Papers by Alvaro Soutullo
Biological Invasions, Dec 3, 2022
Alien species introductions produce strong impacts on invaded communities, altering their structu... more 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.
Between 2000–2020, more than ten new populations of the invasive American bullfrog (Lithobates ca... more Between 2000–2020, more than ten new populations of the invasive American bullfrog (Lithobates catesbeianus) have been reported in the southern cone of South America. We studied the stomach contents of 126 bullfrogs from a population at an early invasion stage in Uruguay (Aceguá, Cerro Largo Department). We observed a rich diet, with extensive prey volume range (1 mm3 to more than 7 000 mm3); the most frequent items were Hymenoptera (19.6%), Coleoptera (16.4%), Amphipoda (13.3%), Anura (8.9%) and Heteroptera (8.7%). Despite some overlap, differences were observed in volume (χ2 = 54.6, p <0.001, d.f. = 2) and prey quantity (F = 8.1, p <0.001, d.f. = 79) between males, females, and juveniles. Juveniles showed significantly higher consumption of terrestrial prey by count (82% of their total ingestion) than adults (29% for males and 32% for females) (χ2 = 28.5, p <0.001, d.f. = 2). Adults, especially females, showed a high frequency of cannibalism (33% of their total ingestion;...
Science of The Total Environment
High resolution XRF scanning documented inter-annual paleolimnological changes of a Subantarctic ... more High resolution XRF scanning documented inter-annual paleolimnological changes of a Subantarctic periglacial lake, during a process of centennial glacier retreat in King George Island, Antarctica. Two major paleoenvironmental stages were inferred from the combined analysis of elemental, molecular and isotopic biomarkers, with a boundary or transition set at about 3200 yr BP. The first stage was characterized by a relatively low allochthonous organic content, reduced productivity and nitrogen levels. Such paleoenvironmental conditions are interpreted as a terrestrial system under periglacial influence, where material influx was related to erosion process from the melt water discharge, because of the proximity to the Collins Glacier ice cap. After the major Holocene glacier advance dated at about 3500 yr BP, the ice cap retreat led to the formation of Lake Uruguay, which involved in filling processes leading to moraine deposits, proglacial meltwater channels, and lakes next to the land glacier. During the second stage, with the onset of the Current Warm Period, prior to 1900 CE the stabilization of the Zr/Rb ratio within the laminated sediments documented the origin of the lacustrine sedimentation system, with subsequent increases in the sedimentation rate and biomass content (total nitrogen and organic carbon). Time series analyses revealed that the lake displayed variability cycles related to El Niño Southern Oscillation (ENSO), as reflected by high resolution sedimentological proxies for grain size, weathering,
Bird Study, Jul 1, 2008
Capsule Dispersing juvenile Golden Eagles are habitat generalists that do not regularly use tempo... more Capsule Dispersing juvenile Golden Eagles are habitat generalists that do not regularly use temporary settlements.
Biological Conservation, 2012
Populations of migratory birds can be affected by events happening at both breeding and wintering... more Populations of migratory birds can be affected by events happening at both breeding and wintering grounds. The Sahel is a vast region holding a large number of wintering tans-Saharan migratory European birds, and current land-use changes there may represent a threat for these species. We used satellite tracking data from the migratory Montagu's harrier to evaluate habitat use of the species during the wintering season, and whether the current network of protected areas is effective to provide their habitat needs during that season. We also developed an ecological niche model for the species in Western-Central Sahel to check if the most suitable sites are included within current protected areas. Tracked harriers occupied a large region encompassing a total of eight countries. The most preferred habitats during winter were croplands and some natural vegetation habitats, especially grasslands. Protected areas only covered a small proportion of the overall wintering grounds of tracked harriers and the most suitable areas for the species in Western Sahel. Increasing the extent of preferred natural habitats within protected areas should benefit the conservation of this and probably other insect-eating raptors. However, substantial increases in extent and number of protected areas in sub-Saharan Africa are very unlike to occur. Conservation action in the region should therefore be mostly focused on improving land use planning and management outside protected areas, specially enhancing agricultural practices to make biodiversity conservation compatible with poverty alleviation. These can be chiefly targeted at an area of <20,000 km 2 of very suitable habitat for these species.
Animal Conservation, May 1, 2007
Geographic information systems (GIS)-based habitat-suitability modelling is becoming an essential... more Geographic information systems (GIS)-based habitat-suitability modelling is becoming an essential tool in conservation biology. A multi-scale approach has been proposed as a particularly useful way to identify different factors affecting habitat preferences. In this paper, we developed predictive models of potentially suitable habitat for golden eagles Aquila chrysaetos at three spatial scales in a representative Mediterranean area on the Iberian Peninsula. We used logistic regression through a generalized linear model (GLM) to model golden eagle breeding habitat preferences. The best-occurrence GLM models were those that involved topographic factors as independent predictors. Golden eagles seemed to prefer rugged and higher places of the study area for nesting. Climatic factors identified cold temperatures in January and temperate ones in July as the best predictors of eagles' occurrence. This was also higher in places with less agricultural areas and higher surface of pine forests. The distribution of potentially suitable area matches the distribution of mountain ranges, mainly in inner sectors of the study area. In contrast, potentially suitable nest sites in coastland areas remain unoccupied by golden eagles. Avoidance of coastland places for nesting may be due to the synergistic effects of human avoidance and the occurrence of potential competitors, like the endangered Bonelli's eagle Hieraaetus fasciatus. When mapped at a fine spatial resolution, the best GLM model identified large areas that fall outside the current network of protected areas. We therefore propose three new important bird areas for the region.
Journal of Mammalogy, 2021
Felids are among the species most threatened by habitat fragmentation resulting from land-use cha... more Felids are among the species most threatened by habitat fragmentation resulting from land-use change. In the Uruguayan Savanna ecoregion, about 30% of natural habitats have been lost, large felids have been eradicated from most of the region, and the impact of anthropogenic threats over the smaller species that remain is unknown. To develop management strategies, it is important to enhance knowledge about species population structure and landscape connectivity, particularly when land-use change will continue and intensify in the next years. In this study, we evaluate the population structure and gene flow of Geoffroy’s cat in the Uruguayan Savanna ecoregion. We generated a matrix of 11 microsatellite loci for 70 individuals. Based on Bayesian approaches we found that within the Uruguayan Savanna, Geoffroy’s cat shows high levels of genetic variability and no population structure. However, we observed genetic differences between individuals from the Uruguayan Savanna and those from t...
Utilizamos información publicada e inédita sobre mamíferos, reptiles y anfibios amenazados para i... more Utilizamos información publicada e inédita sobre mamíferos, reptiles y anfibios amenazados para identificar áreas de gran riqueza de especies amenazadas dentro de la Reserva de Biósfera Bañados del Este (Uruguay). Esa información fue luego comparada con una propuesta de zonificación de la reserva. Todas las especies analizadas fueron registradas dentro de las zonas propuestas como de conservación. Sin embargo, dada la falta de información actualizada sobre la distribución de estas especies fuera de esas zonas, no fue posible comparar su valor para la protección de especies amenazadas con el de otros sectores de la reserva. En los últimos 22 años menos del 25% de la reserva ha sido relevado. Mientras que el sector sur ha sido relativamente bien estudiado, la mayor riqueza de especies amenazadas se registró en la poco estudiada zona norte, cerca del límite con Brasil. Es por lo tanto altamente prioritario incrementar el conocimiento de la distribución y abundancia de las especies dent...
Environmental Conservation, Oct 28, 2022
Se evaluó el rendimiento de cinco índices no paramétricos de riqueza de especies (ICE, Jack1, Jac... more Se evaluó el rendimiento de cinco índices no paramétricos de riqueza de especies (ICE, Jack1, Jack2, Chao2 y Bootstrap) utilizando inventarios disponibles para tres grupos de vertebrados dentro de la Reserva de Biósfera Bañados del Este, Uruguay. Los datos utilizados fueron compilados de colecciones zoológicas, bibliografía, notas de campo y otras fuentes no publicadas. Todos los índices brindaron buenas estimaciones de la verdadera riqueza una vez que cerca del 50% de las localidades estudiadas fueron consideradas, pero sólo Jack2, ICE y Chao2 brindaron buenas estimaciones con muestras más pequeñas. Para datos que no han sido colectados sistemáticamente, y que poseen diferentes grados de exactitud, sugiero utilizar simultaneamente los índices ICE, Jack1 y Jack2 para evaluar cuán exhaustivos son los inventarios disponibles. Juntos, estos índices brindan buenas estimaciones de la verdadera riqueza, incluso cuando el esfuerzo de muestreo es pequeño, y definen un rango de valores dentr...
There are very few studies on Neotropical river otters (Lontra longicaudis) in Uruguay. However, ... more There are very few studies on Neotropical river otters (Lontra longicaudis) in Uruguay. However, the species is nowadays considered to be fairly common in the country. This paper reports on its distribution and current conservation status in the Uruguayan Atlantic basin. It provides some information on activity patterns, diet, and interactions with fishermen. The presence of otters was evaluated through interviews with fishermen and local people, and through field surveys in 1999 and 2000. Otter presence was recorded in every lagoon and tributary surveyed. Local people consider that Neotropical river otters are currently more abundant than they were 10 years ago. This recovery is probably the consequence of the ceasing of commercial hunting. Otters are both day and night active, though foraging takes place more during the night. All year round, otters are frequently seen in small groups, which may indicate that they are more social than generally thought. Most of the dietary items r...
How effective is the MERCOSUR’s network of protected areas in representing South America’s ecoreg... more How effective is the MERCOSUR’s network of protected areas in representing South America’s ecoregions?
Polar Research
For more than 20 years Antarctic Treaty Parties have been discussing how to appropriately manage ... more For more than 20 years Antarctic Treaty Parties have been discussing how to appropriately manage cumulative impacts in the continent. Preventing cumulative impacts requires the fluent exchange of information to enable proper and timely assessment of, and response to, the impacts that result from multiple activities, undertaken by multiple stakeholders and supervised by different Parties. This is a particular challenge for the effective management of Antarctic Specially Protected Areas (ASPAs), as a lack of coordination may potentially put at risk the fulfillment of their conservation objectives. Here we suggest that incorporating lessons learnt from protected areas management elsewhere might improve the effectiveness of ASPAs and provide valuable experiences and insights on how to better manage cumulative impacts in the rest of the continent. Key concepts to incorporate in Antarctica’s environmental management toolbox include (1) the notion of adaptive management, which is a corners...
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Papers by Alvaro Soutullo