60 that are considered “calcifying organisms” that use calcium in their shells like mollusks and crustaceans. When the pH of the water decreases, there are a lower concentration of calcium ions and a higher dissolution rate of calcium carbonate, which in turn can weaken the shells of these calcifying organisms (Long et al., 2013). Kelp forests are also a habitat for shellfish, which can have a positive impact on biodiversity (Duarte et al., 2017). Red king crab is Alaska’s largest shellfish export and the second largest fishery export, accounting for $2.5B from 1975 to 2018, not adjusting for inflation (Alaska Department of Fish and Game, n.d.-b). With greater ocean acidification, red king crabs must spend more energy to maintain calcification, which leads to a decrease in their population over time (Long et al., 2013). Macroalgae like kelp have the potential to mitigate ocean acidification through their metabolic processes and create areas of high pH that can ultimately help shellfish, such as red king crab (Duarte et al., 2017). Regulators do not allow crab harvesting when population numbers decrease past a certain point, in order to allow the stock to grow back to farming size. In 2021, the Bristol Bay crab fishery closed due to low king crab numbers. The industry lost $30M due to the closure, which included not only profits to the fishing companies but also the salaries of 400 fisherman who were not employed in the 2021 crabbing season (McKenney, 2021). The red king crab population may be declining for other reasons, such as increased predation by salmon due to the warming water, but kelp forests offer a way to head off some of the population loss. These benefits that kelp offers would be limited if the kelp is harvested. Kelp is most effective at combatting ocean acidification during the summer when the days are longer, which lengthens the photoperiod of kelp. With kelp typically seeded in the fall and harvested in the spring, the effects are likely to be less with harvested kelp because the kelp is not left to grow in the summer. Kelp also offers a habitat to shellfish and other marine organisms only when the kelp is in the water (Duarte et al., 2017). One study also suggests that the reduction in pH that kelp offers only happens near the surface of the water, limiting kelp’s impact (Hirsh et al., 2020). For more information on ocean acidification and its implications for Alaska’s fishing industry, see the article by Perillo in this volume. Kelp has the potential to ward off nutrient pollution, such as the overgrowth of phytoplankton and algae, which occurs when there is excess phosphorus and nitrogen in the water. The resulting eutrophication can have detrimental effects on marine ecosystems, including plant die-offs and ocean dead zones, areas that lack enough oxygen to support normal marine life (Chislock et al., 2013). Nitrogen and phosphorus can be point source pollutants, which generally can be limited by regulation, but they also can be released from nonpoint sources, including excess soil or fertilizer, which is swept into the water over entire regions. This type of dispersed pollution is much harder to regulate and keep out of the water. Seaweed works as a natural bioextractant and is one of the only options for removing such pollution once it has entered the water. When seaweed grows, it uses nitrogen and phosphorus from the water, thereby offering protection from eutrophication. Seaweed also releases oxygen into the water, which can mitigate existing ocean dead zones that have resulted from eutrophication. This process is not limited by farming, because the pollutants are removed just by growing the kelp; however, the kelp does need to be near the source (Racine et al., 2021). As Alaska does not have a large population or substantial agriculture, this use for kelp may be limited (McKinley Research Group, 2021). Although Alaska does not face substantial pollution, Alaska’s southcentral and southwest coasts are in open ocean low oxygen zones, and one area in Alaska’s southeast coast is hypoxic, a dead zone (Crowder et al., 2019). Kelp farms could be used to mitigate potential harm that may arise in these areas from lack of oxygen. Recommendations and Conclusion There are four main ways that Alaskan kelp can be used: as a whole food, an ingredient, a shellfish habitat, and a carbon sink. The State of Alaska needs to develop strategies to engage farmers in each of these kelp industries. The biggest challenge for Alaskan kelp is high production costs, which prevent Alaskan kelp farmers from entering the hydrocolloid market, because of the availability of cheap seaweed
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