Category Archives: Red tide, algae

Amusing Monday: Watching green waters for St. Patrick’s Day

In Chicago, it has become a tradition to dye the Chicago River bright green to celebrate St. Patrick’s Day, as shown in a timelapse video featured by ABC News. But some waterways are naturally green, so I have posted eight videos from throughout the world to show these natural wonders.

Huge crowds of people visit the Chicago River each year to see the color change, which lasts about five hours, according to a report by Jennifer Wood in Mental Floss.

At one time, a green dye was used as needed to identify sources of sewage flowing into the river, Jennifer reports. The result was an occasional green splotch seen in the river. In 1962, a member of the local plumbers union thought it would be a good idea to dye the entire river green for St. Patrick’s Day. It has since become an annual tradition — although in 1966 the dye was changed to a nontoxic vegetable-based coloring at the insistence of environmentalists.

Today, environmentalists are still grumbling about artificially turning the river green, not so much because of damage to the ecosystem — which is really unknown — but because the river is much healthier than it has been in 150 years, according to a report by Steven Dahlman in Loop North News.

“I think [it] sends a message to people that the river is not alive,” said Margaret Frisbie, executive director of Friends of the Chicago River. “Dyeing the river green does not respect that resource.”

In a story written for Smithsonian magazine, Jennifer Billock reports that no dye is needed if you really want to enjoy St. Patrick’s Day in or around a green waterway. The source of the green color varies from one place to another and may include natural minerals, algae growth or even optical illusions based on reflections or depth.

Jennifer talked to Rick Stumpf, an oceanographer who said one of his favorite places is Florida Bay in the Keys, where the green color is a reflection of seagrass just a few feet underwater.

Our tour of green waterways begins with Lake Carezza, in South Tyrol, Italy. The lake is fed from underground springs, and the level of the lake changes with the seasons.

According to a local fairy tale, a wizard fell in love with a beautiful water nymph while watching her braid her hair at the edge of the lake. To get her attention, a witch advised him to dress up as a jewel merchant and cast a rainbow across the lake. He followed her instructions except that he forgot to change his clothes. The water nymph realized his true identity and disappeared into the lake. In frustration, the wizard destroyed the rainbow, which fell into the lake, and then he tossed all of his jewels into the water, leaving the lake with its unusual colors.

Wai-O-Tapu is a lake in an 18-square-mile geothermal area in New Zealand’s Taupo Volcanic Zone. The green color of the water, which is somewhat milky and yellowish, is due to particles of sulfur floating in the water.

The area has been protected as a scenic reserve since 1931 and includes a tourism attraction known as Wai-O-Tapu Thermal Wonderland. Marked hiking trails provide visitors access to natural hot springs and mud pools.

The Verzasca River in Switzerland is a 19-mile river known for its turquoise-colored water and colorful rocks. The swift river, which flows into Lake Maggiore, is popular with scuba divers.

The green colors are provided by natural algae growing in the water as well as the reflection of vegetation along the shoreline.

Ambergris Caye, the largest island in Belize, offers the sea-green colors of a tropical paradise. It is mainstay for tourists who wish to swim or dive in the Caribbean Sea. Visitors can enjoy the marine life of Belize Barrier Reef, the longest reef system in North America, second in the world after the Great Barrier Reef of Australia.

Blue Spring State Park features the largest spring on Florida’s St. Johns River, a critical winter refuge for manatees. To protect the manatees, the spring pool is closed from Nov. 15 to March 15.

From the pool, a vertical cave plunges down to a room about 90 feet deep. At about 120 feet down, the cave constricts and water pours swiftly out of the spring, which produces about 165 million gallons of water per day.

In addition to the pool, the park includes a historic home and offers boat tours, hiking trails and camping sites.

Lake Quilotoa in Ecuador is a deep crater lake in the Andes formed by the collapse of a volcano following an eruption about 600 years ago. The green color is caused by dissolved minerals.

In five hours, visitors can hike around the volcano’s caldera, which is about two miles across. Pack mules and guides are available in and around the village of Quilotoa.

Sproat Lake is located in the center of Vancouver Island in British Columbia. In addition to lakeside homes, three provincial parks are located along the shore.

Sproat Lake Provincial Park features a variety of trails, including one trail that reaches the eastern side of the lake. A wall of rock carvings, named K’ak’awin, depict mythological creatures. The age of the petroglyphs is unknown.

Abyss Pool is the name of a hot spring in the West Thumb Geyser Basin of Yellowstone National Park. In 1883, a visitor to the park called the pool “a great, pure, sparkling sapphire rippling with heat.”

The pool is about 50 feet deep. A geyser in the pool had no record of eruption until 1987, when the first eruption was followed by several others until June 1992. The eruptions were up to 100 feet high.

Plans coming together for recycling wastewater from town of Kingston

All the pieces are falling into place for an upgrade of Kingston’s sewage-treatment plant to produce high-quality reclaimed water for irrigation, stream restoration and groundwater recharge.

Kingston Wastewater Treatment Plant
Photo courtesy of Golder and Associates

By the end of this year, a study by Brown and Caldwell engineers is expected to spell out the location and size of pipelines, ponds and infiltration basins. The next step will be the final design followed by construction.

When the project is complete, Kingston’s entire flow of wastewater will be cleaned up to Class A drinking water standards. During the summer, the water will be sold to the Suquamish Tribe for irrigating White Horse Golf Course. During the winter, most of the flow will drain into the ground through shallow underground pipes. Some of the infiltrated water will make its way to nearby Grover’s Creek, boosting streamflows and improving water quality in the degraded salmon stream.

Another major benefit of the project will be the elimination of 42 million gallons of sewage effluent per year — including about 3,000 pounds of nitrogen — which gets dumped into Kingston’s Appletree Cove. I wrote about the effects of nitrogen and what is being done to save Olympia’s Budd Inlet in five stories published this week in the Encyclopedia of Puget Sound, as I described in Water Ways on Thursday.

The Kingston project, estimated to cost $8 million, has been under study for several years, and Kitsap County Commissioner Rob Gelder said he’s pleased to see the effort coming together.

“The Kingston Recycled Water Project is pivotal, and I’m very happy to be partnering with the Suquamish Tribe,” Rob said in an email. “The best thing we can do for our environment and to enhance water availability is to not discharge treated flows into Puget Sound. We are uniquely positioned to benefit from strategic investments of this nature in the coming years.”

The Kitsap Peninsula is essentially an island where the residents get 80 percent of their drinking water from wells. North Kitsap, including Kingston, could be the first area on the peninsula to face a shortage of water and saltwater intrusion — which is why new strategies like recycled wastewater are so important.

The latest feasibility study was launched last October under a $563,000 contract with Brown and Caldwell. The work includes a detailed study of soils and analysis of infiltration rates, according to Barbara Zaroff of Kitsap Public Works who has been coordinating the project. The location of the pipeline and ponds for storing water near White Horse Golf Course also will be determined.

Funding for the study includes a $150,000 grant from the U.S. Bureau of Reclamation with $150,000 from the Suquamish Tribe. Kitsap County recently received a loan for up to $558,000 to support the study.

I last wrote about the Kingston Recycled Water Project in Water Ways three years ago, when I also discussed a similar project in Silverdale, where recycled water will come from the Central Kitsap Wastewater Treatment Plant.

Nitrogen and plankton: Do they hold the missing keys to the food web?

In a way, some of Puget Sound’s most serious ecological problems have been hiding in plain sight. I have been learning a lot lately about plankton, an incredibly diverse collection of microscopic organisms that drift through the water, forming the base of the food web.

Sources of nitrogen in Puget Sound (click to enlarge)
Graphic: Washington Department of Ecology

To put it simply, the right kinds of plankton help to create a healthy population of little fish that feed bigger fish that feed birds and marine mammals, including the endangered Southern Resident killer whales. On the other hand, the wrong kinds of plankton can disrupt the food web, stunt the growth of larger creatures and sometimes poison marine animals.

OK, that’s a bit of an oversimplification, but Puget Sound researchers are just beginning to understand the profound importance of a healthy planktonic community to support a large part of the food web. That’s one of the main points that I try to bring out in five stories published today in the Encyclopedia of Puget Sound. I am grateful to the many researchers who have shared their knowledge with me.

Average daily nitrogen coming in from rivers and wastewater treatment plants (1 kg = 2.2 pounds)
Graphic: Washington Department of Ecology

These stories tie together several major issues all related to nutrients — mainly nitrogen — that feed the marine phytoplankton, which use their chlorophyll to take energy from the sun as they grow and multiply. In the spring and summer, too much nitrogen can mean too much plankton growth. In turn, excess plankton can lead to low-oxygen conditions, ocean acidification and other significant problems.

The complex interplay of planktonic species with larger life forms in Puget Sound is still somewhat of a mystery to researchers trying to understand the food web. As part of the effort, the Washington Department of Ecology is working on a computer model to show how excess nitrogen can trigger low-oxygen conditions in the most vulnerable parts of the Salish Sea, such as southern Hood Canal and South Puget Sound.

Areas of Puget Sound listed as “impaired” for dissolved oxygen (click to enlarge)
Graphic: Washington Department of Ecology

Stormwater is often cited as the most serious problem facing Puget Sound, and we generally think of bacteria and toxic chemicals flowing into the waterway and causing all sorts of problems for the ecosystem. But stormwater also brings in nitrogen derived from fertilizers, animal wastes and atmospheric deposits from burning fossil fuels. Stormwater flows also pick up natural sources of nitrogen from plants and animals that end up in streams.

Sewage treatment plants are another major source of human nitrogen. Except for a few exceptions, not much has been done to reduce the release of nutrients from sewage-treatment plants, which provide not only nitrogen but also micronutrients such as vitamins and minerals. Some experts suspect that nutrients other than nitrogen help to determine which types of plankton will dominate at any given time.

I plan to follow and report on new scientific developments coming out of studies focused on the base of the food web. Meanwhile, I hope you will take time to read this package of related stories:

Puget Sound report tells the environmental story that took place in 2016

The year 2016 may be regarded as a transition year for Puget Sound, coming between the extreme warm-water conditions of 2014 and 2015 and the more normal conditions observed over the past year, according to the latest Puget Sound Marine Waters report.

Click on image to view report
Photo: Todd Sandell, WDFW

The report on the 2016 conditions was released this past week by the Marine Waters Workgroup, which oversees the Puget Sound Ecosystem Monitoring Program (PSEMP). The report includes data collected in 2016 and analyzed over the past year.

Some findings from the report:

  • Water temperatures were well above normal, though not as extreme as in 2015.
  • A warm spring in 2016 caused rapid melting of mountain snowpack and lower streamflows in late spring and summer.
  • Dissolved oxygen levels were lower than average in South Puget Sound, Central Puget Sound and Hood Canal, with the most intense oxygen problems in southern Hood Canal, although no fish kills were reported.
  • It was a year for the growth of Vibrio parahaemolyticus, a bacteria responsible for 46 laboratory-confirmed illnesses, including intestinal upset, among people who ate oysters in Washington during 2016.
  • Paralytic shellfish poisoning (PSP), diarrhetic shellfish poisoning (DSP) and domoic acid (DA) resulted in shellfish closures in 18 commercial and 38 recreational growing areas. But no illness were reported in 2016.
  • DSP was detected at 250 micrograms per 100 grams in blue mussel tissues sampled from Budd Inlet near Olympia last year. That is the highest level of DSP ever detected in Washington state.
  • Overall, zooplankton populations were high in 2016 compared to 2014, but generally not as high as in 2015.

Conditions, known or unknown, were responsible for various effects on fish and wildlife in 2016:

  • It was the worst year on record for the Cherry Point herring stock, which has been decline for years along with more recent declines in South and Central Puget Sound. Five local stocks had no spawn that could be found in 2016. Herring were smaller than average in size.
  • The overall abundance and diversity of marine bird species in 2015-16 were similar to 2014-15.
  • Rhinoceros auklets, however, were reported to have serious problems, which experts speculated could be related to a low abundance and size of herring. On Protection Island, breeding season started out normal, but fledgling success was only 49 percent, compared to 71 percent in 2015. Auklet parents were seen to feed their chicks fewer and smaller fish than usual.
  • Including the Washington Coast, more than 1,000 carcasses of rhinocerous auklets were found by volunteers. The primary cause of death was identified as severe bacterial infections.

If you are an average person concerned about environmental conditions in and around Puget Sound, the two-page summary and four-page highlights section near the beginning of the report will leave you better informed. To dig deeper, peruse the pages that follow.

The report is designed to be easily compared with previous years:

Puget Sound freshens up with a little help from winter snowpack

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.

Amusing Monday: Odd-looking pyrosomes more familiar in the tropics

“I have just watched the moon set in all her glory, and looked at those lesser moons, the beautiful Pyrosoma, shining like white-hot cylinders in the water.”English biologist Thomas H. Huxley, 1849

Warmer-than-normal waters off the coast of Oregon, Washington and British Columbia may be responsible for an invasion of all sorts of creatures normally found to the south in more tropical waters. None of these animals has attracted more attention than the bright bioluminescent pyrosomes, which showed up last spring as the waters of the Pacific Ocean were returning to normal temperatures.

Pyrosomes — which comes from the Greek word “pyro,” meaning fire, and “soma,” meaning body —are large colonies of small tunicates. These are invertebrates that feed by filtering sea water. The individual tunicates, called zooids, hook together to form tubes. The intake siphon of each zooid is aligned to the outside of the tube, while each discharge siphon is aligned to the inside.

The pyrosomes seen in Northwest waters so far are relatively small, thus fitting their nickname “sea pickles.” Nevertheless, they have impressed scientists who have observed them. The first video, above, was made in late July during the 2017 Nautilus Expedition along the West Coast (Water Ways, Sept. 4).

Hilarie Sorensen, a University of Oregon graduate student, participated in a research cruise in May, traveling from San Francisco to Newport in search of jellyfish that had invaded Northwest waters over the previous two years. She didn’t find the jellies she hoped to see, but she was blown away by the pyrosomes, some more than two feet long, and she wondered what they were up to.

“I am interested in how short- and long-term physical changes in the ocean impact biology,” Hilary was quoted as saying in a UO news release. “With all of these pyrosomes this year, I would like to further explore the relationship between their distribution, size and abundance with local environmental conditions.”

Reporter Craig Welch wrote about the recent findings for National Geographic. He quoted Laurie Weitkamp, a biologist with NOAA’s Northwest Fisheries Science Center: “For something that’s never really been here before, the densities are just mind-boggling,” she said. “We’re just scratching our heads.”

Even more impressive are the giant pyrosomes that have not shown up in Northwest waters, at least so far. They are rare even in tropical locales. Check out the second video, which shows a pyrosome found in the Canary Islands in North Africa and estimated to be about 12 feet long.

The third video was filmed in Tasmania south of Australia by Michael Baron of Eaglehawk Dive Centre. It shows both a giant pyrosome and a salp, another colonial creature formed of larger individuals. For the full story on the pyrosome, go to the BBC Two program, “Unidentified glowing object: nature’s weirdest events.”

Another good video on YouTube shows a giant pyrosome in the Maldive Islands off southern India.

Oddly enough, pyrosomes seem to light up in response to light, according to information posted on an invertebrate zoology blog at the University of California at Davis. The colonies may also light up in response to electrical stimulation or physical prodding.

When an individual zooid has activated its luminescence, it will trigger a chain reaction throughout the colony with nearby zooids lighting up in turn.

“When many pyrosomes are present in the same general area it’s possible to observe a vivid array of bright, pale lights produced by the many animals,” said Ian Streiter in the blog post.

“It was just this sort of observation that led the great Thomas Huxley (‘Darwin’s Bulldog’) to remark in 1849: ‘I have just watched the moon set in all her glory, and looked at those lesser moons, the beautiful Pyrosoma, shining like white-hot cylinders in the water.’

Ian concluded, “For those lucky enough to be at sea when they’re around, I imagine there are few sights as pleasant as that of the ‘moonlight’ produced by the fire bodies.”

Other information:

Finally, there is this audio report, “Millions of tropical sea creatures invade waters off B.C. coast,” with commentary from Washington state fisherman Dobie Lyons and zooplankton taxonomist Moira Galbraith of the Institute of Ocean Sciences in Sidney, B.C. They appeared on All Points West, CBC Radio, with Jason D’Souza of Victoria.

With caution, one can avoid the risk of illness when gathering shellfish

If you are planning to gather some shellfish to eat over Labor Day weekend — or anytime for that matter — state health officials urge you to follow the “three Cs” of shellfish — check, chill and cook.

The state’s Shellfish Safety Map shows areas open and closed to harvesting.
Map: Washington State Dept. of Health

At least 10 cases of an intestinal illness called vibriosis have been reported this year to the Washington State Department of Health, all resulting from people picking oysters themselves and eating them raw or undercooked. The disease is caused by a bacteria, Vibrio parahaemolyticus, an organism that occurs naturally and thrives in warm temperatures.

“The shellfish industry follows special control measures during the summer months to keep people who choose to eat raw oysters from getting sick,” said Rick Porso, director of the Office of Environmental Health and Safety, in a news release. “For those who enjoy collecting and consuming their own shellfish, it’s important that they follow a few simple measures to stay healthy.”

The combination of warm weather, lack of rain and low tides all contribute to the growth of bacteria in oysters growing on the beach.

The state Department of Health uses the “three Cs” as a reminder for recreational shellfish harvesters as well as people who gather shellfish from their own beaches:

  • CHECK: Before heading to the beach, make sure that shellfish in the area are safe to eat. The Shellfish Safety Map, updated daily, will tell you where it is safe to gather shellfish. At the moment, many areas are closed because of paralytic shellfish poison produced by a type of plankton. Unlike Vibrio, PSP cannot be destroyed by cooking.
  • CHILL: Gather shellfish as the tide goes out, so they are not allowed to sit for long in the sun. Put them on ice immediately or get them into a refrigerator.
  • COOK: Cooking at 145 degrees F. for at least 15 seconds should destroy Vibrio bacteria, health officials say. It is not enough to cook them until their shells open.

Symptoms of vibriosis include diarrhea, abdominal cramps, nausea, vomiting, headache, fever and chills. The illness usually runs its course in two to three days. For information see “Vibriosis” on the Department of Health’s website.

Symptoms of paralytic shellfish poisoning usually begin with tingling of the lips and tongue, progressing to numbness in fingers and toes followed by loss of control over arms and legs and difficulty breathing. Nausea and vomiting may occur. PSP can be a life-threatening condition, so victims should seek medical help immediately. For information, see “Paralytic shellfish poison” on the Department of Health’s website.

Besides health advisories, the Shellfish Safety Map mentioned above also includes the water-quality classification, a link to shellfish seasons to determine whether a beach is legally open along with other information,

Petition seeks to revoke Department of Ecology’s clean-water authority

Citing pollution problems in Puget Sound, an environmental group is asking the Environmental Protection Agency to revoke Washington state’s authority to enforce the federal Clean Water Act.

Northwest Environmental Advocates, based in Portland, says a review of 103 discharge permits issued by the Washington Department of Ecology shows a failure to control nitrogen pollution. Excess nitrogen reduces oxygen levels in the water and triggers algae blooms, resulting in serious problems in Puget Sound, according to a petition submitted to the EPA.

“Ecology determined that over 80 percent of the human sources of nitrogen in Puget Sound comes from cities and towns, but it continues to issue discharge permits as if it were completely ignorant of these facts,” Nina Bell, the group’s executive director, said in a news release.

“It’s just flat out illegal to issue permits that contribute to harmful pollution levels,” she added. “These permits are the walking dead, existing merely to create the impression that the state is doing its job to control water pollution when it is not.”

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Invasive species need to be on Legislative agenda

With invasive green crabs entering Puget Sound from the north and invasive mussels discovered in Montana to the east, the Legislature will be called on to make some critical funding decisions to ward off potential invaders.

Zebra mussels cover a native mussel in the Great Lakes. Photo: U.S. Fish and Wildlife Service
Zebra mussels cover a native mussel in the Great Lakes. // Photo: U.S. Fish and Wildlife Service

Green crabs and freshwater zebra and quagga mussels are not the only aquatic invasive species of concern. As I described in a story published in the Encyclopedia of Puget Sound, state officials worry about the potential import of all sorts of harmful species via ballast water and the hulls of vessels.

To fully address the threats through prevention and enforcement, the Washington Department of Fish and Wildlife estimates that $5.2 million per year is needed. That would move Washington ahead of Oregon and Idaho in addressing the problems. Each of those states spent about $1.3 million in 2014, while California spent about $10.7 million. Washington’s current budget for dealing with aquatic invasive species is one of the lowest in the country at $900,000 a year.

Increases in the program would be phased in over six years, increasing from $900,000 a year in the current budget to $2.3 million in the next biennium, according to a proposal to be submitted to the Legislature. It would go to $4.7 million five years from now.

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Close call, but Hood Canal may escape a major fish kill this fall

With some luck, southern Hood Canal may avoid a major fish kill this year, as we observe extremely low oxygen levels beginning to dissipate.

oxygen

It looks like the fish around Hoodsport dodged a bullet on Friday when south winds pushed the surface layer of oxygenated water to the north, bringing hypoxic waters up from below, according to data from the Ocean Remote Chemical Analyzer (ORCA) buoy near Hoodsport.

University of Washington researchers watching the conditions issued this alert on Friday: “Hypoxic waters have been observed intermittently at the surface at our Hoodsport mooring — in addition to the Twanoh mooring —consistent with the strong southerly winds and upwelling conditions we’ve been seeing over the past few days.”

Seth Book, who monitors the water conditions for the Skokomish Tribe, said he was on vacation last week and did not make his usual rounds to observe potential fish kills. But we have not heard of any reports of dead or dying marine life along the shores of Hood Canal.

The risk of a fish kill is still present, and another strong wind out of the south has the potential to bring more low-oxygen water to the surface. The layers of water and the timing appear similar to last year, when south winds brought deep-water fish — such as ratfish — to the surface, as Seth recorded in a video. See Water Ways, Sept. 1, 2015.

depth

Each summer, sunny weather brings a growth of phytoplankton that eventually dies, sinks to the bottom and decays, a process that consumes oxygen. The result is extremely low levels of oxygen near the bottom of Hood Canal, a situation that continues until a surge of seawater in late summer or fall pushes in from the Pacific Ocean.

Because of its higher salinity, that seawater comes in along the bottom and pushes up the low-oxygen water, which gets sandwiched between the ocean water and the more oxygenated water near the surface. If the surface layer gets displaced suddenly by the wind, the fish have no place to go to get oxygen. That appeared to be the condition on Friday, but now the middle layer is growing thinner as it mixes with the layers above and below.

Conditions are improving, Seth confirmed, “but the negative side of me still says we have low D.O.” Crabs, shrimp and deep-water fish may be out of the woods for this year, thanks to higher levels of oxygen in the incoming seawater, but mid-level fish are still at risk until the water column equalizes to a greater extent.

In July, areas farther north in Hood Canal, such as Dabob Bay, experienced low-oxygen conditions, which drove a variety of fish to the surface, Seth told me. Of particular interest were thousands of Pacific herring trying to breathe by staying in the upper foot of water along the shore.

“We have dodged something so far this year,” Seth said. “I am hopeful because we are now into September and we can see this intrusion continuing.”

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