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The seasonal variation in the water- soluble constituents of Gracilaria Iichenoides collected from. Palk Bay has been studied. An economic method has been worked out for the extraction of agar from the seaweed.

We took advantage of regional differences in environmental forcing and consumer abundance to examine the relative importance of nutrient availability (bottom-up), grazing pressure (top-down), and storm waves (disturbance) in determining the standing biomass and net primary production (NPP) of the giant kelp Macrocystis pyrifera in central and southern California. Using a nine-year data set collected from 17 sites we show that, despite high densities of sea urchin grazers and prolonged periods of low nutrient availability in southern California, NPP by giant kelp was twice that of central California where nutrient concentrations were consistently high and sea urchins were nearly absent due to predation by sea otters. Waves associated with winter storms were consistently higher in central California, and the loss of kelp biomass to winter wave disturbance was on average twice that of southern California. These observations suggest that the more intense wave disturbance in central California limited NPP by giant kelp under otherwise favorable conditions. Regional patterns of interannual variation in NPP were similar to those of wave disturbance in that year-to-year variation in disturbance and NPP were both greater in southern California. Our findings provide strong evidence that regional differences in wave disturbance overwhelmed those of nutrient supply and grazing intensity to determine NPP by giant kelp. The important role of disturbance in controlling NPP revealed by our study is likely not unique to giant kelp forests, as vegetation dynamics in many systems are dominated by post-disturbance succession with climax communities being relatively uncommon. The effects of disturbance frequency may be easier to detect in giant kelp because it is fast growing and relatively short lived, with cycles of disturbance and recovery occurring on time scales of years. Much longer data sets (decades to centuries) will likely be needed to properly evaluate the role of disturbance relative to other processes in determining patterns of NPP in other systems.

Despite decades of effort, viable algal biofuels remain a distant vision. High-lipid microalgae for biodiesel is plagued by low productivity, poor biomass quality, and pond instability, so conversion of non-specific algal biomass into other fuels is now the favored approach. Nevertheless, with low productivity and high costs,microalgae cannotprovide the annualtonnage of biomassneededfor fuelproduction.Analternative source of easily produced algal biomass has been available for decades. Algalturf scrubbing (ATS) robustly cultivates indigenous algae in an open flume photobioreactor. It is a proven, cost-effective, point- and non point-source treatment method for recycling the aquatic nutrient pollution whose levels threaten to exceed sustainable earth system boundaries. Using ATS to reverse nutrient loading in eutrophic waters would produce copious algal biomass at essentially no cost, for biofuel production or for development into other bioproducts.

Global production of farmed salmon and trout in saltwater was 1.82 million metric tons in 2007, three times more than any other farmed marine fish category. Development of this industry teaches that, for fish farming to succeed, containment systems must be easily deployed and operated and governments must create space in their coastal waters where farms can be located. Neither of these circumstances exists presently in the United States and, until this changes, other lessons that salmon farming teaches can only provide research or policy guidance. These include the importance of selecting a good fish to farm and making them “affordable” by being efficient. Salmon farmers achieved the latter through mechanization, industry scale, and a focus on good fish health and performance.Salmon farming also teaches that various plant and animal ingredients can be used in salmon feed and that its future growth will not be limited because salmon is a carnivore, as some have suggested. In fact, carnivorous fish, such as salmon, may turn out to be some of the most ecologically efficient species to farm. It is noteworthy, too, that it took 40 years to establish an industry with the capacity to produce 1.82 million metric tons of fish per year while the United States imported 2.36 million metric tons of seafood in 2008, 83% of its needs, much of it from foreign farms. If future international competition for these same supplies leads to national seafood shortages, it will be hard to replace it quickly with products from domestic aquaculture.