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Gray laboratory

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Research interests:

Aquatic communities are facing a variety of environmental stressors including climate change, increased nutrient levels, pollution, acidification, and invasive species introductions. While the impacts of these interacting stressors are being studied extensively, our ability to accurately forecast the response of communities to environmental change remains poor. My research aims to understand and predict the impacts of short- and long-term environmental change on aquatic communities. I use a mix of field and laboratory experiments, synoptic surveys, and time-series analyses in my research (See figure right). Some of the big picture questions I hope to answer in my future research include:

  1. How are humans impacting aquatic environments?
  2. How will environmental change affect zooplankton communities in inland lakes?
  3. Why do communities respond the way they do to environmental change? In other words, what factors control community responses to environmental stressors?

How are humans impacting aquatic environments?

Global temperature increases have led to many physical changes in northern hemisphere lakes, including increased surface water temperatures, changes in water stratification, and earlier ice-out timing. The impacts of these ongoing changes on biota are not yet fully understood, but some possibilities include altered phenology, changing food-web relationships, altered chemical partitioning of contaminants, and the replacement of cold-water species with those adapted to higher temperatures. Rigorous scientific studies are needed to document how the environment is changing and to provide relevant information to natural resource managers and policy-makers.

Over the past three years I have been fortunate to play a key role in a large collaborative study that has documented changes in lake surface temperatures around the globe. For this study we synthesized temperature trend data for over 200 lakes around the globe. We worked with remote sensing scientists from NASA to obtain temperature data for about half the lakes, and we collaborated with investigators from around the globe to get in situ temperature data. We found that lakes are warming faster than the oceans and faster than the surrounding air. We also found that seasonally ice-covered lakes warmed faster than all other lakes in our database.

I have also recently been involved in various other projects documenting environmental change. I have contributed to projects examining long-term trends in water clarity, productivity, and temperature in Lake Baikal, Russia. I worked with an undergraduate student to examine plastic accumulation along Great Lakes beaches. I have also worked on projects tracking the continuing spread of the invasive spiny water flea, Bythotrephes longimanus.

figure 1

Approaches used to test hypotheses in the Gray laboratory

sampling mesocosms

Sampling mesocosms on Lake George

hauling plankton

Sampling plankton on Lake Baikal

gltc lakes 

Lakes analyzed for long-term temperature trends with the Global Lake Temperature Collaboration

How will environmental change affect zooplankton communities in inland lakes?

Understanding the potential impacts of climate change on aquatic habitats is one of the most challenging tasks currently facing aquatic ecologists. I am currently working on a project to examine how zooplankton on the Great Plains will respond to a changing climate. Zooplankton are an important link in the aquatic food web, allowing for the transfer of energy from primary producers (phytoplankton) to higher trophic levels such as fish. My research is examining the roles played by evolution and dispersal as salinity levels change in lakes on the Great Plains. I am using a combination of field, laboratory, and mathematical modeling techniques to determine if the zooplankton Daphnia, will be able to “keep up” with changes in the environment through adaptation or dispersal to new lakes. The study relies on the field of resurrection ecology to examine how fast salinity tolerance can evolve as salinity levels change.

I have also examined how zooplankton communities in Lake Baikal, Russia have changed in response to long-term environmental changes. Lake Baikal is one of the world’s largest lakes, and is home to a unique food web that contains many endemic cold-water plankton and fish species that support a population of the world’s only freshwater seal. This collaborative research has been aimed at evaluating the potential impacts of changing plankton communities on the Lake Baikal food web as a whole.


Experiment in progress... cubitainers suspended off of a floating platform in Moon Lake, North Dakota


The shore of Lake Baikal near Bolshiye Koty

Why do communities respond the way they do to environmental change?

Anthropogenic acidification is one of the best-studied stressors affecting aquatic ecosystems, making it an ideal case for examining the factors that influence community responses to environmental change. I have conducted extensive work with acid-damaged zooplankton communities in lakes located on the north shore of Lake Huron in Killarney Provincial Park, Ontario. As pH levels have increased in these lakes there is evidence that acid-sensitive species are attempting to recolonize. Unfortunately, community recovery has occurred at a rate much slower than expected based on documented pH increases. My work has focused on elucidating the factors that may be slowing community responses to increasing pH levels. I have used two approaches: (1) field experimentation to determine which variables impact the probability of recolonization of damaged lakes by acid-sensitive species; and (2) modeling and statistical analyses to determine the factors that drive variation in zooplankton communities across the landscape.

osa lake

Ontario Society of Artists Lake in Killarney Provincial Park


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