Evidence for massive and recurrent toxic blooms of Alexandrium catenella in the Alaskan Arctic

Abstract

Among the organisms that spread into and flourish in Arctic waters with rising temperatures and sea ice loss are toxic algae, a group of harmful algal bloom species that produce potent biotoxins. Alexandrium catenella, a cyst-forming dinoflagellate that causes paralytic shellfish poisoning worldwide, has been a significant threat to human health in southeastern Alaska for centuries. It is known to be transported into Arctic regions in waters transiting northward through the Bering Strait, yet there is little recognition of this organism as a human health concern north of the Strait. Here, we describe an exceptionally large A. catenella benthic cyst bed and hydrographic conditions across the Chukchi Sea that support germination and development of recurrent, locally originating and self-seeding blooms. Two prominent cyst accumulation zones result from deposition promoted by weak circulation. Cyst concentrations are among the highest reported globally for this species, and the cyst bed is at least 6× larger in area than any other. These extraordinary accumulations are attributed to repeated inputs from advected southern blooms and to localized cyst formation and deposition. Over the past two decades, warming has likely increased the magnitude of the germination flux twofold and advanced the timing of cell inoculation into the euphotic zone by 20 d. Conditions are also now favorable for bloom development in surface waters. The region is poised to support annually recurrent A. catenella blooms that are massive in scale, posing a significant and worrisome threat to public and ecosystem health in Alaskan Arctic communities where economies are subsistence based.

Growing Degree-Day Measurement of Cyst Germination Rates in the Toxic Dinoflagellate Alexandrium catenella

“…The lines depict the degree-days to median germination ( DD 50 ) for each population. A similar plot was originally published in Anderson et al ( 37 ) but not fully explained.…”

“…It is still possible to hypothesize cyst beds’ response to changing bottom water conditions under the assumption that fluxes are driven primarily by germination. Through the application of DD scaling, changes in the timing, intensity, and duration of cyst germination were recently estimated for a massive A. catenella cyst bed across the Chukchi Sea ( 37 ). The authors applied a generalized temperature–germination rate relationship from observations of several North American cyst populations.…”

Low Levels of Contaminants Stimulate Harmful Algal Organisms and Enrich Their Toxins

“…The hormetic enhancement of harmful algae by low, sub-NOAEL doses of contaminants suggests potential changes in the disease burden epidemiology, with likely effects beyond areas that are currently known to be at risk . This becomes of even greater concern in the light of unknown interactive effects between climate change (e.g., documented changes due to global warming , ) and environmental pollution, which could lead to antagonistic, additive, or synergistic effects at low doses.…”

“…Aquatic harmful algal blooms (HABs) are considered a climate change costressor in freshwater and marine ecosystems as well as a major environmental issue that can severely affect aquatic ecosystems, human health, and the economy (see also ). HABs can result in acute human illness, primarily due to phycotoxins ingested through contaminated seafood, direct skin contact, or inhalation. − Blooms of harmful cyanobacteria also enter water supply systems in all major continents but Antarctica. − The toxic effects of HABs are often similar to infectious diseases, such as norovirus, thus making their diagnosis difficult or impossible .…”

Definition of a saxitoxin (STX) binding code enables discovery and characterization of the Anuran saxiphilin family

“…Saxitoxin (STX), one of the most lethal non-peptidyl neurotoxins, blocks the bioelectrical signals in nerve and muscle required for life by inhibiting select voltage-gated sodium channel (Na V ) isoforms ( 1–3 ). Cyanobacteria and dinoflagellate species associated with oceanic red tides produce this bis-guanidinium small molecule and its congeners whose accumulation in seafood can cause paralytic shellfish poisoning (PSP), a commer c ial fishing and public health hazard of growing importance due to climate change ( 1, 3–5 ). Its extreme lethality has also earned STX the unusual distinction of being the only marine toxin declared a chemical weapon ( 1, 3 ).…”