Does Environmental Warming Increase Invasion of Alpine Zooplankton Communities by Montane Species?
A 28-Day Warming Experiment
An experiment was completed using zooplankton from an alpine lake (Pipit Lake, Banff National Park) to determine if an increase in dispersal potential and water temperature (+7°C) would facilitate invasion by species from montane lakes.
The experiment used 18 aquaria at each of two temperatures, 13 °C and 20 °C. The hottest temperature corresponded with a modeled prediction of climate warming in mountain regions, and the colder temperature approximates an average summer day in an alpine lake. The three treatments were:
- Control: Alpine Species Only
- Invaded: Alpine and Montane Species
- Filtered and Invaded: Only Montane Species
Preliminary results show that warming suppresses the predatory species H. arcticus, which facilitates colonization by montane species, but only if they can overcome dispersal barriers that preclude them from alpine lakes even though they appear to be able to thrive if placed into this type of environment. The herbivorous species D. middendorffiana, however, remains relatively unaffected. The findings suggest that climate warming may shift alpine zooplankton community structure towards daphnid species, which can affect ecosystem processes, such as primary production and food availability for higher tropic levels, such as fish. The figure below shows the number of individuals or species present in the warm and cold tanks, where spp is an abbreviation for species.
The preliminary findings suggest that the adaptability of mountain zooplankton to environmental change such as climate warming is low, particularly since montane species appear incapable of readily dispersing to high-elevation alpine lakes. Other conclusions are:
- Alpine zooplankton communities are dispersal-limited due to their physical isolation
- Evidence suggests that warming suppresses predatory alpine copepods, but not daphnids, which enables montane species to become better established if they are capable of dispersal to higher altitudes
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