Long-term oxygen conditions assessed using chironomid assemblages in brook trout lakes from Nova Scotia, Canada

Topical advances and recent studies in paleolimnological research

“…They applied these modern analogs to core samples from a eutrophic lake and demonstrated that this approach could be used to document past food web community composition, to infer historic linkages, and to assess long-term changes in food web structure and function. Kurek et al (2012) used fossil chironomids to assess pre-industrial hypolimnetic oxygen concentrations in a series of lakes in Nova Scotia, Canada to determine if there was evidence of declining water quality that might have impacted brook trout (Salvelinus fontinalis) populations, as suggested by contemporary limnological data. Fossil data showed evidence of stable chironomid assemblages since pre-indus- These studies highlight the importance of using paleolimnological data in conjunction with modern limnological sampling to address concerns about changes in water quality and food web structure.…”

Establishing past environmental conditions and tracking long-term environmental change in the Canadian Maritime provinces using lake sediments

“…The pre-industrial chironomid assemblage also showed that deepwater O 2 levels are likely naturally low in these lakes and have not deteriorated significantly since pre-industrial times (Kurek et al 2012). Overall, this study suggested that efforts to enhance brook trout angling in Nova Scotia should focus on lakes that provide better than marginal habitat, as climate warming is likely to enhance problems with deepwater O 2 in lakes of only marginal habitat suitability (Kurek et al 2012).…”

“…However, it is difficult to ascertain how effective these spot measurements are for reflecting annual variability, and a longer-term perspective was needed to assess water quality deterioration and set mitigation goals for these lakes. Consequently, a subset of 12 lakes from the initial water quality survey was analyzed for larval chironomid remains (Kurek et al 2012), as chironomids are effective paleolimnological indicators of deepwater oxygen (Quinlan and Smol 2002). The results of this study suggested that chironomid assemblages have been remarkably stable since pre-industrial times and no major changes in hypolimnetic O 2 were inferred (Kurek et al 2012).…”

“…Consequently, a subset of 12 lakes from the initial water quality survey was analyzed for larval chironomid remains (Kurek et al 2012), as chironomids are effective paleolimnological indicators of deepwater oxygen (Quinlan and Smol 2002). The results of this study suggested that chironomid assemblages have been remarkably stable since pre-industrial times and no major changes in hypolimnetic O 2 were inferred (Kurek et al 2012). The pre-industrial chironomid assemblage also showed that deepwater O 2 levels are likely naturally low in these lakes and have not deteriorated significantly since pre-industrial times (Kurek et al 2012).…”

“…To address many of the major water-quality issues facing freshwater resources in the Maritime provinces, a large number of paleolimnological studies have recently been conducted in Nova Scotia and southern New Brunswick (e.g., Harris et al 2006;Ginn et al 2007b;Korosi and Smol 2012a;Kurek et al 2012) (Fig. 1).…”