If you notice an orange tint to the waters of Central Puget
Sound, it’s not your imagination. It is a dense plankton bloom
dominated by the dinoflagellate Noctiluca scintillans.
Noctiluca scintillans bloom
comes ashore at Saltwater State Park in Des Moines on Monday of
this week.
Video: Washington Department of Ecology
Noctiluca is often seen in some numbers at this time of
year, but it may be a bit more intense this time around, according
to Christopher Krembs, an oceanographer with the Washington
Department of Ecology. Christopher tells me that the orange color
may stick around awhile.
The orange-colored species does not produce any toxins found to
be harmful to humans, but it is not exactly a friendly organism
either. It often shows up in marine waters that are out of balance
with nutrients or impaired in some other way. It can gobble up
other plankton that feed tiny fish and other creatures, but it does
not seem to provide a food supply that interests very many species
— probably because of its ammonia content. Consequently,
Noctiluca is often referred to as a “dead end” in the food
web.
In the latest “Eyes
Over Puget Sound” report, one little note caught my attention:
“Puget Sound is fresher than it’s ever been the past 17 years.”
Jellyfish are largely missing
this fall from Puget Sound. Some patches of red-brown algae, such
as this one in Sinclair Inlet, have been observed.
Photo: Washington Department of Ecology
At least temporarily, something has changed in the waters of
Puget Sound over the past few months. It may not last, but it
appears to be a good thing.
The monthly EOPS report, compiled by a team of state
environmental experts, lays out recent water-quality data for the
Department of Ecology. The report also includes personal
observations, aerial photographs and scientific interpretations
that keep readers abreast of recent conditions while putting things
in historical context.
The “fresh” conditions called out in the report refers to the
salinity of Puget Sound, which is driven largely by the freshwater
streams flowing into the waterway. The reference to 17 years is a
recognition that the overall salinity hasn’t been this low since
the current program started 17 years ago.
Dissolved oxygen, essential to animals throughout the food web,
was higher this fall than we’ve seen in some time. Hood Canal,
which I’ve watched closely for years, didn’t come close to the
conditions that have led to massive fish kills in the past. The
only problem areas for low oxygen were in South Puget Sound.
Water temperatures in the Sound, which had been warmer than
normal through 2015 and 2016, returned to more average conditions
in 2017. Those temperatures were related, in part, to the warm
ocean conditions off the coast, often referred to as “the blob.” In
South Puget Sound, waters remained warm into October.
Why is the water fresher this fall than it has been in a long
time? The reason can be attributed to the massive snowpack
accumulated last winter, according to oceanographer Christopher
Krembs, who leads the EOPS analysis. That snowpack provided
freshwater this past spring, although rivers slowed significantly
during the dry summer and continued into September.
“We had a really good snowpack with much more freshwater flowing
in,” Christopher told me, adding that the Fraser River in southern
British Columbia was well above average in July before the flows
dropped off rapidly. The Fraser River feeds a lot of freshwater
into northern Puget Sound.
Freshwater, which is less dense than seawater, creates a surface
layer as it comes into Puget Sound and floats on top of the older,
saltier water. The freshwater input fuels the circulation by
generally pushing out toward the ocean, while the heavier saltwater
generally moves farther into Puget Sound.
“The big gorilla is the upwelling system,” Christopher noted,
referring to the rate at which deep, nutrient-rich and low-oxygen
waters are churned up along the coast and distributed into the
Puget Sound via the Strait of Juan de Fuca. Lately, that system has
been turned down to low as a result of larger forces in the
ocean.
In an
advisory issued today (PDF 803 kb), NOAA’s Climate Prediction
Center says a weak La Niña is likely to continue through the
winter. For the northern states across the country, that usually
means below-average temperatures and above-average precipitation.
(It’s just the opposite for the southern states.)
With a favorable snowpack already accumulating in the mountains,
experts can’t help but wonder if we might repeat this year’s
conditions in Puget Sound over the next year.
Christopher told me that during aerial flights this fall, he has
observed fewer jellyfish and blooms of Noctiluca (a plankton known
to turn the waters orange) than during the past two years. Most
people think this is a good thing, since these organisms prevail in
poor conditions. Such species also have a reputation as a “dead
end” in the food web, since they are eaten by very few animals.
Christopher said he noticed a lot of “bait balls,” which are
large schools of small fish that can feed salmon, birds and a
variety of creatures. “I assume most of them are anchovies,” he
said of the schooling fish.
I would trade a jellyfish to get an anchovy on any day of the
year.
Eyes Over Puget Sound shot
some amazing plankton blooms this week, including this one between
Bainbridge Island and Seattle. / Photos courtesy of
EOPS
Team members for Eyes Over Puget Sound, a Washington Department
of Ecology program, were excited to discover and report on a second
major plankton bloom during their flight this week.
“The real show came at the end of the day when we got to Edmonds
and started to see a bright orange Noctiluca bloom. It was huge! It
persisted all the way to South East Passage. It was the most
extensive bloom I have ever seen. Every direction you looked, there
it was. It’s as if Puget Sound was on fire!
“The size of this bloom made me wonder … Why is it happening in
the Main Basin and not in South Sound? Why is it happening again?
Why don’t we know more about its appearance and ferocious appetite
for phytoplankton? Could it be that our imprint on Puget Sound is
artfully surfacing to remind us of our daily connection to the
Sound? Could these large blooms be a clue of a shift in the food
chain?”
The report provides all kinds of good information, which I will
review more carefully when I get the chance. General observations
include red-brown blooms in Port Townsend Bay, Discovery Bay and
Bellingham Bay. Large mats of accumulated plankton were seen in
Samish Bay. Clusters of jellyfish were spotted in Budd, Totten and
Eld Inlets, all in South Puget Sound.
EOPS provides aerial observations of sea surface conditions
between landings, when water is sampled for a variety of
conditions. Weather and general oceanographic conditions also are
reported after each flight.
Taken over Winslow on
Bainbridge Island, this photo shows a Noctiluca bloom with the
Bainbridge Island ferry in the background. / Photo by
Christopher Krembs, Ecology
Plankton blooms reported last week from numerous locations in
Puget Sound were confirmed and examined from the air Monday by
Christopher Krembs and his colleagues at Eyes Over Puget Sound.
The marine monitoring group for the Department of Ecology
reported notable Noctiluca blooms, as I reported in a story in
Friday’s Kitsap Sun. The blooms are relatively harmless and not
unexpected, given the mild weather and freshwater flows that bring
nutrients into Puget Sound. They are earlier than in recent years,
however.
Christopher also observed heavy sediment flows coming out of the
Fraser River near Vancouver and moving south along the Canadian
border. These and many other observations can be reviewed by
downloading the latest
report on Ecology’s website.
A brightly colored plankton
called Noctiluca was observed last week along the shore of
Bremerton’s Evergreen-Rotary Park. / Kitsap Sun photo
by Meegan M. Reid.
