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Compositional and functional homogenization of freshwater fish communities due to urbanization in the Greater Toronto Area
Compositional and functional homogenization of freshwater fish communities due to urbanization in the Greater Toronto Area
How do fish communities respond to urbanization?
How do fish communities respond to urbanization?
Results from a fourth-corner analysis of fish traits, sample site environmental data, and fish community composition. Colours: Blue β strong evidence for a positive relationship Light blue β moderate evidence for a positive relationship White β little evidence for any relationship Pink β moderate evidence for a negative relationship Red β strong evidence for a negative relationship. For instance, we have strong evidence that Riparian Natural Cover (Pct_Rip_NC) is negatively associated with low and high spawning temperature for fish: fewer plants around a stream means fish in that stream will likely have a higher temperature at which they spawn.Β
Plot of Shannon-Wiener (an index of biodiversity) by invasive to native species ratio (closer to 1 β more invaders) and coloured by richness (a different measure of biodiversity). As more invaders are present, biodiversity tends to decline nonlinearly, but there is variation in how strong this relationship isΒ
Supervised by Dr. Jonathan Ruppert and with assistance from Dr. Andrew Chin at the Toronto and Region Conservation Authority (TRCA), I conducted a computational biology project aiming to understand how fish communities in streams across the 9 watersheds in the Greater Toronto Area (GTA) change in response to urban development. Specifically, I applied co-ordination, co-inertia, and multivariate modelling analyses to fish community composition, environmental trait data, and species trait data to understand the impacts of urbanization and invasive species abundance on the compositional and functional diversity of fish communities around the GTA.
I found that urban development was associated with decreased biodiversity both in terms of community composition (i.e. species present) and function (i.e. species traits present). I also found that urban development was associated with higher invasive species abundance, which in turn further decreased community diversity.
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