Recommendations for Ongoing and Future Studies

Old Crow Flats

Based on paleolimnological analyses and aerial images from the OCF, Chapter 2 was able to identify lake drainage as the cause of a water-level decline in OCF 48. However, the

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OCF is a vast heterogeneous landscape with lakes that span broad hydrological gradients (Turner et al., 2010; 2014). Thus, information is needed to determine whether the knowledge gained from analyses at Lake OCF 48 is representative of other lakes in the OCF, including lakes with different modern-day hydrological conditions. OCF 48 has previously been classified as a lake that oscillates between snowmelt- and rainfall-dominated hydrological categories (Turner et al., 2010), but other lakes exist solely in each of these groups as well as in an evaporation-dominated category (Turner et al., 2010). Consequently, it is important to test whether lake-drainage is the cause of the apparent wide-spread water-level declines in lakes from all hydrological categories (rainfall-, snowmelt- or evaporation-dominated), or if the cause of previous water-level declines is related to the modern day hydrological

conditions. This is particularly important as there will be different consequences for the environment and community depending on whether lake-drainage or lake-evaporation is the dominant cause of the wide-spread declines.

To date, the template established in Chapter 2 (Figure 6.1) has been used to assess for water-level declines due to lake-drainage or lake-expansion in six other lakes in the OCF which span a larger hydrologic gradient (Shaker, 2011; Tondu, 2012; Turner, 2013). Lake expansion and drainage cycles were identified for each of the six lakes, but with variable timing. This suggests that each lake has different threshold levels that trigger drainage and independent factors or catchment characteristics (e.g., vegetation) that control the timing and length of each phase. Research by Turner et al. (2014) has also since shown the importance of catchment vegetation in the contemporary hydrology of OCF lakes, thus this factor may in fact play an important role in determining which lakes follow the expansion-drainage

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Collecting information from a larger number of lakes spanning the OCF using the quick LOI method would be an efficient and useful way to establish the potential dominance of lake expansion-drainage cycles in the landscape. Records from additional lakes would allow the refinement of baselines developed in this thesis (i.e., length of cycles, or frequency of

drainage). Aerial images could also be combined with these studies to help identify lakes that have experienced a water-level decline and narrow down the time frame needed for

paleolimnological studies.

Hudson Bay Lowlands

Given that Chapter 3 and Chapter 4 focused on only one and two LSG-disturbed ponds, respectively, it is important to test the results and the suggested protocols from this thesis on a larger data set with more LSG-disturbed ponds and over multiple years with different meteorological conditions. Using the results of Chapter 3 and Chapter 4, I worked with Parks Canada to help design a monitoring program for summers 2014 and 2015 that would help refine approaches with a larger dataset. While setting up this monitoring program in June 2014, the field team spoke with Rocky Rockwell, a waterfowl biologist and LSG expert, about the LSG population expansion. He informed us that in addition to the areas actively used and disturbed by LSG, where LSG disturbed ponds from Chapter 3 and 4 were located, there is an area within the coastal fen that has been so severely degraded that it has been depleted of vegetation to the point of abandonment by the LSG (Figure 6.4). Taking this information into account, I helped to select 15 new ponds for Parks Canada in June 2014 to track the effects of LSG disturbance and test and refine approaches recommended in this thesis (Figure 6.5). We selected five new non-disturbed ponds to act as controls, five actively

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LSG disturbed ponds that had a similar visual state to WAP 20 and WAP 21 and five severely disturbed ponds from the area identified by Rocky Rockwell. These severely degraded ponds were added to see if the suggested protocols were also effective in this new class of ponds. Additionally, it would help identify if there is any evidence of recovery to, or towards the pre-disturbance state after the LSG left, or if recovery to this point has been non- existent. Data from this thesis and the 15 new ponds will help test and refine approaches that are planned to be implemented in a new study of ~30 LSG disturbed ponds in July 2015. For this ongoing monitoring program, a suite of key indicators and pond responses that most effectively tracked the effects of the LSG population expansion and disturbance in Chapters 3 and 4 were recommended to Parks Canada (Table 6.1). Emphasis was placed on carbon isotope measurements (δ13

CDIC and Δ13CDIC-POM), as they were far more informative than the standard limnological variables in capturing differences in between the disturbed and non- disturbed ponds. With ongoing monitoring by Parks Canada, results will continue to help refine approaches and track the effect of stressors on ponds in WNP. These tools may also be applicable in other northern wetlands facing the stress of waterfowl population expansion. Tracking the effects of waterfowl disturbance on carbon cycling in the North is particularly important as these northern wetlands play influential roles in the carbon cycle, and if LSG disturbance in WNP and waterfowl disturbance in other locations continues to grow, there may be potential for large-scale shifts in the carbon cycle and balance.

With continued climate warming, WNP is likely to become increasingly dynamic, which may lead to altered carbon behaviour in this landscape in addition to changes from LSG disturbance in the coastal fen. WNP spans additional vegetation zones (interior peat plateau palsa bog and boreal spruce forest) and lies in regions of both continuous and

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discontinuous permafrost (Rouse, 1991). Permafrost is a large carbon store and concerns exist with the effects of continued climate change on permafrost thaw and the consequences of this to the carbon budget (Schuur et al., 2008; Zimov et al., 2008). Additionally, increased thermokarst activity as a result of climate warming may influence carbon dynamics through the transfer of terrestrial carbon to aquatic systems by peat erosion and pond expansion (Kling et al., 1991; 1992; McGuire et al., 2009). Also, increased wetness or dryness of the landscape could occur through pond expansion or pond drainage and desiccation, resulting in increased CH4 and CO2 emissions, respectively (Edwards et al., 2009; McGuire et al., 2009; van Huissteden et al., 2011). Chapter 3 and 4 of this thesis have indicated that carbon cycling of ponds is sensitive to LSG disturbance and it would stand to reason that throughout a broad, dynamic park like WNP, there may also be changes in carbon behaviour spatially and in response to different stressors. As carbon cycling is a very important aspect of northern wetlands, future studies should focus on identifying the controls on carbon pathways in WNP ponds at a landscape scale.

To identify controls on carbon pathways in WNP ponds, repeated measurements of the carbon isotope composition of dissolved inorganic carbon (δ13CDIC), as well as a range of limnological parameters and water isotope compositions were collected from 36 ponds from the different ecozones of WNP over three years (2010-2012) to assess influence of internal and external factors on carbon behaviour. Preliminary results show that the ponds possessed a very broad range of δ13

CDIC values, spanning -29.5‰ to +1.8‰, suggesting that this is a sensitive index of pond carbon balance. Spatial variability was substantial, and exceeded seasonal variability of individual ponds. Coastal fen ponds had the highest δ13CDIC values (range: -12.0 to +1.8‰; mean: -3.4‰), followed by the boreal spruce forest ponds (range: -

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18.5 to -2.4‰; mean: -10.8‰) and the interior peat plateau palsa bog ponds which had the lowest mean δ13

CDIC value (-13.3‰) but spanned a considerable range (-29.5 to -0.6‰). The high δ13

CDIC values in the coastal fen ponds can be attributed to atmospheric CO2 exchange, which provides a 13C-enriched source of carbon to the ponds. Supporting this interpretation are water isotope data, which indicate that these ponds tend to receive low amounts of snowmelt runoff and likely low supplies of soil-derived 13C-depleted DIC due to catchments with sparse tundra vegetation. Water isotope data and mid-range δ13CDIC values suggest that boreal spruce forest ponds receive greater snowmelt runoff and soil-derived 13C-depleted DIC from their more densely vegetated catchments, but are also likely influenced by productivity-driven 13C-enrichment. The broad range of δ13CDIC values for the interior peat plateau palsa bog ponds appears to be associated with variation in pond size. The large interior peat plateau palsa bog ponds had relatively high δ13CDIC values (range: -8.1 to -0.6‰; mean: -4.2‰), which were similar to coastal fen ponds and may also suggest that

atmospheric CO2 exchange is the dominant pathway that supplies carbon to these ponds. In contrast, the small interior peat plateau palsa bog ponds had low δ13CDIC values (range: -29.5 to -20.0‰; mean: -24.0‰), which can be attributed to the input of soil-derived 13C-depleted DIC and possibly high rates of organic matter respiration in the pond water column. These preliminary findings suggest that external and internal factors (e.g., catchment vegetation, hydrology, productivity, respiration) are drivers of carbon balance in ponds of WNP. How these factors respond to ongoing climate warming will have a strong influence on pond carbon balance.

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Slave River Delta

Although research presented in Chapter 5 has shown no evidence of enhanced metal concentrations since onset of oil sands development, studies closer to the facility have shown elevated deposition of metals and PAHs within an approximately 50-km radius of a central point where upgraders are concentrated (e.g., Kelly et al., 2009; 2010). Therefore, future studies are important and should focus on study sites closer to the Alberta oil sands. This thesis and previous research (Chapter 5, Hall et al. 2012, Wiklund et al. 2014) have identified that sediment records contained in floodplain lakes provide a valuable source of information for characterizing pre-development baseline concentrations, and assessing temporal patterns of change for evidence of pollution. However, this thesis also illustrated that knowledge of the flood history of SD2 was crucial in assessing pollution and determining important vectors and sources. Future studies in complex and dynamic depositional environments closer to the Alberta oil sands should ensure they incorporate paleohydrological information. This would allow researchers to quantify the relative importance of natural versus industrial supplies.

Given that Chapter 5 focused on only one lake, SD2, it remains unknown if the findings from SD2 are representative of other lakes in the SRD and best represent the sediment quality of the Slave River. SD2 is a flood-dominated lake, but one that has not flooded frequently since ~2000 when development of oil sands has accelerated.

Consequently, it would be important to sample another lake that has had more frequent and recent flooding to confirm that the Slave River is not an important vector for the transport of contaminants from the Alberta oil sands to the SRD. Additionally, given that the SRD is a heterogeneous and dynamic landscape with lakes that span broad hydrological categories (Brock et al., 2007), future studies should focus on sampling lakes in other hydrological