A Synopsis of Global Mapping of Freshwater Habitats and Biodiversity: Implications for Conservation

Abstract

Accurately mapping freshwater habitats and biodiversity at high-resolutions across the globe is essential for assessing the vulnerability and threats to freshwater organisms and prioritizing conservation efforts. Since the 2000s, extensive efforts have been devoted to mapping global freshwater habitats (rivers, lakes, and wetlands), the spatial representation of which has changed dramatically over time with new geospatial data products and improved remote sensing technologies. Some of these mapping efforts, however, are still coarse representations of actual conditions. Likewise, the resolution and scope of global freshwater biodiversity compilation efforts have also increased, but are yet to mirror the spatial resolution and fidelity of mapped freshwater environments. In our synopsis, we find that efforts to map freshwater habitats have been conducted independently of those for freshwater biodiversity; subsequently, there is little congruence in the spatial representation and resolution of the two efforts. We suggest that global species distribution models are needed to fill this information gap; however, limiting data on habitat characteristics at scales that complement freshwater habitats has prohibited global high-resolution biogeography efforts. Emerging research trends, such as mapping habitat alteration in freshwater ecosystems and trait biogeography, show great promise in mechanistically linking global anthropogenic stressors to freshwater biodiversity decline and extinction risk.

The freshwater biome gradient framework: predicting macroscale properties based on latitude, altitude, and precipitation

“…For example, far less is known about tropical waters than temperate ones with respect to diversity and ecosystem rates. Another key issue is mapping biodiversity at the appropriate scale (McManamay et al 2018). Many biotic characteristics (e.g., food chain length, food web connectivity, rates of production and decomposition, endemism, and omnivory) have been poorly studied across broad spatial scales.…”

Threats of global warming to the world’s freshwater fishes

“…In general, organisms may adapt to climate change (or escape from future extremes) by moving to more suitable locations 53 . Accounting for this possibility is challenging due to the uncertainties and data gaps associated with current and future barriers in freshwater systems (e.g., dams, weirs, culverts, sluices) 54 . In addition, data needed to reliably estimate dispersal ability is still lacking for the majority of the species 55 .…”

Anthropogenically driven climate and landscape change effects on inland water carbon dynamics: What have we learned and where are we going?

“…Third, small waterbodies, including headwater streams and ponds, are hotspots of C cycling, especially emissions (Holgerson & Raymond, 2016; Rosentreter et al, 2021), but their role globally remains difficult to accurately assess given the limitations of satellite imagery in quantifying their areal coverage (McManamay et al, 2018). Ponds likely have high C burial, with man‐made agricultural ponds having among the highest rates of C burial across all lentic waterbodies (Downing et al, 2008; Mendonça et al, 2017; Taylor et al, 2019).…”