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One of the main drivers of biodiversity loss is the introduction of exotic invasive species. In 2011, an abundant population of Crangonyx pseudogracilis, a freshwater amphipod native to North America, was detected in Portugal. This study allowed us to better understand its biology, analysing the population dynamics in a temporary river and a small lake for one year, and to follow its expansion. Our results showed that this species reproduces in the temporary river during most of the year, but in the lake only from March to July. Amphipod density decreases from May to October and increases from November to April. As usual, females were larger than males, but the proportion of females was higher than males at both sampling locations. Finally, we noticed a great increase in C. pseudogracilis distribution area in relation to what was observed in 2014, with a diffusion coefficient of 2495.27 km2/year and a spread rate of 26 km/year. However, no overlap was yet detected between native and exotic amphipod species.

Biological invasions pose significant challenges in the Anthropocene, impacting ecosystem biodiversity and functioning. Ecological Niche Modeling is widely used to evaluate potential areas at risk of invasions, aiding in the prevention of invasive-species expansion and guiding conservation efforts in freshwater ecosystems. The main objectives of this study were to model the ecological niche and evaluate remaining suitable habitat areas for the occurrence of five potentially invasive species of freshwater decapods in South America: Dilocarcinus pagei, Macrobrachium amazonicum, M. jelskii, M. rosenbergii, and Procambarus clarkii. Occurrence data from the Global Biodiversity Information Facility were complemented with a literature systematic review. Variables used in the models were obtained from the Worldclim and EarthEv databases. Ecological Niche Modeling was performed using the Biomod2 and sdm package algorithms. Our results indicated a suitable area of up to 11% of South America. Model evaluations yielded favorable TSS and AUC values (>0.7 and >0.8). The suitable areas projected for South America included several hydrographic basins and Protected Areas. The information generated in our study can help identifying areas susceptible to decapod invasion in South America and support local management and decisions. [ABSTRACT FROM AUTHOR]

The freshwater pearl mussel Margaritifera margaritifera has been suffering major population declines in Europe. This endangered species is a host specialist and exclusively requires salmonid species (Salmo trutta and Salmo salar) to complete its life cycle. In theory, obligatory biotic interactions should deserve special conservation attention, because the loss or massive decline of fish hosts may elicit the extirpation of their affiliated species. While many threats disturbing M. margaritifera are similarly affecting salmonids, climate change is particularly alarming, with the potential to significantly change the fish‐mussel dynamics.To evaluate the importance of including the occurrence of fish hosts for predicting the distribution of M. margaritifera in Europe, three datasets were used to build species distribution models (SDMs) with a maximum entropy (MaxEnt) approach: (1) environmental variables (ENV); (2) probability of fish hosts occurrence (FH); and (3) environmental variables and probability of fish hosts occurrence (ENV + FH). We identified the environmental variables that better explain M. margaritifera distribution and modelled its current and future distribution under a suite of climate change scenarios. Furthermore, projections were used to evaluate the adequacy of current networks of European protected areas in covering the suitable habitats for M. margaritifera.Results showed that incorporating data about fish hosts into M. margaritifera SDMs avoided the overprediction of geographical projections and, to a minor extent, improved model performance (area under the curve: ENV = 0.851; FH = 0.848; ENV + FH = 0.867). The distribution range of M. margaritifera in Europe is expected to contract in all future timeframes and emission scenarios considered. Forecasts point to large contractions particularly in central and southern Europe and lowland regions. The European network of protected areas fails to protect 69% of the current and 66%–67% of the future predicted M. margaritifera distribution.This study clearly illustrates the importance of including mussel–fish hosts interactions for accurately predicting M. margaritifera's distribution. The response of M. margaritifera to environmental variables highlights its vulnerability to the higher temperatures, particularly in southern Europe. While predictions indicate large contractions in M. margaritifera's distribution as a result of future climate change, the current European network of protected areas fails to safeguard M. margaritifera.This work provides strong evidence for proposing the generalised use of biotic information about hosts in addition to purely environmental variables to model the distribution of freshwater mussels, as well as for other species with obligatory biotic interactions. Building SDMs such as those discussed here can inform political decision‐making about the likely scenarios for species occurrence in future decades, the requirements needed for an effective conservation strategy, and the regions where conservation should be a priority. [ABSTRACT FROM AUTHOR]

Global biodiversity is at risk owing to climate change, and freshwater ecosystems are expected to suffer the most. In recent years niche-based models (NBMs) have been used to predict species distribution and are an important tool for conservation and management of aquatic ecosystems. In this work, the current and future climatic suitability areas of the invasive species Corbicula fluminea, which has known adverse ecological and economic impacts, were investigated., The species distribution modelling was based on nine algorithms in BIOMOD2, summarized in an ensemble forecasting approach. To model the species distribution, eight climatic parameters related to temperature and precipitation variables were considered. Three time frames (current, 2050 and 2070) were modelled using four increasing CO2 emission scenarios., The performance of individual models was excellent according to the area under the receiver operating characteristic curve (AUC) and good to excellent according to true skill statistics (TSS). Annual mean temperature, minimum temperature of the coldest month and mean temperature of the coldest quarter were the most important variables predicting C. fluminea occurrence. Of the total continental area, 6.6% was predicted to be suitable for C. fluminea in current conditions., In the future, suitable area will increase from the current value of 6.6% to values from 9.4% to 12.6%, according to the 2050 projections and up to 12.7% in 2070 in high emission scenarios., Overall, the results indicate that climate change will favour the expansion of C. fluminea into new river basins, especially at higher latitudes, and that future climatic scenarios may double the suitable area for Corbicula fluminea. [ABSTRACT FROM AUTHOR]