Chris Parrish
Department of Ocean Sciences, Memorial University of Newfoundland
Food Web Resiliency
This project uses observational and experimental approaches to establish relationships between multiple environmental stressors (e.g. warming and acidification) and the elemental composition (carbon, nitrogen and phosphorus) and presence of different lipid classes and trophic markers in a particulate organic matter and key organisms of the lower pelagic and benthic food webs.
Transfers of energy and essential nutrients through marine food webs are vital to ecosystem function, resilience, biodiversity, and sustainability, and therefore provide a useful metric by which the cumulated impacts of natural and anthropogenic stressors can be assessed and the success of conservation actions evaluated. These transfers depend on the quantity of primary production and the quality or nutritive value of the organic matter synthesized by phytoplankton and passed up the food web during trophic interactions. In this regard, lipids provide the densest form of energy transferred from algae to vertebrates and include essential fatty acids considered to be important drivers of health and stability in organisms, ecosystems and humans.
We will evaluate spatial gradients at the local (Bay of Sept-Iles) and large scales and perform controlled perturbation experiments in shore-based microcosms. The large-scale component will provide macro-ecological perspective through the collection of plankton samples along a natural North-South gradient in growth conditions. Results will be used to evaluate the stability of major energy pathways and refine trophic indicators of ecosystem stress/resilience.
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Zooplankton and phytoplankton samples and many environmental variables (e.g., temperature, light, nutrients, pH and total alkalinity) were collected at 38 stations along macro-ecological gradients of conditions linking Sept-Iles and the High Arctic during the expedition of CCGS Amundsen.
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The analyses of the total, new, and regenerated production variables were completed.
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All the samples for the extraction of lipids and fatty acids were prepared, and extractions and analyses were performed.
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Lipid and fatty acid laboratory analyses are completed for the zooplankton samples, and phytoplankton samples are nearing completion.
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Compiling data and performing statistical analysis is in progress.
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Developing the experimental procedure for microcosm setups were finalized.
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All the processing and analysis of ancillary samples collected in the Arctic including analysis of nutrients, pH, the elemental composition of organic matter, primary productivity, nitrogen uptake, temperature and light availability is completed.
