Research on the interaction of microplastics and aquatic organisms has been mainly focused on the evaluation of various impacts on animals while aquatic vascular plants have been so far understudied. In this commentary, we summarized knowledge about interactions of microplastics with aquatic vascular plants and highlighted potential ecological implications. Based on recent research, microplastics have minimal impacts on plants. However, they are strongly attracted to plant tissues, adsorbed, and accumulated by plants. Several mechanisms drive microplastics adsorption and accumulation; the most possibly electrostatic forces, leaf morphology, and presence of periphyton belong among the most important ones. Adsorbed microplastics on plant tissues are easily ingested by herbivores. Plants can thus represent a viable pathway for microplastics to enter aquatic food webs. On the other hand, the strong interactions of microplastics with plants could be used for their phytostabilization and final removal from the environment. Aquatic vascular plants have thus an important role in the behavior and fate of microplastics in aquatic ecosystems, and therefore, they should also be included in the future microplastic research.

Sublethal insecticide exposure poses risks for many non-target organisms and is a challenge for successful implementation of integrated pest management (IPM) programs. Next to detrimental effects of short-term insecticide exposure on fitness-related traits of organisms, also properties such as chemical signaling traits can be altered, which mediate intra- and interspecific communication. We investigated the effects of different durations of larval sublethal exposure to the pyrethroid lambda-cyhalothrin on performance traits of larvae and adults of the herbivorous mustard leaf beetle, Phaedon cochleariae. Moreover, by applying a direct contact and olfactometer bioassays, we determined the reaction of a generalist predator, the ant Myrmica rubra, towards insecticide-exposed and unexposed herbivore larvae and their secretions. Already short-term sublethal insecticide exposure of a few days caused a prolonged larval development and a reduced adult body mass of males. These effects may result from an insecticide-induced reduction in energy reserves. Furthermore, ants responded more frequently to insecticide-exposed than to unexposed larvae of P. cochleariae and their secretions. This increased responsiveness of ants towards insecticide-exposed larvae may be due to an insecticide-induced change in synthesis of chrysomelidial and epichrysomelidial, the dominant compounds of the larval secretion, which act defensive against various generalist predators. In conclusion, the results highlight that short-term insecticide exposure can impair the fitness of an herbivorous species due to both direct toxic effects and an increased responsiveness of predators. Consequently, exposure of single non-target species can have consequences for ecological communities in both natural habitats and IPM programs.

Crude oil and its constituents can have adverse effects on ecological and human health when released into the environment. The Canadian Council of Ministers of the Environment (CCME) has developed remedial guidelines and a risk assessment framework for both ecological and human exposure to PHC. One of the assumptions used in the derivation of these guidelines is that plants are unable to take up PHC from contaminated soil and therefore subsequent exposure at higher trophic levels is not a concern. However, various studies suggest that plants are indeed able to take up PHC into their tissues. Consumption of plants is a potential exposure pathway in both ecological (e.g., herbivorous and omnivorous birds, and mammals) and human health risk assessments. If plants can uptake PHC, then the current approach for risk assessment of PHC may underestimate exposures to ecological and human receptors. The present review aims to assess whether or not plants are capable of PHC uptake and accumulation. Twenty-one articles were deemed relevant to the study objective and form the basis of this review. Of the 21 primary research articles, 19 reported detectable PHC and/or its constituents in plant tissues. All but five of the 21 articles were published after the publication of the CCME Canada-Wide Standards. Overall, the present literature review provides some evidence of uptake of PHC and its constituents into plant tissues. Various plant species, including some edible plants, were shown to take up PHC from contaminated soil and aqueous media in both laboratory and field studies. Based on the findings of this review, it is recommended that the soil-plant-wildlife/human pathway should be considered in risk assessments to avoid underestimating exposure and subsequent toxicological risks to humans and wildlife.

The perennial evergreen woody shrub, Rhododendron tomentosum, confers associational resistance against herbivory and oviposition on neighbouring plants through passive adsorption of some of its constitutively emitted volatile organic compounds (VOCs). The adsorption process is dependent on transport of VOCs in the air. In polluted atmospheres, the VOCs may be degraded and adsorption impeded. We studied the effect of elevated ozone regimes on the adsorption of R. tomentosum volatiles to white cabbage, Brassica oleracea, and the oviposition of the specialist herbivore Plutella xylostella on the exposed plants. We found evidence for adsorption and re-emission of R. tomentosum volatiles by B. oleracea plants. Ozone changed the blend of R. tomentosum volatiles and reduced the amount of R. tomentosum volatiles recovered from B. oleracea plants. However, plants exposed to R. tomentosum volatiles received fewer P. xylostella eggs than control plants exposed to filtered air irrespective of whether R. tomentosum volatiles mixed with ozone. Ozone disrupts a volatile mediated passive plant-to-plant interaction by degrading some compounds and reducing the quantity available for adsorption by neighbouring plants. The change, however, did not affect the deterrence of oviposition by P. xylostella, suggesting that aromatic companion plants of Brassica crops may confer pest-deterring properties even in ozone-polluted environments.

The amount of food waste generated from modern societies is increasing, which has imposed a tremendous pressure on its treatment and disposal. Food waste should be treated as a valuable resource rather than waste, and turning it into fish feeds would be a viable alternative. This paper attempts to review the feasibility of using food waste to formulate feed pellets to culture a few freshwater fish species, such as grass carp, grey mullet, and tilapia, under polyculture mode (growing different species in the same pond). These species occupy different ecological niches, with different feeding modes (i.e., herbivorous, filter feeding, etc.), and therefore all the nutrients derived from the food waste could be efficiently recycled within the ecosystem. The problems facing environmental pollution and fish contamination; the past and present situation of inland fish culture (focusing on South China); upgrade of food waste based feed pellets by adding enzymes, vitamin-mineral premix, probiotics (yeast), prebiotics, and Chinese medicinal herbs into feeds; and potential health risks of fish cultivated by food waste based pellets are discussed, citing some local examples. It can be concluded that appropriate portions of different types of food waste could satisfy basic nutritional requirements of lower trophic level fish species such as grass carp and tilapia. Upgrading the fish pellets by adding different supplements mentioned above could further elevated the quality of feeds, leading to higher growth rates, and enhanced immunity of fish. Health risk assessments based on the major environmental contaminants (mercury, PAHs and DDTs) in fish flesh showed that fish fed food waste based pellets are safer for consumption, when compared with those fed commercial feed pellets.

In this study, the bioaccumulation of perfluorinated compounds from a food web in Taihu Lake in China was investigated. The organisms included egret bird species, carnivorous fish, omnivorous fish, herbivorous fish, zooplankton, phytoplankton, zoobenthos and white shrimp. Isotope analysis by δ13C and δ15N indicated that the carnivorous fish and egret were the top predators in the studied web, occupying trophic levels intermediate between 3.66 and 4.61, while plankton was at the lowest trophic level. Perfluorinated carboxylates (PFCAs) with 9–12 carbons were significantly biomagnified, with trophic magnification factors (TMFs) ranging from 2.1 to 3.7. The TMF of perfluorooctane sulfonate (PFOS) (2.9) was generally comparable to or lower than those of the PFCAs in the same food web. All hazard ratio (HR) values reported for PFOS and perfluorooctanoate (PFOA) were less than unity, suggesting that the detected levels would not cause any immediate health effects to the people in Taihu Lake region through the consumption of shrimps and fish.

Recent evidence from novel phytotron and free-air ozone (O3) fumigation experiments in Europe and America on forest tree species is highlighted in relation to previous chamber studies. Differences in O3 sensitivity between pioneer and climax species are examined and viewed for trees growing at the harsh alpine timberline ecotone. As O3 apparently counteracts positive effects of elevated CO2 and mitigates productivity increases, response is governed by genotype, competitors, and ontogeny rather than species per se. Complexity in O3 responsiveness increased under the influence of pathogens and herbivores. The new evidence does not conflict in principle with previous findings that, however, pointed to a low ecological significance. This new knowledge on trees' O3 responsiveness beyond the juvenile stage in plantations and forests nevertheless implies limited predictability due to complexity in biotic and abiotic interactions. Unravelling underlying mechanisms is mandatory for assessing O3 risks as an important component of climate change scenarios.

To evaluate plant and herbivore responses to nitrogen we conducted a fertilization study at a low and high pollution site in the mixed conifer forests surrounding Los Angeles, California. Contrary to expectations, discriminant function analysis of oak herbivore communities showed significant response to N fertilization when atmospheric deposition was high, but not when atmospheric deposition was low. We hypothesize that longer-term fertilization treatments are needed at the low pollution site before foliar N nutrition increases sufficiently to affect herbivore communities. At the high pollution site, fertilization was also associated with increased catkin production and higher densities of a byturid beetle that feeds on the catkins of oak. Leaf nitrogen and nitrate were significantly higher at the high pollution site compared to the low pollution site. Foliar nitrate concentrations were positively correlated with abundance of sucking insects, leafrollers and plutellids in all three years of the study.

Veterinary antibiotics are widely used in livestock production and can be released to the environment via manure, affecting non-target organisms. Recent studies provide evidence that antibiotics can adversely affect both plants and insects but whether antibiotics in soil also affect trophic interactions is unknown.We tested whether antibiotics grown in sand as soil substitute with environmentally relevant concentrations of penicillin, sulfadiazine and tetracycline affect the survival of aphids feeding on plants (two crop and one non-crop plant species). Apera spica-venti, Brassica napus, and Triticum aestivum individuals were infested with aphids that were monitored over four weeks. We did not observe effects of penicillin or tetracycline on plants or aphids. However, sulfadiazine treatments reduced plant growth and increased mortality in the two tested grass species, but not in B. napus. Sulfadiazine subsequently decreased aphid density indirectly through reduced host plant biomass. We thus show that an antibiotic at realistic concentrations in a soil substitute can affect several trophic levels, i.e. plants and herbivores. This study contributes to the environmental risk assessment of veterinary antibiotics as it implies that their use potentially affects plant-insect interactions at environmentally relevant concentrations.

Reported here is the first evidence of plastic ingestion by freshwater fishes in the Amazon. Plastic bags, bottles, fishing gear, and other products are entering Amazonian water bodies and degrade into meso- and micro-plastic particles that may be ingested, either directly or indirectly via food chains, by fishes. Examination of stomach contents from 172 specimens of 16 serrasalmid species from lower Xingu River Basin revealed consumption of plastic particles by fishes in each of three trophic guilds (herbivores, omnivores, carnivores). Overall, about one quarter of specimens and 80% of species analyzed had ingested plastic particles ranging from 1 to 15 mm in length. Fourier transform infrared spectroscopy indicated 12 polymer types, including 27% identified as polyethylene, 13% polyvinyl chloride, 13% polyamide, 13% polypropylene, 7% poly(methyl methacrylate), 7% rayon, 7% polyethylene terephtalate, and 13% a blend of polyamide and polyethylene terephtalate. Dimensions of ingested plastic particles varied among trophic guilds, even though the frequency and mass of ingested particles were not significantly different among fishes with different feeding habits.