Study contributes to the implementation of marine farms and opens new economic possibilities for communities on the north coast of SP
In research guided by professor Jansle Vieira Rocha, from the Geoprocessing Laboratory of the Faculty of Agricultural Engineering (Feagri) at Unicamp, oceanographer Valéria Cress Gelli, from the North Coast Regional Research Center of the Fisheries Institute of the State Department of Agriculture from São Paulo, developed a doctoral thesis that aimed to contribute to the orderly and responsible cultivation of the macroalga Kappaphycus alvarezii, with a view to obtaining its extract as an agricultural biofertilizer on the northern coast of the State of São Paulo.
This alga, originating from the Philippines and introduced to Brazil in 1995 from seedlings imported from Japan, has shown to have great potential in mariculture (cultivation of marine organisms). Despite studies proving that the species does not pose any danger of invasive proliferation, for biosafety reasons and in view of the knowledge of the time, Brazilian legislation, through Ibama, restricted its cultivation to certain areas of the country's coast, including the strip that It extends from the North coast of SP to Sepetiba Bay, in the State of RJ.
The cultivation of algae is encouraged throughout the planet not only because of the natural products they derive, including gelatins – such as carrageenan, used to add creaminess to foods and cosmetics –, biofuels and biofertilizers, but also because they are responsible for more than 50% of atmospheric oxygen production and carbon dioxide (CO) sequestration2), which in the carbon credits market is currently traded at ten dollars per ton. The researchers' work aimed to study the technical and economic feasibility of producing biofertilizer from the cultivation of the macroalgae Kappaphycus alvarezii, and selecting the most suitable areas for its cultivation on the coast of São Paulo. For the researcher, “the study is justified given the decline in fishing stocks. The implementation of macroalgae cultivation (algiculture) can be an alternative to mitigate the problem, keep fishermen in their place of origin, generate income and employment, in addition to proposing new forms of sustainable development and encouraging the implementation of the activity in a planned manner to coastal communities, whose economic base is based on sun and beach tourism”.
Data from FAO (2019) indicated that the cultivation of this algae constitutes an important economic activity in more than ten countries. In 2017, its production was 1,5 million tons and represented 171 million dollars. In 2018, Brazil imported around two tons of its gelatin at a cost of 17,5 million dollars.
Marine algiculture has a great capacity for producing biomass in a short space of time and studies show that this macroalgae grows by 3,8% to 8,7% per day without using any nutrients. Algae also absorb nutrients and heavy metals in polluted places, serve as shelter for other marine organisms, reduce wave action in coastal areas, remove carbon dioxide from the atmosphere, and generate jobs, income and business for coastal communities. They also constitute sources of hydrocolloids, bioactives, fertilizers and biofuels and can be used directly in human food and as an ingredient in animal feed.
The work
Based on the hypothesis that this extraction would be a technically and economically viable activity that could be developed in an orderly manner on the North coast of São Paulo, the work followed three aspects, explains the professor. The first focused on evaluating the economic and technical viability of algiculture to obtain biofertilizer by fishing communities, in family modules of 0,2 hectares of water depth, in a system of floating rafts and planting in tubular nets (figure) , so that this small producer would have an economic alternative to face the fishing off-season and the increasing shortage of fish.
Having established these viabilities, the second focus focused on the selection of suitable locations for the implementation of mariculture, carried out using geotechnology tools. Studies of the 10-year sea surface temperature time series were carried out with the MODIS sensor on the Terra satellite, in locations along the north coast; macroalgae growth associated with environmental factors; and finally applied a method for hierarchization, through interviews with researchers in the area for mapping. Several criteria were taken into account, such as environmental legislation, areas close to river mouths, sheltered areas without conflicts with fishing and tourist activities, sea surface temperature and depth.
The studies led to the selection and quantification of approximately 2.300 hectares of “areas most suitable” for macroalgae cultivation, however the areas were restricted to 1.300 hectares due to environmental legislation as a result of the 2008 IBAMA Normative Instruction.
With the implementation of areas occupied solely with the cultivation of the macroalgae K. alvarezii, it was possible to estimate that the activity would generate around 7 thousand jobs, a gross revenue of R$ 64 million and would also sequester 15 thousand tons of CO2.
Extract production
Macroalgae is commonly cultivated to extract gelatin (carrageenan), but this processing requires high investments in facilities and equipment, qualified labor, energy and large water consumption, conditions that are impractical for local communities. Therefore, explains Valéria, “we chose to encourage the production of the extract in an artisanal way, which involves simple processing, separating the juice and pomace, through a homemade infrastructure (figure)”. The liquid fraction can be bottled and sold directly to farmers or even to biofertilizer industries that use it as raw material. As there are already suppliers of this extract, the researchers' expectation is that it can also be sold by the producer through cooperatives to interested companies.
The work focused more specifically on the production of this macroalgae extract that serves as a biofertilizer or agricultural stimulant. The efficiency of the extract, used in specific concentrations and used foliarly, is reported in several scientific works relating to the cultivation of okra, soybeans, green beans, tomatoes, rice, pepper, peanuts, bananas, corn and sugar cane. In this case, for example, the use of 1% increased productivity by around 25% in four harvests
The extract is considered environmentally sustainable, biodegradable, non-toxic, non-polluting and does not contaminate humans and animals. Its foliar application promotes faster germination of plant seeds, increases harvest yield, improves seed quality, has low carbon emissions and is low cost.
Conclusions
The author considers that the cultivation of the macroalgae Kappaphycus alvarezii constitutes a sustainable, technically and economically viable alternative. The implementation of algiculture can be encouraged in a responsible and orderly manner on the coast of São Paulo along with the coastal communities of the State of São Paulo.
The work made it possible, in a first phase, to identify 44 sites suitable for the implementation of algiculture based on different restrictions and factors specific to the species Kappaphycus alvarezii, directly contributing to future projects in public policies.
Given its low cost and the integrative elements of an innovative nature, the methodology used in this study could be adopted for other species cultivated superficially. Valéria considers that the study can bring contributions to the São Paulo State Coastal Management Program, especially in relation to Coastal Ecological Economic Zoning, as well as to the Apa Marinha Management Plan for the North coast, since the estimated potential can be representative for the economy of the municipalities of Ubatuba, Caraguatatuba, São Sebastião and Ilhabela, in addition to the possibility of its application also being extended to the southern coast of the state of RJ and the coasts of other Brazilian municipalities.