Toward process‐based conservation prioritizations for freshwater ecosystems

1. Over the last two decades, systematic conservation planning has been increasingly applied in terrestrial and marine systems. The approach has traditionally been lagging in freshwater environments, partly because considering unique ecological processes, such as connectivity and propagation of threats along river networks, is a key factor for conservation success in freshwater landscapes. This review highlights advances in freshwater planning in the last decade, but also discusses areas in need of increased efforts.
2. Including riverine connectivity and disturbances are largely resolved topics. Both processes have been included in major conservation planning software packages and applied globally. Theoretical advances to connectivity in wetlands and groundwater systems have started to appear, but no encompassing framework has emerged. Spatial solutions to conservation planning in lakes do not yet exist.
3. Some headway has been made when dealing with functional connectivity and genetic processes. For the latter, approaches have been developed to deal with cryptic biodiversity and to investigate the adequacy of conservation plans to include genetic diversity. Functional connectivity has been included in conservation plans in ephemeral waterscapes, and initial steps have been made to include migratory species in conservation prioritizations.
4. Conservation planning in socio‐ecological landscapes is catching up with biophysical prioritizations. Multiple protection tiers have been realized in river conservation planning frameworks, and freshwater scientists are leading the charge in both multi‐objective planning and in including direct functional responses. We conclude that tight integration between ecological sciences and optimization approaches is needed to further process‐based conservation planning.

     

Promoting connectivity between priority freshwater sites for conservation in intermittent hydrological systems

1. Systematic conservation planning in freshwater ecosystems faces multiple challenges because of the dynamic nature of rivers and their multiple dimensions of connectivity. In intermittent hydrological systems connectivity is functional when water is available, allowing the exchange of aquatic individuals between isolated freshwater ecosystems. Integrating these isolated systems in their hydrological context is essential when identifying priority areas for conservation, in order to try to minimize the propagation of threats into target water bodies (management units) from the surrounding landscape.
2. Here, the use of a systematic planning approach is demonstrated to identify a set of priority management units to preserve freshwater biodiversity in an arid system of fragmented water bodies immersed in a landscape subject to a range of impacts.
3. Twenty-six water-dependent taxa from 59 mountain rock pools (gueltas) of three southern Mauritanian mountains were used as a case study. A conservation planning tool (marxan ) was used to find priority conservation areas to integrate intermittent hydrological systems in their hydrological context, promote connectivity, and minimize the downstream propagation of threats. Three types of connectivity were analysed: (i) no connectivity, (ii) connectivity between gueltas, and (iii) connectivity between gueltas and sub-catchments.
4. Considering different types of longitudinal connectivity affects the number and spatial allocation of the priority gueltas selected, and the conservation status of the gueltas and their upstream areas. Incorporating connections between gueltas and upstream locations in the modelling resulted in the selection of gueltas in areas with a low human footprint and in the increased connectivity of the solutions.
5. The results obtained revealed important locations for local biodiversity conservation, and the method presented can be used when assessing the propagation of potential waterborne threats into isolated management units. The framework developed allows connectivity to be addressed in conservation planning. It can be replicated in regions with similar isolated habitats that connect through intermittent hydrological systems and can also be applied to lateral and vertical hydrological connectivity.

     

Approaches to the selection of a network of freshwater ecosystems within New Zealand for conservation

1. Although the freshwater environments of New Zealand once comprised an extensive interconnected network of rivers, lakes, and wetlands, their extent, condition, and connectivity have been reduced since human settlement, with consequent impacts on ecosystem functioning and the species that reside within them. An imbalance in the protection of freshwater ecosystems, with significant under‐representation of lowland freshwater ecosystems, makes these the most threatened ecosystems in New Zealand.
2. Recent policy initiatives are attempting to take a whole‐catchment view, i.e. ‘from the mountains to the sea’. There is also an increased focus on the restoration of vulnerable water bodies that still support moderate values, in preference to previous long‐term restoration programmes for the most degraded freshwater sites. The outcomes of these programmes have been less certain, with opportunities lost for systems that are declining in condition but have not yet reached the threshold of degradation for investment.
3. This work demonstrates the gains that can be made through the use of spatial conservation prioritization software to identify priority catchments for freshwater restoration, emphasizing the representation of a full range of ecosystems and species, while also taking account of longitudinal‐connectivity constraints within catchments.
4. Third‐order subcatchments were the most suitable scale for this prioritization, to capture the most important components within the largest river catchments. Populations of important native fish populations and the locations of major terrestrial conservation projects were also considered when assessing priorities; iteratively chosen weightings were applied to control the balance of representation across these different features.
5. Consideration was also given to existing patterns of protection, in order to assess the biodiversity representation within areas currently protected and to identify sites that would provide maximum additional benefits if restored or protected.
6. The resulting subcatchment prioritizations have contributed strongly to regional collaborative restoration processes.

     

A phylogenetic perspective on biodiversity patterns of Afrotropical freshwater crabs (Crustacea,Decapoda, Potamonautidae)

1. Evolutionary‐based measures of biodiversity play an increasingly important role in theoretical conservation biology, complementing more traditional methods such as patterns of species richness and endemicity.
2. To date, very few studies have used evolutionary data to assess patterns of biodiversity in the Afrotropical region, particularly for freshwater invertebrate taxa.
3. In the present study, the monophyletic Afrotropical freshwater crab family Potamonautidae was used to investigate how phylogenetic data can be combined with other metrics to help develop conservation plans for regional and species‐based conservation efforts.
4. The Afrotropical freshwater crabs make an exceptional group to demonstrate the utility of a phylogeny‐based approach to conservation, as there have recently been a number of phylogenetic studies on this family, the IUCN Red List conservation status is available for almost every species, and accurate distributional range data are available for all species.
5. The conservation priority of this fauna is assessed in relation to the Afrotropical freshwater ecoregions using three traditional measures of biodiversity and two phylogenetic diversity metrics.
6. The results of Evolutionarily Distinct Globally Endangered and Heightened Evolutionary Distinctiveness and Globally Endangered analyses identify both the freshwater crab species and the areas of high conservation priority in the Afrotropical region.

     

Spatial distribution patterns of fish egg and larval assemblages in the lower reach of the Yangtze River: Potential implications for conservation and management

1. River fish diversity is threatened by anthropogenic environmental alteration to landscapes. The early life-history stages of fish play an important role in maintaining diversity and population recruitment and can be heavily influenced by landscape patterns. Information on temporal and spatial distribution patterns of fish eggs and larvae is also important for biodiversity conservation and management of fish resources.
2. The Yangtze River possesses a high diversity of fishes, including many commercially important species. The economy along the lower reach of the river is well developed, and most of the area is experiencing high pressure from human impacts. This section of the Yangtze River connects with the largest freshwater lake in China at the upstream end and flows into the estuary at the downstream end. These two landscape features are likely to have a significant impact upon the spatial distributions of fish egg and larval assemblages.
3. Environmental variables, fish eggs, and larval assemblages were sampled in three locations, at Hukou, Anqing, and Jingjiang, in the lower reach of the Yangtze River. The results suggest that the higher number of species and greater abundance in upstream sites reflect the critical function of connectivity of Poyang Lake with the river for fish recruitment in the lower Yangtze. The delayed bloom of larval fish, occurrence of estuarine species, and a lower species number and abundance of freshwater fish downstream reflect the influence of tidal intrusion from the estuary.
4. This study highlights the value of maintaining natural river–lakes connectivity in the Yangtze River as a conservation measure. The connected river–lake system should be designated as a priority area for fish resource protection in the lower reach of the Yangtze River. We recommend further measures to break down barriers between the river and other lakes and to restore the natural lateral connectivity of the floodplain ecosystem.

     

The importance of ecosystem‐based management for conserving aquatic migratory pathways on tropical high islands: a case study from Fiji

• 1. Tropical, high islands of the Pacific have developed unique freshwater fish faunas that are currently threatened by a range of human activities. This paper documents distinct differences in life history strategies from fish communities found in streams of Fiji compared with fish assemblages in freshwater systems on larger continental land masses. While river systems of northern Australia and Papua New Guinea have a high proportion of freshwater residents, the Fiji fauna is dominated by amphidromous gobiids that migrate across a broad range of habitats throughout their life cycle.
• 2. The number of amphidromous fish species and the number of all fish species in mid‐reaches of Fiji rivers are significantly affected by loss of catchment forest cover and introductions of tilapia (Oreochromis spp.). On average, stream networks with established Oreochromis spp. populations have 11 fewer species of native fish than do intact systems. The fish that disappear are mostly eleotrid and gobiid taxa, which have important dietary and economic value.
• 3. Based on the strong links between catchment land clearing, non‐native species introductions and loss of migratory pathways for freshwater fish, spatial information was compiled on a national scale to identify priority areas for conservation in Fiji with intact connectivity between forests, hydrologic networks and coral reefs. Areas with high connectivity included remote, largely undeveloped regions of Vanua Levu (Kubulau, Wainunu, Dama, Udu Point, Natewa, Qelewara) and Taveuni, as well as smaller mapping units (Naikorokoro, Sawakasa) of Viti Levu with low density of roads and high relative amounts of mangroves and reefs.
• 4. These priority areas for conservation can only be effectively protected and managed through cross‐sectoral collaboration and ecosystem‐based approaches. Copyright © 2009 John Wiley & Sons, Ltd.

     

Effectiveness of protected area networks in representing freshwater biodiversity: the case of a Mediterranean river basin (south‐eastern Spain)

• 1. Biodiversity is probably at greater risk in freshwater systems than in other ecosystems. Although protected areas (PAs) play a vital role in the protection of biodiversity and are the mainstay of most conservation polices, the coverage of biodiversity by existing PA networks is often inadequate and few reserves are created that take into consideration freshwater biota.
• 2. In this paper an attempt is made to address the performance of protected areas in the context of freshwater biodiversity conservation using data records for water beetles in a Mediterranean river basin.
• 3. Although the present PAs in the study area cover a relatively high number of water beetle species, the distribution and extent of reserves is still inadequate or insufficient to protect freshwater biodiversity, especially species of conservation concern.
• 4. Alternative area‐selection methods (hotspots and complementary) were more efficient than PAs for representing water beetles. Within these, complementarity was the most efficient approach, and was able to represent all species in a significantly lower area than the current PA network. On the other hand, the future Natura 2000 Network will result in a great increase in the total area of protected land as well as in the biodiversity represented.
• 5. Unfortunately, the occurrence of a species within a protected area is not a guarantee of long‐term survival because the extent of PAs is often insufficient and disturbances occur outside park boundaries. Thus, whole‐catchment management and natural‐flow maintenance are indispensable strategies for freshwater biodiversity conservation.

Copyright © 2006 John Wiley & Sons, Ltd.     

Consequences of connectivity alteration on riverine fish assemblages: potential opportunities to overcome constraints in applying conventional monitoring designs

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Reference vs. present‐day condition: early planning decisions influence the achievement of conservation objectives

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Selecting areas with rare and restricted fish species in mountain streams of Southern Brazil

1. The delimitation of conservation units may be supported by information on compositional (taxonomic), functional, and phylogenetic diversity of a given locality or region. In this context, systematic conservation planning and key biodiversity areas are promising approaches for biodiversity protection.
2. Factors such as species representativeness and exclusivity may be used to identify geographical distribution patterns and select relevant areas for conservation at a local scale.
3. This study aims to identify areas with rare and restricted fish species in mountain streams in Southern Brazil, using a method that unites ecological and biogeographical approaches.
4. Seven river basins and 152 mountain streams in Southern Brazil were sampled to obtain data on the occurrence and abundance of 115 fish species. The rarity status of each species was determined and endemicity analysis was used to find areas of restricted species (ARS) with three cell sizes.
5. Using larger cells, continuous areas were identified and supported by a higher proportion of rare fish species. Using smaller cells, discontinuous areas were identified within each of the river basins, where rare and endemic fish species occur. Most of the smaller areas relevant for protecting fish fauna were located outside of conservation units.
6. Fundamental areas were selected for the protection of fish species in mountain streams in Southern Brazil. Both the method proposed and the areas with rare and restricted fish species identified may be used to support systematic conservation planning and to delimit new priority areas for conservation.

     

Assessing conservation priorities of endemic freshwater fishes in the Tropical Andes region

1. Assessing the effectiveness of protected areas for sustaining species and identifying priority sites for their conservation is vital for decision making, particularly for freshwater fishes in South America, the global centre of freshwater fish diversity. Several conservation planning studies have used threatened freshwater fishes or species that are vulnerable to climate change as conservation targets, but none has included both in priority‐setting analysis.
2. The objectives of this study were to identify gaps in the coverage of the existing protected areas in representing the endemic freshwater fishes of the Tropical Andes region, and to identify conservation priority areas that adequately cover threatened species and species vulnerable to climate change.
3. Data on 648 freshwater fishes from the Tropical Andes were used to identify gaps in the protected area coverage, and to identify conservation priority sites under three scenarios: (i) prioritize threatened species; (ii) prioritize species that are vulnerable to climate change; and (iii) prioritize both threatened species and species vulnerable to climate change.
4. A total of 571 species (88% of all species) were not covered by any protected areas; most of them are restricted to ≤10 catchments. To represent both threatened species and species vulnerable to climate change in the third scenario, 635 catchments were identified as priority areas, representing 26.5% of the study area. The number of irreplaceable catchments for this scenario is 475, corresponding to 22.5% of the total area.
5. The results of this study could be crucial for designing strategies for the effective protection of native fish populations in the Tropical Andes, and for planning proactive climate adaptation. It is hoped that the identification of priority areas, particularly irreplaceable catchments, will help to guide conservation and management decisions in the Andean region.

     

The conservation of migratory fishes in the second largest river basin of South America depends on the creation of new protected areas

1. Freshwater ecosystems, providing valuable goods and services to humans, have been subjected to multiple human impacts, among which climate change plays a central role in threats to species. It is expected that protected areas, the cornerstone of biodiversity conservation efforts, will assume a decisive role in protecting freshwater species from the impacts of climate change.
2. This study assessed the effects of climate change on migratory fish of the second largest neotropical river basin, evaluating the effectiveness of protected areas in safeguarding fish species, and hence the ecological functions that they perform and the ecosystem resources that they provide. The present range of 23 migratory fish of economic interest in the Paraná–Paraguay basin was estimated and the responses to future climatic shifts projected to the middle and end of the 21st century were examined, quantifying predictive uncertainties.
3. Changes and losses of climatically suitable areas will trigger severe contractions in range, with the greatest impact on the most valuable species in commercial fishing, where range losses are likely to surpass 65% in the future. The main channel of the Upper Paraná River and tributaries of its left margin are projected to serve as climatic refuges for many species, and such regions are not affected by high predictive uncertainty. The results revealed that protected areas do not sufficiently protect migratory fish at present, and that they will continue to offer negligible protection in the face of climate change.
4. This study alerts decision makers to the potential damage to inland fishery resources from climate change and provides useful information to guide conservation strategies spatially. We advocate that the creation of new protected areas and the redesign of the existing network to encompass regions that maximize current and future occupancy of migratory fish are crucial to conserve the valuable ecological, societal, and economic benefits that they provide.

     

Catchment zoning to enhance co‐benefits and minimize trade‐offs between ecosystem services and freshwater biodiversity conservation

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Mountains‐to‐the‐sea conservation: An island perspective

1. Island nations such as New Zealand provide valuable insights into conservation challenges posed by strongly connected and recently developed or exploited freshwater and marine ecosystems.
2. The narrow land mass, high rainfall, and steep terrain of New Zealand, like many other island nations, mean that land‐based stressors are rapidly transferred to freshwater habitats and propagated downstream to coastal environments via short, fast‐flowing river systems.
3. Freshwater and marine environments are linked through faunal life histories; for example, diadromous fishes, many of which are considered threatened or at risk of extinction, and require cross‐ecosystem conservation to ensure survival of critical life stages and persistence of source populations.
4. Recent invasions of marine and freshwater environments by non‐indigenous species reveal rapid impacts on a naïve biota and highlight conservation conundrums caused by management aimed at enhancing native biodiversity by improving habitat connectivity.
5. Understanding and managing interconnected freshwater and marine ecosystems is a key concept for local indigenous communities, and highlights socio‐cultural connectivity and sustainable local harvesting of traditional resources as key elements of contemporary marine and freshwater conservation planning in New Zealand.

     

Conservation of migratory fishes in the Amazon basin

1. The Amazon basin hosts the Earth's highest diversity of freshwater fish. Fish species have adapted to the basin's size and seasonal dynamics by displaying a broad range of migratory behaviour, but they are under increasing threats; however, no study to date has assessed threats and conservation of Amazonian migratory fishes.
2. Here, the available knowledge on the diversity of migratory behaviour in Amazonian fishes is synthesized, including the geographical scales at which they occur, their drivers and timing, and life stage at which they are performed.
3. Migratory fishes are integral components of Amazonian society. They contribute about 93% (range 77–99%) of the fisheries landings in the basin, amounting to ~US$436 million annually.
4. These valuable fish populations are mainly threatened by growing trends of overexploitation, deforestation, climate change, and hydroelectric dam development. Most Amazonian migratory fish have key ecological roles as apex predators, ecological engineers, or seed-dispersal species. Reducing their population sizes could induce cascading effects with implications for ecosystem stability and associated services.
5. Conserving Amazonian migratory fishes requires a broad portfolio of research, management, and conservation actions, within an ecosystem-based management framework at the basin scale. This would require trans-frontier coordination and recognition of the crucial importance of freshwater ecosystems and their connectivity.
6. Existing areas where fishing is allowed could be coupled with a chain of freshwater protected areas. Management of commercial and subsistence species also needs fisheries activities to be monitored in the Amazonian cities and in the floodplain communities to allow assessments of the status of target species, and the identification of management units or stocks. Ensuring that existing and future fisheries management rules are effective implies the voluntary participation of fishers, which can be achieved by increasing the effectiveness and coverage of adaptive community-based management schemes.

     

Habitat recovery and restoration in aquatic ecosystems: current progress and future challenges

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Freshwater mollusc assemblages and habitat associations in the Danube River drainage,Hungary

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Selecting and ranking areas for conservation of Aegla (Crustacea: Decapoda: Anomura) in southern South America integrating biogeography,phylogeny and assessments of extinction risk

1. The rapid degradation of freshwater habitats in southern South America may cause the extinction of the endemic species of Aegla, as well as other freshwater species and components of riverside environments related to them. Information on the distribution of species and their conservation status is essential for developing conservation strategies.
2. The updated distribution of Aegla in its southernmost distribution was analysed in order to prioritize freshwater ecoregions, applying biogeographical, phylogenetic and conservation status and complementarity approaches.
3. The distributions of the species of Aegla were delineated on maps and plotted against freshwater ecoregions. A data matrix of areas versus species was constructed and a taxon–area cladogram was created. Ecoregions were ranked, based on their species richness and using a complementarity criterion, to create a list of those considered important for conservation. The conservation status of Aegla species was assessed on the basis of the categories and criteria of the International Union for Conservation of Nature (IUCN) to produce a decreasing order of the risk of species extinction. These assessments were combined to define a consensus ranking of the priority areas for conservation.
4. The areas of maximum species richness and endemicity, and consequently highest priority of conservation, were the Lower Parana and Patagonia ecoregions. The Cuyan Desaguadero and Mar Chiquita Salinas Grandes ecoregions were the areas of second priority, and the Chaco and Lower Uruguay ecoregions were the areas with the third priority for conservation. Ten out of the 20 species analysed fall within the threat categories of the IUCN. Sixty per cent of the species of Aegla analysed have at least one population contained in protected areas.
5. The results obtained may be used to design strategies for implementing conservation policies on freshwater species, generate biogeographical atlases and contribute to selecting Ramsar sites.

     

Predation on native fish eggs by invasive round goby revealed by species‐specific gut content DNA analyses

1. Conservation of riverine fish often aims to improve access to spawning grounds and restore longitudinal connectivity by removing migration barriers, and involves substantial investments. However, these investments also enable non‐native predators to invade upstream into spawning areas and potentially adversely affect the recruitment of threatened freshwater fish through egg or fry predation.
2. Detecting egg predation is often challenging. Visual inspections of fish gut contents may underestimate predation of soft materials such as eggs and fry, which limits the discovery of predators preying upon these life‐stages. DNA‐based detection assays may offer a more sensitive tool to assess predation of soft materials.
3. A conservation issue was confirmed by developing and applying a species‐specific DNA‐based detection assay: invasive round goby (Neogobius melanostomus) prey on the eggs or fry of the threatened common nase (Chondrostoma nasus) in Switzerland.
4. DNA‐based detection assays were also developed for five other valuable native fish species, including endangered salmonid and cyprinid river spawners. The applicability of the assays was confirmed in a series of laboratory and field feeding experiments involving eggs and fish tissue. In addition, this work provides a guiding framework for conservation managers regarding the use and applicability of different DNA‐based detection approaches for gut content analysis.
5. The results of this study could inform local conservation measures – such as temporary reductions in the density of round goby at spawning sites prior to spawning – and demonstrate how targeted application of species‐specific molecular markers may advance freshwater fish management.

     

Progress and challenges in freshwater conservation planning

• 1. Freshwater ecosystems and their associated biota are among the most endangered in the world. This, combined with escalating human pressure on water resources, demands that urgent measures be taken to conserve freshwater ecosystems and the services they provide. Systematic conservation planning provides a strategic and scientifically defensible framework for doing this.
• 2. Pioneered in the terrestrial realm, there has been some scepticism associated with the applicability of systematic approaches to freshwater conservation planning. Recent studies, however, indicate that it is possible to apply overarching systematic conservation planning goals to the freshwater realm although the specific methods for achieving these will differ, particularly in relation to the strong connectivity inherent to most freshwater systems.
• 3. Progress has been made in establishing surrogates that depict freshwater biodiversity and ecological integrity, developing complementarity‐based algorithms that incorporate directional connectivity, and designing freshwater conservation area networks that take cognizance of both connectivity and implementation practicalities.
• 4. Key research priorities include increased impetus on planning for non‐riverine freshwater systems; evaluating the effectiveness of freshwater biodiversity surrogates; establishing scientifically defensible conservation targets; developing complementarity‐based algorithms that simultaneously consider connectivity issues for both lentic and lotic water bodies; developing integrated conservation plans across freshwater, terrestrial and marine realms; incorporating uncertainty and dynamic threats into freshwater conservation planning; collection and collation of scale‐appropriate primary data; and building an evidence‐base to support improved implementation of freshwater conservation plans.

Copyright © 2008 John Wiley & Sons, Ltd.