Global aquatic biodiversity keeps declining rapidly, despite international efforts providing a variety of policies and legislations that identify goals for, and give directions to protecting the ...world's aquatic fauna and flora. With the H2020 project AQUACROSS, we have made an unprecedented effort to unify policy strategies, knowledge, and management concepts of freshwater, coastal, and marine ecosystems to support the achievement of the targets set by the EU Biodiversity Strategy to 2020. AQUACROSS has embraced the concept of ecosystem-based management (EBM), which approaches environmental management from a social-ecological system perspective to protect biodiversity and to sustainably harvest ecosystem services. This special issue includes contributions resulting from AQUACROSS, which either tackle selected EBM challenges from a theoretical point of view or apply EBM in one of the selected case studies across Europe. In this article, we introduce relevant topics, address the most important lessons learnt, and suggest where research should go with aquatic EBM. We hope that this special issue will foster and facilitate the uptake of EBM in aquatic ecosystems and, therewith, provide the on-ground applications needed for evaluating EBM's utility to safeguard aquatic biodiversity.
Climate change is predicted to have profound effects on freshwater organisms due to rising temperatures and altered precipitation regimes. Using an ensemble of bioclimatic envelope models (BEMs), we ...modelled the climatic suitability of 191 stream macroinvertebrate species from 12 orders across Europe under two climate change scenarios for 2080 on a spatial resolution of 5 arc minutes. Analyses included assessments of relative changes in species’ climatically suitable areas as well as their potential shifts in latitude and longitude with respect to species’ thermal preferences. Climate‐change effects were also analysed regarding species’ ecological and biological groupings, namely (1) endemicity and (2) rarity within European ecoregions, (3) life cycle, (4) stream zonation preference and (5) current preference. The BEMs projected that suitable climate conditions would persist in Europe in the year 2080 for nearly 99% of the modelled species regardless of the climate scenario. Nevertheless, a decrease in the amount of climatically suitable areas was projected for 57–59% of the species. Depending on the scenario, losses could be of 38–44% on average. The suitable areas for species were projected to shift, on average, 4.7–6.6° north and 3.9–5.4° east. Cold‐adapted species were projected to lose climatically suitable areas, while gains were expected for warm‐adapted species. When projections were analysed for different species groupings, only endemics stood out as a particular group. That is, endemics were projected to lose significantly larger amounts of suitable climatic areas than nonendemic species. Despite the uncertainties involved in modelling exercises such as this, the extent of projected distributional changes reveals further the vulnerability of freshwater organisms to climate change and implies a need to understand the consequences for ecological function and biodiversity conservation.
Lotic freshwater macroinvertebrate species distribution models (SDMs) have been shown to improve when hydrological variables are included. However, most studies to date only include data describing ...climate or stream flow-related surrogates. We assessed the relative influence of climatic and hydrological predictor variables on the modelled distribution of macroinvertebrates, expecting model performance to improve when hydrological variables are included. We calibrated five SDMs using combinations of bioclimatic (bC), hydrological (H) and hydroclimatic (hC) predictor datasets and compared model performance as well as variance partition of all combinations. We investigated the difference in trait composition of communities that responded better to either bC or H configurations. The dataset bC had the most influence in terms of proportional variance, however model performance was increased with the addition of hC or H. Trait composition demonstrated distinct patterns between associated model configurations, where species that prefer intermediate to slow-flowing current conditions in regions further downstream performed better with bC–H. Including hydrological variables in SDMs contributes to improved performance, it is however, species-specific and future studies would benefit from hydrology-related variables to link environmental conditions and diverse communities. Consequently, SDMs that include climatic and hydrological variables could more accurately guide sustainable river ecosystem management.
▸ Water quality and catchment urban land use limited invertebrate assemblages in European rivers. ▸ There was indication for the mitigating effect of hydromorphological restoration measures. ▸ ...Quantile regression was used to describe the limiting effect on the EU-WFD ecological status. ▸ Threshold values differed depending on the method used (quantile regression trees, TITAN). ▸ Need to consider large-scale pressures and management objective (species or functions).
It has been widely stated that pressures acting at large spatial scales influence local habitat conditions and might limit the effects of local restoration measures. However, only a few empirical studies have used statistical methods that have explicitly been developed to investigate such wedge-shaped relationships. The objectives of the present study were (i) to identify pressures acting as limiting factors and to investigate the mitigating effects of local restoration measures in three datasets from European rivers, (ii) to derive thresholds for the ecological status of invertebrates, and (iii) to compare results derived from two statistical approaches, one using aggregated response variables like biological metrics (quantile regression trees), another using taxon-specific responses to derive separate community thresholds for the negative response of sensitive and the positive response of tolerant taxa (Threshold Indicator Taxa Analysis, TITAN). The results indicated that wedge-shaped relationships, typically resulting from limiting factors, are common in datasets from Central European rivers. There was empirical evidence for limiting effects of water pollution and catchment land use and an indication of a mitigating effect of hydromorphological restoration measures. The results emphasize the need to consider such large-scale pressures in river management and restoration because they potentially constrain the effects of local restoration measures. The thresholds derived for the aggregated response variables (metrics) and the community thresholds for sensitive taxa were in good agreement with values reported in the literature but differed markedly depending on the statistical method used. A possible reason is the different focuses of the methods on (i) the threshold for an aggregated response variable (metric), which includes the negative and positive response, and hence, reflects ecosystem functioning, and (ii) the community threshold of sensitive taxa based on taxon-specific negative responses, which is possibly best suited for species conservation issues. However, this interpretation requires further analysis since the results of the two methods showed no consistent differences.
Megafauna species are intrinsically vulnerable to human impact. Freshwater megafauna (i.e., freshwater animals ≥30 kg, including fishes, mammals, reptiles, and amphibians) are subject to intensive ...and increasing threats. Thirty‐four species are listed as critically endangered on the International Union for Conservation of Nature (IUCN). Red List of Threatened Species, the assessments for which are an important basis for conservation actions but remain incomplete for 49 (24%) freshwater megafauna species. Consequently, the window of opportunity for protecting these species could be missed. Identifying the factors that predispose freshwater megafauna to extinction can help predict their extinction risk and facilitate more effective and proactive conservation actions. Thus, we collated 8 life‐history traits for 206 freshwater megafauna species. We used generalized linear mixed models to examine the relationships between extinction risk based on the IUCN Red List categories and the combined effect of multiple traits, as well as the effect of human impact on these relationships for 157 classified species. The most parsimonious model included human impact and traits related to species’ recovery potential including life span, age at maturity, and fecundity. Applying the most parsimonious model to 49 unclassified species predicted that 17 of them are threatened. Accounting for model predictions together with IUCN Red List assessments, 50% of all freshwater megafauna species are considered threatened. The Amazon and Yangtze basins emerged as global diversity hotspots of threatened freshwater megafauna, in addition to existing hotspots, including the Ganges‐Brahmaputra and Mekong basins and the Caspian Sea region. Assessment and monitoring of those species predicted to be threatened are needed, especially in the Amazon and Yangtze basins. Investigation of life‐history traits and trends in population and distribution, regulation of overexploitation, maintaining river connectivity, implementing protected areas focusing on freshwater ecosystems, and integrated basin management are required to protect threatened freshwater megafauna in diversity hotspots.
Efectos Combinados de los Rasgos de la Historia de Vida y el Impacto Humano sobre el Riesgo de Extinción de la Megafauna de Agua Dulce
Resumen
Las especies de megafauna son intrínsecamente vulnerables al impacto humano. La megafauna de agua dulce (es decir, los animales ≥30 kg, incluyendo peces, mamíferos, reptiles y anfibios) está sujeta a amenazas intensivas y en aumento. La Lista Roja de la UICN (Unión Internacional para la Conservación de la Naturaleza) lista a 34 especies en peligro crítico de extinción. Las evaluaciones para esta lista son un cimiento importante para las acciones de conservación, pero permanecen incompletas para 49 (24%) de las especies de megafauna de agua dulce. Como consecuencia, la ventana de oportunidad para la protección de estas especies podría perderse. La identificación de los factores que predisponen a la megafauna de agua dulce a la extinción puede ayudar a predecir el riesgo de extinción para cada especie y facilitar acciones de conservación más efectivas y proactivas. Por lo anterior, recopilamos ocho rasgos de historia de vida para 206 especies de megafauna de agua dulce. Usamos modelos lineales generalizados mixtos para examinar las relaciones entre el riesgo de extinción medido con base en las categorías de la Lista Roja de la UICN y el efecto combinado de diferentes rasgos, así como el efecto del impacto humano sobre estas relaciones para 157 especies clasificadas. El modelo más parsimonioso incluyó al impacto humano y a los rasgos relacionados con el potencial de recuperación de las especies como el ciclo de vida, edad de madurez y fecundidad. La aplicación de este modelo a las 49 especies sin clasificación pronosticó que 17 de ellas están amenazadas. Si consideramos las predicciones del modelo junto con las evaluaciones de la Lista Roja de la UICN, el 50% de todas las especies de megafauna de agua dulce están consideradas como amenazadas. Las cuencas del Amazonas y del Yangtze surgieron como puntos calientes de diversidad mundial, junto con las cuencas del Ganges‐Brahmaputra y el Mekong y la región del mar Caspio. Es urgente evaluar y monitorear a aquellas especies que se pronostica estén amenazadas, especialmente en las cuencas del Amazonas y del Yangtze. Se requieren investigaciones sobre los rasgos de la historia de vida y las tendencias poblacionales y de distribución, la regulación de la sobreexplotación, el mantenimiento de la conectividad entre ríos, la implementación de áreas protegidas enfocadas en los ecosistemas de agua dulce y un manejo integrado de cuencas para proteger a la megafauna de agua dulce en los puntos calientes de diversidad.
摘要
大型淡水动物包含体重超过30千克的鱼类, 哺乳动物, 爬行动物和两栖动物。这些动物易受人类活动影响且面临着日益增长的威胁。其中34种动物已经被国际自然保护联盟(IUCN)濒危物种红色名录评估为极危; 与此同时, 49种大型淡水动物未受到充分的灭绝风险评估。保护这些动物的时机可能会因此错过。鉴别影响大型淡水动物灭绝风险的因素能够帮助开展积极主动且有效的保护行动。我们收集了206个物种的8类生活史特征并运用广义混合线性模型分析了其中157种受到充分评估的物种的红色名录等级与它们的生活史特征以及分布范围内人类活动强度的关系。筛选出的最优模型包含了人类活动强度以及与物种恢复潜能相关的生活史特征, 如寿命, 性成熟时间和繁殖能力。49种未受到充分评估的大型淡水动物中的17种被最优模型预测为受威胁物种。如果综合考虑红色名录评估和模型预测结果, 全球半数大型淡水动物应该被列为受威胁物种。长江和亚马逊流域也应同恒河, 湄公河以及里海区域一起被视为受威胁的大型淡水动物多样性热点区域。为了保护受威胁的大型淡水动物, 在这些多样性热点地区应进行物种生活史调查和物种种群数量和分布范围监测并限制过度捕捞, 维持河流的连通性, 以及建立保护区。
Article impact statement: Life‐history traits and human impact jointly determine extinction risk of freshwater megafauna.
Freshwater megafish species, such as sturgeons, salmonids, carps, and catfishes, have a maximum reported weight ≥30 kg. Due to their charisma and economic value, they have been widely introduced ...outside of their native ranges. Here, we provide a comprehensive overview of the introduction of freshwater megafish and an assessment of their environmental impacts. Of the 134 extant freshwater megafish species, 46% have been introduced to new environments, and of these, 69% have established self‐sustaining alien populations. These introductions affect 59% of the world's main basins, with the USA and western Europe being particular hotspots of megafish introductions. The common carp (Cyprinus carpio) is the most widely introduced species. Using the Environmental Impact Classification for Alien Taxa (EICAT and EICAT+) frameworks, we assessed the severity and type of negative and positive impacts posed by alien megafish on native species. Alien megafish caused negative impacts through nine different mechanisms, with predation being the most frequently reported mechanism, followed by herbivory and competition. Moreover, 58% of the alien megafish species with sufficient data to evaluate the severity of their impacts caused declining populations of native species, or worse, extirpations of native species populations. The positive environmental impacts of alien megafish were far less frequently documented. They include biotic interactions that benefit native species, and the provision of trophic resources or habitats. Widely introduced or extensively studied species are more likely to have documented severe impacts on native species. There is a clear trade‐off between the economic benefits associated with megafish introductions and the severe adverse impacts they have on native biodiversity. Our study highlights the need for comprehensive risk assessments to evaluate the potential environmental impacts of megafish. More research and long‐term monitoring schemes are required to inform management actions to protect biodiversity, particularly in the Global South.
Of the 134 extant freshwater megafish species, 46% have been introduced outside of their native ranges. Over 50% of the alien megafish species with sufficient data to evaluate the severity of their environmental impacts have caused population declines or even extirpations of native species. More research and long‐term monitoring schemes on alien species are required to inform management actions to protect biodiversity, particularly in the Global South.
Aim
Systematic conservation planning is vital for allocating protected areas given the spatial distribution of conservation features, such as species. Due to incomplete species inventories, species ...distribution models (SDMs) are often used for predicting species’ habitat suitability and species’ probability of occurrence. Currently, SDMs mostly ignore spatial dependencies in species and predictor data. Here, we provide a comparative evaluation of how accounting for spatial dependencies, that is, autocorrelation, affects the delineation of optimized protected areas.
Location
Southeast Australia, Southeast U.S. Continental Shelf, Danube River Basin.
Methods
We employ Bayesian spatially explicit and non‐spatial SDMs for terrestrial, marine and freshwater species, using realm‐specific planning unit shapes (grid, hexagon and subcatchment, respectively). We then apply the software gurobi to optimize conservation plans based on species targets derived from spatial and non‐spatial SDMs (10%–50% each to analyse sensitivity), and compare the delineation of the plans.
Results
Across realms and irrespective of the planning unit shape, spatially explicit SDMs (a) produce on average more accurate predictions in terms of AUC, TSS, sensitivity and specificity, along with a higher species detection probability. All spatial optimizations meet the species conservation targets. Spatial conservation plans that use predictions from spatially explicit SDMs (b) are spatially substantially different compared to those that use non‐spatial SDM predictions, but (c) encompass a similar amount of planning units. The overlap in the selection of planning units is smallest for conservation plans based on the lowest targets and vice versa.
Main conclusions
Species distribution models are core tools in conservation planning. Not surprisingly, accounting for the spatial characteristics in SDMs has drastic impacts on the delineation of optimized conservation plans. We therefore encourage practitioners to consider spatial dependencies in conservation features to improve the spatial representation of future protected areas.
Freshwater biodiversity is highly threatened and is decreasing more rapidly than its terrestrial or marine counterparts; however, freshwaters receive less attention and conservation investment than ...other ecosystems do. The diverse group of freshwater megafauna, including iconic species such as sturgeons, river dolphins, and turtles, could, if promoted, provide a valuable tool to raise awareness and funding for conservation. We found that freshwater megafauna inhabit every continent except Antarctica, with South America, Central Africa, and South and Southeast Asia being particularly species rich. Freshwater megafauna co-occur with up to 93% of mapped overall freshwater biodiversity. Fifty-eight percent of the 132 megafauna species included in the study are threatened, with 84% of their collective range falling outside of protected areas. Of all threatened freshwater species, 83% are found within the megafauna range, revealing the megafauna’s capacity as flagship and umbrella species for fostering freshwater conservation.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ripple et al. ( ) have pointed out that despite being listed on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) appendices, freshwater megafauna are often ...illegally harvested for their eggs, meat, and skin. ...the International Union for Conservation of Nature (IUCN) Red List of Threatened Species assessments for 60% of all freshwater megafauna species are either insufficient (i.e., listed as Data Deficient or Not Evaluated) or outdated (i.e., assessments conducted before 2010; IUCN, ). ...24% of them have been pushed to the edge of extinction (i.e., listed as Critically Endangered; IUCN, ).
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