Prof. Morten Foldager Pedersen1, Dr. Karen Filbee-Dexter2, Mr Albert Pessarrodona2, Professor Dorte Krause-Jensen3, Professor Thomas Wernberg2
1Dept. Science And Environment, Roskilde University, Roskilde, Denmark, 2UWA Ocean Institute and School of Biological Sciences, University of Western Australia, Perth, Australia, 3Department of Ecoscience, Aarhus University, Aarhus, Denmark
Coastal ecosystems dominated by seagrasses, mangrove trees and marsh plants have recently been recognized as important ‘Blue Carbon Sinks’. Current debate now centers on the extent to which this also applies to seaweed ecosystems. Global C-sequestration potential by different ecosystems depends on factors such as the areal cover, NPP per unit area and time, the proportion of NPP that is not mineralized through grazing (= detritus production), transport and, finally, the rate and extent by which the plant detritus is decomposed. The latter is important because slow and/or incomplete decomposition will favour C-accumulation and lead to larger steady-state stock of detrital C.
We obtained data from 512 plant decomposition experiments available in the literature and compared decomposition rates and the proportion of refractory detritus among taxonomic groups of seaweeds, and among seaweeds, phytoplankton, seagrasses, mangrove trees, and marsh plants.
Brown seaweeds decomposed slower and contained a larger fraction of refractory compounds than red and green seaweeds and, everything else being equal, should therefore be the most efficient C-sequesters. Seaweeds decomposed more slowly than phytoplankton, but faster than seagrasses, mangrove trees and marsh plants, and the refractory component of their detritus tended to be smaller. Seaweeds may thus be less efficient C-sequesters than seagrasses, mangrove trees and marsh plants per unit area and time. Nevertheless, the Blue-C contribution of seaweeds is likely still important on a global scale due to the much larger area covered by seaweeds and their high NPP per unit area and time.
Presentation Slides – Morten F. Pedersen
Biography:
Morten F. Pedersen’s research is focused on the ecophysiology of marine macrophytes including quantification and fate of net primary production in seagrass and seaweed dominated ecosystems, and the potential role of different macrophytes as potential blue carbon sinks.
