Living in an (elementally) imbalanced world: Is stoichiometry useful in understanding the structure and functioning of an arctic tundra ecosystem?
Humans are causing major perturbations in global biogeochemical cycles, especially carbon, nitrogen and phosphorus. These changes put ecosystems under considerable stress, making it critical to understand the mechanisms that underpin ecosystem structure and functioning. Ecological stoichiometry (elemental ratios) is a recent theoretical approach that is based on the realization that all organisms are made of the same essential elements, and therefore provides a mechanistic link from the cellular level all way up to the biosphere. In particular, plant stoichiometric homeostasis – the ability of a species to maintain a certain elemental composition despite variation in the elemental composition in the soil – may represent a useful complementary trait to other plant traits in understanding and predicting community structure. I investigated its applicability in arctic tundra ecosystems by determining homeostasis indices for seven common tundra vascular species. I then analyzed how these homeostatic values were related to key aspects of ecological performance, such as plant dominance. Overall, these results will evaluate the potential contribution of ecological stoichiometry to predicting the impacts of environmental changes on arctic tundra vegetation.
Resource partitioning through the seasons: a test of a competitive ability – cold tolerance trade-off among closely-related, seasonally breeding beetles
Understanding the factors that maintain and constrain biodiversity and species coexistence is a major goal in ecology. When coexisting species use similar resources, this leads to the question: Why doesn’t one species use all the resources to the exclusion of all others? Trade-offs may be key in preventing one species from dominating all resources in all environments, thus allowing multiple species to coexist. Such trade-offs may be widespread in nature and play an important role in maintaining local biodiversity, but remain poorly described and understood. In this seminar, I will present evidence of seasonal resource partitioning in closely-related coexisting burying beetles (Nicrophorus) and explore a potential competitive-ability – cold tolerance trade-off.
Examining phenological variation of an invasive plant using a developmental model
My research examines the basis for variation in flowering time in an invasive wetland plant, Lythrum salicaria, using a model of stem development. I present time series data from an ongoing common garden experiment at Queen’s University Biological Station, with families representing populations from across a 1000 km transect of eastern North America. I will also discuss the underlying data science challenges I encountered while analyzing repeated and multifaceted observations of nearly 3600 individuals and solutions with broad utility for other researchers.
The Impacts of Plastic Debris on Aquatic Ecosystems
Plastic pollution is reported in freshwater and marine habitats globally. Hundreds of species, across multiple trophic levels, are contaminated with plastic and effects have been demonstrated across several levels of biological organization. Using recent insights, this presentation will discuss the sources, fate and impacts of plastic in aquatic ecosystems.
Chelsea Rochman is a trained Ecologist with emphases in Marine Ecology, Ecotoxicology and Environmental Chemistry. She is interested in the side-effects of industrialization on the environment and its inhabitants. Her broader research interests regard the ecological effects of anthropogenic contaminants on wildlife and human resources (e.g. water, seafood). More specifically, her current focus is the implications of the infiltration of plastic debris into aquatic habitats. In addition to her academic research, Chelsea participates in policy meetings and working groups to translate scientific research beyond academia.
This week we welcome the Friesen lab for an open discussion.
For the love of the planet
The International Panel on Climate Change tells us we have less than 12 years to reduce greenhouse gas (GHG) emissions by 45% below 2010 levels to avoid “climate catastrophe”. We are making some baby-steps in this direction, but change is slow. What can we, as time-crunched biologists, do to help generate this magnitude of change, in so little time? The global community has been able to mitigate environmental crises in the past – how did we do it? What makes a successful social revolution? Who are the main generators of greenhouse gases: individuals or industry? And how do we motivate them to change? The Friesen lab will guide a general discussion, with insights from various professionals from academia, government, and nonprofit organizations, with the goal of generating concrete ideas.
Anthropocene determinants of diversity in island anole lizards
The central aim of my research is to understand how ecological and evolutionary factors combine to determine biodiversity patterns over large spatial and temporal scales. To do this, I use radiations of Anolis lizards on Caribbean islands as a natural experiment to test hypotheses about macroevolution, biogeography, and community ecology. In this seminar, I will ask how biogeographic patterns and community structure, both of which bear strong signatures of macroevolutionary history, are being reshaped by human activities in the Anthropocene. Specifically, I will ask how classic biogeographic factors (e.g., island area and isolation) and economic trade combine to predict species richness in invaded island faunas, and how natural climate gradients and recent land use patterns jointly predict the assembly of local communities within islands.
How changing biodiversity in the Canadian Arctic is affecting seabirds: from pathogens to predators, bacteria to bears
We often view the Arctic as a pristine wilderness largely free of environmental threats. Times are changing. I’ll provide a few examples of changing conditions currently affecting eider duck populations in Arctic Canada: harvest, emerging diseases, and changing predatory regimes. Infectious disease is a potentially important driver of wildlife population dynamics although the demographic effects of disease in free-ranging hosts have proven difficult to quantify. Avian cholera is a highly virulent disease of birds that has circulated among common eider populations in Europe and North America for several decades. The disease has recently appeared in the Canadian Arctic where high annual mortality, coupled with near total reproductive failure on affected colonies, has raised fears over local extirpation and severe population decline. In this study, our group used data from a marked population of northern common eiders (S. m. borealis) to estimate vital rates before and during a multi-year cholera outbreak. Nesting success remains below replacement level and there has been no evidence for population recovery. Climate change can also influence species directly by modifying their physical environment or indirectly by altering interactions among organisms. Changes affecting the ecology of top predators are a particular concern because variation in predator behaviour has the potential to restructure food webs and lead to cascading ecological impacts on prey populations. Polar bears (Ursus maritimus) are a top predator in the circumpolar Arctic and are adapted to use sea ice as a platform to hunt seals. Advancement in the timing of sea ice break-up in the spring has recently reduced the access of seals to bears, and has been associated with increased bear predation of eider eggs on islands in summer. The proportion of days on which bears are present on eider duck colonies before their median annual laying date has more than doubled during the past two decades. Nest success has also declined raising concern about the long-term viability of ground-nesting bird populations such as eiders that are unaccustomed to such intensive depredation by bears.