Viruses impact host cells and have indirect effects on ecosystem processes. Plankton such as ciliates can reduce the abundance of virions in water, but whether virus consumption translates into ...demographic consequences for the grazers is unknown. Here, we show that small protists not only can consume viruses they also can grow and divide given only viruses to eat. Moreover, the ciliate
sp. foraging on chloroviruses displays dynamics and interaction parameters that are similar to other microbial trophic interactions. These results suggest that the effect of viruses on ecosystems extends beyond (and in contrast to) the viral shunt by redirecting energy up food chains.
Plant diversity experiments generally find that increased diversity causes increased productivity; however, primary productivity is typically measured in the presence of a diverse food web, including ...pathogens, mutualists and herbivores. If food web impacts on productivity vary with plant diversity, as predicted by both theoretical and empirical studies, estimates of the effect of plant diversity on productivity may be biased. We experimentally removed arthropods, foliar fungi and soil fungi from the longest‐running plant diversity experiment. We found that fungi and arthropods removed a constant, large proportion of biomass leading to a greater reduction of total biomass in high diversity plots. As a result, the effect of diversity on measured plant productivity was much higher in the absence of fungi and arthropods. Thus, diversity increases productivity more than reported in previous studies that did not control for the effects of heterotrophic consumption.
Microplastics are widespread in aquatic environments and can be ingested by a wide range of organisms. They can also be transferred along food webs. Estuaries and other tidal wetlands may be ...particularly prone to this type of pollution due to their particular hydrological characteristics and sewage input, but few studies have compared wetlands with different anthropogenic pressure. Furthermore, there is no information on microplastic transfer to secondary intertidal consumers such as shorebirds.
We analysed intertidal sediments, macroinvertebrates and shorebirds, from three important wetlands along the Eastern Atlantic (Tejo estuary, Portugal; Banc d’Arguin, Mauritania and Bijagós archipelago, Guinea-Bissau), in order to evaluate the prevalence and transfer of microplastics along the intertidal food web. We further investigated variables that could explain the distribution of microplastics within the intertidal areas of the Tejo estuary.
Microfibers were recorded in a large proportion of sediment samples (91%), macroinvertebrates (60%) and shorebird faeces (49%). μ-FTIR analysis indicated only 52% of these microfibers were composed of synthetic polymers (i.e. plastics). Microfiber concentrations were generally higher in the Tejo and lower in the Bijagós, with intermediate values for Banc d’Arguin, thus following a latitudinal gradient. Heavier anthropogenic pressure in the Tejo explains this pattern, but the relatively high concentrations in a pristine site like the Banc d’Arguin demonstrate the spread of pollution in the oceans. Similar microfiber concentrations in faeces of shorebirds with different foraging behaviour and similar composition of fibres collected from invertebrate and faeces suggest shorebirds mainly ingest microfibers through their prey, confirming microfiber transfer along intertidal food webs.
Within the Tejo estuary, concentration of microfibers in the sediment and bivalves were positively related with the percentage of fine sediments and with the population size of the closest township, suggesting that hydrodynamics and local domestic sewage are the main factors influencing the distribution of microfibers.
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•Microfibers are widespread in all three studied wetlands.•We report for the first time microfibers in shorebird faeces and gizzards.•Microfibers in sediment and animals are more abundant in the most humanised site.•Shorebirds appear to mainly ingest microfibers indirectly through their prey.•Abundance of microfibers correlates with grain size and human population size.
Microfibers are abundant in intertidal sediments and organisms of three wetlands along the eastern Atlantic and are transferred along local food webs.
Microplastics (MPs) are widely distributed in marine environments and ingested by marine organisms, especially zooplankton. Chaetognaths, typical carnivorous zooplankton, are pivotal in the food ...chain from secondary producers, such as copepods, to higher trophic level species. However, little is known about their MP ingestion. In this study, based on field observation data, for the first time, we studied seasonal characteristics and risks of MPs ingested by chaetognaths in Jiaozhou Bay and assessed effects of key prey copepods on MP ingestion by chaetognaths. MP/chaetognath values in February, May, August, and November were 0.19, 0.17, 0.15, and 0.39, respectively, showing no significant seasonal variation. Chaetognaths predominantly ingested MPs that were fiberous in shape, 101-400 µm in size and polyester in polymer type, with no significant seasonal variations. The risk of MP load in chaetognaths was low, but there are higher polymeric hazards and potential ecological risks. MP/chaetognath values were positively correlated with the copepod abundance and MP/copepod values. The characteristics of MPs ingested by chaetognaths were also highly similar to those of MPs ingested by copepods. However, the overall risk of biomagnification in the copepod-chaetognath food chain was low. This study provided field evidence for MP transfer in the planktonic food chain.Microplastics (MPs) are widely distributed in marine environments and ingested by marine organisms, especially zooplankton. Chaetognaths, typical carnivorous zooplankton, are pivotal in the food chain from secondary producers, such as copepods, to higher trophic level species. However, little is known about their MP ingestion. In this study, based on field observation data, for the first time, we studied seasonal characteristics and risks of MPs ingested by chaetognaths in Jiaozhou Bay and assessed effects of key prey copepods on MP ingestion by chaetognaths. MP/chaetognath values in February, May, August, and November were 0.19, 0.17, 0.15, and 0.39, respectively, showing no significant seasonal variation. Chaetognaths predominantly ingested MPs that were fiberous in shape, 101-400 µm in size and polyester in polymer type, with no significant seasonal variations. The risk of MP load in chaetognaths was low, but there are higher polymeric hazards and potential ecological risks. MP/chaetognath values were positively correlated with the copepod abundance and MP/copepod values. The characteristics of MPs ingested by chaetognaths were also highly similar to those of MPs ingested by copepods. However, the overall risk of biomagnification in the copepod-chaetognath food chain was low. This study provided field evidence for MP transfer in the planktonic food chain.
Microplastics are plastic pieces <5 mm in size that are more harmful than large plastic debris. The world's oceans contain large amounts of these particles, and their presence is severely affecting ...the marine organisms. Smaller aquatic organisms ingesting microplastics, mistaking them for food, and their subsequent entry into the food chain is of significant concern. Rivers are major carriers of these materials from the terrestrial environment to the oceans. In this study, for the first time, we have done the source-to-sink characterization of microplastics (5 mm–0.3 mm) for a tropical Indian river, namely the Netravathi River, which debouches into the Arabian Sea. Here, we present a detailed investigation made on water, sediments and soil samples collected from the river catchment. All the samples showed the presence of microplastics with a mean numerical abundance of 288 pieces/m3 (water), 96 pieces/kg (sediment) and 84.45 pieces/kg (soil). Fibres, films and fragments are the main categories obtained from the catchment. The microplastics present in the samples were mostly transparent and white coloured which are due to the decay of plastic carry bags, packing materials and fishing lines. Different coloured microplastics were also present in lesser numbers. Polyethylene (PE) and polyethylene terephthalate (PET) are the most abundant polymers present in the samples. Fragmentation of larger plastic materials which is due to mismanaged solid waste and garment washing are the primary sources of these materials in the river catchment. Moreover, the sampling sites near to important pilgrim centres like Dharmasthala and Subrahmanya, register higher concentration of fibres released due to washing of clothes. The study concludes that the Netravathi River is contaminated with microplastics from its origin to the sink. However, the spatial distribution and abundance of microplastic particles demonstrate the influence of population distribution, land use and good household practices of waste management in some areas.
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•A source-to-sink investigation on microplastic pollution in an Indian river.•Microplastics varied in their abundance, composition, morphology and colour.•Polyethylene and polyethylene terephthalate are the abundant polymers in the river.•Packaging materials and fibres from clothes contribute to microplastic pollution.•Anthropogenic activities and hydrodynamic factors affect microplastic distribution.
Increasing abundance of microplastics (MP) in marine and freshwaters is currently one of the greatest environmental concerns. Since plastics are fairly resistant to chemical decomposition, breakdown ...and reutilization of MP carbon complexes requires microbial activity. Currently, only a few microbial isolates have been shown to degrade MPs, and direct measurements of the fate of the MP carbon are still lacking. We used compound-specific isotope analysis to track the fate of fully labelled
C-polyethylene (PE) MP carbon across the aquatic microbial-animal interface. Isotopic values of respired CO
and membrane lipids showed that MP carbon was partly mineralized and partly used for cell growth. Microbial mineralization and assimilation of PE-MP carbon was most active when inoculated microbes were obtained from highly humic waters, which contain recalcitrant substrate sources. Mixotrophic algae (Cryptomonas sp.) and herbivorous zooplankton (Daphnia magna) used microbial mediated PE-MP carbon in their cell membrane fatty acids. Moreover, heteronanoflagellates and mixotrophic algae sequestered MP carbon for synthesizing essential ω-6 and ω-3 polyunsaturated fatty acids. Thus, this study demonstrates that aquatic micro-organisms can produce, biochemically upgrade, and trophically transfer nutritionally important biomolecules from PE-MP.
We investigate the distribution and effects of polystyrene microplastic (MP) particles in exposure experiments with the ecotoxicology model organism Daphnia magna. The aim was to investigate the ...short and long-term toxicity of MP at different concentrations. To achieve this goal, the effects of 6 μm commercially available polystyrene beads on two different life-stages of D. magna: < 24 h old juveniles and 9 days old adults was assessed. The following end points in test animals were measured: (1) survival, (2) growth, (3) individual and population fecundity, (4) age at maturation and (5) body size of newborn offspring. These response variables were followed in two acute and two chronic experiments. The acute experiments showed that MP is not acutely toxic to D. magna within 48 h, but cause added mortality within 120 h. The juveniles were about 50% more sensitive than the adults tested. In life-cycle experiments testing chronic exposure to MP, again, animals exposed as juveniles at relatively high concentrations, i.e. > 30 μg ml−1 showed higher sensitivity. We observed slightly increased mortality, reduced growth and stimulation of early reproduction at the cost of later reproduction. Animals exposed after reaching adulthood did not show increased mortality and showed a stimulation response with higher reproductive rates than the control group. However, both the growth rate of mother animals and the body size of newborn declined with increasing dose of MP. We conclude that these effects indicate a role of MP in mechanical interaction/interference with the animal on the level of feeding (clogging filtering functions), digestion (gut filled with plastic particles), and/or other animal behavior. The study also illustrates how MP with slow break-down rates may accumulate in the environment and enter the food-chain as obstructing non-food particles in filter-feeding organisms.
•Microplastic shows toxicity after long time exposure.•Effects are significantly different between juvenile and adult.•Microplastic show significant effects on second generation.
Biodiversity is typically considered as a one-dimensional metric (e.g., species richness), yet the consequences of species loss may be different depending on where extinctions occur in the food web. ...Here, I used a manipulative field experiment in a temperate subtidal marine system to explore the implications of diversity loss at multiple trophic levels for ecosystem functioning and food web structure. The four manipulated predators included the small painted goby and common prawn, which are also fed on by the larger black goby and shore crab. Antagonistic interactions between the manipulated predators (e.g., intraguild predation, intimidation, interference competition) limited their negative effects on the rest of the food web. Top-down control was so suppressed at the highest level of multitrophic diversity that the resulting food webs were as complex and productive as those containing no manipulated predators. Negative interactions between the predators weakened as multitrophic diversity decreased, however, resulting in stronger consumption of lower trophic levels and a simpler food web with lower rates of two key ecosystem processes: primary production and decomposition. These results show how indirect interactions between predators on multiple trophic levels help to promote the complexity and functioning of natural systems.
Moths are the most taxonomically and ecologically diverse insect taxon for which there exist considerable time-series abundance data. There is an alarming record of decreases in moth abundance and ...diversity from across Europe, with rates varying markedly among and within regions. Recent reports from Costa Rica reveal steep cross-lineage declines of caterpillars, while other sites (Ecuador and Arizona, reported here) show no or only modest long-term decreases over the past two decades. Rates of decline for dietary and ecological specialists are steeper than those for ecologically generalized taxa. Additional traits commonly associated with elevated risks include large wingspans, small geographic ranges, low dispersal ability, and univoltinism; taxa associated with grasslands, aridlands, and nutrient-poor habitats also appear to be at higher risk. In temperate areas, many moth taxa limited historically by abiotic factors are increasing in abundance and range. We regard the most important continental-scale stressors to include reductions in habitat quality and quantity resulting from land-use change and climate change and, to a lesser extent, atmospheric nitrification and introduced species. Site-specific stressors include pesticide use and light pollution. Our assessment of global macrolepidopteran population trends includes numerous cases of both region-wide and local losses and studies that report no declines. Spatial variation of reported losses suggests that multiple stressors are in play. With the exception of recent reports from Costa Rica, the most severe examples of moth declines are from Northern Hemisphere regions of high human-population density and intensive agriculture.
The occurrence of microplastics in the aquatic environment has become a growing concern globally. Microplastics pose a hazard to the ecological system, and their presence, particularly in the water, ...has an adverse impact on human health and the ecosystem. Microplastics are released into the environment directly from everyday used plastic items, degradation of plastics, industries, and wastewater treatment plants. Once these contaminants enter the water, aquatic life feeds on them, and microplastics enter the food chain and cause severe health hazards. An assessment of microplastics' ecological risks is essential; however, it is challenging in the present scenario due to limited information available. To fill these knowledge gaps, this paper comprehensively reviews the sources and transport of microplastics in the water environment and their environmental and health effects, global policy frameworks, analytical techniques for microplastic detection, and control strategies to prevent microplastics release in the aquatic environment.
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•Summarizes up to date findings on Occurrence, fate, and removal of microplastic in aquatic environment.•Critically reviews the effect of various factors responsible for microplstic pollution in water environment.•Discussed global policy framework to control microplastic pollution.•Features the analytical techniques for microplstic detection in water.•Identifies the strategies to control the release of microplastics in water environment.
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