Comparative deterministic and probabilistic approaches for assessing the aquatic ecological risk of pesticides in a mixed land use basin: A case study in Uruguay

Environmental concentrations of 25 pesticides in superficial water were employed to conduct an ecological risk assessment (ERA) in a mixed land-use basin utilized as a drinking water source. A deterministic risk assessment (RQ) was utilized to evaluate the chronic risk to aquatic biota, while a probabilistic risk assessment (PRA) approach was applied to assess the acute and chronic risk in the most sensitive species and at the community level. A high risk was identified for insecticides (pyrethroids, organophosphates and organochlorines). RQs ranged from 4.0e-4 (2,4-D) to 105.3 (ethion) considering median concentrations and from 8.0e-4 (2,4-D) to 230 (p,p'-DDT) considering extreme concentrations. Temporal variation in ΣRQs showed the highest risk during spring and summer months, which is related to the crop calendar and land use in the Laguna del Cisne basin. For PRA, the probability of exceeding the hazardous concentration HC5 (5th percentile) was higher for the most sensitive species in chronic exposure, especially for cypermethrin (38.9 %), permethrin (25.6 %), and chlorpyrifos (16.6 %). In the case of acute exposures, the probability of surpassing HC5 was higher for the entire freshwater biota, with the highest values observed for bifenthrin (28.3 %), cypermethrin (25.5 %), permethrin (11.75 %), and ethion (11.1 %). The advantages and disadvantages of PRA for assessing pesticide ecological risk were compared with the conventional deterministic RQs approach, highlighting that PRA offers improvements over the deterministic risk assessment, especially for organophosphate pesticides. Additionally, PRA provides a more comprehensive evaluation of risk for both short and long-term exposure, has the potential to incorporate others available toxicity data (e.g., LD50, Daily Intake), and utilizes different hazardous concentrations, such as HC5, HC10, and HC50. Our findings emphasize the urgent need to establish a national regulatory framework to evaluate and mitigate pesticide risks in aquatic ecosystems, especially in drinking water source like Laguna del Cisne.

Effects of urbanization and accessibility to sanitation services on water quality in urban streams in Uruguay

The world's urban population is growing rapidly, and threatening natural ecosystems, especially streams. Urbanization leads to stream alterations, increased peak flow frequencies, and reduced water quality due to pollutants, morphological changes, and biodiversity loss, known as the urban stream syndrome. However, a shift towards recognizing urban streams as valuable natural systems is occurring, emphasizing green infrastructure and nature-based solutions. This study in Uruguay examined water quality in various watersheds with different urbanization levels and socio-environmental characteristics along a precipitation gradient. Using Geographic Information Systems (GIS) and in situ data, we assessed physicochemical parameters, generated territorial variables, and identified key predictors of water quality. We found that urbanization, particularly urban areas, paved areas, and populations without sanitation, significantly influenced water quality parameters. These factors explained over 50% of the variation in water quality indicators. However, the relationship between urbanization and water quality was non-linear, with abrupt declines after specific urban intensity thresholds. Our results illustrate that ensuring sanitation networks and managing green areas effectively are essential for preserving urban stream water quality. This research underscores the importance of interdisciplinary teams and localized data for informed freshwater resource management.

Multicompartmental monitoring of legacy and currently used pesticides in a subtropical lake used as a drinking water source (Laguna del Cisne, Uruguay)

A pilot annual monitoring survey (April 2018-March 2019) was conducted to investigate the presence of pesticides in superficial water and fish in Laguna del Cisne, one of the most critical drinking water sources in Uruguay. A total of 25 pesticide residues were detected in superficial water (89.3 % of the samples). Pesticide's temporal distribution was associated with crops and livestock practices, with higher occurrences in spring and summer than in autumn and winter. The most frequent compounds in superficial water were the insecticide chlorantraniliprole, and the herbicides glyphosate (including its metabolite AMPA) and metolachlor. The levels of Organochlorine pesticide, p,p'-DDT, was in some cases two order of magnitude above the international water quality guidelines for Ambient Water Criteria. In fishes, eight different pesticides were detected, at concentrations from 1000 to 453,000 ng·kg^-1. The most frequent pesticides found were propiconazole, chlorpyrifos, and p,p'-DDE. The widespread occurrence of pesticides in fish suggests potential exposure effects on fish populations and the aquatic ecosystem. The sampling approach of this work allowed monitoring the continuous concentrations of several pesticides in surface waters and fishes to establish the influence from past and current agriculture practices in Laguna del Cisne basin. For safety measures, continuous monitoring programs must be performed in this system to prevent toxicity impacts on aquatic organisms and human health.

Human land-uses homogenize stream assemblages and reduce animal biomass production

1. Human land-use change is a major threat to natural ecosystems worldwide. Nonetheless, the effects of human land-uses on the structure of plant and animal assemblages and their functional characteristics need to be better understood. Furthermore, the pathways by which human land uses affect ecosystem functions, such as biomass production, still need to be clarified. 2. We compiled a unique dataset of fish, arthropod and macrophyte assemblages from 61 stream ecosystems in two Neotropical biomes: Amazonian rainforest and Uruguayan grasslands. We then tested how the cover of agriculture, pasture, urbanization and afforestation affected the taxonomic richness and functional diversity of those three species assemblages, and the consequences of these effects for animal biomass production. Single trait categories and functional diversity were evaluated, combining recruitment and life-history, resource and habitat-use, and body size. 3.The effects of intensive human land-uses on taxonomic and functional diversities were as strong as other drivers known to affect biodiversity, such as local climate and environmental factors. In both biomes, the taxonomic richness and functional diversity of animal and macrophyte assemblages decreased with increasing cover of agriculture, pasture, and urbanization. Human land-uses were associated with functional homogenization of both animal and macrophyte assemblages. Human land-uses reduced animal biomass through direct and indirect pathways mediated by declines in taxonomic and functional diversities. 4. Our findings indicate that converting natural ecosystems to supply human demands results in species loss and trait homogenization across multiple biotic assemblages, ultimately reducing animal biomass production in streams.

Diet and debris ingestion of skuas on Fildes Peninsula, King George Island, Antarctica

Using pellet analysis, we characterized the diet and plastic and non-plastic debris ingestion of skuas (Catharacta spp.) during 2017-2020 summer seasons along the coastal sector of Fildes Peninsula (King George Island, Antarctica). In addition, we conducted the same analysis during the 2020 breeding season on reproductive territories of south polar (Catharacta maccormicki) and brown (Catharacta antarctica lonnbergi) skua. Our results confirm the generalist and opportunistic habits of both skua species. Additionally, it has been proposed that brown skua displaces south polar skua from penguin breeding colonies given its higher competitive abilities, and our results suggest this might not have happened during the study period. Along with evidence from other studies, this work underlines the idea that potential local anthropogenic sources of plastic and non-plastic debris at Fildes Peninsula need to be further addressed to improve current mitigation efforts.

Human pressure drives biodiversity-multifunctionality relationships in large Neotropical wetlands

Many studies have shown that biodiversity regulates multiple ecological functions that are needed to maintain the productivity of a variety of ecosystem types. What is unknown is how human activities may alter the 'multifunctionality' of ecosystems through both direct impacts on ecosystems and indirect effects mediated by the loss of multifaceted biodiversity. Using an extensive database of 72 lakes spanning four large Neotropical wetlands in Brazil, we demonstrate that species richness and functional diversity across multiple larger (fish and macrophytes) and smaller (microcrustaceans, rotifers, protists and phytoplankton) groups of aquatic organisms are positively associated with ecosystem multifunctionality. Whereas the positive association between smaller organisms and multifunctionality broke down with increasing human pressure, this positive relationship was maintained for larger organisms despite the increase in human pressure. Human pressure impacted multifunctionality both directly and indirectly through reducing species richness and functional diversity of multiple organismal groups. These findings provide further empirical evidence about the importance of aquatic biodiversity for maintaining wetland multifunctionality. Despite the key role of biodiversity, human pressure reduces the diversity of multiple groups of aquatic organisms, eroding their positive impacts on a suite of ecological functions that sustain wetlands.

Does color play a predominant role in the intake of microplastics fragments by freshwater fish: an experimental approach with Psalidodon eigenmanniorum

Microplastics (MPs) have been reported in fish species from several freshwater environments. However, the mechanisms underlying MPs ingestion by fish are still unclear, although they are important to determine the pathway of MPs along freshwater environments food webs. Here, we investigates a fundamental question of why wild freshwater fish ingest plastic. To address this, we conducted a laboratory experiment to assess MP fragments intake according to color (red, green, yellow, white, black, and blue) by a small omnivorous fish species Psalidodon eigenmanniorum (Characidae). Results showed that yellow and blue were the most consumed fragments, whereas fish avoided white fragments. Although it is not yet clear how plastic coloration relates to the selectivity and feeding of freshwater fish, the visual skills at a species-specific level could plausibly explain why certain colors are attractive or deterrent to a particular fish species. This data set can be used as a screening tool that could help to understand the mechanisms underlying the patterns of plastic ingestion by fish, with special emphasis on the color of plastic particles. Future research on mechanisms MPs intake by fish, also providing a multi-species approach is highly recommended.

NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Regime shifts in a shallow lake over 12 years: consequences for taxonomic and functional diversity, and ecosystem multifunctionality

Under increasing nutrient loading, shallow lakes may shift from a state of clear water dominated by submerged macrophytes to a turbid state dominated by phytoplankton or a shaded state dominated by floating macrophytes. How such regime shifts mediate the relationship between taxonomic and functional diversity and lake multifunctionality is poorly understood. We employed a detailed database describing a shallow lake over a 12-year period during which the lake has displayed all the three states (clear, turbid, and shaded) to investigate how species richness, functional diversity of fish and zooplankton, ecosystem multifunctionality, and five individual ecosystem functions (nitrogen and phosphorus concentrations, standing fish biomass, algae production, and light availability) differ among states. We also evaluated how the relationship between biodiversity (species richness and functional diversity) and multifunctionality is affected by regime shifts. We showed that species richness and the functional diversity of fish and zooplankton were highest during the clear state. The clear state also maintained the highest values of multifunctionality as well as standing fish biomass production, algae biomass, and light availability, whereas the turbid and shaded states had higher nutrient concentrations. Functional diversity was the best predictor of multifunctionality. The relationship between functional diversity and multifunctionality was strongly positive during the clear state, but such relationship became flatter after the shift to the turbid or shaded state. Our findings illustrate that focusing on functional traits may provide a more mechanistic understanding of how regime shifts affect biodiversity and the consequences for ecosystem functioning. Regime shifts towards a turbid or shaded state negatively affect the taxonomic and functional diversity of fish and zooplankton, which in turn impairs the multifunctionality of shallow lakes.

Non-native fishes homogenize native fish communities and reduce ecosystem multifunctionality in tropical lakes over 16 years

Non-native species are considered a major global threat to biodiversity, and their expansion to new ecosystems has recently increased. However, the effect of non-native species on ecosystem functioning is poorly understood, especially in hyperdiverse tropical ecosystems of which long-term studies are scarce. We analyzed the relationship between richness, biomass, and β-diversity of non-native and native fishes during 16 years in five hyperdiverse tropical shallow lakes. We further elucidated how an observed increase in the proportion of richness, biomass, and β-diversity of non-native over native fishes affect crucial multifunctional processes of lakes (decomposition, productivity). We found a general positive relationship between the richness and biomass of non-native and native fishes. However, the slope of this relationship decreased continuously with time, displaying an increase in non-native species richness and a decrease in native species richness over time. We also detected a negative relationship between the β-diversity of non-native and native fishes over time. Moreover, the increase in the non-native:native ratio of species richness, biomass, and β-diversity over time decreased ecosystem multifunctionality. Our results suggest that non-native fishes caused a homogenization of the native fish species over time, resulting in impoverishment of ecosystem multifunctionality; in part because non-native fishes are less productive than native ones. Therefore, focus on long-term effects and use of multiple biodiversity facets (α- and β-diversity) are crucial to make reliable predictions of the effects of non-native fish species on native fishes and ecosystem functioning.

Human impacts and the loss of Neotropical freshwater fish diversity

Abstract Neotropical Ichthyology promotes the Special Issue (SI) “Human impacts and the loss of Neotropical freshwater fish diversity” with the purpose of publishing relevant scientific articles on the current biodiversity crisis and the loss of Neotropical freshwater fishes in the Anthropocene. The SI is composed of 22 publications, being two review articles and 20 original articles. A total of 107 researchers contributed to these papers, involving 44 institutions based in Brazil and six other countries. Published articles investigated main anthropic activities and their impacts on fish diversity, with special focus on river regulation, mining, land use changes, aquaculture, and fisheries. Studies provided evidence about the loss of fish diversity in the Neotropics, including fish kill events, demographic changes, contamination, changes in assemblage structure, loss of taxonomic and functional diversity, besides the degradation of ecosystem functions and services, and the lack of effective protection and conservation. Studies were conducted in rivers, streams, lakes, and reservoirs from different Neotropical systems. The studies published in this SI represent a relevant sample of the current worrisome situation of freshwater fishes in the Neotropical region and call for urgent revision in environmental policies, management and conservation initiatives, and socioeconomic priorities.

Biodiversidata: A novel dataset for the vascular plant species diversity in Uruguay

Background

South America hosts some of the world's most prominent biodiversity hotspots. Yet, Uruguay - a country where multiple major ecosystems converge - ranks amongst the countries with the lowest levels of available digital biodiversity data in the continent. Such prevalent data scarcity has significantly undermined our ability to progress towards evidence-based conservation actions - a critical limitation for a country with a strong focus on agricultural industries and only 1.3% of the land surface guarded by protected areas. Under today's rapid biodiversity loss and environmental changes, the need for open-access biodiversity data is more pressing than ever before. To address this national issue, Biodiversidata - Uruguay's first Consortium of Biodiversity Data - has recently emerged with the aim of assembling a constantly growing database for the biodiversity of this country. While the first phase of the project targeted vertebrate biodiversity, the second phase presented in this paper spans the biodiversity of plants.

New information

As part of the second phase of the Biodiversidata initiative, we present the first comprehensive open-access species-level database of the vascular plant diversity recorded in Uruguay to date (i.e. all species for which data are currently available and species presence has been confirmed). It contains 12,470 occurrence records from across 1,648 species and 160 families, which roughly represents 60% of the total recorded flora of Uruguay. The primary biodiversity data include extant native and introduced species from the lycophytes, ferns, gymnosperms and angiosperms groups. Records were collated from multiple sources, including data available in peer-reviewed scientific literature, institutional scientific collections and datasets contributed by members of the Biodiversidata initiative. The complete database can be accessed at the Zenodo repository: doi.org/10.5281/zenodo.3954406.

Correction to: Water quality evaluation of two urban streams in Northwest Uruguay: are national regulations for urban stream quality sufficient?

The original version of this article unfortunately contained an error in the published paper.

Water quality evaluation of two urban streams in Northwest Uruguay: are national regulations for urban stream quality sufficient?

Poor water quality in urban streams places at risk the health of urban residents and the integrity of urban environments, ultimately leading to the "urban stream syndrome." In response to growing concerns regarding urban streams in Uruguay, we evaluated the spatiotemporal variation in water quality parameters in two urban streams, the Ceibal and La Curtiembre streams, over 12-18 months. A proposal for an Urban Water Quality Index (UWQI) was developed based on national water quality standards for two stream classes to assess variability in overall stream condition over time. Both streams displayed extremely high levels of fecal coliform concentrations in mid-downstream sites and relatively high levels of total dissolved phosphorus and ammonia well above the national standards of 0.025 mg/L and 0.02 mg/L, respectively. Nitrate was consistently below the national maximum of 44.3 mg/L, calling to question the adequacy of this standard for designated uses. Over 40% of samples had oxygen levels below the national standard of 5 mg/L, and a dead zone (average 1.5 mg/L) was detected in the downstream reach of the La Curtiembre stream. Despite differences in land use and urban context, monthly observations of nutrients and coliforms indicated high levels of contamination in mid-downstream reaches, which could present a health risk for the populations in Paysandú and Salto. This study highlights the degradation of urban streams in two major cities in Uruguay and the need for a comparative diagnosis of stream condition as a basis for decision-making regarding urban development and water resources.

Mesoplastics and large microplastics along a use gradient on the Uruguay Atlantic coast: Types, sources, fates, and chemical loads

Plastic pollution is a global problem with great local and regional variability. Plastic litter reaches beaches directly and indirectly through different pathways, due to both terrestrial and marine pressures. In this study, we assess and characterize meso and microplastic pollution on four Uruguayan oceanic beaches along a gradient of tourist use within a complex regional coastal marine system. In Punta del Diablo we found a total mean density of 106 items m^-2 of different debris (pellets, fragments, and foams) with different polymeric compositions, and diverse persistent bioaccumulative and toxic chemicals (PAHs, PCBs, OCs, heavy metals). However, the trend of plastic debris densities along this gradient was not what was expected. Fabeiro, one of the sites furthest from the urban center, had the highest total mean density of plastics (292 items m^-2) suggesting that marine influences (winds, currents, and beach orientation) have a preponderant role in the distribution of micro and mesoplastics. Meanwhile, the density in the urban site (Pueblo) was highest during summer (March, 201 items m^-2), 200 times higher than the density observed in winter (July, 1 item m^-2). Although this difference could be associated to the peak season (southern summer), the analysis of types of plastics (171 pellets m^-2 vs. 8 cigarette butts m^-2) suggested a predominance of marine inputs. Seasonal changes in the configuration of the beaches due to natural geomorphological dynamics imply alternating states (Source or Sink of debris) that also affect the final density of plastics in the system. The relative importance of both sources is highly variable throughout the year and understanding them may directly improve beach management and stranded coastal plastic litter cleaning.

Female masculinization and reproductive success in Cnesterodon decemmaculatus (Jenyns, 1842) (Cyprinodontiforme: Poeciliidae) under anthropogenic impact

Aquatic organisms are exposed to a myriad of chemical compounds, with particular concerns focused on endocrine disruptors. Growing scientific evidence indicates that these compounds interfere with normal endocrine function and could affect the reproductive system of humans and wildlife. We analyzed the proportion of masculinized females, defined by elongation and fusion of the anal fin rays, and the extent of masculinization, masculinization index, defined by anal fin length divided by the standard length, of Cnesterodon decemmaculatus resident to areas of agricultural and urban-industrial activities in the Arroyo Colorado basin. Additionally, a bioassay was carried out to assess the potential effects of masculinization on reproductive success, measured as the number of viable progenies, using pregnant females from the site downstream of the urban-industrial zone. Masculinized females were observed in all sampling sites, particularly downstream of the urban-industrial area, where over 80% of females presented abnormal sexual characteristics and the highest masculinization index was registered. In the laboratory, masculinized adult females showed male mating behavior, and survival of their progeny was lower than those of normal females. To our knowledge, this is the first report of endocrine disruption in field-collected C. decemmaculatus, and the first evaluation of the reproductive success of masculinized females. Finally, our results support C. decemmaculatus as an excellent sentinel species due to its wide distribution, easy culture in laboratory conditions, and its potential capability to respond to sources of pollution, particularly endocrine disruptors.

Preliminary field study of hepatic porphyrin profiles of Astyanax fasciatus (Teleostei, Characiformes) to define anthropogenic pollution

The implementation of eco-toxicological assessment in South America is presently limited due to significant scientific information gaps concerning native species and their potential use as biomarkers. Recently, a common southern hemisphere fish species, Astyanax fasciatus, has been pointed out as a potential bio-indicator to anthropogenic pollution. This is a small, abundant, Neotropical characid, which is widely distributed from Central America south, to the Rio de la Plata Basin of western Uruguay. Our study found a statistically significant increase of coproporphyrin, uroporphyrin and protoporphyrin concentrations in hepatic tissues of A. fasciatus collected from a stream segment with high anthropogenic disturbance (due mainly to agricultural derivatives and motor vehicle transportation activities). Although the area studied showed differences in up and downstream limno-chemical parameters, these differences were not related to the increase of hepatic porphyrin concentrations. Based on the results of our study, we conclude that A. fasciatus is a good bio-indicator of exposure to environmental contaminants, and we propose that this abundant fish species be considered as a sentinel organism for monitoring potential disturbances to freshwater ecosystems.