SiO2. Nano-ZnO was the most toxic NM to R. subcapitata and D. magna, while nano-CuO was found to be very toxic to L. minor. Nano-CuO was very toxic to Caco-2 and HepG2 cells, particularly at the highest tested concentrations, while the other NM showed no toxicity to the different cell lines. The HC5 and PNEC values are still highly protective, due to data limitations. However, the present study provides consistent evidence of the potential risks of both nano-CuO and nano-ZnO against aquatic organisms and also their effects on public health.


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