Microplastics (MPs) are ubiquitous pollutants found in marine, freshwater and terrestrial ecosystems. With so many MPs in aquatic systems, it is inevitable that they will be ingested by aquatic ...organisms and be transferred up through the food chain. However, to date, no study has considered whether MPs can be transmitted by means of ontogenic transference, i.e. between life stages that use different habitats. Here, we determine whether fluorescent polystyrene beads could transfer between Culex mosquito life stages and, particularly, could move into the flying adult stage. We show for the first time that MPs can be transferred ontogenically from a feeding (larva) into a non-feeding (pupa) life stage and subsequently into the adult terrestrial life stage. However, transference is dependent on particle size, with smaller 2 µm MPs transferring readily into pupae and adult stages, while 15 µm MPs transferred at a significantly reduced rate. MPs appear to accumulate in the Malpighian tubule renal excretion system. The transfer of MPs to the adults represents a potential aerial pathway to contamination of new environments. Thus, any organism that feeds on terrestrial life phases of freshwater insects could be impacted by MPs found in aquatic ecosystems.
Biological invasions are increasing worldwide, damaging ecosystems and socioeconomic sectors. Two decades ago, the “100 of the world’s worst” invasive alien species list was established by the IUCN ...to improve communications , identifying particularly damaging ‘flagship’ invaders globally (hereafter,
worst
). Whilst this list has bolstered invader awareness, whether
worst
species are especially economically damaging and how they compare to other invaders (hereafter,
other
) remain unknown. Here, we quantify invasion costs using the most comprehensive global database compiling them (InvaCost). We compare these costs between
worst
and
other
species against sectorial, taxonomic and regional descriptors, and examine temporal cost trends. Only 60 of the 100
worst
species had invasion costs considered as highly reliable and actually observed estimates (median: US$ 43 million). On average, these costs were significantly higher than the 463
other
invasive species recorded in InvaCost (median: US$ 0.53 million), although some
other
species had higher costs than most
worst
species. Damages to the environment from the
worst
species dominated, whereas
other
species largely impacted agriculture. Disproportionately highest
worst
species costs were incurred in North America, whilst costs were more evenly distributed for
other
species; animal invasions were always costliest. Proportional management expenditures were low for the
other
species, and surprisingly, over twice as low for the
worst
species. Temporally, costs increased more for the
worst
than
other
taxa; however, management spending has remained very low for both groups. Nonetheless, since 40 species had no robust and/or reported costs, the “true” cost of “some of the world’s
worst
” 100 invasive species still remains unknown.
Environmental gradients may alter the ecological impacts of invasive alien species. In marine systems such as the Baltic Sea, current salinity is variable and seawater freshening is projected in ...future, potentially facilitating novel keystone predators. Here, we examine the influence of salinity variation in the western Baltic Sea (i.e. ambient 10, then 7 and 4 ppt) on the functional response (FR) of the Harris mud crab Rhithropanopeus harrisii towards benthic macroinvertebrate prey at different densities. Rhithropanopeus harrisii displayed a Type II FR across salinities towards larval chironomids, due to a consistently high resource consumption rate at low prey densities. Feeding rates were significantly reduced at 4 ppt (mean 6 chironomid prey killed day−1) compared to 10 ppt and 7 ppt (9 killed day−1). Search efficiencies tended to be greatest at 10 ppt, whereas handling times were shortest — and maximum feeding rate highest — at the intermediate 7 ppt. These results suggest a slight reduction in predatory impact by R. harrisii at lower salinities. Nevertheless, across most prey densities, FRs were not significantly different, indicating sustained interaction strength across a range of salinity regimes.
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•Salinity can be highly variable spatiotemporally in enclosed sea systems.•Functional response of invasive mud crab Rhithropanopeus harrisii quantified.•Invasive crab feeding followed a hyperbolic Type II functional response.•Feeding rates were highest at 10 ppt and 7 ppt compared to 4 ppt.•Ecological impacts are reduced at the lowest salinity level.
Plastic pollution is a growing problem that threatens all habitat types globally. However, relatively little is known about the extent of macroplastics in African freshwater ecosystems. This study ...explored the distribution and concentration of different macroplastic debris types in Nandoni reservoir, South Africa over four sites (2 high household- and 2 low household-density) and two seasons (cool-dry, hot-dry). Similarities were observed for macroplastic debris numbers and weights across sites and seasons. Although slight insignificant differences in macroplastics abundances were observed, no significant relationships were recorded between household density (i.e. as proxy for human population density) and macroplastic debris abundances. The amount of plastic debris and ‘species’ (i.e. γ-diversity value) decreased with distance from the shoreline, with the highest amount of plastic debris and ‘species’ being observed at the shoreline in all sites and seasons. Polypropylene was the most dominant (>45%) in terms of abundance for both seasons and sites. The information derived serves as a baseline for future studies on macroplastic distributions along freshwater reservoir shorelines.
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•Macroplastics highly abundant along a subtropical reservoir shoreline.•Household density did not significantly influence macroplastic abundance.•Macroplastic occurrence slightly different between cool-dry and warm-dry seasons.•Macroplastic debris consisted of five identifiable resins, and one unknown.•A baseline for future macroplastic pollution quantifications is provided.
Biological invasions are a growing ecological and socioeconomic problem worldwide. While robust predictions of impactful future invaders are urgently needed, understandings of invader impacts have ...been challenged by context-dependencies. In aquatic systems in particular, future climate change could alter the impacts of invasive non-native species. Widespread warming coupled with sea freshening may exacerbate ecological impacts of invaders in marine environments, compromising ecosystem structure, function and stability. We examined how multiple abiotic changes affect the potential ecological impact of an emerging invasive non-native species from the Ponto-Caspian region — a notorious origin hotspot for invaders, characterised by high salinity and temperature variation. Using a comparative functional response (feeding rates across prey densities) approach, the potential ecological impacts of the gammarid Pontogammarus maeoticus towards native chironomid prey were examined across a range of current and future temperature (18, 22 °C) and salinity (14, 10, 6, 2 ppt) regimes in a factorial design. Feeding rates of P. maeoticus on prey significantly increased with temperature (by 60%), but were not significantly affected by salinity regime. Gammarids displayed significant Type II functional responses, with attack rates not significantly affected by warming across all salinities. Handling times were, however, shortened by warming, and thus maximum feeding rates significantly increased, irrespective of salinity regime. Functional responses were significantly different following warming at high prey densities under all salinities, except under the ambient 10 ppt. Euryhalinity of invasive non-native species from the Ponto-Caspian region thus could allow sustained ecological impacts across a range of salinity regimes. These results corroborate high invasion success and field impacts of Ponto-Caspian gammarids in brackish through to freshwater ecosystems. Climate warming will likely worsen the potential ecological impact of P. maeoticus. With invasions growing worldwide, quantifications of how combined elements of climate change will alter the impacts of emerging invasive non-native species are needed.
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•Ecological impacts of Pontogammarus maeoticus increased with temperature.•Salinity effects were non-significant across temperatures (14–2 ppt; 18–22 °C).•Gammarids displayed hyperbolic Type II functional responses in all treatments.•Future salinity regime shifts will not lessen ecological impacts via predation.•Warming will heighten the ecological impacts of this emerging invasive species.
Predatory non-indigenous species (NIS) have profound impacts on global ecosystems, potentially leading to native prey extinction and reshaping community dynamics. Among mechanisms potentially ...mediating predator impacts and prey invasion success are predator preferences between native vs. non-indigenous prey, a topic still underexplored. Using functional response and prey preference experiments, this study focused on the predation by the non-indigenous Japanese brush-clawed shore crab,
Hemigrapsus takanoi
, between the native gammarid
Gammarus duebeni
and the analogous non-indigenous
Gammarus tigrinus
. Although
H. takanoi
showed subtle differences in its functional response type between the two prey species, its preferences across their environmental frequencies were not strongly influenced by the prey invasion scenario. The findings highlight the need for a comprehensive understanding of interactions in ecosystems with multiple NIS, offering fresh insights into complex feeding interactions within marine environments.
Microplastics (MPs) continue to proliferate and pollute aquatic and terrestrial environments globally. The impacts of MP pollution on ecosystems and their functioning remain poorly quantified, with ...most research hitherto focusing on marine ecosystems. There is a paucity of information on the impacts of MPs in freshwater ecosystems, despite the broad range of pathways through which MPs can proliferate and the extensive range of species which actively ingest MPs in these systems. Of particular interest are organisms that bridge aquatic and terrestrial habitats. The present study thus examines the uptake, ontogenic transference and effect of different concentrations (0, 50, 100 and 200 MPs mL−1) and sizes (2 and 15 μm) of polystyrene MPs between aquatic and terrestrial life stages of Culex pipiens complex mosquitoes. Both 2 and 15 μm MPs transferred from the aquatic larval to terrestrial adult stage of Culex mosquitoes, and uptake correlated tightly with initial exposure concentration. However, neither concentration nor size of MPs significantly influenced mortality rates between the aquatic larval and terrestrial adult stage. There was also no impact of MPs on the weight of emerging mosquito adults. We thus demonstrate that MPs can be transferred ontogenically through organisms with complex life histories, presenting a potential pathway for dispersal of MPs into terrestrial environments. We also show that MPs exposure does not affect mortality rates between life stages of freshwater Culex populations. This suggests that MPs do not impact nutritional uptakes, with unhampered development to adulthood facilitating subsequent dispersal of MPs aerially and between freshwater and terrestrial habitats.
Polystyrene MP beads (yellow dots) are ingested by Culex mosquito larvae and transferred to the non-feeding pupal stage during metamorphosis. When adults emerge they carry the MPs in their abdomen from the freshwater up into the terrestrial environment. The amount of plastic transferred reduces with each stage but has no impact on growth or mortality. Display omitted
•Culex mosquito larvae readily eat microplastics.•Microplastics are transferred from feeding to non-feeding life stages during metamorphosis.•Adult mosquitoes that have eaten microplastics as larvae emerge into the terrestrial environment with them in their guts.•Microplastic ontogenic transference is dependent on particle size.•Microplastics had no impact on the growth or mortality of the organism (here a mosquito).
Climate change could shift the impacts of biological invasions on aquatic ecosystems. Sea freshening is an often-inconspicuous consequence of climatic change that may modify invasive alien species ...performance in enclosed seas. Several gammarid crustaceans have been particularly successful aliens across fresh, brackish, and marine waters. Here, we use comparative functional responses (feeding rates across resource densities) to examine the ecological impacts of an invasive alien (
Gammarus tigrinus
) and native (
Gammarus locusta
) gammarid, present in the Baltic Sea, under three different salinity regimes (14, 10, 6) toward larval chironomid prey. Feeding rates differed between the two species, but these differences depended on salinity, whereby at the lowest salinities, the invasive alien species showed significantly improved performance compared to the native species. Both gammarids exhibited hyperbolic Type II functional responses, with attack rates similar across salinity regimes. Handling times were significantly shortened, and maximum feeding rates heightened, in the alien under sea freshening scenarios compared to the native. These results have implications for enclosed sea systems, where projected freshening could shift the performance advantage toward invasive alien species over natives, thereby exacerbating their ecological impacts.
The United States has thousands of invasive species, representing a sizable, but unknown burden to the national economy. Given the potential economic repercussions of invasive species, quantifying ...these costs is of paramount importance both for national economies and invasion management. Here, we used a novel global database of invasion costs (InvaCost) to quantify the overall costs of invasive species in the United States across spatiotemporal, taxonomic, and socioeconomic scales. From 1960 to 2020, reported invasion costs totaled $4.52 trillion (USD 2017). Considering only observed, highly reliable costs, this total cost reached $1.22 trillion with an average annual cost of $19.94 billion/year. These costs increased from $2.00 billion annually between 1960 and 1969 to $21.08 billion annually between 2010 and 2020. Most costs (73%) were related to resource damages and losses ($896.22 billion), as opposed to management expenditures ($46.54 billion). Moreover, the majority of costs were reported from invaders from terrestrial habitats ($643.51 billion, 53%) and agriculture was the most impacted sector ($509.55 billion). From a taxonomic perspective, mammals ($234.71 billion) and insects ($126.42 billion) were the taxonomic groups responsible for the greatest costs. Considering the apparent rising costs of invasions, coupled with increasing numbers of invasive species and the current lack of cost information for most known invaders, our findings provide critical information for policymakers and managers.
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•From 1960 to 2020 reported costs of US biological invasions were at least $1.22 tril.•Annual invasion costs increased from $2 bil in 1960–69 to $21 bil in 2010–20.•Most costs were damages ($896 bil), with lower management investments ($47 bil).•Agriculture sector ($510 bil) and terrestrial habitat ($644 bil) were impacted most.•Knowledge gaps in reporting make these monetary costs severely underestimated.
Rates of biological invasion continue to accelerate and threaten the structure and function of ecosystems worldwide. High habitat connectivity, multiple pathways, and inadequate monitoring have ...rendered aquatic ecosystems vulnerable to species introductions. Past riverine invasion dynamics were largely restricted to large rivers, leaving out smaller rivers that commonly harbour high freshwater biodiversity. Moreover, biodiversity time series have rarely been used to investigate invasions across larger spatial-temporal scales, limiting our understanding of aquatic invasion dynamics. Here, we used 6067 benthic invertebrate samples from streams and small rivers from the EU Water Framework Directive monitoring program collected across Central Europe between 2000 and 2018 to assess temporal changes to benthic invertebrate communities as well as non-native species. We assessed invasion rates according to temperature, precipitation, elevation, latitude, longitude, and stream type. Overall, average daily temperatures significantly increased by 0.02 °C per annum (0.34 °C in total) while annual precipitation significantly decreased by 0.01 mm per annum (−67.8 mm over the study period), paralleled with significant increases in overall species richness (12.3 %) and abundance (14.9 %); water quality was relatively stable. Non-native species richness increased 5-fold and abundance 40-fold, indicating an ongoing community shift from native to non-native species. The observed increase in invasions was stronger in low mountain rivers compared to low mountain streams, with the share of non-native species abundance and richness declining with increasing elevation and latitude but increasing with temperature. We found thermophilic non-native species invasion success was greatest in larger sized streams, at lower latitudes, lower elevations and higher temperatures. These results indicate that widespread environmental characteristics (i.e., temperature) could heighten invasion success and confer refuge effects (i.e., elevation and latitude) in higher sites. High altitude and latitude environments should be prioritised for prevention efforts, while biosecurity and management should be improved in lowland areas subject to greater anthropogenic pressure, where non-native introductions are more likely.
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•We analyzed alien species in Central Europe using a dataset of 6067 samples obtained between 2000 and 2018.•Overall community richness and abundance increased by 12.3 and 14.9 %, respectively.•Non-native species richness increased 5-fold and their abundance 40-fold.•Elevation and stream size significantly predicted the success of thermophilic non-native species.
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