Identifying a suite of surrogate freshwaterscape fish species: a case study of conservation prioritization in Ontario's Far North,Canada

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Freshwater fish community structured more by dispersal limitation than by environmental heterogeneity

Abstract –  We examined the relative contribution of environmental heterogeneity and dispersal limitation on freshwater fish community composition in 18 Greek protected lakes and reservoirs. Environmental heterogeneity was measured by spatial pattern metrics (calculated by digital map processing, e.g., patch richness density, area-weighted mean patch area), altitude, maximum lake depth and trophic status. Dispersal limitation was measured by straight-line distances among lake centres. Ecosystems were clustered according to species composition. We examined the correlation of similarity in species composition among ecosystems with that of environmental heterogeneity and with straight-line distances, for the entire dataset, as well as for the occurring clusters. Fish species richness increased with ecosystem area and decreased with altitude. The clusters identified (aquatic ecosystems of Northern vs. ecosystems of Western Greece), implied an underlying biogeographical pattern as defined, with Pindus range acting as a natural barrier. Between ecosystems similarity, based on fish species composition, showed a weak to insignificant correlation with environmental heterogeneity, but was significantly correlated to dispersal limitation for the entire dataset as well as within each occurring cluster. Thus, natural barriers, species biogeography and dispersal limitation played a more significant role in shaping freshwater fish communities than environmental heterogeneity.     

Captive breeding and sanctuaries for the endangered African anabantid Sandelia bainsii, the Eastern Cape rocky

The African anabantid Sandelia bainsii Castelnau is in danger of extinction in the near future if urgent steps are not taken to prevent further degradation of its habitat. A combination of environmental education programmes, environmental journalism, captive breeding programmes, provision of sanctuaries, survey work and new research are being used to prevent the extinction of S. bainsii. A recent study using video recordings has for the first time clarified the reproductive behaviour of this anabantid. This new information will aid in the planning of the captive breeding strategy. Several small trial sanctuary areas have been established within the Kowie River catchment area, South Africa. Environmental education is an important component involving school groups, youth groups, concerned adults and National Science and Technology Festival audiences. The severe pressures put on the freshwater ecosystems within this relatively arid country have been highlighted. A clear management plan is required if this large anabantid and other local freshwater species are to survive. This paper summarizes existing knowledge of S. bainsii and suggests positive conservation steps which should be implemented within the natural range of this species     

Science for conserving Amazon freshwater ecosystems

1. The Amazon Basin is being degraded at unprecedented rates, yet conservation efforts have implemented protected areas to curb deforestation, leaving freshwater ecosystems vulnerable to degradation. Amazon freshwater ecosystems are largely unprotected because a terrestrial bias has limited the ability of science to affect policy.
2. Overcoming this bias requires increasing exchange of information among stakeholders across the basin to raise awareness of threats to Amazon freshwater ecosystems and promote discussions and access to conservation solutions. To help address this need, this Special Issue collates 15 synthetic articles that advance knowledge and identify conservation solutions.
3. Three articles highlight the importance of considering the hydrological and limnological processes that control the integrity of these freshwater ecosystems and offer new insights on how to extrapolate them across the basin.
4. Three articles on crocodilians, aquatic mammals, and migratory fishes document threats and knowledge gaps, and identify the missing role of governments as an impediment to conservation of their populations.
5. Three articles evaluate the multi-faceted effects of hydropower dams on fish, birds, and floodplain trees. They reinforce perceptions that dams are key environmental threats and offer guidance for improving protocols for dam site selection and impact assessment.
6. Three articles assessing the effectiveness of protected areas to safeguard fish and aquatic invertebrates show there is an urgent need to redesign the Amazon protected area network to adequately protect freshwater biota.
7. Three forward-looking articles show that: (i) conservation initiatives by local communities are ‘bright spots’ for freshwater conservation; (ii) microchemistry analyses of the ear bones of fishes could boost the knowledge base needed to conserve them; and (iii) strengthening the Amazon conservation framework requires a reversal of Brazil's current governmental priorities, remobilization of stakeholders, investments in capacity building, and expanding protections to terrestrial and freshwater ecosystems.

     

Advances in remote sensing of freshwater fish habitat: A systematic review to identify current approaches,strengths and challenges

Remote sensing technology offers the ability to derive information on freshwater fish habitats across broad geographic areas and has the potential to transform approaches to monitoring. However, the numerous platforms, sensors and analytical software that are available may overwhelm those interested in utilizing this important technology and thus limit its broad application and uptake. Our review is intended to shed light on the capacity of this technology to transform freshwater fish habitat monitoring by examining the fundamental characteristics of the major remote sensing technologies that have been used for characterizing freshwater habitats, conducting a systematic literature review of studies that have used remote sensing technologies to characterize freshwater fish habitats and, highlighting some of the key habitat features, fish species and regions, that have been examined. Lastly, we identify the relative strengths and weaknesses of the various remote sensing technologies that can be used, recommend future research that could help improve the use of these technologies, and, provide a series of important considerations for those who are interested in utilizing these technologies for freshwater fish habitat characterization.     

Spatial properties of sessile benthic organisms and the design of repeat visual survey transects

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Modelling the habitat requirement of riverine fish species at the European scale: sensitivity to temperature and precipitation and associated uncertainty

Abstract – Species distribution models (SDMs) have been widely used for different purposes such as studying species niche or forecasting the effects of global change on species distribution. Nevertheless, these models are often calibrated on datasets that only cover a fraction of the species’ realised niches, which could lead to unrealistic results. The aim of this study was to model the habitat requirements of 21 freshwater fish species that are native to Europe, using a dataset that accurately reflects their realised niches. Both temperature and precipitation were used as climatic factors to model the habitat requirements of the species, and the uncertainty associated with the fitted environment–occurrence relationships was examined. The results demonstrated the importance of accounting for these two climatic components when estimating the habitat requirements of riverine fish species and whether the uncertainty associated with model expectations varies with the species and the environmental factor considered. These results are discussed with regard to the known ecology of the 21 riverine fish species and within the perspective of climate change.     

Role of photoperiod and melatonin in the regulation of ovarian functions in Indian carp <Emphasis Type="Italic">Catla catla</Emphasis>: basic information for future application

The major carp Catla catla is a popular freshwater edible fish and an extensively cultured species in India. However, basic information on the physiology of reproduction is lacking in this species. By virtue of its surface feeding habit, it maintains close contact with environmental light, and is a species of choice for the study of temporal organization of reproduction under natural and experimental conditions for understanding environmental and/or endocrine mechanisms that control the annual reproductive cycle. The present review covers information gathered in recent years to emphasize the temporal pattern of reproductive events and the importance of photoperiod and melatonin, a hormone of the pineal gland that links the environment with the endocrine system in the regulation of reproduction. Finally, the outcome of the research is discussed in terms of its direct and indirect applications to aquaculture of this species with a view to manipulate its breeding at a desired time of the year to meet market demand.     

Freshwater conservation planning informed and validated by public participation: The Ebro catchment,Spain, as a case study

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

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The randomised response technique: A valuable approach to monitor pathways of aquatic biological invasions

Anglers can be significant vectors for non‐native species (NNS) in freshwater ecosystems, and monitoring their behaviour can be a useful way to counteract biological invasions. However, anglers may be unwilling to reveal their real behaviour in conventional surveys. In this study, the Randomised Response Technique (RRT) and the Bean Method (BM) survey technique were compared using direct questions to obtain frequency estimates of four angler behaviours that may affect NNS management in freshwater ecosystems: angling without a license, release of macroinvertebrates in the environment, use of fish bait and unauthorised fish restocking. Higher estimates were obtained from responses to RRT than BM questions, and BM provided contradictory results. Use of the RRT is recommended in those human dimension studies that explore angler behaviour as a vector for aquatic invasions.     

Self‐confidence of anglers in identification of freshwater sport fish

Although several studies have focused on how well anglers identify species using replicas and pictures, there has been no study assessing the confidence that can be placed in angler's ability to identify recreationally important fish. Understanding factors associated with low self‐confidence will be useful in tailoring education programmes to improve self‐confidence in identifying common species. The purposes of this assessment were to quantify the confidence of recreational anglers to identify 13 commonly encountered warm water fish species and to relate self‐confidence to species availability and angler experience. Significant variation was observed in anglers self‐confidence among species and levels of self‐declared skill, with greater confidence associated with greater skill and with greater exposure. This study of angler self‐confidence strongly highlights the need for educational programmes that target lower skilled anglers and the importance of teaching all anglers about less common species, regardless of skill level.     

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

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Conservation of freshwater fish in the British Isles: Proposals for management

1. Recent checklists of the freshwater fish of the British Isles have included 42 native and 13 introduced species. Of the former, however, two are extinct now and eight are threatened in various ways. In addition there are several important stocks of common native species under threat. 2. Protection for British fish exists mainly through legislation and protected sites of various designations. The legislation is inadequate in some respects and very few of the protected sites were actually established for their fish interest. Nevertheless, in Great Britain, 37 species of fish occur in National Nature Reserves. The overall status of fish in Sites of Special Scientific Interest is unknown. 3. The main conservation options for managing freshwater fish resources are habitat restoration, stock transfer to new sites, captive breeding and cryopreservation. The first two of these are regarded as the most useful for the long-term conservation of threatened species. Improved legislation would also help, especially in relation to preventing the import and transfer of potentially harmful species. 4. As well as the implementation of conservation management programmes for rare fish, research and monitoring studies are also needed in order to aid management and maintain a watch on populations of important species. In addition, national fish databases and registers of important stocks are an important background for overall fish conservation and management.     

Moving beyond fitting fish into equations: Progressing the fish passage debate in the Anthropocene

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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.     

Mapping China's freshwater fishes: diversity and biogeography

Freshwater fishes worldwide face an array of threats from dam construction, river fragmentation, pollution, over‐exploitation and interactions with introduced species. Such impacts are especially prevalent in densely populated countries undergoing rapid development, and their effects are felt most strongly where regional fish diversity is high. We reviewed studies of the distribution of freshwater fish species throughout China to map a biogeographical pattern and ascertain the environmental factors contributing to this distribution. We then linked this information to identify geographic areas to be recommended as the focus of conservation efforts. A total of 920 species in 302 genera, 54 families and 21 orders were recorded. Among the recorded species, 73% were Cypriniformes and 12% were Siluriformes. Cyprinidae was the most dominant family with 473 species, followed by Balitoridae with 157 species. The administrative division of the biogeography of China's freshwater fishes consisted of nine regions, including the Qinghai‐Tibetan Plateau Region, Oriental Region, Northwest Region, South Region, Loess Plateau Region, Heilongjiang Region, Upper Yangtze Region, 3H Plain Region and Middle‐Lower Yangtze Plain Region. The river system was the primary factor in determining China's freshwater fish biogeography. Under stepwise regression analysis, river discharge was found to be the most influential factor in determining richness, followed by population size and net primary productivity. The higher level of fish endemicity and sensitivity to environmental change led to the identification of Southwest China and the higher areas of Qinghai‐Tibetan Plateau as the primary areas to be considered for fish conservation and potential natural reserves.     

基于CART算法的长江口鱼种丰富度预测

长江口是西太平洋最大的河口生态系统和典型的生态群落交错区,预测鱼类生物多样性对评价其生态系统有着重要的科学指示意义。结合2012―2013年长江口15个站点的渔业资源和环境调查数据,利用分类与回归树(CART)算法中的回归树算法,构建了长江口鱼种丰富度预测模型。基于1-SE准则,最优决策树的复杂性参数设置为0.067,结果表明,盐度、溶解氧和季节是影响长江口鱼类生物多样性的主要因子。此外,使用2014年的观测数据对回归树模型预测的长江口鱼种丰富度予以验证,均方根误差(RMSE)、平均相对误差(ARE)和平均绝对误差(AAE)值的统计结果显示,回归树模型在春、夏季的预测效能优于秋、冬季,模型总体上呈现出了较好的预测能力,表明利用CART算法对长江口鱼种丰富度进行预测是可行的。     

Spatial and temporal patterns in fish community structure and abundance in the largest U.S. river swamp,the Atchafalaya River floodplain,Louisiana

Long‐term monitoring is critical for documenting population and community trends and for management, especially in large river‐floodplain ecosystems that provide important services. Levees have reduced active floodplains in most large rivers, but connectivity in some reaches could promote community resilience. Using multivariate tools and regression, we examined spatial and temporal structure in fish community samples from two decades (>1000 samples, >100 sites) in one of the largest relatively intact river‐floodplain ecosystems in North America – the Atchafalaya River (ARB), Louisiana. Assemblages exhibited significant structure temporally and spatially, with most substantial effects of year and hydrologic subdivisions; however, season and water level also influenced community structure. Temporal trends in communities were limited to few areas, while declines in species richness were more widespread; however, rarefied richness trends suggested that declines were slight. Recent and long‐term declines in abundance of economically important species (e.g., Black Crappie, Largemouth Bass, Bigmouth Buffalo) and increases in others (e.g., Smallmouth Buffalo, Blue Catfish, Freshwater Drum) drove differences among time periods. Our results suggest that the hydrologic subdivisions of the ARB may be an appropriate scale at which to manage fish populations, hydrology and water quality. Although we could not account for several important factors affecting fish communities in the ARB (e.g., hurricanes, major floods), and were limited by sampling variability, our findings highlight the utility of long‐term datasets from large river‐floodplain ecosystems for identifying important scales for management, determining species contributions to community change and forming hypotheses about anthropogenic and environmental drivers of variation in fish communities.     

Habitat disruption and the identification and management of functional trait changes

Aquatic ecosystems are facing escalating threats from urbanization, habitat loss and projected impacts of climate change, which both individually and in combination have the potential to fundamentally alter ecosystem functioning. While it is well established that habitat disturbances can affect the composition and diversity of aquatic communities, only recently have studies considered whether such impacts result in changes in species’ functional traits. We consider how functional traits of freshwater and marine fishes respond to environmental change, and how shifts in the expression of these traits can impact community dynamics and key ecological processes, including trophic interactions and nutrient transfer. We find that a multitude of functional traits, including behavioural and sensory traits, is sensitive to habitat disturbances. We demonstrate how these trait changes can be used to reveal hidden “ecological diversity” as well as serving as early indicators of environmental perturbation. We conclude that management strategies that consider the fundamental biological responses of fishes to habitat disturbance will be particularly effective in determining causal relationships within the ecological network. While detailed information on trait function is often lacking, even some general understanding of trait function and importance will facilitate targeted and efficient ecosystem management. We urge fisheries biologists and aquatic ecosystem managers to consider the role of functional traits in facilitating effective habitat restoration and management.