Freshwater biodiversity is under great threat across the globe as evidenced by more severe declines relative to other types of ecosystems. One of the main stressors responsible for these concerning trends is habitat fragmentation, degradation, and loss stemming from anthropogenic activities including energy production, urbanization, agriculture, and resource extraction. Habitat protection and restoration both play an integral role in efforts to save freshwater biodiversity and associated ecosystem services from further decline. In this paper, we summarize the sources of threats associated with habitat fragmentation, degradation, and loss, and then outline response options to protect and restore freshwater habitats. Specific response options are to: legislate the protection of healthy and productive freshwater ecosystems; prioritize habitats for protection and restoration; enact durable protections; conserve habitat in a coordinated and integrated manner; engage in evidence-based restoration using an adaptive management approach; ensure that potential freshwater habitat alterations are mitigated or off-set; and future-proof protection and restoration actions. Such work should be done through a lens that engages and involves local community members. We identify three broad categories of obstacles that arise during the implementation of the response options outlined: a) scientific (e.g., inaccessible data or uncertainties), b) institutional and management (e.g., capacity issues or differing goals across agencies), and c) social and political (e.g., prioritizing economic development over conservation initiatives). The protection and restoration of habitats is key to bending the curve for freshwater biodiversity, with a comprehensive, connected, and coordinated effort of response options needed to protect intact habitats and restore fragmented, degraded, and lost habitats and the biodiversity and ecosystem services that they support.
For millennia humans have extracted biological and physical resources from the planet to sustain societies and enable the development of technology and infrastructure. Growth in the human population and changing consumption patterns have increased the human footprint on ecosystems and their biodiversity, including in fresh waters. Freshwater ecosystems and biodiversity face many threats and it is now widely accepted that we are in a biodiversity crisis. One means of protecting and restoring freshwater biodiversity is to better manage the exploitation of freshwater biota and aggregate resources (e.g., sand, gravel, boulders). Here we outline the threats arising from such exploitation and identify response options to ensure that methods and levels of extraction are sustainable and allow recovery of over-exploited freshwater biodiversity and ecosystems. The guidance we provide will enable practitioners, policy makers, and resource stewards to embrace effective, sustainable, and evidence-based approaches to resource extraction. Response options for managing species exploitation include strengthening assessment and reporting, using science-based approaches to reduce overexploitation and support recovery, embracing community engagement, and building or tightening legislation. Response options for managing exploitation of freshwater aggregate resources include reducing demand for harvest, strengthening governance, reporting, and monitoring of environmental impacts, and promoting the restoration of degraded ecosystems or compensating for losses. Diverse case studies highlight examples of where various management actions have been implemented in an effort to consider how they can be scaled up and adapted to other contexts. Managing exploitation will be a key aspect of broader initiatives needed to protect and restore freshwater biodiversity around the globe.
Within the Laurentian Great Lakes, many native fishes use wetlands for spawning; however, these areas are also used by non-native common carp (Cyprinus carpio) that may impart negative ecological impacts. There is interest to manage common carp using barriers to decrease passage to specific habitats (e.g., their spawning sites), but these barriers could also exclude native wetland obligate spawners such as largemouth bass (Micropterus salmoides) and northern pike (Esox lucius). Our objective was to determine if differences in phenologies, specifically, spawning movements could be exploited in shallow areas to operate seasonal barriers that are opened and closed to promote selective fragmentation. Using a long-term dataset from the Cootes Paradise Marsh fishway (Hamilton, Ontario), we generated predictive models based on cumulative growing degree day (CGDD) for all three fishes. These models successfully predicted earlier arrival by all species in a warmer year and delayed spawning movements during a cold year, supporting the role of temperature as a driver of interannual variation in spawning movements. We then compared the fishway model predictions to movement timing to spawning habitat within nearby Toronto Harbour; movement data was derived from acoustic telemetry information. We found that the models performed well and predictions were correlated with movements of all three species, but performance was weakest for northern pike. It is our hope that managers could use these predictive models to assist in the operation of seasonal barriers to optimize control of non-native common carp, while minimizing negative impacts for native species that require access to coastal wetlands.
Permit (Trachinotus falcatus) support recreational fisheries in South Florida, and there is limited monitoring to assess population trends. To address this knowledge deficiency, we conducted a survey of Permit anglers and fishing guides to collect local ecological knowledge (LEK) on fisheries trends, focused mainly on the Florida Keys. Respondents indicated a significant decline in Permit fishing quality starting in 1995 and through 2019, with greater declines in the Upper Florida Keys and Biscayne Bay. Further, declines in Permit fishing quality were more pronounced on flats habitats compared to nearshore reefs and shipwrecks. Reduction in Permit body size, an indicator of fisheries overexploitation, was not reported. Specifically, there were no significant reported differences in Permit size across time and regions. Respondents indicated the greatest potential drivers of changes in fishing quality were water quality, boat traffic, and habitat quality. As a species that aggregates on reefs and shipwrecks to spawn but also relies on nearshore flats for foraging, Permit are potentially vulnerable to a wide range of stressors that need to be included in intervention and local fisheries management plans. Given the inherent challenges with implementing biological surveys for Permit, LEK derived from the recreational fishing sector represents an important source of knowledge, notwithstanding the biases that are associated with such approaches.
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