Hypoxia and Function

This project examines how oxygen concentrations and trawling activities influence seabed invertebrate diversity and abundance, as well as the capacity of seabed ecosystems (including microbes and invertebrates) to undertake critical functions such as the breakdown of organic matter and regenerating of nutrients essential for phytoplankton that form the base of the food chain.

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Although previous research has documented changes associated with reduced oxygen and bottom trawling, we know little about how these human perturbations act in concert. The continental margin off Vancouver Island offers a unique opportunity to examine the cumulative effects of these drivers of change because oxygen concentrations and trawling activities have both been mapped in detail and indicate locations where these activities overlap and locations with either one of the activities or neither occurs. These maps provide an opportunity to examine separate and combined effects of these activities on seabed organisms spanning from microbes to small invertebrates to fish adaptation. This work will include experimental manipulations of oxygen to determine how changes alter function in short-term incubations. We will also examine how these activities influence flatfish, an “ecosystem engineer” that plays a major role in role in recycling silica and other nutrients.

Project Deliverables / Achievements

  • Producing functional-response curves between fishing/hypoxia and benthic microbial and macrofaunal communities and ecosystem function are in progress.

  • Three hypoxia transects in Saanich Inlet are surveyed.

  • Analysis of transect imagery and data for community changes spatially (i.e. along dissolved oxygen gradient) and over time is completed.

  • Identification of biodiversity components that may mitigate impacts of stressors is in progress.

  • A metric (Fisher Information Statistic) for determining the degree of ‘chaos’ in an assemblage as a stressor change is modified and tested.

  • Analyses of flatfish growth characteristics to determine hypoxia effects on growth are completed.

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Saanich Inlet