Speed Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Assessment of the Effect of Reduced Irradiance on the Carbon Sequestration Potential of Wellington Harbour Macroalgae.  (#247)

Alexandra Northmore 1
  1. Victoria University of Wellington - Te Herenga Waka, Wellington, WELLINGTON, New Zealand

Macroalgae are critical contributors to coastal environments supporting ecosystem function through their structure, biomass, and primary production. Recently their potential to contribute to "Blue Carbon" efforts has been explored. Macroalgae may contribute through the fixation of carbon at the primary production level. However, current estimates are largely based on the ratio of dissolved inorganic carbon (DIC) uptake to oxygen evolved - which may vary between 50 and 250%. In addition to this, the impact of sediment (through reduced irradiance) can limit the productivity of macroalgae which can negatively influence their carbon sequestration potential as macroalgae must remain productive to uptake DIC and evolve oxygen. This work aims to provide refinement to global models of macroalgae carbon sequestration potential, investigating the DIC uptake: Oxygen evolved ratio and how it changes between key species in Wellington Harbour (NZ) and how different light levels impact this. It also aims to inform how remediation of the local coastal light environment may increase carbon sequestration potential.  This work involves intensive surveying to quantify macroalgae cover in Wellington; as well as a multitude of in-lab incubations finely assessing the rates of DIC uptake and oxygen evolution between eight different species at three different light levels. 

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