Freshwater fish functional and taxonomic diversity above and below Niagara Falls

Abstract

The Niagara River, which connects two Great Lakes (Erie and Ontario) and forms a border between Canada and the United States, has experienced decades of abiotic and biotic disturbance as well as long-term restoration efforts. Given the iconic riverscape and importance as a binational fisheries resource, a biodiversity assessment of the mainstem Niagara River fish assemblage is overdue. Here, fish assemblage and habitat data from a standardized boat electrofishing program of the Niagara River were combined with species trait data related to substrate associations, diet preferences, reproductive strategies, and body size to quantify biodiversity patterns among river sections (sites above and below Niagara Falls), seasons (spring, summer, fall), and years (2015–2017). Sixty-five species were captured representing a variety of trait combinations. Significant differences in functional dispersion and divergence (i.e., functional diversity) were observed between river sections, seasons, and (or) years. The fish community captured in the lower river in spring 2015 had both the highest average functional dispersion (2.08 ± 0.32 SD) and divergence (0.88 ± 0.04 SD) compared to the other seasonal sampling efforts, but relatively few fishes were captured (n = 686). Although non-native fishes represented a small portion of the catch over the 3 years (8.6% of catch), the seasonal presence (spring and fall) of mostly introduced large-bodied salmonids expanded functional trait space in the lower river during these periods. The importance of rare species on functional diversity metrics suggests further insight on local species detection probabilities is needed to understand if differences in functional diversity reflect ecological patterns or are driven by sampling design.

Intraspecific diversity of threespine stickleback (Gasterosteus aculeatus) populations in eastern Canada

“…In the roughly 10-12.4 thousand years since becoming established in eastern Canada, threespine stickleback have spread across the coastal regions of the Atlantic and Hudson Bay drainages. Populations can be found as far south along the Atlantic coast as the Chesapeake Bay in the United States, north to Baffin Island, west to the northwestern edge of Hudson Bay and inland to Nueltin Lake in Nunavut, and up the Great Lakes-St. Lawrence River Basin to Niagara Falls or Lake Ontario, as they may be absent from the lower Niagara River (Oliver 1964;Scott and Crossman 1973;Lee et al 1980;McKillop and McKillop 1997;Lamothe et al 2021). Threespine stickleback are typically anadromous-spawning in freshwater and then migrating out to sea-and have established numerous freshwater populations across their eastern North American range.…”

Intraspecific diversity of threespine stickleback (Gasterosteus aculeatus) populations in eastern Canada

“…In the roughly 10-12.4 thousand years since becoming established in eastern Canada, threespine stickleback have spread across the coastal regions of the Atlantic and Hudson Bay drainages. Populations can be found as far south along the Atlantic coast as the Chesapeake Bay in the United States, north to Baffin Island, west to the northwestern edge of Hudson Bay and inland to Nueltin Lake in Nunavut, and up the Great Lakes-St. Lawrence River Basin to Niagara Falls or Lake Ontario (Oliver 1964;Scott and Crossman 1973;Lee et al 1980;McKillop and McKillop 1997;Lamothe et al 2021). Threespine stickleback are typically anadromous-spawning in freshwater and then migrating out to sea-and have established numerous freshwater populations across their eastern North American range.…”