Resolving the issues of translocated species in freshwater invasions

Biological invasions, driven by human-mediated species movements, pose significant threats to global ecosystems and economies. The classification of non-native species is a complex issue intertwining ecological considerations and ethical concerns. The need for nuanced and less ambiguous terminology is emphasised, considering biogeographic, evolutionary, and ecological principles. In-country translocations of native species into ecosystems in which they do not naturally occur, are often overlooked and are the least regulated among species movements, despite being increasingly common in conservation. Our case studies, spanning various ecosystems and taxa, illustrate the diverse impacts of translocations on native species and ecosystems. The challenges associated with translocated species underscore the urgency for robust risk management strategies and rigorous monitoring. A comprehensive and adaptable management framework that considers translocated species for evidence-based management decisions is critical for navigating the complexities of translocations effectively, ensuring the conservation of biodiversity and ecosystem sustainability

Exploring invasiveness and versatility of used microhabitats of the globally invasive Gambusia holbrooki.

Introductions of non-native species can lead to severe impacts, including the decline of ecosystem function through deleterious impacts on species diversity. The successful establishment of non-native species in new environments is the first barrier a species must overcome, ultimately depending on its ability to either cope with or adapt to local site-specific conditions. Despite the widespread distribution and ecological consequences of many freshwater invaders, site-specific and climatic preferences are often unknown, as in the case of the Eastern mosquitofish Gambusia holbrooki, a global invader considered as a pervasive threat to endemic species. Here, we determined the ecological features and preferred site-specific conditions of G. holbrooki in Türkiye, which spans a wide range of diverse biogeographically distinct ecosystems, by surveying populations from 130 localities in 2016 and 2017. Gambusia holbrooki were detected by hand-net in 48 of these sites (19 lotic, 29 lentic). It showed a preference for shallow waters with medium sized rocks, and abundances differed spatially across a latitudinal gradient and was influenced predominantly by variations in pH. The only other factors predicting its presence were low current velocities and gravel substrate, highlighting its ecological versatility in utilising a wide range of microhabitats. Bioclimatic models suggest that G. holbrooki is found in areas with an average annual temperature ranging from 10 to 20 °C, but with temperature not being a limiting factor to its invasion. Gambusia holbrooki shows a preference for xeric freshwater ecosystems and endorheic basins, as well as temperate coastal rivers, temperate upland rivers, temperate floodplain rivers and wetlands, and tropical and subtropical coastal rivers. These results, particularly the wide occurrence with only few limiting factors, emphasise the invasion potential of mosquitofish and should substantiate the need for localised invasive species management and conservation efforts, particularly in smaller or insular areas where mosquitofish and endemic fish species co-exist

High trophic similarity between non-native common carp and gibel carp in Turkish freshwaters: Implications for management

Although the detrimental ecological and economic effects of introducing freshwater fish species have been extensively documented, non-native freshwater fishes continue to be introduced in large numbers globally to enhance fisheries and aquaculture. In Turkey, stocking of common carp Cyprinus carpio is practised to provide food security for people and job security for artisanal fishers, resulting in a country-wide distribution. These stockings, however, increase the risk of accidental introductions and have led to introductions and subsequent invasions of gibel carp Carassius gibelio, a globally invasive and highly detrimental fish species. Here, we assessed the growth types, body conditions and trophic interactions via bulk carbon and nitrogen stable isotope analysis of common and gibel carp in both natural and artificial water bodies in Turkey. The results indicated that common and gibel carp express similar growth types and body conditions in all waters and have similar trophic ecologies. This leads to substantial trophic niche overlaps in waters where they co-occur, with the potential for strong interspecific competition. Considering the ongoing stocking of common carp for fishery enhancement, we recommend to specifically target these stockings in waters where gibel carp has already become invasive. Our findings, indeed, suggest that common carp releases have the potential to hamper invasive gibel carp populations by increasing the competitive interactions between the two species

A co-development approach to conservation leads to informed habitat design and rapid establishment of amphibian communities

1. Effective wildlife restoration is a critical requirement of many conservation actions. The outcome of conservation interventions can be optimised through knowledge of species’ habitat requirements, but few studies consider the impact of using explicit evidence from dedicated local research to inform the design phase of habitat management. Furthermore, interventions administered externally from the top down, whilst simpler than those developed in discussion with multiple stakeholders including land managers (i.e. co-development), run the risk of failing to engage local people. 2. In this study, we focus on interventions in the Scottish Highlands to improve the availability and suitability of breeding ponds for local amphibian assemblages. We collected and analysed data based on 129 ecological variables across 88 reference ponds to quantify the local habitat preferences. We used the findings from these analyses to inform the construction or restoration of 25 intervention ponds co-developed in partnership with stakeholders (landowners, foresters, citizen scientists and government agencies). Following the interventions, we monitored amphibian communities at these sites over 4 years. We assessed presence and abundance of all five native amphibians (the anurans Rana temporaria and Bufo bufo, and the salamanders Lissotriton helveticus, L. vulgaris and Triturus cristatus) using egg searching, dip-netting, torching and trapping. 3. The new habitats were overall characterised by ecological conditions more favourable to amphibians than the reference ponds. We recorded a total of 51 colonisation events. Within two breeding seasons after construction or restoration, the intervention ponds hosted the full complement of species, mirroring amphibian diversity patterns found in the local reference ponds. 4. Our study shows that ecological research to quantify local habitat requirements and working with commercial land-managers to ensure equitable benefits prior to designing conservation actions can promote rapid and efficient recovery of wildlife

A Biodiverse Rich Environment Does Not Contribute to a Better Diet: A Case Study from DR Congo

The potential of biodiversity to increase and sustain nutrition security is increasingly recognized by the international research community. To date however, dietary assessment studies that have assessed how biodiversity actually contributes to human diets are virtually absent. This study measured the contribution of wild edible plants (WEP) to the dietary quality in the high biodiverse context of DR Congo. The habitual dietary intake was estimated from 2 multiple-pass 24 h dietary recalls for 363 urban and 129 rural women. All WEP were collected during previous ethnobotanical investigations and identified and deposited in the National Botanical Garden of Belgium (BR). Results showed that in a high biodiverse region with precarious food security, WEP are insufficiently consumed to increase nutrition security or dietary adequacy. The highest contribution came from Dacryodes edulis in the village sample contributing 4.8% of total energy intake. Considering the nutrient composition of the many WEP available in the region and known by the indigenous populations, the potential to increase nutrition security is vast. Additional research regarding the dietary contribution of agricultural biodiversity and the nutrient composition of WEP would allow to integrate them into appropriate dietary guidelines for the region and pave the way to domesticate the most interesting WEP

Taming the terminological tempest in invasion science

\ua9 2024 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society. Standardised terminology in science is important for clarity of interpretation and communication. In invasion science – a dynamic and rapidly evolving discipline – the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions. A standardised framework is therefore needed for a clear, universally applicable, and consistent terminology to promote more effective communication across researchers, stakeholders, and policymakers. Inconsistencies in terminology stem from the exponential increase in scientific publications on the patterns and processes of biological invasions authored by experts from various disciplines and countries since the 1990s, as well as publications by legislators and policymakers focusing on practical applications, regulations, and management of resources. Aligning and standardising terminology across stakeholders remains a challenge in invasion science. Here, we review and evaluate the multiple terms used in invasion science (e.g. ‘non-native’, ‘alien’, ‘invasive’ or ‘invader’, ‘exotic’, ‘non-indigenous’, ‘naturalised’, ‘pest’) to propose a more simplified and standardised terminology. The streamlined framework we propose and translate into 28 other languages is based on the terms (i) ‘non-native’, denoting species transported beyond their natural biogeographic range, (ii) ‘established non-native’, i.e. those non-native species that have established self-sustaining populations in their new location(s) in the wild, and (iii) ‘invasive non-native’ – populations of established non-native species that have recently spread or are spreading rapidly in their invaded range actively or passively with or without human mediation. We also highlight the importance of conceptualising ‘spread’ for classifying invasiveness and ‘impact’ for management. Finally, we propose a protocol for classifying populations based on (i) dispersal mechanism, (ii) species origin, (iii) population status, and (iv) impact. Collectively and without introducing new terminology, the framework that we present aims to facilitate effective communication and collaboration in invasion science and management of non-native species

Tracking a killer shrimp: Dikerogammarus villosus invasion dynamics across Europe

Aim: Invasive alien species are a growing problem worldwide due to their ecological, economic and human health impacts. The “killer shrimp” Dikerogammarus villosus is a notorious invasive alien amphipod from the Ponto-Caspian region that has invaded many fresh and brackish waters across Europe. Understandings of large-scale population dynamics of highly impactful invaders such as D. villosus are lacking, inhibiting predictions of impact and efficient timing of management strategies. Hence, our aim was to assess trends and dynamics of D. villosus as well as its impacts in freshwater rivers and streams. Location: Europe. Methods: We analysed 96 European time series between 1994 and 2019 and identified trends in the relative abundance (i.e. dominance %) of D. villosus in invaded time series, as well as a set of site-specific characteristics to identify drivers and determinants of population changes and invasion dynamics using meta-regression modelling. We also looked at the spread over space and time to estimate the invasion speed (km/year) of D. villosus in Europe. We investigated the impact of D. villosus abundance on recipient community metrics (i.e. abundance, taxa richness, temporal turnover, Shannon diversity and Pielou evenness) using generalized linear models. Results: Population trends varied across the time series. Nevertheless, community dominance of D. villosus increased over time across all time series. The frequency of occurrences (used as a proxy for invader spread) was well described by a Pareto distribution, whereby we estimated a lag phase (i.e. the time between introduction and spatial expansion) of approximately 28 years, followed by a gradual increase before new occurrences declined rapidly in the long term. D. villosus population change was associated with decreased taxa richness, community turnover and Shannon diversity. Main Conclusion: Our results show that D. villosus is well-established in European waters and its abundance significantly alters ecological communities. However, the multidecadal lag phase prior to observed spatial expansion suggests that initial introductions by D. villosus are cryptic, thus signalling the need for more effective early detection methods

Assessment of habitat and survey criteria for the great crested newt (Triturus cristatus) in Scotland: a case study on a translocated population

The great crested newt Triturus cristatus has declined across its range due to habitat loss, motivating research into biotic and abiotic species determinants. However, research has focused on populations in England and mainland Europe. We examined habitat and survey criteria for great crested newts in Scotland, with focus on a large, translocated population. Adult counts throughout the breeding season were obtained annually using torchlight surveys, and Habitat Suitability Index (HSI) assessed at created ponds (N = 24) in 2006 (immediately post-translocation) and 2015 (9 years post-translocation). In 2006, ‘best case’ HSI scores were calculated to predict habitat suitability should great crested newts have unrestricted access to terrestrial habitat. Abiotic criteria included in and omitted from current great crested newt survey guidelines were assessed using data recorded in 2015. Some ponds had improved HSI scores in 2015, but overall failure to meet predicted scores suggests management is needed to improve habitat suitability. Great crested newt activity was positively associated with moon visibility and phase, air temperature, and pH, but negatively correlated with water clarity. Importantly, our results indicate there are abiotic determinants specific to Scottish great crested newts. Principally, survey temperature thresholds should be lowered to enable accurate census of Scottish populations

A global-scale screening of non-native aquatic organisms to identify potentially invasive species under current and future climate conditions

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium-and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement. Decision support tools AS-ISK Hazard identification Non-native species Risk analysis Climate changepublishedVersio