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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.

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.

Sea ranching of sandfish is being piloted as a means to enhance the recovery of depleted natural stocks and provide a supplemental source of income for artisanal fishers. Participatory and adaptive approaches were employed in the establishment and management of sea ranches to ensure that benefits accrue to both the ‘rights-holders’ and other community members. Three pilot sea-ranching sites have been established in north-western Luzon, the Philippines. The sites are managed by members of a local association of small fishers with the support of the municipal government, which granted limited exclusive-use rights to the sea-ranch managers. Each site was delineated into two major use zones: the 1-ha no-take release and nursery area, and the 4-ha reserve area. Multiple releases of cultured sandfish juveniles produced from local wild broodstock were conducted in the sites. Within 7–10 months, effective spawning populations were established in the sea-ranching sites when the density of reproductively mature (>200 g) individuals (ind) exceeded 100 ind/ha. Growth and survival rates were variable among sites. At the Bolinao sea ranch, the maximum estimated overall density reached 1,119 ind/ha, with an estimated survival rate of 39% after 19 months. Mass spawning of sandfish in the sea ranch further demonstrated that community-based sandfish sea ranching can help rebuild depleted wild populations. Among the major threats to sustainability are periodic poaching and storms, which reduce harvestable biomass and economic returns to the rights-holders. Sea ranching should be integrated within a broader fishery management framework to improve the management of sea cucumber fisheries.

Culture studies have been carried out on a local population of the agar-producing red seaweed Graci/aria verrucosa to ascertain the optimum range of environmental factors for growth, with a view to potential mariculture. The plants grew well at 15 - 25°C, poorly at cooler temperatures, and did not survive 30°C. Despite little salinity variation in the natural habitat, the population was shown to be euryhaline, with reasonable growth from 9 to 45%0 salinity, although plants grew maximally around the salinity of full seawater. An irradiance of 80 fl.mol m-2 S-l was sufficient for maximal growth, and growth was not severely reduced at 850 fl.mol m-2 S-l (the highest experimental irradiance). Agar content was 32 - 34% of the dry weight, and this level was not significantly affected by 4 weeks' growth at various temperatures.

Kultuurstudies is uitgevoer op 'n inheemse populasie van die agar-produserende rooi seewier Graci/aria verrucosa om die optimale bereik te bepaal van omgewingsfaktore wat die groei be·fnvloed, met die oog op moontlike marikultuur. Plante groei goed tussen 15 en 25°C, swak by laer temperature, en hulle oorleef nie 30°C nie. Ondanks min skommelinge in die soutgehalte van die natuurlike omgewing, blyk die populasie eurihalien te wees, met 'n redelike groei tussen 9 en 45%0 soutgehalte, alhoewel plante maksimaal gegroei het by 'n soutgehalte rondom die van normale seewater. 'n Beligting van 80 fl.mol m-2 S-l is voldoende om optimale groei te bewerkstellig, terwyl groei nie ernstig afgeneem het by 250 fl.mol m-2 S-l (die hoogste eksperimenteel toegepaste beligting) nie. Die agargehalte bedra 32 - 34% van die droe gewig, en hierdie waarde is nie beduidend be·fnvloed deur vier weke se groei by verskillende temperature nie.