Invasive species versus pollutants: Potential of Limnoperna fortunei to degrade glyphosate-based commercial formulations

Agricultural nonpoint source pollutant loads into water bodies in a typical basin in the middle reach of the Yangtze River

Phosphorus and nitrogen pollution from agricultural nonpoint sources heavily burden the water environment, and a scientific calculating system is needed to calculate the pollutant loads under the water pollution treatment. This study established a system to calculate the coefficients of agricultural nonpoint source pollutants into water bodies in the subregion in Poyang Lake basin in the middle reach of the Yangtze River combining with multiple driving factors. Validation results showed that the errors of the typical unit were 30.58% for total phosphorus (TP), 13.43% for total nitrogen (TN) and 33.93% for ammonia nitrogen (NH3-N), respectively. The errors of the subregion were 26.92% for TP, 31.83% for TN and 29.15% for NH3-N, respectively. Besides, there were higher TP and TN loads in the east area of subregion in both units and county scales, which indicated the heavy phosphorus and nitrogen burden on water environment. In contrast, higher NH3-N loads occurred in the north area of subregion. The establishment of coefficient system for agricultural pollutants into water bodies and the pollutant loads calculation would provide enlightenment for water pollution treatment and agricultural nonpoint source pollution controlling.

Ecological risk assessment of glyphosate and its possible effect on bacterial community in surface sediments of a typical shallow Lake, northern China

Glyphosate is a widely used herbicide worldwide and its prevalent presence in aquatic ecosystems poses a threat to living organisms. This study evaluated potential ecological risk of glyphosate to sediment-dwelling organisms and assessed the probable effect of glyphosate on structure and predicated function of sediment-attached bacterial communities from a large shallow lake in northern China based on 16S rRNA high-throughput sequencing. Results suggested that glyphosate showed a medium to high concentration (up to 8.63 mg/kg) and chronic risk to sediment-dwelling organisms (10% samples exhibiting medium to high risk quotient), especially in sites nearby farmland and residential areas in August. Bacterial community identification based on 16S rRNA sequence indicated some species of dominant phylum Proteobacteria and Campilobacterota (e.g., Steroidobacteraceae, Thiobacillus, Gallionellaceae, Sulfurimonadaceae) were stimulated while some species of dominant phylum Actinobacteriota, Acidobacteriota and Firmicutes (e.g., Nocardioidaceae, Microtrichales, Vicinamibacteraceae, Paenisporosarcina) were inhibited by glyphosate accumulation. The stimulating species were related to sulfur-oxidizing, sulfate-, iron-, or nitrate-reducing bacteria; The inhibiting species were related to plant bacterial endophytes, polyphosphate-accumulating organisms (PAOs) and denitrifers. Correspondingly, promoted bacterial metabolic functions of "sulfite respiration", "nitrogen respiration", "aromatic compound degradation" and "nitrification" but suppressed "cellulolysis", "manganese oxidation", "anoxygenic photoautotrophy S oxidizing" and "nitrate denitrification" were predicated on functional annotation of prokaryotic taxa. Although these results could only partly suggest the impacts of glyphosate on the bacterial communities due to the lack of actual results from control experiments, the identified Steroidobacteraceae could be thought as a bioindicator in the future mechanism study for the ecological effect and bioremediation of glyphosate. This work intends to arise the concern about the depletion of biodiversity and bacterial metabolic functions with contribution of glyphosate in part in eutrophic lakes.

A global synthesis of ecosystem services provided and disrupted by freshwater bivalve molluscs

Identification of ecosystem services, i.e. the contributions that ecosystems make to human well-being, has proven instrumental in galvanising public and political support for safeguarding biodiversity and its benefits to people. Here we synthesise the global evidence on ecosystem services provided and disrupted by freshwater bivalves, a heterogenous group of >1200 species, including some of the most threatened (in Unionida) and invasive (e.g. Dreissena polymorpha) taxa globally. Our systematic literature review resulted in a data set of 904 records from 69 countries relating to 24 classes of provisioning (N = 189), cultural (N = 491) and regulating (N = 224) services following the Common International Classification of Ecosystem Services (CICES). Prominent ecosystem services included (i) the provisioning of food, materials and medicinal products, (ii) knowledge acquisition (e.g. on water quality, past environments and historical societies), ornamental and other cultural contributions, and (iii) the filtration, sequestration, storage and/or transformation of biological and physico-chemical water properties. About 9% of records provided evidence for the disruption rather than provision of ecosystem services. Synergies and trade-offs of ecosystem services were observed. For instance, water filtration by freshwater bivalves can be beneficial for the cultural service 'biomonitoring', while negatively or positively affecting food consumption or human recreation. Our evidence base spanned a total of 91 genera and 191 species, dominated by Unionida (55% of records, 76% of species), Veneroida (21 and 9%, respectively; mainly Corbicula spp.) and Myoida (20 and 4%, respectively; mainly Dreissena spp.). About one third of records, predominantly from Europe and the Americas, related to species that were non-native to the country of study. The majority of records originated from Asia (35%), with available evidence for 23 CICES classes, as well as Europe (29%) and North America (23%), where research was largely focused on 'biomonitoring'. Whilst the earliest record (from 1949) originated from North America, since 2000, annual output of records has increased rapidly in Asia and Europe. Future research should focus on filling gaps in knowledge in lesser-studied regions, including Africa and South America, and should look to provide a quantitative valuation of the socio-economic costs and benefits of ecosystem services shaped by freshwater bivalves.

Ecosystem services provided by the exotic bivalves Dreissena polymorpha, D. rostriformis bugensis, and Limnoperna fortunei

The ecosystem services approach to conservation is becoming central to environmental policy decision making. While many negative biological invasion-driven impacts on ecosystem structure and functioning have been identified, much less was done to evaluate their ecosystem services. In this paper, we focus on the often-overlooked ecosystem services provided by three notable exotic ecosystem engineering bivalves, the zebra mussel, the quagga mussel, and the golden mussel. One of the most significant benefits of invasive bivalves is water filtration, which results in water purification and changes rates of nutrient cycling, thus mitigating the effects of eutrophication. Mussels are widely used as sentinel organisms for the assessment and biomonitoring of contaminants and pathogens and are consumed by many fishes and birds. Benefits of invasive bivalves are particularly relevant in human-modified ecosystems. We summarize the multiple ecosystem services provided by invasive bivalves and recommend including the economically quantifiable services in the assessments of their economic impacts. We also highlight important ecosystem disservices by exotic bivalves, identify data limitations, and future research directions. This assessment should not be interpreted as a rejection of the fact that invasive mussels have negative impacts, but as an attempt to provide additional information for scientists, managers, and policymakers.

Rethinking the term "glyphosate effect" through the evaluation of different glyphosate-based herbicide effects over aquatic microbial communities

Glyphosate-based herbicides (GBH) -the most widely used herbicides in agriculture worldwide-are frequently generalized by the name of "glyphosate". However, GBH encompass a variety of glyphosate salts as active ingredient and different adjuvants, which differ between products. These herbicides reach water bodies and produce diverse impacts over aquatic communities. Yet, the risk assessment assays required for the approval focus mostly on active ingredients. Herein, we compared the effect of five different GBH as well as of monoisopropylamine salt of glyphosate (GIPA) on aquatic microbial communities from natural shallow lakes that were mixed and allowed to evolve in an outdoor pond. We performed an 8-day long assay under indoor control conditions to evaluate the effects of exposure on the structure of nano-plus microphytoplankton (net phytoplankton, with sizes between 2 and 20 μm and >20 μm, respectively) and picoplankton (size ranging between 0.2 and 2 μm) communities through microscopy and flow cytometry, respectively. Significantly different effects were evident on the structure of microbial communities dependent on the GBH, even with herbicides sharing similar active ingredients. Each GBH evoked increases of different magnitude in bacterioplankton abundance. Furthermore, GIPA and a formulation decreased the abundance of a phycocyanin-rich (PC-rich) picocyanobacteria (Pcy) cytometric population and GIPA further altered Pcy composition. Also, two GBH increased net phytoplankton total abundance and, unlike the tested GBH, no apparent effect of GIPA was detected on this community structure. These results demonstrate that GBH effects on aquatic microbial communities should not be summarized as "glyphosate" effects considering that the formulations have effects beyond those exerted by the active ingredients alone. This work intends to alert on the lack of real knowledge regarding the consequences of the variety of GBH on natural aquatic ecosystems. Indeed, the wide use of the term "glyphosate effect" should be thoroughly rethought.

Recent Progress and Prospects in Catalytic Water Treatment

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory water contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite the advantages provided in terms of kinetics of transformation, selectivity, and energy saving, numerous attempts have not yet led to implementation at an industrial scale. This review examines investigations at different scales for which controversies and limitations must be solved to bridge the gap between fundamentals and practical developments. Particular attention has been paid to the development of solar-driven catalytic technologies and some other emerging processes, such as microwave assisted catalysis, plasma-catalytic processes, or biocatalytic remediation, taking into account their specific advantages and the drawbacks. Challenges for which a better understanding related to the complexity of the systems and the coexistence of various solid-liquid-gas interfaces have been identified.

Glyphosate: Uses Other Than in Glyphosate-Resistant Crops, Mode of Action, Degradation in Plants, and Effects on Non-target Plants and Agricultural Microbes

Glyphosate is the most used herbicide globally. It is a unique non-selective herbicide with a mode of action that is ideal for vegetation management in both agricultural and non-agricultural settings. Its use was more than doubled by the introduction of transgenic, glyphosate-resistant (GR) crops. All of its phytotoxic effects are the result of inhibition of only 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), but inhibition of this single enzyme of the shikimate pathway results in multiple phytotoxicity effects, both upstream and downstream from EPSPS, including loss of plant defenses against pathogens. Degradation of glyphosate in plants and microbes is predominantly by a glyphosate oxidoreductase to produce aminomethylphosphonic acid and glyoxylate and to a lesser extent by a C-P lyase to produce sarcosine and phosphate. Its effects on non-target plant species are generally less than that of many other herbicides, as it is not volatile and is generally sprayed in larger droplet sizes with a relatively low propensity to drift and is inactivated by tight binding to most soils. Some microbes, including fungal plant pathogens, have glyphosate-sensitive EPSPS. Thus, glyphosate can benefit GR crops by its activity on some plant pathogens. On the other hand, glyphosate can adversely affect some microbes that are beneficial to agriculture, such as Bradyrhizobium species, although GR crop yield data indicate that such an effect has been minor. Effects of glyphosate on microbes of agricultural soils are generally minor and transient, with other agricultural practices having much stronger effects.