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Watershed Exports to the Coastal Ocean

Investigating exports of terrestrial materials to the ocean from a coastal temperate rainforest landscape.

Suzanne Tank, Allison Oliver, Ian Giesbrecht, Bill Floyd

In 2013 the Hakai Institute established a year-round sampling program and sensor network to quantify the amount and character of terrestrial exports to the marine environment of Kwakshua Channel. At each of the seven watersheds we sample freshwater at the stream outlet and estuarine/marine water from adjacent channel locations. Mid-channel sites monitored through the Hakai oceanographic monitoring program connect with the Kwakshua Watershed Program, representing the end of the terrestrial to marine continuum. Samples from all locations are analyzed for a suite of parameters including dissolved organic carbon (DOC), nutrients, and optical properties such as absorbance by ultraviolet light and fluorescence. We are using in-situ sensors to continuously measure stream stage (height) and dissolved carbon. Concurrently, the hydrology project is building rating curves that will be used to estimate stream discharge and ultimately material fluxes. The hydrology and biogeochemistry data will be used to examine watershed exports of DOM in relation to storms and seasons. We are also using stable isotopes and the optical properties of DOM to trace the transport of terrestrial material into the estuarine/marine environment. Our initial data from these diverse sources show substantial variation over time and among watersheds: a rich dataset for discovering and modeling interactions of terrestrial and marine ecosystems.

Photo by Ian Giesbrecht