Geographic patterns of the climate sensitivity of lakes

Abstract

Climate change is a well‐recognized threat to lake ecosystems and, although there likely exists geographic variation in the sensitivity of lakes to climate, broad‐scale, long‐term studies are needed to understand this variation. Further, the potential mediating role of local to regional ecological context on these responses is not well documented. In this study, we examined relationships between climate and water clarity in 365 lakes from 1981 to 2010 in two distinct regions in the northeastern and midwestern United States. We asked (1) How do climate–water‐clarity relationships vary across watersheds and between two geographic regions? and (2) Do certain characteristics make some lakes more climate sensitive than others? We found strong differences in climate–water‐clarity relationships both within and across the two regions. For example, in the northeastern region, water clarity was often negatively correlated with summer precipitation (median correlation = −0.32, n = 160 lakes), but was not correlated with summer average maximum temperature (median correlation = 0.09, n = 205 lakes). In the midwestern region, water clarity was not related to summer precipitation (median correlation = −0.04), but was often negatively correlated with summer average maximum temperature (median correlation = −0.18). There were few strong relationships between local and sub‐regional ecological context and a lake's sensitivity to climate. For example, ecological context variables explained just 16–18% of variation in summer precipitation sensitivity, which was most related to total phosphorus, chlorophyll a, lake depth, and hydrology in both regions. Sensitivity to summer maximum temperature was even less predictable in both regions, with 4% or less of variation explained using all ecological context variables. Overall, we identified differences in the climate sensitivity of lakes across regions and found that local and sub‐regional ecological context weakly influences the sensitivity of lakes to climate. Our findings suggest that local to regional drivers may combine to influence the sensitivity of lake ecosystems to climate change, and that sensitivities among lakes are highly variable within and across regions. This variability suggests that lakes are sensitive to different aspects of climate change (temperature vs. precipitation) and that responses of lakes to climate are heterogeneous and complex.

Differential Responses of Maximum Versus Median Chlorophyll‐a to Air Temperature and Nutrient Loads in an Oligotrophic Lake Over 31 Years

“…Our work also highlights that oligotrophic lakes may be particularly sensitive to the combined threat of climate and land-use change. Similar to findings in other studies (e.g., Ho et al, 2019), there is mounting evidence that oligotrophic lakes are particularly sensitive to a changing climate separate from land-use-induced increases in nutrient load (Carey, Ibelings, et al, 2012;McCullough et al, 2019;Oleksy, 2019;Sadro et al, 2019). Our scenario analysis indicates that increased nutrient load in combination with higher air temperature had the greatest effect on chlorophyll-a concentration ( Figure 6), furthering the evidence of the dual threat of climate and land-use change.…”

The role of warm, dry summers and variation in snowpack on phytoplankton dynamics in mountain lakes

“…In North American lakes located in regions with less topographic complexity, heterogeneity in factors like landscape cover, lake morphometry, and nutrient loading can lead to large variation in responses to the same climatic drivers (Rose et al 2016, McCullough et al 2019). In the southern Rocky Mountains, lake locations in small headwater basins with low vegetation cover, short open‐water seasons, and extreme topographic relief seems to simplify the drivers of lake phytoplankton down to weekly precipitation (or lack thereof), monthly and daily temperatures, and a few morphometric characteristics.…”

Lake Water Levels and Associated Hydrologic Characteristics in the Conterminous U.S.

“…Two years of observations is insufficient to detect associations between lake hydrologic characteristics and climate over time. In addition, climate effects on lakes at broad spatial extents are highly variable due to underlying lake, watershed, and regional variation (McCullough et al 2019). Environmental factors such as lake morphology and freshwater-linkages may interact with land cover and water management to affect lake hydrology in unexpected ways.…”