Dr Caitlin Blain1, Dr Nick Shears1
1University Of Auckland, Leigh, New Zealand
Kelp forests are widely acknowledged as some of the most productive ecosystems on the planet. Despite this, the contribution of kelp forests to marine carbon sinks in unclear due to large gaps in our understanding about the production and fate of carbon produced by these highly productive ecosystems. Here, we examine carbon storage, fixation and loss in Ecklonia radiata forests across a large-scale turbidity gradient, and discuss the potential value of New Zealand kelp forests in CO₂ offset schemes. We show that the quantity of carbon fixed annually by kelp forests was up to 4.7 times greater than that stored as standing stock, but that high turbidity levels can have severe impacts on both the quantity and fate of carbon produced. At highly turbid sites, fixed carbon goes directly into tissue growth and is subsequently eroded. In contrast, up to 39 % of the total carbon fixed by kelp at pristine sites is likely released as dissolved organic carbon (DOC). Subsequent degradation experiments revealed that DOC was more stable than particulate organic matter, likely owing to the relatively high levels of humic-like substances in DOC. Our results highlight the potential for kelp forests to donate particulate organic matter in coastal carbon cycles while suggesting a large source of carbon that is generally unaccounted for in estimates of the contribution of kelp to coastal carbon cycles.
Presentation Slides – Caitlin Blain
Biography:
Caitlin is a research fellow at the University of Auckland’s Leigh Marine Laboratory where she studies the function and ecological services provided by kelp forests.
