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There is growing research interest in the ethnobiology, socio-economics and management of mangrove forests. Coastal residents who use mangroves and their resources may have considerable botanical and ecological knowledgeable about these forests. A wide variety of forest products are harvested in mangroves, especially wood for fuel and construction, tannins and medicines. Although there are exceptions, mangrove forest products are typically harvested in a small-scale and selective manner, with harvesting efforts and impacts concentrated in stands that are closer to settlements and easiest to access (by land or by sea). Mangroves support diverse, local fisheries, and also provide critical nursery habitat and marine productivity which support wider commercial fisheries. These forests also provide valuable ecosystem services that benefit coastal communities, including coastal land stabilization and storm protection. The overlapping of marine and terrestrial resources in mangroves creates tenure ambiguities that complicate management and may induce conflict between competing interests. Mangroves have been cut and cleared extensively to make way for brackish water aquaculture and infrastructure development. More attention is now given to managing remaining forests sustainably and to restoring those degraded from past use. Recent advances in remotely sensed, geo-spatial monitoring provide opportunities for researchers and planners to better understand and improve the management of these unique forested wetlands.

Kappaphycus alvarezii (Fig. 1, below), Kappaphycus striatum and Eucheuma denticulatum belong to a group of commercially important species known as the “Eucheumoid algae” and are known in the trade as “cottonii” and “spinosum”. These three species are the main source of kappa and iota carrageenan, being responsible for about 88% of worldwide raw material.

Statistical data from the FAO's (Food and Aquaculture Organization of United Nations) Fisheries and Aquaculture Departments show that the production in 2007 of these three species was about 1.6 million wet tons, with a landed value of some US$175 million.

Commercial farms are located mainly in the Philippines, Indonesia, Tanzania, Mozambique, Zanzibar, and a few Pacific Islands. The success of these farms resulted in the introduction of Kappaphycus and Eucheuma to more than 25 countries, but many of them ceased farming at an experimental stage.

Commercial seaweed farming efforts are expanding worldwide. The use of new species, ecosystems, and practices present many opportunities for novel research and resource management. The purpose of this project was to evaluate and advance seaweed aquaculture practices in the Western Gulf of Maine. Saccharina latissima (sugar kelp) is the species of focus because it is currently the most farmed macroalga in the Northeastern United States. Fieldwork supporting the empirical studies was conducted January 2016 - May 2019 in Casco and Saco Bays, ME. Growth, yield, morphology, elemental and isotopic composition, and enzymatic activity of S. latissima were quantified across four sites. These observations were used to evaluate the nitrogen bioextraction efficiency of S. latissima farms in this region and the effect of distal-end trimming on the morphology and yield of S. latissima. Additionally, Maine kelp aquaculture was used as a case study to determine if the Ecosystem Approach to Aquaculture was suitable for seaweed farming and to explore the application of a multi-criteria screening model to guide the market-specific siting of seaweed aquaculture. Findings from these studies depict a high variability in ambient environmental conditions between sites and in morphological and compositional variability between individual sporophytes. On a hectare-to-hectare basis, the nitrogen bioextraction by kelp farming in the region far exceeded the nitrogen loading from riverine or atmospheric sources. Distal-end trimming had a significant effect on S. latissima stipe and blade morphology and increased late-season production yields. Furthermore, the Ecosystem Approach to Aquaculture was found to be applicable to the development of kelp aquaculture beyond Asia. Specific attention should be given to maintaining genetic diversity, developing best management practices, and integrating wild and farmed kelp management. Lastly, the screening analysis showed that the application of criteria specific to end-market uses of seaweed biomass results in uniquely optimal areas for cultivation. These findings are novel contributions to the fields of aquaculture research, coastal management, and phycology, and they provide a platform for continued research and development of seaweed aquaculture in the region.