Search

Protecting freshwater biodiversity from non-native invasive species and their impacts is crucial for minimising both regional and global deterioration of ecosystem services. The yellow peacock bass Cichla ocellaris, a predatory freshwater fish endemic to the Amazon region, has been translocated within several Neotropical ecoregions, exhibiting harmful effects on biodiversity. In order to facilitate the prioritization of management efforts, which are essential for defining conservation actions in extensive and diverse areas, we propose a risk assessment index that integrates multiple ecological and environmental variables within a comprehensive framework, here applied for C. ocellaris. By considering fish species richness, occurrence frequency, and climate suitability, our index provides a more nuanced understanding of invasion risks. Within regions categorized as high and very high risk, where ecological impacts of C. ocellaris have been extensively documented (e.g., the Southern and North-East Brazilian regions, as well as Central American and Caribbean ecoregions), numerous environments are increasingly conducive to the establishment of this invasive species, exacerbated by a surge in dam constructions. Our analysis projects a significant increase in suitable habitats by 5% to 6.5%, with Southern and Northeastern Brazil and Central America identified as critical zones. Thus, our reproducible risk assessment framework, which considers freshwater ecoregions as conservation units, not only directs effective resource allocation for control measures but also enhances our ability to predict and mitigate the ecological impacts of non-native species introductions, providing a valuable tool for both policymakers and conservationists.

Abstract: Aim In this study, the effect of preservation time on total body length and dry weight of adult specimens of the neotropical cladoceran Ceriodaphnia silvestrii preserved with 4% formalin solution were examined. Methods The relationship between these variables was examined under increasing gradual time effects (i.e. 7, 30, and 60 days) after preservation using linear models and analysis of variance. Results Total body length did not statistically differ between fresh and preserved cladocerans at any preservation time, whereas dry weight was drastically reduced with increasing preservation time, with 15, 47 and 57% weight losses. Length-weight relationships were significantly and positively related in all treatments, though higher values of slope were found for fresh and 7 days samples. Conclusions We highlight that, for Ceriodaphnia silvestrii, the use of the formalin solution as a preservation fixative is not adequate when the major interest is biomass estimation. Also, we recommend that dry weight estimations from preserved samples should be done as soon as possible. Finally, considering the preservation losses and intra-specific composition of organisms, the application of correction factors is advised since preserved samples are important in the evaluation of long-term changes of biological communities.