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The negative interaction between multiple invasive species, when an invasive predator benefits from a previously introduced and abundant prey, poses unanticipated challenges for the joint management of invaders. To illustrate this question, we describe the surge and collapse of the invasive apple snail Pomacea maculata population before and after the arrival of the invasive blue crab, Callinectes sapidus, in the Ebro River (NE Spain). These two invaders have coincided for the first time beyond their respective native and prior invasive ranges, and thus lack any previous shared eco-evolutionary history facilitating coexistence. We leverage data from a 9-year apple snail removal programme (2014–2022) conducted by authorities to evaluate the effectiveness of the management programme and describe the apple snail temporal dynamics in the Ebro River. Since its arrival in 2013, the apple snail population increased exponentially along the river and adjacent rice-fields despite labour-intensive eradication efforts. Unexpectedly, riverine populations of the apple snail declined by 90% in 2018 relative to the prior year without apparent association with previous management efforts. Simultaneously, the blue crab was first recorded in the Ebro River in 2018, and its distribution rapidly overlapped the whole area invaded by apple snails. We suggest that over-predation by the blue crab is the main cause of the decline observed in the apple snail, and discuss the implications of this new invader-invader interaction for management. This study underscores the unforeseen consequences of subsequent waves of invasion, and the importance of supporting management with a deeper understanding of ecological interactions among invasive predator and prey species. [ABSTRACT FROM AUTHOR]

Invasive species significantly impact biodiversity and ecosystem services, yet understanding these effects at large spatial scales remains a challenge. Our study addresses this gap by assessing the current and potential future risks posed by 94 invasive species to seven key ecosystem services in Europe. We demonstrate widespread potential impacts, particularly on outdoor recreation, habitat maintenance, crop provisioning, and soil and nitrogen retention. Exposure to invasive species was higher in areas with lower provision of ecosystem services, particularly for regulating and cultural services. Exposure was also high in areas where ecosystem contributions to crop provision and nitrogen retention were at their highest. Notably, regions vital for ecosystem services currently have low invasion suitability, but face an average 77% increase in potential invasion area. Here we show that, while high-value ecosystem service areas at the highest risk represent a small fraction of Europe (0-13%), they are disproportionally important for service conservation. Our study underscores the importance of monitoring and protecting these hotspots to align management strategies with international biodiversity targets, considering both invasion vulnerability and ecosystem service sustainability.Non-native species may pose a threat not only to native biodiversity, but also to the provision of ecosystem services. Here, the authors quantify the potential impact of invasive species on a set of ecosystem services across Europe. [ABSTRACT FROM AUTHOR]

Managing the impacts of invasive alien species (IAS) is a great societal challenge. A wide variety of terms have been used to describe the management of invasive alien species and the sequence in which they might be applied. This variety and lack of consistency creates uncertainty in the presentation and description of management in policy, science and practice. Here we expand on the existing description of the invasion process to develop an IAS management framework. We define the different forms of active management using a novel approach based on changes in species status, avoiding the need for stand-alone descriptions of management types, and provide a complete set of potential management activities. We propose a standardised set of management terminology as an emergent feature of this framework. We identified eight key forms of management: (1) pathway management, (2) interception, (3) limits to keeping, (4) secure keeping, (5) eradication, (6) complete reproductive removal, (7) containment and (8) suppression. We recognise four associated terms: prevention; captive management; rapid eradication; and long-term management, and note the use of impact mitigation and restoration as associated forms of management. We discuss the wider use of this framework and the supporting activities required to ensure management is well-targeted, cost-effective and makes best use of limited resources. [ABSTRACT FROM AUTHOR]

We assessed how establishment patterns of non-native freshwater, marine and terrestrial species into Northwest Europe (using Great Britain, France, Belgium and the Netherlands as the study countries) have changed over time, and identified the prevalent pathways and vectors of recent arrivals. Data were extracted from 33 sources on (a) presence/absence and (b) first year of observation in the wild in each country, and (c) continent(s) of origin, (d) invasion pathway(s), (e) invasion vector(s) and (f) environment(s) for 359 species, comprising all non-native Mollusca, Osteichthyes (bony fish), Anseriformes (wildfowl) and Mammalia, and non-native invasive Angiospermae present in the area. Molluscs, fish and wildfowl, particularly those originating from South America, arrived more recently into Northwest Europe than other groups, particularly mammals, invasive plants and species originating from North America. Non-deliberate introductions, those of aquatic species and those from elsewhere in Europe and/or Asia increased strongly in importance after the year 2000 and were responsible for 69, 83 and 89 % of new introductions between 2001 and 2015, respectively. Non-deliberate introductions and those from Asia and North America contributed significantly more to introductions of invasive species in comparison to other non-native species. From the 1960s, ornamental trade has increased in importance relative to other vectors and was responsible for all deliberate introductions of study groups since 2001. Non-deliberate introductions of freshwater and marine species originating from Southeast Europe and Asia represent an increasingly important ecological and economic threat to Northwest Europe. Invertebrates such as molluscs may be particularly dangerous due to their small size and difficulties in detection. Prevention of future invasions in this respect will require intensive screening of stowaways on boats and raising of public awareness. [ABSTRACT FROM AUTHOR]

Lakes in Bangladesh face many threats including habitat loss, over-exploitation of resources, pollution (e.g. sewage, waste dumping), climate change and the introduction of non-native species. To support effective lake management, we developed and tested the first Bangladesh Lake Biotic Index (BLBI), an index based on macroinvertebrates with the potential to assess and monitor the ecological status of lakes. Twenty sites in each of fourteen representative lakes were surveyed during the wet and dry seasons in 2009 and 2010 (total N = 560) to investigate the variation in macroinvertebrate assemblages, and their response to several physical and chemical parameters. The BLBI of a particular lake was calculated according to taxa tolerance scores, allowing categorization of the studied lakes according to their ecological status: least polluted, moderately polluted and highly polluted. BLBI was positively related to traditional structural metrics including species diversity and richness, evenness, and presence of taxa sensitive to pollution such as Ephemeroptera and Trichoptera. Outcomes from this study provide basic information on the ecological status of lakes in Bangladesh, and encourage the use and development of biomonitoring methods for the assessment and conservation of lakes in developing Asian countries. [ABSTRACT FROM AUTHOR]

Horizon scanning for high-risk invasive non-native species (INNS) is crucial in preparing and implementing measures to prevent introductions, as well as to focus efforts in the control of species already present. We initiated a trans-national horizon-scanning exercise focused on four countries in western Europe: Great Britain, France, Belgium and The Netherlands, which share similar environmental and socio-economic characteristics. We followed a structured four-step approach combining existing knowledge about INNS, with a collaborative identification of priorities for research and management: (1) systematic review of potential INNS of concern, (2) discrimination of INNS into an Alert and Black List depending on their absence or presence in the study area respectively, (3) risk analysis of the Alert List, and (4) expert ranking of species in the Black List. Amongst species not yet present in the four countries (i.e. Alert List), assessors reliably pointed to the Emerald ash-borer ( Agrilus planipennis) and Sosnowski's hogweed ( Heracleum sosnowskyi) as those INNS with the highest risk of invasion and impact. The Japanese knotweed ( Fallopia japonica), Himalayan balsam ( Impatiens glandulifera), zebra mussel ( Dreissena polymorpha) and killer shrimp ( Dikerogammarus villosus) were consistently highlighted as some of the most problematic INNS already present in the study area (i.e. Black List). The advantages of our combined approach include that it is inclusive of all-taxa, prioritizes both established and emerging biological threats across trans-national scales, and considers not only the ecological impact, but also potential direct economic consequences as well as the manageability of invasive species. [ABSTRACT FROM AUTHOR]

Numerous wetland restoration projects have been implemented in recent years to mitigate the increasing loss of global wetland surface area caused by human activities. Most of these projects have focused on the local recovery of habitats and species diversity, with little evaluation of functional recovery. We aimed at demonstrating that constructing wetlands on a degraded floodplain increases not only the taxonomic, but also the functional diversity of macroinvertebrate assemblages by providing greater water quality to the local fauna. We studied the macroinvertebrate community using taxonomic and functional diversity indices, and the physicochemical characteristics of three wetlands constructed 5-25 years ago, and three relict natural wetlands on the floodplain of a regulated river (Ebro River, NE Spain). Constructed wetlands demonstrated significantly greater taxonomic abundance and richness of macroinvertebrates than natural wetlands. At the functional level, the richness and Shannon diversity of biological traits relating to reproduction, respiration, dispersal and feeding were also greater in constructed wetlands, which is partly explained by low inorganic nitrogen concentration in these habitats. In contrast, a high content of phosphorus and water organic matter led to the lowest values of taxonomic and functional diversity found in natural wetlands. We conclude that it is essential to consider not only taxonomic but also functional aspects at all stages of a restoration project in order to optimize its long-term efficacy to provide and support key species and functions. [ABSTRACT FROM AUTHOR]

Letter to the Editor [ABSTRACT FROM AUTHOR]

Ecosystem metabolism is an important measure of wetland restoration efficiency, and serves to indicate if the system is capable of processing energetic resources. Despite its value, ecosystem metabolism has rarely been included in monitoring programs. In this study, we aimed to achieve the following objectives: (i) compare net ecosystem production (NEP) rates of constructed vs. natural wetlands; (ii) identify the highest NEP rate habitats; and (iii) define the main environmental factors regulating NEP in different wetland types. Pelagic and benthic NEP rates and physicochemical features were measured in three natural and five constructed wetlands in the middle Ebro River floodplain (NE Spain). Statistical analyses showed pelagic NEP rates peaked in natural wetlands, which produced up to 187.5 mg C m h compared to lower rates in constructed wetlands (up to 46.2 mg C m h). Pelagic NEP responded positively to temperature, total dissolved solids, and nutrients. Benthic NEP rates were 3 to 30-fold greater than pelagic in natural (up to 994.9 mg C m h) and constructed (up to 1,551.5 mg C m h) wetlands, and were heavily influenced by habitat type, with NEP peaking in areas dominated by submerged vegetation and fine organic sediment. Rapid recovery in aquatic communities (i.e. macroinvertebrate diversity) has been previously reported for the studied wetlands; however, our study suggests a slower recovery of functional processes (i.e. pelagic NEP) in constructed habitats. We therefore strongly advocate the inclusion of ecosystem function in the design and evaluation of restoration projects to optimise long-term wetland ecosystem sustainability. [ABSTRACT FROM AUTHOR]

In this study we use a combination of techniques to assess the general risk of invasion by the aquatic invader Dikerogammarus villosus in Great Britain at multiple scales. First, bioclimatic models (Support Vector Machine algorithm) were used to identify regions showing the highest climatic match with the European range of the species, and that might be at highest risk of initial colonization if provided with propagules. The model showed that nearly 60% of Great Britain shows the minimum bioclimatic suitability for the species, particularly southern and eastern England. Afterwards, a Network Analysis was used to model the natural spatio-temporal spread of the killer shrimp in the Great Ouse River catchment (SE England), the first region invaded by this species. This model suggested that the northern part of the catchment, including two relevant Ramsar sites (Ouse Washes and Wicken fen) are at serious risk of being invaded in the short-term (<5 years). Taking into account the rapid spread of the killer shrimp in other European countries, its broad environmental tolerance, the high climate suitability of broad areas of Great Britain to the species, the current spread of other Ponto-Caspian species, and the high natural and artificial connectivity of the hydrological network, we conclude that D. villosus is very likely to continue its spread in Great Britain, dramatically affecting the native biodiversity. The multi-scale approach proposed in this study combines large-scale bioclimatic models with local-scale dispersal models, providing managers with a powerful spatial and temporal basis for informed decision-making. [ABSTRACT FROM AUTHOR]

Methods to characterize hydrological connectivity at riparian wetlands are necessary for ecosystem management given its importance over ecosystem structure and functioning. In this paper, we aimed to describe hydrological connectivity at one Ebro River reach (NE Spain) and test a method to perform such characterization. Continuous surface water level and temperature data were recorded at five riparian wetlands during the period October 2006-June 2007. Combining water level and temperature, we classified the examined wetlands in three groups, which mainly differed in the dominant water source during different flood stages. Firstly, a comparison of water level fluctuations in riparian wetlands with those in the river channel during events with different characteristics was used to describe hydrological connectivity. Such comparison was also used to extract quantitative hydrological connectivity descriptors as the wetland response initiation time. Secondly, water temperature series were divided in phases with different average, range and daily oscillation, and these parameters were interpreted for each phase to identify dominant flowpaths. By doing so, a more complete description of hydrological connectivity was achieved. Our method provided useful insights to describe hydrological connectivity using a qualitative approach that can be expanded if required to include quantitative parameters for studies of biotic assemblages or ecosystem processes. [ABSTRACT FROM AUTHOR]