|Black seaweed (Laak’ásk) is one of the most commonly harvested types of seaweed by Hoonah residents and is highly sought and widely used at a variety of cultural events. Other commonly harvested seaweeds and intertidal plants include bull kelp (geesh), ribbon seaweed (k’áach’), bladderwrack (tayeidí), sea lettuce, goose tongue (suktéitl’) and beach asparagus (sukkáadzi). Not only are seaweeds an important nutritional source, rich in vitamins and minerals, but kelps are also an important carbon sequestration method that can help ocean acidification and global warming. Kelp forests and intertidal plants also serve as vital nurseries for juvenile crab and salmon. Community members have reported that seaweeds dry out more now than they used to because of higher temperatures while they are exposed, and are concerned about harvesting from areas with high human development or traffic (particularly near the cruise ship docks from Icy Strait Point). Local harvesters have also reported that location and season impacts the taste, color and texture of seaweed, and thus if environmental conditions or harvest locations change in the future, it is likely that many of the characteristics of seaweed may change as well.
SEAWEEDS ARE MOST THREATENED BY CHANGING ECOSYSTEM DYNAMICS, PARTICULARLY FROM CHANGING LEVELS OF PREDATION.
Sea stars and sea otters are some of the most important animals that help protect kelp forests. Both are voracious predators, which hunt the sea urchins and other animals that eat the kelp. When those species suffer population losses, they can’t keep the urchins at bay, which leads to urchin barrens, or massive swaths of the ocean floor that were once teaming with life but have now been entirely consumed by urchins. While it’s still not entirely clear what’s causing sea star wasting disease, it’s led to massive die offs along the west coast and may be linked to climate change. Combined with a loss of sea otters in the Lower 48, it’s resulted in massive losses to kelp forests (primarily bull kelp). While the number of sea otters in Southeast has been on the rise following their reintroduction, otters are still threatened by climate change and may suffer losses in the future, which would also be a loss for the kelp forests.
CHANGING WATER CHEMISTRY CAN NEGATIVELY IMPACT THE GROWTH OF SEAWEEDS, BUT INTERTIDAL PLANTS
ARE EXPECTED TO ADAPT WELL.
Seaweeds are sensitive to rising ocean temperatures and their growth is stunted when the water gets too warm. Ocean acidification may have mixed results on seaweed and it’s still unclearly how exactly they’ll respond. While decreasing pH slows grazing by many animals, it also weakens the tissues of seaweeds and it’s still unclear how those forces are likely to balance. Many intertidal plants are accustomed to variable water conditions and are likely to adapt well to future changes. Sea asparagus is particularly adaptable and already thrives in a wide range of environmental conditions, from southeast Alaska to Israel, and has a high tolerance for drought and heat.
SEAWEEDS AND INTERTIDAL PLANTS ARE ALSO THREATENED BY MARINE POLLUTION AND HUMAN DEVELOPMENT.
Seaweeds are also sensitive to changes in their growing environments—if areas have been disturbed by construction or large events of run-off, they often have a hard time coming back. Algal blooms, driven by warmer waters, can restrict the growth of seaweeds, and toxic runoff from spills on land can make the problem even worse. Thankfully, seaweeds naturally act like water filters, and if they’re given enough time to recover between events, they can improve water quality and help clean up the local conditions.
THE HARVEST LOCATIONS OF INTERTIDAL PLANTS ARE LIKELY TO CHANGE DUE TO SEA LEVEL DROP.
Just as the locations of clam and cockle beds are likely to change due to the drop in sea level because of post-glacial rebound, harvesting locations for intertidal plants such as beach asparagus and goose tongue may change. It is unknown whether those locations will be more or less accessible to local users, but harvesters will likely need to find new places to source those plants as the shoreline evolves. This problem will be worsened by erosion from increased severe weather events.
2.1: Protect intertidal areas where beach greens are commonly harvested from future developments and seek to limit marine pollution that would harm the heath or growth of wild plants.
1.1: Research possibilities for local or commercial scale seaweed farming of relevant species of seaweeds.