Unlike the negative effects of caged fed-fish aquaculture, like those related to salmon culture, plant-based aquatic farming has a positive effect on both the aquatic environment and its biodiversity and is carbon negative.
Cultivating seaweeds and aquatic plants is conducted without use of fertilizers or any other input. This, besides being economic and environmentally sound on itself, cleans the water because these plants uptake nutrients already in the water for their growth, just as terrestrial plants uptake nutrients from the soil. In hypernutrified waters this is called bioremediation.
Cultivating seaweeds and aquatic plants may well be the solution to massive algal and aquatic plant blooms that happen largely because of excess nutrients in water that come from land. Seaweeds also oxygenate the water, contributing to decrease hypoxic or ‘dead’ zones which are the byproduct of massive microalgal blooms.
We have shown that seaweed cultivation attracts and promotes marine biodiversity, presumably by providing shaded/protected spaces and/or feed. We envision that the very small areas of the sea and lakes that will eventually be cultivated (e.g., less than 1% of the ocean may provide as much biomass as all agriculture) will be oases of cleaner waters and enriched marine life.
Aquatic plant cultivation is also a powerful contribution to mitigating and adapting to climate change. The standing aquatic crop biomass constitutes a carbon sink and the uptake of nitrogen from the water decreases the release of nitrous oxide, a powerful greenhouse gas. Another, related, effect that is being demonstrated, is that seaweeds, by taking up CO2 from the water for their photosynthesis, decrease acidification—which is negatively affecting marine life everywhere. In climate change adaptation terms, to not depend on rainfall or on water availability for crop production is a major contribution from this solution.
Our current research, soon to be published, shows that floating seaweeds and aquatic plants both reflect more sunlight and inhibit its penetration into the water as compared to surrounding bare surfaces. This can be used as a nature-based tool for climate intervention via solar radiation management. For example, as ocean heating and heat waves are killing coral reefs and other sea life, cultivating seaweeds in key areas around e.g. coral reefs may well decrease the temperature of the water in what we call the ‘shade house’ effect of seaweed cultivation.
Additionally, we complement plant production with eco-friendly, filter-feeding fish and shellfish culture, and herbivorous fish culture fed with seaweeds. Filter feeders have a net positive effect in cleaning waters since they uptake more organic matter than what they release back. The culture of herbivorous fish (including abalone and sea urchins) fed with seaweeds cultivated in situ, is an integrated polyculture that is very different in environmental terms from fish culture that requires massive amounts of feed that come from fisheries and agriculture.
To avoid genetic pollution or invasions (e.g. when non-native fish escape from cages) we only promote the use of native species, of both plants and animals.
With these and other considerations, we are promoting an integrated, highly productive and eco- friendly manner to manage and value our aquatic environments.
Safeguarding the aquatic environment and biodiversity is a top priority embedded into the production systems we promote.