Abstract
A high resolution coastal and ocean hydrodynamic model system was used to investigate the transport and deposition patterns of Particulate Organic Matter (POM) from kelp farmed at three locations of different properties: a sheltered location, an exposed location, and an offshore location. Published values on the sinking speeds of organic particles from kelp were used, spanning several orders of magnitude. Recent work on quantifying the release of particulate organic matter from farmed kelp was used to link the release of carbon to possible cultivation volumes and scenarios, and finally to link this to the potential for carbon loading on the ocean floor. The results are presented in terms of loading and distribution per unit harvested kelp, and the loading estimates are compared with estimates of natural (background) primary production. According to the simulation results, organic matter may be transported anything from a few (hundred) meters up to a hundred km away from the release site, depending on the sinking rates, time of release, and the location. The depth at which the matter settles on the sea floor likewise depends on the properties of the matter and the sites. The time until settlement varied from minutes to several hundred hours. The results underscore the importance of constraining the dispersal and deposition of detritus from kelp cultivation in order to better understand and quantify associated environmental risks posed by organic loading, and the potential for seafloor carbon sequestration by kelp farming as a nature based climate solution.
Highlights
Recent work suggests that the potential for macroalgae aquaculture globally is great, outside of Asia, that currently produces more than 99% of the 32 million tons wet weight cultivated per annum (Lehahn et al, 2016; Hadley et al, 2018; van der Molen et al, 2018; Broch et al, 2019; FAO, 2020; Forbord et al, 2020; Aldridge et al, 2021; Duarte et al, 2021)
Around 60% of the Particulate Organic Matter (POM) released from the offshore site was transported at least 2 km from the center of the release site in Scenario A, and more than 20% of the POM was transported more than 16 km away from the offshore site
We have approached the problem of how kelp POM released from different kelp cultivation sites is distributed in time and space by applying a hydrodynamic model
Summary
Recent work suggests that the potential for macroalgae aquaculture globally is great, outside of Asia, that currently produces more than 99% of the 32 million tons wet weight cultivated per annum (Lehahn et al, 2016; Hadley et al, 2018; van der Molen et al, 2018; Broch et al, 2019; FAO, 2020; Forbord et al, 2020; Aldridge et al, 2021; Duarte et al, 2021). During the grow out phase in culture, as in natural populations, macroalgal tissue fragments are shredded and entire plants dislodged (Parke, 1948; Sjtun, 1993; Krumhansl and Scheibling, 2012; Zhang et al, 2012; Pedersen et al, 2020; Fieler et al, 2021). Both these processes contribute to the pool and export of Particulate Organic Matter (POM).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
