Tropical seaweeds for human food, their cultivation and its effect on biodiversity enrichment
Introduction
Needed increases in world food production are hindered by growing land and water shortages and by climate change (Falkenmark et al., 2009, OECD/FAO, 2012, UNU, 2012); however, at sea space abounds and food production does not require any freshwater (Radulovich, 2011). The use of seaweeds (macroalgae)—the only existing choice for primary production at sea—for human food and other applications, has grown to ~ 21 million tonnes (Mt) on a fresh weight basis annually, of which ~ 20 Mt are cultivated at sea, the rest is from natural harvests (FAO, 2012, FAO, 2013). It is considered that 76% of world seaweed production and 88% of its value are for direct food consumption (Chopin, 2012). However, 99.8% of cultivated production happens in only nine countries, of which eight are Asian (four of them tropical: Indonesia, Philippines, Malaysia and Vietnam), and one African (Tanzania, particularly Zanzibar); the remaining 15 tropical countries with some cultivation reported produce a combined yearly total of only ~ 32,000 t (FAO, 2012).
Although tropical seaweeds have amply demonstrated ‘cultivability’ and productivity, and their nutritional adequacy and edibility as human food have also been shown, at least at the laboratory level (e.g., Black, 1952, Matanjun et al., 2009, McDermid and Stuercke, 2003, Reed, 1907, Robledo and Freile, 1997), most of the limited cultivation experience outside Asia is for hydrocolloid uses, as it is, e.g., for Zanzibar (Msuya, 2011). In all countries of tropical Latin America, the Caribbean and most of Africa seaweeds are essentially an ignored resource, and scant or no cultivation is reported for any purpose much less for food (FAO, 2012).
Given the overarching opportunity this may represent, it was considered convenient to evaluate seaweeds as a food source, including their cultivation and effects on biodiversity in Costa Rica, a country with coasts on both the Pacific ocean and the Caribbean sea and an abundance of native seaweed species (Fernández-García et al., 2011, Wehrtmann and Cortés, 2009). Since there is a generalized lack of proven methodology to follow, it was necessary to establish and implement an agriculture-like protocol to conduct this work, thus expanding aims into generating specific experience which can be of use in the context of coastal tropical developing countries seeking solutions at sea to their food-production limitations.
Section snippets
Materials and methods
Work was conducted in Costa Rica from early-2011 through mid-2013 in the near-shore waters of the Cahuita/Puerto Viejo region of the Caribbean coast and in the Gulf of Nicoya, Central Pacific and Cuajiniquil, North Pacific coast. Since it was considered essential to use only native species, at least at this early stage, the procedure followed consisted of prospecting for seaweed species, pre-selecting species, evaluating pre-selected species as food and for their cultivability, and final
Prospecting and pre-selection
Prospecting on the Caribbean coast proved very rewarding, where a variety of brown, green and red seaweed species were easily collectable in most places sampled, with banks of the smaller species growing on rocks and corals while sizable and often dense ‘prairies’ of the larger ones (with up to 1.0 m tall often ‘bushy’ individuals of Bryothamnion spp., Dictyota spp. and Sargassum spp.) could be found growing on some sandy shallow bottoms. This abundance left the more complicated searches to
Discussion
Although prospecting for different seaweed species was relatively easy in the Caribbean given the abundance of species and individuals, this was not the case for the Pacific, where searches in different locations and seasons were needed to obtain sufficient material of a few promising species. Even then, this is a continuing line of work since several key species both in the Pacific and the Caribbean remain to be found, and cultivation and replenishment from wild material is often needed for
Acknowledgments
Funding for this work was provided by a Grand Challenges grant (OPP1045878) from the Bill and Melinda Gates Foundation to the University of Costa Rica. Early stages of this work were funded by a Development Marketplace grant from the World Bank (141-07) through the ‘Sea Gardens’ project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Thanks are given to the Ministry of Environment and Energy of Costa Rica for
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