October 6, 2021 — Changes in the northern Alaskan Arctic ocean environment have reached a point at which a previously rare phenomenon—widespread blooms of toxic algae—could become more commonplace. These blooms potentially threaten a wide range of marine wildlife and the people who rely on local marine resources for food. That is the conclusion of a new study about harmful algal blooms of the toxic algae Alexandrium catenella published in the journal Proceedings of the National Academy of Science. Microscopic algae in the ocean are most often beneficial and serve as the base of the marine food web. However, some species produce potent neurotoxins that can directly and indirectly affect humans and wildlife.
Dormant Cysts Could Seed a Toxic Bloom
The study was led by scientists at the Woods Hole Oceanographic Institution (WHOI) in collaboration with colleagues from NOAA’s Northwest Fisheries Science Center and researchers in the United States, Japan, and China. It looked at samples from seafloor sediments and surface waters collected during 2018 and 2019. Samples were taken in the region extending from the Northern Bering Sea to the Chukchi and Beaufort Seas north of Alaska. The sediment samples allowed the researchers to count and map Alexandrium cysts. The cysts are a seed-like resting stage that lies dormant in the seafloor for much of the year, germinating or hatching only when conditions are suitable. The newly hatched cells swim to the surface and rapidly multiply using the sun’s energy. This produces a “bloom” that can be dangerous due to the family of potent neurotoxins, called saxitoxins, that the adult cells produce.
When the algae are consumed by some fish and all shellfish, those toxins can accumulate to levels that can be dangerous to humans and wildlife. In fish, toxin levels can be high in digestive and excretory organs (e.g., stomach, kidney, liver), but are very low in muscle and roe. Although fish can be potential toxin vectors, the human poisoning syndrome is called paralytic shellfish poisoning. Symptoms range from tingling lips, to respiratory distress, to death. The toxin can also cause illness and death of marine wildlife such as larger fish, marine mammals, and seabirds. This is of particular concern for members of coastal communities, Alaskan Native Villages, and Tribes in northern and western Alaska who rely on a variety of marine resources for food.
Read the full article at NOAA Fisheries