Taxonomic and geographic gaps in understanding the functional effects of imperilled fishes on freshwater ecosystems

The effects that fishes have on rates of one or more ecosystem processes (hereafter referred to as functional effects) are often invoked as an important reason for imperilled species conservation. However, the degree to which we understand these effects is rarely evaluated for most groups of fishes. We assessed how well the functional effects of freshwater and diadromous fishes, one of the most imperilled groups of animals, are quantified to date. We found that 88% of studies considering the functional effects of imperilled North American fishes were conducted on one family, Salmonidae. Studies of the functional effects of fishes were also concentrated in Pacific drainages of North America, with few studies in hotspots of imperilled fish diversity such as the Southeastern United States, the arid Southwest and central Mexico. Our results demonstrate the vast taxonomic and geographic gaps in our functional understanding of imperilled fishes and highlight the need to broaden this work to justify the argument that they are functionally important in the ecosystems they inhabit.     

Fishing for conservation of freshwater tropical fishes in the Anthropocene

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Population prioritization for conservation of imperilled warmwater fishes in an arid‐region drainage

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Biogeographic freshwater fish pattern legacy revealed despite rapid socio‐economic changes in China

Understanding drivers of freshwater fish assemblages is critically important for biodiversity conservation strategies, especially in rapidly developing countries, which often have environmental protections lagging behind economic development. The influences of natural and human factors in structuring fish assemblages and their relative contributions are likely to change given the increasing magnitude of human activities. To discriminate natural and human drivers of fish diversity and assemblage patterns in developing countries with rapid socio‐economic development, a dataset of 908 freshwater fish species and 13 metrics including three categories of both natural (i.e., biogeographic) and human drivers (i.e., economic growth, inland fisheries) in China were analysed with machine learning algorithms (i.e., self‐organizing map, random forest). Here, we found that biogeographic drivers explained 21.8% of the observed fish assemblage patterns in China and remained stronger predictors when compared to human drivers (i.e., 15.6%, respectively). Freshwater fish species richness was positively correlated to rainfall, air temperature, surface water area and inland fisheries production but negatively correlated with urbanization. In addition, the strong structuring effects of climatic variables on Chinese fish richness patterns suggested that the fish assemblages could be particularly vulnerable to climate change. Our results showed that natural biogeographic factors still dominate in driving freshwater fish assemblage patterns despite increased human disturbances on aquatic ecosystems in a rapidly developing country. These findings consequently suggested that we should consider both natural (e.g., climate) and human (e.g., urbanization, inland fisheries) factors when establishing aquatic conservation strategies and priorities for developing countries that are experiencing rapid socio‐economic changes.     

Scale‐dependent effects of isolation on seasonal patch colonisation by two Neotropical freshwater fishes

The metapopulation paradigm has been central to improve the conservation and management of natural populations. However, despite the large number of studies on metapopulation dynamics, the overall support for the relationships on which the paradigm is based has not been strong. Here, we studied the occupancy dynamics of two Neotropical fishes (i.e., Pimelodella gracilis and Leporinus friderici) to investigate two fundamental premises of the metapopulation paradigm, that is, that isolation and area/habitat quality affect colonisation and extinction probabilities in predictable ways. In order to do this, we used a modification of occupancy models that allows modelling the probability of a site's occupancy as a function of the occupancy of its neighbourhood. We found a weak positive effect of neighbourhood occupancy on P. gracilis colonisation, which is consistent with the propagule rain metapopulation, that is, colonists arriving from outside the studied system. However, we found a strong negative neighbourhood effect on extinction probability, suggesting that declining populations from stream sections are rescued from extinction by neighbouring patches. In contrast, the effect of neighbourhood occupancy on the metapopulation dynamics of L. friderici was in the opposite direction, affecting positively colonisation but not affecting extinction rates, which is consistent with the classical metapopulation model. In addition, the occupancy dynamics of both species were affected by water velocity. To our knowledge, this is the first study to link directly dispersal to local population dynamics in Neotropical fishes, and one of the few studies doing inferences on spatial population dynamics based on direct estimates of neighbourhood occupancy.     

Exploring uncertainty in population viability analysis and its implications for the conservation of a freshwater fish

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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.     

Issues for the conservation and management of Falkland Islands freshwater fishes

• 1. The Falkland Islands, in the cool‐temperate south‐western Atlantic Ocean, have an impoverished freshwater fish fauna, with only two indigenous species certainly present there: the Falklands minnow, Galaxias maculatus, and the zebra trout, Aplochiton zebra. Additional species whose presence there is uncertain are the southern pouched lamprey, Geotria australis, and the Patagonian puyen, Galaxias platei. Brown trout, Salmo trutta, were introduced in the mid‐20th century, and sea‐migratory (diadromous) populations are widespread.
• 2. Distributions of zebra trout and brown trout, particularly, are complementary, suggesting that brown trout are having detrimental impacts on zebra trout. Zebra trout have suffered massive decline over the past few decades and remain largely in restricted areas that brown trout have not yet invaded.
• 3. Owing to their sea‐migratory habits, it can be expected that brown trout will eventually invade all significant streams on the Falkland Islands. This raises issues of serious concern since zebra trout are also probably sea‐migratory, and therefore need access to and from the sea to complete their life cycles. Therefore, any streams accessible to zebra trout are potentially accessible also to brown trout, raising the spectre that eventually brown trout will invade all the streams where zebra trout persist.
• 4. The existence of landlocked populations of zebra trout provides some form of protection from brown trout invasion, though a landlocked stock does not represent the full behavioural and genetic diversity of zebra trout in Falkland's waters, and must be regarded as a last resort means for conservation.

Copyright © 2001 John Wiley & Sons, Ltd.     

Identifying important sites for conservation of freshwater biodiversity: extending the species-based approach

Abstract  Species richness in relation to area of habitat is extremely high in many freshwater groups, with an estimated 12 000 fish, 5000 amphibians and 2000 mollusc species dependent on freshwater habitats. Other major groups dependent upon fresh waters include, reptiles, insects, plants and mammals. The IUCN Redlist and The Nature Conservancy assessments both indicate the serious vulnerability and degradation of inland water habitats world-wide. It is evident that there are neither the resources nor the time to protect all areas where species are under threat. Clearly a method is needed for prioritising inland water sites for conservation at both local and regional scales. IUCN held a workshop in June 2002 to develop a method for prioritising important inland water sites for biodiversity conservation. The goal of the workshop was to develop a method which would help to focus on conservation efforts and funds at the regional scale and would serve as a tool for active conservation efforts at the local scale. The method was developed on the foundations of a review of the existing site prioritisation schemes for terrestrial, marine and freshwater ecosystems. Expert representatives for a broad range of priority taxa and for existing schemes provided input to the development of the site prioritisation method. This paper describes the development of the method, the selection criteria adopted, guidelines for their use and the site selection procedure.     

Recommendations for monitoring freshwater fishes in river restoration plans: A wasted opportunity for assessing impact

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Freshwater fishes of Southeast Asia: potential for the aquarium fish trade and conservation issues

SoutheastAsia is an area rich in biodiversity, with a high degree ofendemism in both flora and fauna. Many freshwater fish specieshave been exploited for the ornamental fish trade. As thepopulation in South East Asia increases, vast tracts of forestsare cleared for agricultural, industrial and urbanizationpurposes. To conserve and sustainably exploit the wild fishpopulation, measures should be adopted to protect this naturalresource. Already, several ornamental species have been severelyoverexploited, e.g. bala shark (Balantiocheilos melanopterus),pygmy loach (Botia sidthimunki) and arowana (Scleropagesformosus), but the extirpation of local populations occurs formany reasons, including deforestation, and not just because offishing for the trade. There are also still many species thathave great ornamental fish potential. Wild fish species have alsobeen successfully bred in captivity and conserved, e.g. tigerbarb (Puntius tetrazona), bala shark, pygmy loach and arowana.Other methods of conservation include public education, leavingpristine forests intact and reforestation. The aquarium trade ofthe bala shark, harlequin rasbora (Rasbora heteromorpha), clownloach (Botia macracanthus), arowana and sawfish (Pristismicrodon) is discussed     

A review of the biology and status of Cape Fold Ecoregion freshwater fishes

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IUCN Red List of freshwater fishes and lampreys in Flanders (north Belgium)

Red Lists are used to assess the extinction risk of species. Regional IUCN criteria were applied to categorise 42 indigenous freshwater fish species in Flanders into Red List categories. As such, three species are assessed as Regionally Extinct, eight as Critically Endangered, two as Endangered and eight as Vulnerable. A further five species are considered Near Threatened, 15 species as Least Concern and one species is Data Deficient. Five species disappeared from the Regionally Extinct category compared with the previous Red List (1988) as a consequence of improved water quality of estuaries and reintroduction programmes. In total, 62% of the freshwater fish species in Flanders was considered extinct or threatened. This is higher than neighbouring regions and Europe as a whole (44%). This new Red List of freshwater fishes in Flanders can be used to inform conservation actions.     

Vulnerability of Cape Fold Ecoregion freshwater fishes to climate change and other human impacts

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Assessing upstream invasion risk in alien freshwater fishes based on intrinsic variations in swimming speed performance

Managing the spread and impact of invasive species requires an understanding of what limits their dispersal into new areas. Here, we investigated an intrinsic component of invasive species dispersal, via assessments of the swimming speed performance of four species of alien freshwater fish at risk of invading the upper reaches of a montane river system in south‐east Australia. Using water flow measurements taken from a range of potential barriers to their upstream dispersal (fishways, culverts, natural riffle habitats), we assessed the likelihood of alien species passage based on intrinsic differences in swimming speed performance. With the four alien fish species displaying a wide range of sprint swimming speed (U_sprint) capabilities, our logistic regression analysis identified pipe culverts as being a challenge to dispersal by all but the largest individuals of one species (Rainbow trout, Oncorhynchus mykiss). Notably, fishway installations facilitating passage of the sympatric threatened species, Macquarie perch (Macquaria australasica), could allow upstream dispersal of a key threatening species (European perch, Perca fluviatilis). Our study highlights the utility of locomotor capabilities for assessing the likelihood of upstream dispersal by species following human‐assisted introductions to the lower parts of a catchment.     

Conservation of freshwater biodiversity in key areas of the Colombian Amazon

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Top‐down conservation targets and bottom‐up management action: creating complementary feedbacks for freshwater conservation

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Too little but not too late? Biology of a recently discovered and imperilled freshwater fish in a drying temperate region and comparison with sympatric fishes

• 1. Small‐bodied freshwater fishes are commonly overlooked in threatened species management despite being highly imperilled. Before this study, the newly described little pygmy perch (Nannoperca pygmaea) was known from only 0.06 km² of habitat in a single catchment in south‐western Australia and a lack of knowledge prevented an understanding of its conservation status and priority actions.
• 2. The present study determined the distribution, biology, and movement patterns of N. pygmaea and compared these with other small, sympatric percihthyids to assess its conservation status and likely resilience to threatening processes.
• 3. The current ‘extent of occurrence' of N. pygmaea was determined to be 3,420 km² and the ‘area of occupancy' was 10 km². Nannoperca pygmaea inhabited permanent refuge pools in the main stem of an ephemeral, secondarily salinized catchment where salinities remained <6 ppt during summer.
• 4. During winter N. pygmaea undertook a short upstream migration into a seasonally flowing freshwater tributary to serially spawn. The timing of reproduction was partitioned among three sympatric pygmy perches within the austral winter/spring period.
• 5. The species qualifies as ‘Endangered' under the IUCN Red List assessment criteria. Its restriction to freshwater refugia within salinized rivers suggests that N. pygmaea may have a limited salinity tolerance similar to the sympatric, threatened Nannatherina balstoni, and that the species is susceptible to prolonged drought, drying of critical baseflow refuges, increasing salinization, and introductions of alien species.
• 6. The study serves as an example that small‐bodied freshwater fishes need greater research attention to understand the biological and environmental mechanisms underpinning their decline.

     

The Alliance for Freshwater Life: A global call to unite efforts for freshwater biodiversity science and conservation

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