Can Seaweed Farming Play a Role in Climate Change Mitigation and Adaptation?

Abstract

Seaweed aquaculture, the fastest-growing component of global food production, offers a slate of opportunities to mitigate, and adapt to climate change. Seaweed farms release carbon that maybe buried in sediments or exported to the deep sea, therefore acting as a CO 2 sink. The crop can also be used, in total or in part, for biofuel production, with a potential CO 2 mitigation capacity, in terms of avoided emissions from fossil fuels, of about 1,500 tons CO 2 km −2 year −1 . Seaweed aquaculture can also help reduce the emissions from agriculture, by improving soil quality substituting synthetic fertilizer and when included in cattle fed, lowering methane emissions from cattle. Seaweed aquaculture contributes to climate change adaptation by damping wave energy and protecting shorelines, and by elevating pH and supplying oxygen to the waters, thereby locally reducing the effects of ocean acidification and de-oxygenation. The scope to expand seaweed aquaculture is, however, limited by the availability of suitable areas and competition for suitable areas with other uses, engineering systems capable of coping with rough conditions offshore, and increasing market demand for seaweed products, among other factors. Despite these limitations, seaweed farming practices can be optimized to maximize climate benefits, which may, if economically compensated, improve the income of seaweed farmers.

Environmental impacts and implications of tropical carrageenophyte seaweed farming

“…As such, seaweed farming could be used as a tool for improving habitat quality (FAO 2018). Seaweed farms could thus help seagrass beds by improving adjacent water quality (Duarte et al 2017) rather than harming them through shading. The potential benefits from farms to water quality have not been rigorously tested in the field.…”

Modelling potential production and environmental effects of macroalgae farms in UK and Dutch coastal waters

“…Marine macroalgae fix CO2, acting as a sink for anthropogenic CO2 ("Blue Carbon", Nellemann et al, 2009;Duarte et al, 2017) and absorb dissolved nutrients from the water column, helping to remediate nutrient release from anthropogenic 15 sources such as agricultural runoff, waste water treatment and aquaculture ('bioremediation', e.g. Fei, 2004;He et al, 2008;Chopin et al, 2001;Lüning and Pang, 2003;Sanderson et al, 2012;Smale et al, 2013).…”

Remote sensing mapping of macroalgal farms by modifying thresholds in the classification tree

“…Macroalgae dominate coastal waters around the world, particularly in rocky shores, and play an important role in maintaining coastal ecosystem balance (Troell et al 1999;Sondak and Chung 2015) due to its high potential in reducing eutrophication and sequestrating carbon (Duarte et al 2017;Xiao et al 2017). It also provides as healthy food supply and medicinal ingredients in our daily life (Wei et al 2013;Philippsen et al 2014).…”

“…The rapid growth and healthy nutrients of macroalgae favor high productivity and provide a significant commercial value (Abreu et al 2011;Aitken et al 2014). Macroalgae aquaculture makes up 27% of total marine aquaculture production to date (Duarte et al 2017). Among various countries, China is the largest producer and consumer of macroalgae, accounting for about two-thirds of the global production (Mazarrasa et al 2014).…”

“…Coastal marine environments are complex due to the interaction between watershed inputs and ocean waters and the dynamics added by waves and wind. The rapidly expanding macroalgal farming areas and their important roles in marine environment and ecosystems (Duarte et al 2017;Xiao et al 2017) require efficient monitoring measures. Mapping macroalgae in coastal areas is still an issue, and no attempts at doing so using remote sensing analyzed by modified CTs have been reported.…”