Freshwater salinization

A primary focus of my postdoctoral research has been investigating the environmental, social, and economic consequences associated with freshwater salinization. This includes experimental manipulations, field investigations, and using sensor networks to model risks. My research on freshwater salinization has demonstrated that salts can disrupt the functions of ecological communities, and that different salt types (e.g., CaCl2and MgCl2) toxicologically affect organisms in unique ways. Additionally, road salt additives such as beet juice can act as fertilizers, increasing the productivity of freshwater environments. These results are important, because numerous anthropogenic activities are increasing the salinization of freshwater ecosystems, and unique ions and pollutants are associated with each anthropogenic activity. The results from these studies were used by the European Commission to compose an Environmental Policy Report, promoting that governments in the European Union limit the use of alternative road salts and additives. Additionally, these results led to an invited opinion paper that highlights the need for global, ion-specific regulations and management solutions to protect freshwater environments.

Climate warming and environmental stressors

I use experimental freshwater ponds to understand how climate change interacts with local environmental stressors to affect the structure and function of freshwater food webs. Local stressors that could mediate the effects of climate change include invasive species, nutrient pollution, and increased browning through altered dissolved organic carbon cycles (pictured above). My research has demonstrated that climate warming can negatively affect freshwater environments by altering the distribution of biomass from pelagic to benthic communities. However, the magnitude of these effects depends on the availability of nutrients, the ratio of nutrients and dissolved organic carbon, and the intensity of UV radiation. Additionally, the positive effect of climate change for benthic organisms depends on the presence of invasive species, which can alter nutrient cycling and the biomass of freshwater algae.

Invasive species

Invasive species that are established within an area are thought to negatively affect ecosystem function and disturb habitats, paving the way for new invasive species. To understand if invasive species compete or facilitate one another, I use functionally diverse invasive mollusks in experimental freshwater communities. To understand how multiple invasive species interact to affect freshwater environments, I study functionally diverse invasive mollusks using experimental and observational approaches. My experimental research has demonstrated that invasive mollusks interact to affect the concentration and ratios of limiting nutrients in freshwater environments. These resulting nutrient ratios can affect the diversity of native consumers, and alter the productivity of freshwater environments. Additionally, the densities of invasive mollusks and the concentrations of pollutants can determine the magnitude of their effects in freshwater environments. Field surveys at Lake George indicate that the density and distribution of invasive snails can alter the distribution and abundance of native invertebrates and fish species.

Mechanisms affecting patterns of diversity

I use experimental and observational approaches to understand how anthropogenic activities and environmental factors affect patterns of species richness. Experimentally, I test fundamental ecological theories using a model zoopankton community. These data are used to understand how how environmental factors such as heterogeneity, energy, and habitat area interact to affect species richness patterns. I also survey nearshore communities at Lake George to understand the long-term consequences of urban developments on the diversity of littoral environments in lakes. For the past four years, I have surveyed the chemistry, algae, zooplankton, and macroinvertebrates at dozens of locations across Lake George. These data are also coupled with high-frequency sensor data and food-web models to predict the effects of anthropogenic activities on ecosystem functions such as lake metabolism, and ecosystem services such as water clarity.