Caribbean-Wide, Negative Emissions Solution to Sargassum spp. Low-Cost Collection Device and Sustainable Disposal Method

Abstract

Sargassum spp. blooms exacerbated by climate change and agricultural runoff are inundating Caribbean beaches, emitting toxic fumes and greenhouse gases through decomposition. This hurts tourism, artisanal fishing, shore-based industry, human health, standards-of-living, coastal ecology, and the global climate. Barriers, collection machinery, and Sargassum valorization have been unable to provide sufficient, sustainable, or widespread relief. This article presents a total Sargassum management system that is effective, low-impact, and economically scalable across the Caribbean. Littoral Collection Modules (LCMs), attached to artisanal fishing boats, collect Sargassum in nets which are brought to a barge. When full, the barge is towed to the deep ocean where Sargassum is pumped to ~150–200 m depth, whereafter it continues sinking (Sargassum Ocean Sequestration of Carbon; “SOS Carbon”). Costing and negative emissions calculations for this system show cleanup costs <$1/m3 and emissions reduction potential up to 1.356 → 3.029 tCO2e/dmt Sargassum. COVID-19 decimated Caribbean tourism, adding to the pressures of indebtedness and natural disasters facing the region. The “SOS Carbon strategy” could help the Caribbean “build back better” by establishing a negative emissions industry that builds resilience against Sargassum and flight shame (“flygskam”). Employing fishermen to operate LCMs achieves socioeconomic goals while increasing Sargassum cleanup and avoiding landfilling achieves sustainable development goals.

Brown algae invasions and bloom events need routine monitoring for effective adaptation

“…Nearshore and offshore prevention methods have been trialled for pelagic Sargassum including: floating inflated interception barriers to stop seaweed arriving inshore, and 'in ocean' mechanised collection via small vessels-both with varied success [36,75]. There is almost no documentation of the costs of prevention across all four selected brown seaweeds (table 2), and no clear approach to evaluation of the effectiveness of alternative strategies.…”

Science and policy lessons learned from a decade of adaptation to the emergent risk of sargassum proliferation across the tropical Atlantic

“…Early investigations suggest that sustainable products could be manufactured from fresh sargassum biomass through a biorefinery approach [70,71]. The supply chain for such products could involve coastal communities and fishers harvesting the biomass at sea [72]. However, it will likely require technologies to allow production at scales that are beyond the reach and affordability of the smaller communities [69,73].…”

The Impact of Sargassum Inundations on the Turks and Caicos Islands

“…The CERMES Best practice guide states that is it generally agreed that in-water removal close to shore is preferable to beach collection if locally permitted [37]. This is reflected by the increasing use of containment booms across the region and new innovations in boat based collection systems [38,39]. If beach collection is necessary, then manual removal is preferable for relatively small volumes of sargassum [37].…”