Karenia mikimotoi is a toxic dinoflagellate alga with a cosmopolitan distribution and is a commonly reported red tide species. Blooms of K. mikimotoi have caused large fish and benthic invertebrate mortalities resulting in major economic losses. A recent publication of NCCOS sponsored research reports, for the first time, on a massive K. mikimotoi bloom that occurred in Kachemak Bay and lower Cook Inlet (Alaska) in 2013.

Time series of MODIS-Aqua satellite near-infrared chlorophyll reflectance imagery of south-central Alaska captured over the course of the 2013 K. mikimotoi bloom.. The image captured on October 1 showed high levels of bioluorescence in Kachemak Bay, during the bloom peak, and indicated high biomass. Credit: Vandersea et al., 2020.

In September of 2013 an unusual and immense dinoflagellate bloom in Kachemak Bay, AK caused the water in much of the Bay to be a dark amber color with reports of tinted seafoam. There was heightened public concern over the immensity of the bloom as well as small scale fish kills that were reported. The color and increased foam on the water led local residents to term the phenomenon the “beer tide.” Light microscopy observations revealed a monospecific bloom of an unknown dinoflagellate that prompted additional efforts to resolve the species’ identification. A species-specific molecular method (qPCR) was developed and used to confirm that the dinoflagellate was Karenia mikimotoi. This was the first reported occurrence for a bloom of K. mikimotoi in Alaska.

Light micrograph of Karenia mikimotoi cell obtained from bloom sample in Kachemak Bay, AK. Arrowhead denotes flagellum. Scale bar =50 microns (μm). Credit: Vandersea et al., 2020.

By comparing K. mikimotoi cell abundances to a time series of environmental data, the researchers were able to investigate factors associated with bloom development and eventual bloom decline which will improve future predictive HAB capabilities. The publication also presents an approach to guide future HAB response efforts in the region.

The investigation was led by NCCOS scientists with partners from the Kachemak Bay National Estuarine Research Reserve, Alaska Department of Environmental Conservation, Alaska Ocean Observing System, and two private companies.

Citation:  Vandersea, Mark, Patricia Tester, Kris Holderied, Dominic Hondolero, Steve Kibler, Kim Powell, Steve Baird, Angela Doroff, Darcy Dugan, Andrew Meredith, Michelle Tomlinson, and R. Wayne Litaker, 2020. An extraordinary Karenia mikimotoi "beer tide" in Kachemak Bay Alaska. Harmful Algae 92, February 2020, 101706. https://doi.org/10.1016/j.hal.2019.101706

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• 2014: Working with State to Document First Occurrence of Harmful Karenia mikimotoi Algae in Alaskan Waters

Maps of study area: (A) Location of study area in Alaska, (B) Lower Cook Inlet and Kachemak Bay with transects 3, 6 and 7 and sampling stations, (C) Detail of Kachemak Bay with sampling stations on transects 4 and 9, the Kasitsna Bay Laboratory and Jakolof Bay. Credit: Vandersea et al., 2020.