Spatial distribution of exotic fish species in the Guadiana river basin, with two new records

This work updates the spatial distribution of the exotic fish species in the Guadiana river basin. To this effect, 241 river stretches and 37 reservoirs and lakes were sampled, corresponding to 261 UTM 10 × 10 Km squares. A total of 12 exotic species were found, including two new species that had not been previously cited in the area, the channel cat-fish (Ictalurus punctatus) and the roach (Rutilus rutilus). These two species, related to lentic systems, had a very restricted distribution in the basin, probably as a consequence of its recent introduction. The expansion of the remaining exotic species was also confirmed. Some species as the pumpkinseed sunfish (Lepomis gibbosus), the mosquitofish (Gambusia holbrooki) or the largemouth bass (Micropterus salmoides) have become common components of the fish community, not only in reservoirs but also in lotic systems.Este trabajo actualiza la distribución espacial de las especies de peces exóticas presentes en la cuenca del río Guadiana. Para ello se han muestreado 241 tramos fluviales y 37 embalses y lagos que se corresponden con 261 cuadrículas UTM 10 × 10 Km. Se encontró un total de 12 especies de peces exóticos, incluyendo dos nuevas especies no citadas hasta el momento en la cuenca: el pez gato punteado (Ictalurus punctatus) y el rutilo (Rutilus rutilus). Estas dos especies, relacionadas con medios leníticos, tuvieron un área de distribución muy restringida en la cuenca, consecuencia probable de su reciente introducción. Además se confirmó la expansión del resto de especies exóticas. Algunas de ellas como el pez sol (Lepomis gibbosus), la gambusia (Gambusia holbrooki) o el black-bass (Micropterus salmoides) se han convertido en componentes habituales de las comunidades de peces, no s'olo en embalses, sino también en medios lóticos

Invasive species and habitat degradation in Iberian streams: An analysis of their role in freshwater fish diversity loss

Mediterranean endemic freshwater fish are among the most threatened biota in the world. Distinguishing the role of different extinction drivers and their potential interactions is crucial for achieving conservation goals. While some authors argue that invasive species are a main driver of native species declines, others see their proliferation as a co-occurring process to biodiversity loss driven by habitat degradation. It is difficult to discern between the two potential causes given that few invaded ecosystems are free from habitat degradation, and that both factors may interact in different ways. Here we analyze the relative importance of habitat degradation and invasive species in the decline of native fish assemblages in the Guadiana River basin (southwestern Iberian Peninsula) using an information theoretic approach to evaluate interaction pathways between invasive species and habitat degradation (structural equation modeling, SEM). We also tested the possible changes in the functional relationships between invasive and native species, measured as the per capita effect of invasive species, using ANCOVA. We found that the abundance of invasive species was the best single predictor of natives' decline and had the highest Akaike weight among the set of predictor variables examined. Habitat degradation neither played an active role nor influenced the per capita effect of invasive species on natives. Our analyses indicated that downstream reaches and areas close to reservoirs had the most invaded fish assemblages, independently of their habitat degradation status. The proliferation of invasive species poses a strong threat to the persistence of native assemblages in highly fluctuating environments. Therefore, conservation efforts to reduce native freshwater fish diversity loss in Mediterranean rivers should focus on mitigating the effect of invasive species and preventing future invasions

Incorporating ecological functions in conservation decision making

Systematic conservation planning has become a standard approach globally, but prioritization of conservation efforts hardly considers species traits in decision making. This can be important for species persistence and thus adequacy of the conservation plan. Here, we developed and validated a novel approach of incorporating trophic information into a systematic conservation planning framework. We demonstrate the benefits of this approach using fish data from Europe's second largest river, the Danube. Our results show that adding trophic information leads to a different spatial configuration of priority areas at no additional cost. This can enhance identification of priority refugia for species in the lower position of the trophic web while simultaneously identifying areas that represent a more diverse species pool. Our methodological approach to incorporating species traits into systematic conservation planning is generally applicable, irrespective of realm, geographical area, and species composition and can potentially lead to more adequate conservation plans.SL was supported by ARC DECRA fellowship, project number DE130100565. VH was supported by a Ramon y Cajal contract (RYC‐2013‐13979) funded by the Spanish Government

Filling gaps in a large reserve network to address freshwater conservation needs

Freshwater ecosystems and biodiversity are among the most threatened at global scale, but efforts for their conservation have been mostly peripheral to terrestrial conservation. For example, Natura 2000, the world's largest network of protected areas, fails to cover adequately the distribution of rare and endangered aquatic species, and lacks of appropriate spatial design to make conservation for freshwater biodiversity effective. Here, we develop a framework to identify a complementary set of priority areas and enhance the conservation opportunities of Natura 2000 for freshwater biodiversity, using the Iberian Peninsula as a case study. We use a systematic planning approach to identify a minimum set of additional areas that would help i) adequately represent all freshwater fish, amphibians and aquatic reptiles at three different target levels, ii) account for key ecological processes derived from riverscape connectivity, and iii) minimize the impact of threats, both within protected areas and propagated from upstream unprotected areas. Addressing all these goals would need an increase in area between 7 and 46%, depending on the conservation target used and strength of connectivity required. These new priority areas correspond to subcatchments inhabited by endangered and range restricted species, as well as additional subcatchments required to improve connectivity among existing protected areas and to increase protection against upstream threats. Our study should help guide future revisions of the design of Natura 2000, while providing a framework to address deficiencies in reserve networks for adequately protecting freshwater biodiversity elsewhere.We acknowledge funding support provided by Griffith University and Ramon y Cajal Program (RYC-2013-13979) to VH. PB and AFF were supported by EDP Biodiversity Chair. PS was supported by a grant funded by FCT (SFRH/BPD/39067/2007)

EU's conservation efforts need more strategic investment to meet continental commitments

The European Union (EU) has made significant conservation efforts in the last two decades, guided by the Birds and Habitats Directives, currently under evaluation. Despite these efforts a large proportion of priority species are still in unfavorable condition and continue declining. For this reason, a thoughtful review of the implementation of conservation efforts in Europe is needed to identify potential causes behind this poor effectiveness. We compiled information on the distribution of all conservation funds under the LIFE‐Nature, the main financial tool for conservation in Europe. We found that LIFE‐Nature has not adequately covered continental conservation needs. The majority of funds have been directed toward nonthreatened species or regions of low conservation priority. Given the limited resources available, two key aspects are in urgent need for revision and improvement. First, the distribution of funds should be guided by continental and global conservation needs and planned at the EU scale. Second, new mechanisms are required to set conservation priorities in a dynamic fashion, rather than relying on fixed lists (i.e., the Directives’ Annexes) that may rapidly become outdated. These improvements would require new mechanisms to set priorities and redistribution of conservation efforts, supported by adequate policy and a more effective top‐down control on investment.V.H. and M.C. were supported by two Ramón y Cajal contracts funded by the Spanish Ministry of Science and Innovation (RYC‐2013‐13979 and RYC‐2010‐06431, respectivey)

Invasive species and habitat degradation in Iberian streams: an explicit analysis of their role and interactive effects on freshwater fish biodiversity loss

The diversity of life on Earth is under the so called biodiversity crisis, which is specially pressing in freshwater ecosystems. Habitat loss and degradation and invasive species are commonly cited as the main causes. Distinguishing the role of each extinction driver and their potential interactions through a mechanistic understanding of impact is crucial for achieving conservation goals. 2. We analyze whether freshwater fish invasive species are mere passengers co-occurring in the biodiversity loss process driven by habitat degradation or as main drivers of the decline of native fish communities in an Iberian basin. Moreover, since few invaded ecosystems are free from habitat loss and degradation, we also tested whether native species simply responded to the abundance of invasive species or if habitat degradation modified the functional relationships between natives and invasive species. 3. We found invasive species to be leading the decline of freshwater fish native communities, while habitat degradation neither played an active role nor influenced invasive species per capita effect on natives. Lower reaches and areas close to reservoirs held the most seriously injured fish communities independently of their habitat degradation status. Then Mediterranean freshwater fish show some resilience to habitat perturbations while invasive species should be raised to the center of attention of conservation actions. Moreover, the essential ecological role that hydrologically stable reaches might play for native communities’ persistence in highly fluctuating environments, such as the Mediterranean, is endangered by the proliferation of invasive species in those environments. 4. Synthesis and applications: Conservation efforts to reduce biodiversity loss among Mediterranean areas freshwater fish communities should focus on mitigating the effect of invasive species especially in better conserved areas. However, the high cost and low efficiency of management actions against invasive species may difficult the effective fight against invasive threats, while new tools such as harder legislation could help reduce the current introduction rates. The roles of different drivers leading the decay of native communities should not be directly extrapolated across taxonomic groups and/or environments, but be analyzed in different particular situations in order to tackle objective management plans facing the current biodiversity problem

Efficiency of species survey networks can be improved by integrating different monitoring approaches in a spatial prioritization design

Public participation to monitoring programs is increasingly advocated to overcome scarcity of resources and deliver important information for policy-making. Here, we illustrate the design of optimal monitoring networks for bird species of conservation concern in Catalonia (NE Spain), under different scenarios of combined governmental and citizen-science monitoring approaches. In our case study, current government efforts, limited to protected areas, were insufficient to cover the whole spectrum of target species and species-threat levels, reinforcing the assumption that citizen-science data can greatly assist in achieving monitoring targets. However, simply carrying out both government and citizen-science monitoring ad hoc led to inefficiency and duplication of efforts: some species were represented in excess of targets while several features were undersampled. Policy-making should concentrate on providing an adequate platform for coordination of government and public-participatory monitoring to minimize duplicated efforts, overcome the biases of each monitoring program and obtain the best from both

A mixed integer programming approach for multi-action planning for threat management

Planning for management actions that address threats to biodiversity is important for securing its long term persistence. However, systematic conservation planning (SCP) has traditionally overlooked this aspect and just focused on identiying priority areas without any recommendation on actions needed. This paper develops a mixed integer mathematical programming (MIP) approach for the multi-action management planning problem (MAMP), where the goal is to find an optimal combination of management actions that abate threats, in an efficent way while accounting for connectiivty. An extended version of the MAMP model (MAMP-E) is also proposed that adds an expression for minimizing fragmentation between different actions. To evaluate the efficiency of the two models, they were applied to a case study corresponding to a large area of the Mitchell River in Northern Asutralia, where 45 species of freshwater fish are exposed to the presence of four threats. The evaluation compares our exact MIP approach with the conservation planning software Marxan and the heuristic approach developed in Cattarino et al. (2015). The results obtained show that our MIP models have three advantages over their heuristic counterparts: shorter execution times, higher solutions quality, and a solution quality guarantee. Hence, the proposed MIP methodology provides a more effective framework for addressing the multi-action conservation problem.Peer ReviewedPostprint (published version

The effects of habitat and prey availability on otter (Lutra lutra) diet and distribution in the Sierra Norte de Sevilla Natural Park

La nutria está ampliamente distribuida en el Parque Natural Sierra Norte de Sevilla y en su entorno inmediato. En el área de estudio la nutria tendió a intensificar el uso del hábitat desde los tramos de cabecera hacia los tramos más bajos. Como era de esperar la disponibilidad de alimento fue también un factor decisivo para explicar el uso del hábitat por la nutria. El análisis de la dieta reveló que la presa más importante fue el barbo (Barbus sclateri). Existió una elevada correlación entre el tamaño medio y máximo de los barbos y el uso del hábitat por la nutria, de manera que ésta utilizó más los tramos con barbos de mayor talla. Esta misma correlación se observó también para las bogas (Chondrostoma willkommii). La nutria consumió hasta 20 tipos de presas distintas en el área de estudio: 11 especies de peces (barbo, calandino, pez sol, colmilleja, cachuelo, boga, pardilla y trucha), siete vertebrados no peces (rana, sapo, urodelos, culebra de agua, aves y micromamíferos) y dos invertebrados (cangrejo rojo americano e insectos). De todas ellas las más importantes, en orden decreciente, fueron el barbo, seguido a gran distancia por el cangrejo rojo (Procambarus clarkii) y la rana común (Rana perezi). En conjunto, en este resultado destaca sobremanera la importancia que adquirieron los peces en la dieta de la nutria. El 61% de los individuos consumidos y el 84% de la biomasa correspondió a peces. La dieta de la nutria varió según las condiciones ambientales y, en general, se ajustó a las presas disponibles en cada lugar. Sin embargo, cuando se comparó la abundancia de presas en el medio y en la dieta se observó que la nutria mostró preferencia o rechazo por algunas especies y/o tallas de las que seleccionó las mayores, salvo en el caso del pez sol (Lepomis gibbosus), en el que este patrón se invertía. En la situación actual y a la luz de los resultados obtenidos se puede concluir que el estado de conservación de la nutria en el Parque Natural Sierra Norte de Sevilla parece bueno o muy bueno.__________________________The otter is widespread through all the Parque Natural Sierra Norte de Sevilla and surrounding areas. We found that the otter varied its intensity of use of habitat in the course of the portion of the longitudinal gradient defined as headwaters-middle reaches. The otter tended to use more intensively middle reaches instead of headwaters, related to food sources availability. The otter fed on 20 different preys: 11 different freshwater fish species (The Iberian barbell, calandino, the sun fish, the Iberian sandsmelt, the Iberian chub, the Iberian nase, pardilla and common trout), seven vertebrates no fishes (common frogs, common toads, urodels, water snakes, birds y micromamifers) and two invertebrates (the red swamp crayfish and insects). Within all these preys the Iberian barbell (Barbus sclateri), the red swamp crayfish (Procambarus clarkii) and common frog (Rana perezi) stood out in this order of preference. 61% of preys and 84% of total biomass corresponded to freshwater fish individuals. This fact underlines the high importance that freshwater fishes had for the otters´ diet within the study area. However, otter’s diet showed a faithfully pattern in relation to preys availability, since they mainly fed on the most available preys. This general pattern must be specified, as the otter tended to select or reject some fish species and/or fish sizes. Long sized fishes were specially consumed except for the sun fish (Lepomis gibbosus) with which this general pattern appeared inverted. In summary we can say that the Sierra Norte´s otter population is in good or very good health