Check out this great video from UW's Applied Physics Lab
to learn how our network of ORCA (Oceanic Remote Chemical Analyzer)
buoys has helped scientists track the "blob" and it's effects in local
waters, including fish kills in Hood Canal.
From Jan Newton, Allad Devol and Wendi Ruef, University of Washington:
A fish kill occurred in late August in Hood Canal, documented by observations from the Skokomish Tribe and by ORCA buoy oxygen measurements by the University of Washington. The fish kill was most severe on 29 August, but with stress and some mortality observed both before and after.
Seth Book and others from the Skokomish Tribe DNR observed thousands of dead fish and crab on Friday, which was covered by the media. On Saturday-Sunday, we anticipated even more fish kill, due to sustained southerly winds, but the lowest oxygen waters stayed deep, below ~10 m. Videos show the fish and crabs confined to a narrow surface layer, which maintained sufficient oxygen.
A couple things to clarify from the media reports:
- Worst year? The low oxygen levels in southern Hood Canal were the most extreme we have measured, even worse than in 2006 and 2010. However, the fish kill events in 2003, 2006 and 2010 appear to have been worse than this year, at least so far.
- Blob effect? The effect of the blob (warmer than typical NE Pacific ocean waters) was last fall, when the ocean waters entering Puget Sound were warmer (less dense) and did not flush the southern reach of Hood Canal. The year 2015 started with hypoxic waters in southern Hood Canal. The blob, still offshore now, is not affecting current conditions. Strong coastal upwelling during June is what is flushing Hood Canal now. This seasonal intrusion started about a month earlier than normal, which is lucky because oxygen conditions would have worsened until the flushing started.
Oxygen conditions in Hood Canal appear to be improving as flushing continues. Conditions today at Hoodsport show the entire water column is above hypoxic levels; at Twanoh there is severe hypoxia (less than 1 mg/L) at 10 m depth, but the deepest waters now have oxygen concentrations above this.
Visit ORCA and NANOOS for more information on hypoxia in Washington waters.
Lingcod from the 2006 Hood Canal fish kill event. Photo credit: Hood Canal Dissolved Oxygen Program
Fish kills in Hood Canal occur when hypoxic waters are rapidly upwelled
to the surface, usually when seasonal southerly wind storms push surface waters aside to be replaced with less oxygenated water from below. The rapid upward movement of low oxygen water to the surface traps fish, suffocating them.
The abnormal
weather and oceanic conditions which we've seen this year (the 'blob,' drought, etc.) have resulted in extreme hypoxia in Hood
Canal. But these anomalies have also set up Hood Canal for early seasonal flushing from oceanic intrusions, which could replenish oxygen levels.
Fish kill risk depends on whether seasonal storms or
complete flushing occur first, which is especially relevant at the moment with southerly winds expected in Hood Canal over the weekend. Which will win? Hopefully the fish!
Find out more from the Oceanic Remote Chemical Analyzer (ORCA) Fish Kill Advisory and
follow real-time oxygen levels monitored in Hood Canal on NVS.
Dead ratfish from the 2010 Hood Canal fish kill event. Photo credit: Ron Figlar-Barnes
written by Stephanie Moore, NOAA Northwest Fisheries Science Center
The dinoflagellate Alexandrium catenella. Photo credit: Gabriela Hannach, King County
In September and October 2014, there was an unprecedented
harmful algal bloom of Alexandrium in Hood Canal that contaminated shellfish
with potent biotoxins. The area where the bloom took place has historically
been biotoxin free. Alexandrium produce a suite of neurotoxins, called saxitoxins,
which can cause paralytic shellfish poisoning in humans who consume
contaminated shellfish. The regulatory limit for human consumption is 80 ug
saxitoxin equivalents per 100 g shellfish tissue. At the peak of the event,
shellfish toxicity was 12,688 ug STX equiv./100 g.
The Washington State Dept. of
Health and the local shellfish growers are concerned that the large bloom may
have resulted in a new "seed bed" forming (i.e., a concentrated area
of cysts that are deposited to benthic sediments and provide the inoculum for
blooms the following season) that could increase bloom risk in this area next
year.
In late January, scientists
from NOAA Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) and collaborators Cheryl Greengrove and
Julie Masura at the University of Washington Tacoma participated in a research
cruise aboard the UW’s R/V Barnes to do some small scale cyst mapping in the
area of the large bloom. Ian Jefferds from Penn Cove Shellfish contributed
funds to purchase lab consumables needed to do the cyst mapping.
Heading out of Pleasant Harbor aboard R/V Barnes
The Craib Corer takes a single, undisturbed core sample from
the top of the sediment layer
Prepping the Craib Corer for deployment
The samples were taken back to the lab is Seattle and analysis will begin this week. If cysts were deposited in the area, the Washington State
Dept. of Health will need to be more vigilant and dedicate more resources for
biotoxin monitoring in this area, and any future dredging activity that could
disturb the cysts and suspend them up into the water column where they could
germinate should be planned outside of the time of year that supports
blooms.
Visit the NANOOS HABs Information Page for more information on Harmful Algal Blooms in the Pacific Northwest.
A videographer from NOAA Fisheries Ocean Media Center joined the cruise to document the effort
Okay, so no one says that but they might as well... I mean, whoever heard of a
body of salt water this far from the poles freezing? That’s what was
going through my head as I drove our 20’ aluminum boat into the icy sheet last
winter.
It started out as a normal, albeit cold, field day for the
Oceanic Remote Chemical Analyzer (ORCA) team. We launched the M/V
Mackinaw at Twanoh State Park and drove out to our research buoy in Lynch Cove
to replace the CTD package and repair the winch control box. We thought
we were prepared for a cold day on the water, armed with extra layers, beanies,
scarves and multiple pairs of wool socks, but then the snow started. I
always seem to forget how difficult it is to do precise, mechanical work on
cold metal instruments with cold metal tools, while constantly being splashed
by cold, cold water. The work was taking much longer than anticipated
with all of this cold on cold. When we eventually finished the required
maintenance I pointed the boat toward the ORCA Hoodsport buoy where we were
scheduled to work on the router. As we turned around Sisters Point I
noticed a definite line on the water surface ahead of me. “Weird, that looks
just like…” CRUNCH!!!
Standing on the bow of the M/V Mackinaw as we try to push
our way through the ice
Before I could even finish my thought we were startled with a sudden crash as the Mackinaw tried pushing through a sheet
of ice.I slowed down and carefully
backed us out through the path we had just cut, and then motored along the
margin to see if there was any way through.No luck.A flock of seagulls
stood on the ice and watched us while we made a call and sent photos to our incredulous
supervisor at the University of Washington.There was no way we’d be able to continue.We couldn’t see the end of the ice sheet and
even if we made it through we’d lose too much daylight to get any work done.After a few more minutes playing with the chunks
of ice that had broken free of the sheet, we headed back to Twanoh to get our
boat out of the cold water.
Snapping some photos while we wait for confirmation to call
it a day
Encountering ice in Hood Canal surprised our group but
apparently it’s not that strange.Fresh water
that flows from the Skokomish River into Hood Canal tends to float on top of
the denser salt water, creating a thin fresh layer.When temperatures drop this layer can freeze,
just like any body of fresh water.If
temperatures stay low for long enough, the ice sheet can reach from shore to
shore like we witnessed... I’ve even heard stories of people driving wagons
across the canal in previous centuries!
