Motivation: One of the key threats to lake biota from climate change is the prospect of expanding or contracting the thermal niche breadth within lakes. Thermal tolerances restrict the habitat available to thermal specialists in lakes, making them highly susceptible to warming. The expansion of thermal niche breadth within a lake could lead to the introduction of thermal specialists that previously could not live there. However, if lake thermal niche breadth is contracting, lakes may lose thermal specialists, resulting in the loss of their associated ecosystem functions. Such community shifts could lead to new species interactions and ecological surprises.
Question and Approach: Here we will use long-term temperature data to determine whether global lakes tend to have disappearing or appearing thermal niches. We will assess which thermal ranges are shifting most at the global scale. We will also assess which specific lake types have the largest losses or gains in thermal niche breadth. To determine whether the appearance or disappearance of thermal niches actually leads to the appearance or disappearance of species, we will validate our approach using long-term species abundance data from 5-10 lakes where such data are available.
-Long-term (approximately 30+ years) time series of temperature profile data from lakes. Longer time series will also be included. Time series will ideally be measured at least weekly through the full year. But, time series composed of fewer temperature profiles per year, or single profile measurements during open-water seasons will be also be accepted. Data gaps of up to approximately 5 years will be accepted. Profiles must consist of at least two measurements—one measurement at or near the surface and one measurement at or near the bottom of the lake. High resolution measurements across depth which capture the thermocline are preferable.