The alarming state of freshwater biodiversity in Canada

Abstract

Little is known about the current state of freshwater biodiversity in Canada, one of the countries with the greatest amount of surface waters in the world. To address this knowledge gap, we compiled a list of all available assessments of conservation status for freshwater species (over 3,000 taxa) and further evaluated the overall status of six distinct taxonomic groups, focusing on organisms reliant on freshwaters [i.e., aquatic plants, invertebrates (with a focus on freshwater mussels), fishes, herpetofauna (reptiles and amphibians), birds, and mammals]. Overall, 11.7% of all freshwater species of plants and animals assessed were found to be ‘at risk’ (i.e., listed as ‘Threatened’, ‘Endangered’, or ‘Extirpated’) and 17.9% identified as ‘Special Concern’. We found that 37.9% of species lacked sufficient data to enable their status to be assessed. Data gaps in Canada’s assessment of its freshwater species were most prevalent in invertebrates (excluding freshwater mussels). Given the alarming state of freshwater biodiversity in Canada, we conclude by providing recommendations that focus on evaluating temporal trends and informing conservation actions.

Comparative analysis of zooplankton diversity in freshwaters: What can we gain from metagenomic analysis?

“…This is especially the case for freshwaters, where monitoring efforts are limited and yet provide habitat for a disproportionate number of taxa per unit area (Strayer & Dudgeon, 2010). Currently, there are insufficient observational data for many taxa such that we cannot even assess the state of at least ~40% of freshwater species in Canada (Desforges et al, 2022). Initiatives to improve sequencing coverage of eukaryotic biodiversity are underway, including the Barcode of Life Data System (BOLD) (Ratnasingham & Hebert, 2007), the International Barcode of Life (IBOL) (https://ibol.org/), the Earth BioGenome Project (https://www.earthbiogenome.org/), i5K for arthropods (Robinson et al, 2011), and Diat.barcode for Diatoms (Rimet et al, 2019).…”

“…This is especially the case for freshwaters, where monitoring efforts are limited and yet provide habitat for a disproportionate number of taxa per unit area (Strayer & Dudgeon, 2010). Currently, there are insufficient observational data for many taxa such that we cannot even assess the state of at least ~40% of freshwater species in Canada (Desforges et al, 2022).…”

Effects of generations in captivity and elevated rearing temperature on Ontario hatchery brook trout (Salvelinus fontinalis) fry quality and survival

“…Climate change is causing increased rates of declines in cold-water adapted species such as salmonids (Myers et al, 2017). To combat the trends in decreasing populations, captive breeding programs have been put into place (Desforges et al, 2022; Rytwinski et al, 2021), yet introduce a new suite of domestication conditions (Farquharson et al, 2021) that either selects for individuals to become optimally adapted to these benign conditions – and subsequently unable to cope with extraneous stressors, or reduces reproductive fitness through various means. Temperature stressors (intentional hatchery practices for conservation and/or production efficiency) along with captive-selection pressures are known to interact and further reduce fitness of salmonids when released into wild settings (Kostow, 2004).…”

“…Climate change has been predicted to increase air and water temperatures globally (Creed et al, 2017), with freshwater aquatic ecosystems particularly vulnerable because of their dependency on air and precipitation temperatures combined with higher levels of human use (relative to size) compared to marine systems (Bunn, 2016; Cook, Burness, et al, 2018; Hanna et al, 2018; Potts et al, 2021; Stitt et al, 2014; Woodward et al, 2010). Effects are especially impactful on cold-water adapted freshwater species, including the economic- and culturally important salmonid group of fishes which have shown declines in abundance that are 64% higher than projected due to a combination of elevated water temperatures and loss of suitable habitat (Creed et al, 2017; Desforges et al, 2022; Lake et al, 2000; Myers et al, 2017). Specifically, elevated temperatures have been shown to impact the reproductive performance and survival of salmonids via multiple mechanisms: increased metabolic rates forcing energetic reallocation to homeostasis versus reproduction (Fenkes et al, 2016); the inhibition of production of hormones required for gonadogenesis reducing the overall reproductive potential of fishes (King et al, 2007; Pankhurst & King, 2010); and accelerated and subsequent underdeveloped hatch state of eggs (Baird et al, 2002; Hayes et al, 1953; McDermid et al, 2012).…”

Morphological description and life history of the Philippine endemic Limnonectes leytensis Leyte swamp frog in Rogongon, Iligan City, Philippines

“…Apart from this, they are also considered one of the most effective indicators of ecological health (Guzy et al 2012). Frogs being amphibians, are among the planet's most threatened taxa, which puts most of the species vulnerable to becoming extinct (Desforges et al 2022). They are also less mobile, have smaller home ranges, and thus may be affected with a greater impact through alteration of their habitat (Beebee 2013).…”