Deeper waters are changing less consistently than surface waters in a global analysis of 102 lakes

Abstract

Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either surface water temperatures or thermal stability within lakes, and only 8.4% was explained by lake thermal region or local lake characteristics in a random forest analysis. These findings suggest that external drivers beyond our tested lake characteristics are important in explaining long-term trends in thermal structure, such as local to regional climate patterns or additional external anthropogenic influences.

Climate change drives widespread shifts in lake thermal habitat

“…Similarly, some species of Daphnia, a common herbivorous zooplankton genus, partially rely on photoperiod as a cue for diapausing eggs to develop in spring, thereby limiting their capacity to track earlier phytoplankton blooms as lake temperatures change 39,40 . Anoxic zones may hinder for a model lake with an average temperature increase of 1.14 °C between baseline (a) and recent (b) time intervals, consistent with known warming trends (1980s to 2010s) 1,17,24,56 . c-f, White dashed lines delineate expected habitats for three model taxa which are ecologically restricted in their depth (species 1 (d); a hypothetical low-light specialist phytoplankton), seasonality (species 2 (e); a spring migratory fish) and both depth and seasonality (species 3 (f); a diapausing benthic invertebrate).…”

Depth diversity gradients of macrophytes: Shape, drivers, and recent shifts

“…In fact, climate and land use change influence all the highly connected chemical and physical gradients known to significantly affect DDG (Hossain et al., 2017 ). Thus, the following hypotheses can be formulated (Figure 4 ): (1) As temperatures rise, so do lake surface water temperatures (O'Reilly et al., 2015 ; Pilla et al., 2020 ). This seems to result in shallower epilimnion (Kraemer et al., 2015 ) and generally shallower D max and a lower R max .…”

Response of Aquatic Organisms Communities to Global Climate Changes and Anthropogenic Impact: Evidence from Listvennichny Bay of Lake Baikal

“…Climate warming can change species composition and energy flow in aquatic ecosystems. Globally, lake water temperatures (based on analysis of 102 lakes, including Baikal) have warmed rapidly relative to air temperatures, with significant increases in lake surface water temperatures found at an average rate of +0.37 °C decade −1 , but trends in deep-water temperatures have shown little change [ 5 ]. In this regard, we focused our study on the species composition of aquatic organisms communities in the water column and at the bottom in the coastal zone of Lake Baikal, which is well heated in summer.…”

“…A rise in global surface temperature affects the wind speed, precipitation regime, occurrence of drought and fires on the planet, and the rise of the water level in the World Ocean. At the same time, warming climates are transforming lake ecosystems worldwide [ 5 , 6 ]. For example, due to climate change, Lake Biwa has also exhibited an increase in its water temperature and a shift in its trophic status.…”