Northwest Fisheries Science Center

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A gateway to oceanographic adventures from the Newport Line and beyond

Blog on ocean conditions along the Newport Line and the northern CA Current.

HABs in January 2016?

By Xiuning Du
January 14, 2016

After two months waiting for calmer seas, the Peterson group kicked off the first visit in the New Year to the Newport line on January 8, 2016. So what did we see in the phytoplankton community?

Two-celled short chain diatom Ditylum brightwellii (length = 150μm) from a live water sample. Numerous small chloroplasts present green-brown color.

The phytoplankton species diversity and productivity are usually low this time of a year due to short days and a lack of sunlight. However, the sample from Jan 8 was comprised of 12 species of diatoms which is relatively high compared to other observations in January when very few diatoms were present. While the species diversity of diatoms was high, none were observed in high abundance (several hundred cells per liter). Ten species of dinoflagellates were present in low abundance (1 - 2 cells in a 50 ml subsample). However, one surprising dinoflagellate was also present, Akashiwo sanguinea, which is a species known to cause harmful effects.

A. sanguinea was the star of the phytoplankton community on Jan 8. Watch this video to observe the swimming behavior of this species. A. sanguinea is common in Monterey Bay, California, but it is a truly rare species off Oregon. A. sanguinea does not produce a harmful toxin but it can cause deaths of seabirds through hypothermia. This dinoflagellate excretes surfactants that cause seawater to foam, which in turn coats bird’s feathers, and then they become hypothermic because their feathers lose their insulating properties.

The unarmored dinoflagellate Akashiwo sanguinea (length = 75μm). Numerous chloroplasts radiate from cell center. Left: a live cell; right: a cell preserved in a lugol’s solution.

The last harmful event caused by this species off central Oregon occurred in fall 2009 when the largest bloom on record occurred (Du et al. 2011). Since then, A. sanguinea has been absent in our biweekly samples until last year, 2015. On three sampling days in May, September and October 2015, A. sanguinea was observed, but in very low abundance (20 cells per liter). Therefore, the significant increase in abundance (200-1200 cells per liter) on Jan 8, 2016 is a surprise. Its reappearance from 2015 till now may be related to the continuously warm ocean associated with “the Blob”. A recent study indeed demonstrated that under higher temperatures, A. sanguinea grows 2-3 times faster than normal (Menden-Deuer and Montalbano, 2015).

Two overlapping Pseudo-nitzschia cells (length = 60μm, width = 5μm) collected on Jan 8, 2016.
A living chain-form Pseudo-nitzschia from an unpreserved water sample collected on Jan 8, 2016. Previously, this species was last observed in October 2015.

Pseudo-nitzschia, the diatom that caused an unprecedented toxic bloom in spring/summer 2015, was also present in the Jan sample. The deleterious effects of the 2015 bloom included the closure of razor clamming along the central and southern Oregon coasts since May 2015 and delayed the opening of the Oregon Dungeness crab fishery. Off Newport, Pseudo-nitzschia cells were last observed in mid-October and were absent in November 2015. Now, in early January 2016, larger Pseudo-nitzschia cells appeared again, although there were very few cells.

Will the present warm ocean conditions promote growth of these species to another unprecedented level? Will the El Niño that is occurring at the equator affect the phytoplankton off Oregon? Our frequent monitoring since 2001 taught us that toxic Pseudo-nitzschia events are most likely to occur when the ocean is warm, associated with either warm phase of PDO and/or El Niño events or “the Blob”.

Will we see HABS thrive in the very near future? Stay tuned as we continue our NH line phytoplankton and HAB monitoring and share what we find.

Tagged: HAB, NH Line, Warm Blob

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