Observation by Ryan Bennett: Having spent the first 25 years of my life living, studying, working, and playing in the foothills of the Rockies to the West of Bragg Creek, Alberta, and less than a kilometre from the boundary of the vast tract of public land known as Kananaskis Country, I believe that I am quite attuned to environmental changes in this ecosystem. Given this time frame, It is quite fitting that Thomashow (2003) identified 25 years, or a generation, as the time span required to develop a sufficient familiarity with a particular ecological, and human community.
In the past 5-7 years, we have noticed a distinct increase in the amount of algae that would develop in the pond on our property during the summer. There had always been patches of it, like in any pond, but not to the point where portions of the pond would be nearly entirely covered by a thick mat (Figure 1). Around the same time, we also noticed increased signs of cattle herds present on the portion of public land directly adjacent to our property. Cattle grazing leases have been present in Kananaskis for generations (Government of Alberta, 2008, 2014). However, we had never seen substantial evidence of herds in the small watershed of the unnamed creek that flows off of Boundary Ridge (named for being the boundary of Kananaskis), and onto our property (Figure 2). We started hearing cattle up the hill, and even had a few get through the fence and wind up at our place from time to time. On my frequent wanderings up Boundary Ridge, I began seeing severe trampling, especially around the stream (Figures 5, 6), as well as seeing the cattle themselves from time to time (Figure 4). Figure 3 shows a portion of the stream without any evidence of disturbance, and this pristine image should be used as a baseline for a healthy riparian zone.
Hypothesis #1: The impact of cattle grazing on riparian nutrient loading has been well established, and has also been observed in this region (Jumpingpound Creek Watershed Partnership, 2009). The impact of nutrient loading on algal blooms, and the resulting aquatic trophic cascades has been well documented, as outlined by Schindler (1977), a pioneer in the field of algal ecology. I propose the hypothesis that the increased observed cattle activity upstream is causal to the increase in algae in our pond. - Ryan Bennett, Royal Roads University
Consult by Dr. Brad Stelfox [paraphrased by Ryan Bennett]: Dr. Brad Stelfox is a landscape ecologist, adjunct Biological Sciences faculty member at the University of Alberta, owner of the ALCES Group (a landscape use consultancy), and a family friend who lived only a couple kilometres south of the area in question for many years.
Brad’s comments were lengthy so the parts included in this posting are summaries of his key points. He acknowledges the widely accepted impact of cattle grazing on eutrophication dynamics of nutrient inputs into lotic systems, and he finds it fully plausible that increased cattle activity in the watershed is responsible for the increase in algae. He found the included images instructive. He added that there are two additional factors that may be jointly causal:
Hypothesis #2: Rural residential density in the Bragg Creek area has increased steadily in recent decades, and so has the human caused additions of nitrogen and phosphorous to surficial and groundwater systems via septic systems.
Hypothesis #3: Algal growth can also be affected by climatic variables such as precipitation and temperature. These are possible co-variates that might explain the temporal patterns in algal growth.
Dr. Stelfox added that should investigation into this phenomenon proceed any further, the first steps would be to produce a watershed map identifying surface connectivity between the pond and the grazing area upstream, as well as tracking down temperature and precipitation data for the area going back as far as necessary. Brad concluded by pointing out that the addition of nutrients to lotic systems due to cattle activity is occurring all across North America, and that this issue is deserving of much more attention that it currently gets.
Concluding remarks by Ryan Bennett: I believe that this is a perfect example of cumulative effects, and how the microsystem in my neck of the woods is a microcosm of global nutrient cycles. Rabalais, Turner, & Wiseman (2001) point out the severe hypoxia and eutrophication that has drastically altered the Gulf of Mexico ecosystem in the last half-century, due to agricultural runoff adding nutrients across the entire Mississippi watershed, which encompasses half of the Continental United States. This demonstrates the connections between local, regional, and continental scale processes.
References:
Government of Alberta. (2008). Draft Management Plan For Provincial Recreation Areas – Kananaskis Management Area. Government of Alberta - Tourism, Parks, and Recreation.
Government of Alberta. (2014). South Saskatchewan Regional Plan 2014 - 2024.
Jumpingpound Creek Watershed Partnership. (2009). Jumpingpound Creek State of the Watershed Report.
Rabalais, N. N., Turner, R. E., & Wiseman, W. J. (2001). Hypoxia in the Gulf of Mexico. J. Environ. Qual., 30, 320–329.
Schindler, D. W. (1977). Evolution of Phosphorous Limitation in Lakes. Science, 195, 260–262.
Thomashow, M. (2003). Chapter 4: A Place-Based Perceptual Ecology. In Bringing the Biosphere Home: Learning to Perceive Global Environmental Change (pp. 73–104).
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