Introduction
The data used in this study is part of my larger thesis research which looks at how a variety of stormwater pond habitat variables impact aquatic beetle and water boatman communities and how the communities in these habitats compare to non-urban ponds across Alberta. In order to make connections between water chemistry and aquatic invertebrate communities, I am first interested in investigating what differences and similarities are apparent between the habitats themselves. Which is where this project comes in.
Background
As cities grow, wetlands tend to disappear. And with them, we lose a multitude of ecosystem services. These services, including the wildlife habitat they provide, are sometimes replaced by stormwater management ponds (Hassall & Anderson, 2015). Studies from around the world have found that stormwater ponds can support a diversity of species equal to or sometimes greater than natural wetlands in the same region (Hassall & Anderson, 2015; Vermonden et al, 2009; Le Voil, 2009).
My study investigates how Edmonton's urban invertebrate communities and their biodiversity compare to natural ponds in Alberta. I am particularly interested in what habitat characteristics influence these communities.
Shoreline vegetation, pond connectivity, pond age, and water chemistry are known to impact invertebrate communities (Hassall & Anderson, 2015; Hassall et al., 2011). For the purposes of the statistical analysis described on this website, I will be focusing on pond type (for which different pond types include different vegetation and naturalization levels), pond age, and water chemistry.
In Edmonton, certain types of stormwater ponds are undergoing, or have previously undergone, naturalization. This involves planting vegetation around ponds, allowing natural vegetation to grow in, and ending the practice of mowing grass buffers (City of Edmonton, 2021). A diversity of vegetation on the shore has been shown to have a positive effect on invertebrate species richness and diversity with varying levels of significance ((Vermonden et al., 2009; Noble & Hassall, 2014; Hassall et al., 2011)). Water chemistry has complex effects on invertebrate communities in stormwater ponds (Hassall and Anderson, 2015; Hassall et al., 2011; 2020; Hill et al., 2015). In some cases, water conductivity and pH was found to be associated with lower diversity overall and was significantly higher in SWMPs than in unmanaged rural ponds (Hassall and Anderson, 2015; Hill et al., 2005).
In order to make connections between water chemistry and aquatic invertebrate communities, I am first interested in investigating what differences and similarities are apparent between the habitats themselves. Which is where this project comes in.
My study investigates how Edmonton's urban invertebrate communities and their biodiversity compare to natural ponds in Alberta. I am particularly interested in what habitat characteristics influence these communities.
Shoreline vegetation, pond connectivity, pond age, and water chemistry are known to impact invertebrate communities (Hassall & Anderson, 2015; Hassall et al., 2011). For the purposes of the statistical analysis described on this website, I will be focusing on pond type (for which different pond types include different vegetation and naturalization levels), pond age, and water chemistry.
In Edmonton, certain types of stormwater ponds are undergoing, or have previously undergone, naturalization. This involves planting vegetation around ponds, allowing natural vegetation to grow in, and ending the practice of mowing grass buffers (City of Edmonton, 2021). A diversity of vegetation on the shore has been shown to have a positive effect on invertebrate species richness and diversity with varying levels of significance ((Vermonden et al., 2009; Noble & Hassall, 2014; Hassall et al., 2011)). Water chemistry has complex effects on invertebrate communities in stormwater ponds (Hassall and Anderson, 2015; Hassall et al., 2011; 2020; Hill et al., 2015). In some cases, water conductivity and pH was found to be associated with lower diversity overall and was significantly higher in SWMPs than in unmanaged rural ponds (Hassall and Anderson, 2015; Hill et al., 2005).
In order to make connections between water chemistry and aquatic invertebrate communities, I am first interested in investigating what differences and similarities are apparent between the habitats themselves. Which is where this project comes in.
Stormwater Ponds
Water Chemistry
I have chosen four main water characteristics to examine. This includes measures of conductivity, heavy metal content, pH, and suspended sediments. These characteristics have been chosen as they have all been shown to have variable effects on the biodiversity, species richness, and/or rarity of my focal taxa of aquatic invertebrates, Corixidae and Dytiscidae (Hassall & Anderson, 2014; Biggs, 2005).
Hypotheses
Hypothesis 1: I hypothesize that there will be fewer suspended sediments in natural or naturalized ponds types as these ponds contain a greater biomass of vegetation to intercept sediment. But I do not expect there to be any significant differences between pond type and other water chemistry parameters as land use is highly variable between ponds and thus, I expect water chemistry to look different depending on the nearby human infrastructure.
Hypothesis 2: I hypothesize that with increasing age, ponds will have higher amounts of total heavy metal content, as some heavy metals may build up over time. I also hypothesize that suspended solids will decrease with increasing pond age as older ponds tend to have a greater amount of vegetation that could intercept sediment.
If pond type has little influence on water chemistry parameters, that can tell us how correlated different variables are in our project. Later, when I look at invertebrate diversity in these ponds, I want to know if pond type is a relatively independent variable, or whether it has a significant impact on water chemistry parameters that may need to be analyzed as a covariate. Untangling these likely confounding interactions will require multiple levels of analysis to determine the best way to go about determining which habitat variables are most influential on invertebrate diversity. My larger objective for conducting this analysis is to rule out variables that appear to be having marginal impacts on the habitat as a whole.
Additionally, determining the influence of pond age on water chemistry parameters will be important to management as it will tell us if it is worth putting increased protections and management effort around old stormwater ponds if they turn out to be healthier habitats over time. It can also tell us what we can expect our urban habitats to look like in ten or twenty years time.