Virgilio Hermoso

Threatening processes and conservation management of endemic freshwater fish in the Mediterranean basin: A review

Mediterranean endemic freshwater fish are among the most threatened biota in the world. The Mediterranean basin has experienced substantial reductions in precipitation and water availability, which will worsen with climate change. Current water policy is directed to increase water-supply demands, especially for agriculture, and not to improve water-use efficiency and implement integrated and sustainable water management. Illegal extractions are common, exacerbating problems for important protected areas. Management is needed to mitigate the conflicts between environmental water and human demand, and ensure availability of water to maintain ecological processes and Mediterranean freshwater biodiversity. Water availability is not the only threat, although it is exacerbated by pollution and invasive species. The uneven spatial distribution of threats across the Mediterranean basin requires different strategies to conserve freshwater biodiversity. Implementation of multi-national laws (e.g. Water Framework Directive in the European Union) will help future management of freshwater ecosystems. Management actions must be planned at whole-catchment scales, with collaboration among different countries and water-management authorities. The current reserve area is small compared with other areas in the world and driven by terrestrial interests, and should be evaluated for its effectiveness to protect the Mediterranean freshwater biodiversity.

Reservoirs promote the taxonomic homogenization of fish communities within river basins

Most studies analyzing patterns in biotic homogenization of fish communities have used large-scale approaches, while the community-level effects of species introductions and local extinctions within river basins have been sparsely analyzed. In this article, we examine patterns in freshwater fish α- and β-diversity in relation to the presence of reservoirs in a Mediterranean river (Guadiana river; Iberian Peninsula). We used fish samples from 182 river localities and 59 reservoir ones to address two main questions: (i) do reservoirs favor the establishment of invasive fish species?; and (ii) do reservoirs bear taxonomically homogenized fish communities? Although total species richness was not different between rivers and reservoirs, the latter had more invasive species and less native ones. Fish species found in reservoirs tended to be larger ones, but invasive species of any size showed higher preferences for reservoirs. Native species that were rare or absent in reservoirs were those that showed higher sensitivity to invasive species in rivers. Reservoir fish communities were taxonomically homogenized in relation to river ones, both when considering all fish species and using only natives or only invasive ones. Our results suggest that invasive species occupying reservoirs constitute an ecological filter excluding most native species from such systems. Invasive species in the study area are often widely introduced elsewhere, while native species found in reservoirs are congeneric and ecologically similar to those found in other Iberian studies. Thus, we conclude that reservoirs promote taxonomic homogenization at multiple spatial scales, while could also be promoting the functional homogenization of Iberian fish communities.

Human effects on ecological connectivity in aquatic ecosystems: Integrating scientific approaches to support management and mitigation

Understanding the drivers and implications of anthropogenic disturbance of ecological connectivity is a key concern for the conservation of biodiversity and ecosystem processes. Here, we review human activities that affect the movements and dispersal of aquatic organisms, including damming of rivers, river regulation, habitat loss and alteration, human-assisted dispersal of organisms and climate change. Using a series of case studies, we show that the insight needed to understand the nature and implications of connectivity, and to underpin conservation and management, is best achieved via data synthesis from multiple analytical approaches. We identify four key knowledge requirements for progressing our understanding of the effects of anthropogenic impacts on ecological connectivity: autecology; population structure; movement characteristics; and environmental tolerance/phenotypic plasticity. Structuring empirical research around these four broad data requirements, and using this information to parameterise appropriate models and develop management approaches, will allow for mitigation of the effects of anthropogenic disturbance on ecological connectivity in aquatic ecosystems.

Selecting cost-effective areas for restoration of ecosystem services

Selection of areas for restoration should be based on cost-effectiveness analysis to attain the maximum benefit with a limited budget and overcome the traditional ad hoc allocation of funds for restoration projects. Restoration projects need to be planned on the basis of ecological knowledge and economic and social constraints. We devised a novel approach for selecting cost-effective areas for restoration on the basis of biodiversity and potential provision of 3 ecosystem services: carbon storage, water depuration, and coastal protection. We used Marxan, a spatial prioritization tool, to balance the provision of ecosystem services against the cost of restoration. We tested this approach in a mangrove ecosystem in the Caribbean. Our approach efficiently selected restoration areas that at low cost were compatible with biodiversity targets and that maximized the provision of one or more ecosystem services. Choosing areas for restoration of mangroves on the basis carbon storage potential, largely guaranteed the restoration of biodiversity and other ecosystem services.

Identifying priority sites for the conservation of freshwater fish biodiversity in a Mediterranean basin with a high degree of threatened endemics

The Guadiana River basin’s freshwater fish species richness, endemicity and threatened status (92% of native species are threatened) highlight the need for a large-scale study to identify priority areas for their conservation. One of the most common problems in conservation planning is the assessment of a site’s relative value for the conservation of regional biodiversity. Here we used a two-tiered approach, which integrates an assessment of biodiversity loss and the evaluation of conservation value through site-specific measures. These measures based on the reference condition approach introduce the ability to make objective comparisons throughout the Guadiana River basin, thus avoiding a priori target areas. We identified a set of biodiversity priority areas of special conservation significance—which contain rare taxa as well as intact fish communities—because of their outstanding contribution to the basin’s biodiversity. The inclusion of complete sub-basins in these priority areas might guarantee an optimal solution in terms of spatial aggregation and connectivity. However, the high spatial fragmentation to which the Guadiana River basin is submitted due to river regulation highlights the necessity of a systematic approach to evaluate the capability of the identified priority areas to maintain the Guadiana’s freshwater fish biodiversity.

Data Acquisition for Conservation Assessments: Is the Effort Worth It?

When identifying conservation priorities, the accuracy of conservation assessments is constrained by the quality of data available. Despite previous efforts exploring how to deal with imperfect datasets, little is known about how data uncertainty translates into errors in conservation planning outcomes. Here, we evaluate the magnitude of commission and omission error, effectiveness and efficiency of conservation planning outcomes derived from three datasets with increasing data quality. We demonstrate that investing in data acquisition might not always be the best strategy as the magnitude of errors introduced by new sites/species can exceed the benefits gained. There was a trade-off between effectiveness and efficiency due to poorly sampled rare species. Given that data acquisition is limited by the high cost and time required, we recommend focusing on improving the quality of data for those species with the highest level of uncertainty (rare species) when acquiring new data.

Freshwater ecosystems could become the biggest losers of the Paris Agreement

Securing access to energy for a growing population under the international commitment of reduction of greenhouse emissions requires increasing the contribution of renewable sources to the global share. Hydropower energy, which accounts for >80% of green energy, is experiencing a boom fostered by international investment mainly in developing countries. This boom could be further accelerated by the recent climate agreement reached in Paris. Despite its flexibility, hydropower production entails social, economic and ecological risks that need to be carefully considered before investing in the development of potentially thousands of planned hydropower projects worldwide. This is especially relevant given the weak or nonexistent legislation that regulates hydropower project approval and construction in many countries. I highlight the need for adequate policy to provide the Paris Agreement with new financial and planning mechanisms to avoid further and irreversible damage to freshwater ecosystem services and biodiversity.

Historical data to plan the recovery of the European eel

Summary 1. Long-term perspectives are critical to understand contemporary ecological systems. However, historical data on the distribution of biodiversity have only rarely been used in applied environmental sciences. 2. Here, we use historical sources to reconstruct the historical range of the European eel, a critically endangered species. We then use this baseline range to set range targets for the recovery of the European eel, as opposed to the abundance-based targets established by the European Union, which are constrained by the poor information on pre-collapse stocks. 3. We collected over 10 000 historical freshwater fish records from Spain in the 19th and 16th centuries, as well as over 25 000 records from the global biodiversity information facility (GBIF) to characterize historical and current European eel distribution in the Iberian Peninsula. We converted fish records into an eel presence–absence data set using subcatchment as spatial unit of analysis and modelled eel distribution in the different historical periods. 4. The eel was historically widespread throughout the Iberian Peninsula, but it has lost over 80% of its original range, mainly due to river fragmentation by dams. Distribution models applied to 16th- and 19th-century data showed a high agreement, supporting the use of the 19th-century estimated distribution as a baseline range. We identified the number and identity of dams that should be made passable for accomplishing specific range recovery targets, for example showing that acting upon 20 dams would make available 60% of the baseline eel range. 5. Synthesis and applications. This work exemplifies how insights gained from historical ecology can support and guide present-day management of migratory fishes. Similar approaches could be developed throughout Europe to plan the recovery of the eel, since there are large amounts of historical eel records. Historical baseline ranges for the eel range should be incorporated into the European Union legal mandates aimed at the recovery of the species.

Multi-Action Planning for Threat Management: A Novel Approach for the Spatial Prioritization of Conservation Actions

Planning for the remediation of multiple threats is crucial to ensure the long term persistence of biodiversity. Limited conservation budgets require prioritizing which management actions to implement and where. Systematic conservation planning traditionally assumes that all the threats in priority sites are abated (fixed prioritization approach). However, abating only the threats affecting the species of conservation concerns may be more cost-effective. This requires prioritizing individual actions independently within the same site (independent prioritization approach), which has received limited attention so far. We developed an action prioritization algorithm that prioritizes multiple alternative actions within the same site. We used simulated annealing to find the combination of actions that remediate threats to species at the minimum cost. Our algorithm also accounts for the importance of selecting actions in sites connected through the river network (i.e., connectivity). We applied our algorithm to prioritize actions to address threats to freshwater fish species in the Mitchell River catchment, northern Australia. We compared how the efficiency of the independent and fixed prioritization approach varied as the importance of connectivity increased. Our independent prioritization approach delivered more efficient solutions than the fixed prioritization approach, particularly when the importance of achieving connectivity was high. By spatially prioritizing the specific actions necessary to remediate the threats affecting the target species, our approach can aid cost-effective habitat restoration and land-use planning. It is also particularly suited to solving resource allocation problems, where consideration of spatial design is important, such as prioritizing conservation efforts for highly mobile species, species facing climate change-driven range shifts, or minimizing the risk of threats spreading across different realms.

A Global Assessment of Inland Wetland Conservation Status

&NA; Wetlands have been extensively modified by human activities worldwide. We provide a global‐scale portrait of the threats and protection status of the worlds inland wetlands by combining a global map of inundation extent derived from satellite images with data on threats from human influence and on protected areas. Currently, seasonal inland wetlands represent approximately 6% of the worlds land surface, and about 89% of these are unprotected (as defined by protected areas IUCN I‐VI and Ramsar sites). Wetland protection ranges from 20% in Central and 18% in South America to only 8% in Asia. Particularly high human influence was found in Asia, which contains the largest wetland area of the world. High human influence on wetlands even within protected areas underscores the urgent need for more effective conservation measures. The information provided here is important for wetland conservation planning and reveals that the current paradigm of wetland protection may be inadequate.