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Alaska 'Orange Goo' Rust Spores Confirmed

Published on: 02/09/2012
Region(s) of Study: Foreign Countries

An 'orange goo' covered the shoreline of the Inupiat village of Kivalina, Alaska last summer. It alarmed residents, perplexed local state and federal agencies and caused an international sensation via the press. Residents thought it was a harmful algal bloom similar to Noctiluca which is common to nearshore Alaska waters. Samples were sent NOAA's Analytical Response Team who identified the orange substance as spores of a rust fungus, but not being experts of terrestrial plants did not make a species identification.

Six months later the substance was identified by forest health professionals at the USDA Forest Service and the Canadian Forest Service to be spores of the rust fungus Chrysomyxa ledicola. This fungus is a plant pathogen that infects the foliage of spruce (Picea spp.) and Labrador tea (Ledumspp.).

Many rust fungi have complex lifecycles, with five spore stages completed on two very different types of host plants. It is thought that the spore stage detected near Kivalina is the aeciospore stage, which is produced on current-year spruce foliage in late summer and spreads through the air to infect Labrador tea. Large scale outbreaks of spruce needle rust are not unprecedented in Alaska, and the large quantities of spores have been known to discolor river water.

The rapid response by NCCOS scientists and outreach specialists to correctly identify the mysterious orange goo quickly resolved health concerns of local residents and provided correct information to the Alaska Fisheries. Spore identification was based on the physical features of the spores (shape, size and appendages) at high magnification using scanning electron microscopy. Genetic sequencing can also be used for identification, but the spores were too degraded for sequencing after storage in seawater.

NCCOS researchers will support USDA's summer 2012 collection effort by providing scanning electron microscopy identification of the spores to track the extent of this fungus in western Alaska.

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