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Alien species introductions produce strong impacts on invaded communities, altering their structure, diversity and functioning. These impacts are interrelated with changes in food web architecture. However, the reorganization or robustness of food webs in the face of invasion is a phenomenon poorly considered in ecology and conservation practices. In this article, we analyze the effects of the invasion of the American bullfrog,Lithobates catesbeianus, on the structure and function of invaded food webs. Specifically, we analyzed the integration of energetic channels by top predators, the relative use of alternative energetic paths by different functional groups and its dependence on body size among invaded and uninvaded communities in Uruguay, South America. The integration of energetic paths at high trophic positions by large body sized consumers was a pervasive feature of food webs among all studied ponds, in spite of turnover in top predator identity and large changes in community composition. Bullfrog post-metamorphs presented high trophic positions, integrating the primary producers and detritus paths, acting as apex predators in invaded food webs. The bullfrog tadpoles presented intermediate positions and were associated with the detritivorous pathway. On the other hand, the relative importance of the primary producers and detritus as carbon sources assimilated into the biomass of fish and invertebrates was altered in invaded systems. The robustness in the integration pattern of energy channels is congruent with its proposed central role in the stability of food webs. These results advance the understanding of the effect of invasions on key structural features of food webs, notably underrepresented in the invasion literature.

The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the implementation of conservation actions both locally and globally has progressively been guided by the identification of biodiversity ‘hotspots’ (areas with exceptional biodiversity). However, different regions of the world differ drastically in the availability of fine-scale data on the diversity and distribution of species, thus limiting the potential to assess their local environmental priorities. Within South America—a megadiverse continent—Uruguay represents a peculiar area where multiple tropical and non-tropical eco-regions converge, creating highly heterogeneous ecosystems, but where the systematic quantification of biodiversity remains largely anecdotal. To investigate the constraints posed by the limited access to biodiversity data, we employ the most comprehensive database for tetrapod vertebrates in Uruguay (spanning 664 species) assembled to date, to identify hotspots of species-richness, endemism and threatened species for the first time. Our results reveal negligible spatial congruence among biodiversity hotspots, and that tetrapod sampling has historically concentrated in only a few areas. Collectively, our study provides a detailed account of the areas where urgent biodiversity monitoring efforts are needed to develop more accurate knowledge on biodiversity patterns, offering government and environmental bodies a critical scientific resource for future planning.

The American bullfrog Lithobates catesbeianus is an invasive species that can strongly affect native amphibian communities through competition, predation, or introduction of diseases. This frog has invaded multiple areas in South America, for which niche models predict suitable environments across much of the continent. This paper reveals the state of the invasion of this species in Uruguay and its possible relationship with the chytrid pathogenic fungus, Batrachochytrium dendrobatidis. Surveys at invaded sites were conducted from 2007 to 2015, identified two populations undergoing recent range expansion (one of them exponential), two populations that failed to establish, and a new record in an urban area of the capital city, Montevideo. In all the analysed feral populations, chytridiomycosis was found. Our data suggest that the invasion of L. catesbeianus in Uruguay is at an early stage, with very localized populations, which might allow for the implementation of cost-effective management plans, with eradication constituting a plausible option.

Background\ud \ud \ud The continental and marine territories of Uruguay are characterised by a rich convergence of multiple biogeographic ecoregions of the Neotropics, making this country a peculiar biodiversity spot. However, despite the biological significance of Uruguay for the South American subcontinent, the distribution of biodiversity patterns in this country remain poorly understood, given the severe gaps in available records of geographic species distributions. Currently, national biodiversity datasets are not openly available and, thus, a dominant proportion of the primary biodiversity data produced by researchers and institutions across Uruguay remains highly dispersed and difficult to access for the wider scientific and environmental community. In this paper, we aim to fill this gap by developing the first comprehensive, open-access database of biodiversity records for Uruguay (Biodiversidata), which is the result of a large-scale collaboration involving experts working across the entire range of taxonomic diversity found in the country. \ud \ud New information\ud \ud As part of the first phase of Biodiversidata, we here present a comprehensive database of tetrapod occurrence records native from Uruguay, with the latest taxonomic updates. The database provides primary biodiversity data on extant Amphibia, Reptilia, Aves and Mammalia species recorded within the country. The total number of records collated is 69,380, spanning 673 species and it is available at the Zenodo repository: https:// doi.org/10.5281/zenodo.2650169. This is the largest and most geographically and taxonomically comprehensive database of Uruguayan tetrapod species available to date and it represents the first open repository for the country.

Effects caused by the invasive American bullfrog (Lithobates catesbeianus) are poorly understood at the community level. This study assessed the effects of a small feral bullfrog population (at lag invasion phase) on the different components of native aquatic communities (phytoplankton, zooplankton, invertebrates, fish and amphibians) of Acegua, Uruguay. Our interest focused on exploring the early local effects of this invasion. We explored whether there existed any difference in taxa richness, abundances and size structure in association to bullfrog invasion, using four seasonal sampling of all the lentic system around the foci (two invaded and five non-invaded ponds). We analysed the occurrence of differences between the invaded and the non-invaded communities: for the taxa richness we used rarefaction, for the abundances and body sizes we used mean tests, and for the tadpole developmental stages we used G-test. We only found statistically significant bullfrog effects, in fish and anuran larvae. The fish assemblage was favoured, reaching greater abundance and body size in the bullfrog invaded ponds. In these ponds, the nektonic tadpoles diminished their abundances, and the benthic tadpoles also reached greater body sizes, but decreasing their recruitment. Our results suggest that bullfrog invasion could have complex effects, acting asymmetrically, affecting different trophic paths, and depending on native species’ habits and attributes. Understanding these effects, in early invasion foci, has a great relevance to awareness of local environmental authorities and the implementation of management plans.

We studied in this work the prevalence of two eukaryotic skin pathogens in a population of the frog Boana pulchella (Anura, Hylidae) from southeastern Uruguay, the fungus Batrachochytrium dendrobatidis (Rhizophydiales) and the protoctistan Valentines rwandae (Ichthyosporea, Dermocystida), between 2012 and 2014. In both cases higher prevalences were recorded in cooler seasons, winter and early spring for B. dendrobatidis (0.78 and 0.95 respectively) and autumn for V. rwandae (0.33 and 0.49), with mean temperatures between 11.5 and 17.8°C. No cases of infection were detected in summer. In both cases the probability of infection was strongly influenced by season (and also the year for B. dendrobatidis), but in neither case the occurrence of the other pathogen was significant. The parasitic cycles seem to occur independently and are likely strongly associated to environmental temperatures. Future field studies on amphibian eukaryotic pathogens from temperate areas of South America should consider seasonal variations., En este trabajo se estudió la prevalencia de dos patógenos cutáneos eucariotas en una población de la rana Boana pulchella (Anura, Hylidae) del sureste de Uruguay, el hongo Batrachochytrium dendrobatidis (Rhizophydiales), y el protista Valentines rwandae (Ichthyosporea, Dermocystida), entre 2012 y 2014. En ambos casos las prevalencias más altas se registraron en épocas frías, invierno y primavera temprana para B. dendrobatidis (0,78 y 0,95 respectivamente) y otoño para V. rwandae (0,33 y 0,49), con temperaturas medias entre 11,5 y 17,8°C. No se detectaron casos de infección en verano. La probabilidad de infección en los dos casos está fuertemente influenciada por la estación (y además por el año para B. dendrobatidis), pero no por la ocurrencia del otro patógeno. Ambos ciclos parasitarios parecen ocurrir independientemente, y son probablemente condicionados en gran medida de la temperatura ambiental. Futuros estudios de campo sobre patógenos eucariotas en anfibios de zonas templadas de Sudamérica deberán tener en cuenta variaciones debidas a la época del año., Asociación Herpetológica Argentina

Esta nota reporta la ocurrencia de una nueva población feral de rana toro americana, Lithobates cathesbeianus, en la localidad de Cerrillos, Departamento de Canelones, Uruguay. Esta población se encuentra dentro de un área protegida de gran importancia nacional. Se recomienda evaluar su estatus y distribución.

A male Leptodactylus latrans was observed calling within a foam nest located at about 40 cm from the edge of the pond. The male was collected (voucher deposited at the Herpetological Collection of the Museo Nacional de Historia Natural, Montevideo, Uruguay, MNHN 9476). Ten minutes after the calling male was removed, we observed an amplectic L. latrans pair laying eggs in the same nest. In addition, a third male was at the edge of the foam nest and sporadically swam under the amplectic pair., Asociación Herpetológica Argentina (AHA)