Just north of the turbid, tidal waters of the South Slough, a tall, white-haired man picks his way along a rocky shoreline. With deft steps, he navigates around saltwater pooling in crevasses, and treads nimbly across fine layers of slippery algae and clumps of washed-up sea palm.
He stops and bends over to the ground, running his fingers along the outline of a fossilized scallop shell, its edges etched in the surface of the brown sedimentary rock. It’s a piece of visible history dating from the Miocene epoch, embedded into the dimension of the landscape.
A little further down the shore, he points at what looks like a small protrusion of curving rock, rounded smooth by waves.
“Do you see this? It’s not a rock. This is a fossilized whale bone,” he says. “It looks like a vertebra.”
He pauses for a moment to look across the water toward the thin finger of the inner jetty at Charleston, Oregon. It stretches across the southern section of Coos Bay, protecting Charleston’s marina from the onslaught of winter storm waves; storms which have occurred with more intensity in recent years.
Since visiting the area as a college student in 1975, marine biologist Mike Graybill has walked the shores along the edge of the Coos Bay Estuary at Fossil Point.
Just inside the dredged channel sits a wrecked salmon fishing boat, its hull slipping backwards into the silver-grey waters.
“If that's a metaphor for an entire fishery to be on the rocks, I can't think of a better one,” he says.
He watched the salmon fishing and logging industries flourish in the 1970s during their heyday in Charleston, and watched them recede from the town like the tides of the bay over the last 30 years.
For 28 of those years, Graybill worked as the manager of the South Slough Estuarine Research Reserve, the wild southern fork of the Coos Bay Estuary, just a few miles south of Fossil Point.
Estuaries are damp, muddy places.
“I like to think of an estuary as a hole in the continent where the water drains out,” said Graybill.
They are also one of the biomes most essential to human civilization, and estuaries play key roles in the processes of the natural world.
A biome: A broader term than habitat, a biome is a major community of plants, animals and other organisms adapted to a specific environment, such as a wetland or desert.
More than 140 miles of freshwater streams drain into the South Slough estuary, mixing in a ceaseless cycle with the saltwater tides of the Pacific Ocean.
The South Slough is inundated with seawater twice a day in what’s called a semidiurnal tide. The murky mixture of fresh water and sea water deposits layers of sand, silt and mud miles into its tidal channels. South Slough has tidal mudflats and sandflats, salt marshes, and freshwater marshes at its southern reach. The marshes act like a sieve, filtering sediments from the water and absorbing pollutants.
A spectrum of river and sea-dwelling plants and animals reside in the brackish, ever-changing waters. The diverse conditions of the estuary create habitat vital for shellfish, fish, salmon, birds, river otters, beavers, elk and humans.
“Civilization that occurs here today would not be possible without the sheltered waters of the harbor that are provided by this estuary,” said Graybill. “Western civilization would not exist without the current relationship that it has with maritime activities.”
Twenty-two of the world’s largest cities are built on estuaries, according to the National Oceanic and Atmospheric Administration.
Estuaries are often named as bays, lagoons, sounds or sloughs. The Coos Bay estuary is the second-largest in Oregon, and branches into the South Slough at its southern point.
It is a coastal plains estuary; the sea floods the valley mouth where the watershed flows into the ocean.
In a watershed, creeks and rivers coalesce along the same slope of land or valley and drain to a nearby place. The watershed that drains into the South Slough is about 600 square miles, said Graybill.
Six year-round creeks and about 20 seasonal creeks flow into the slough. The largest is Winchester Creek.
Because of the constant flow of salt and fresh water, salinity levels in the slough fluctuate, varying by season and by tide.
“Estuary conditions really change depending on the nature and delivery of water into the estuary,” said Graybill. “Rivers that feed this estuary fluctuate very dramatically on a seasonal basis.”
From the drier summer months to stormy winters, creek water flow changes by a factor of 60, he said. In the summer, less fresh water drains into the estuary and the salinity from seawater is stronger.
Salinity also changes like a gradient in the estuary; near its mouth, the slough waters have ocean-like characteristics.
“As you move up into an estuary, the signal of that ocean tends to diminish because the signal of the river begins to emerge,” said Graybill. “If you're a salmon, if you're a crab, if you're anything that lives in the water that's sensitive to that, you're going to know about that signal.”
Just as salinity levels rise and fall, so does the estuary’s acidity, or PH. But instead of the tides, it changes with the rising and setting of the sun. Chlorophyll producing plants like eelgrass and tiny organisms like phytoplankton use energy from sunlight during the day. They generate oxygen while absorbing water-acidifying carbon dioxide in a process called photosynthesis. At night, these photosynthetic processes stop, the water acidity rises, and dissolved oxygen drops, said Graybill.
“Estuaries are dynamic places. The tides come, the tides go. The seasons come, the seasons go. Huge changes happen within each of those periodic cycles,” he said.
Two miles up Winchester’s tidal channel, the creek waters swell to a 10-meter width during high tide. Withstanding the daily shifts in salinity and tide, barnacles cling to the large wood pilings lining the creek’s curves. Young Coho salmon swim the estuary waters, acclimating to oceanic conditions. Standing as still as statues, great blue herons linger in marsh meadows of slough sedge and reed canarygrass, eyeing the silt for young crabs and small fish.
Graybill arrived in 1975 for an undergraduate college summer session at the Oregon Institute of Marine Biology (OIMB), the University of Oregon’s graduate and research campus.
“I was overwhelmed at the richness of the natural world that’s in the vicinity of Charleston,” said Graybill.
It was just one year after the South Slough had been designated as the first estuarine reserve in the nation, to be managed in partnership under the auspices of the National Oceanic and Atmospheric Administration (NOAA) and the state.
Graybill says the designation of the South Slough in 1974 acted like a “handshake” between Oregon and the federal government.
“It’s a very simple law. It’s two pages long. But it sets out the purpose of the reserves, which is to be used for long-term research and education, and it sets out how it should be managed.”
The South Slough was the first implementation of the 1972 federal Coastal Zone Management Act. The act recognized that estuarine regions like the South Slough were vital to fisheries and economic activities, according to Graybill.
“The intensification of human development on the shorelines of estuaries, these places that form where rivers meet the sea, was going to accelerate through the coming years,” said Graybill. “There was a calling by congress to better understand the role that estuaries play in fisheries, in our economy and in all the other uses that human civilization depends on them for.”
Graybill says the reserve is protected from human activities and uses that would alter the dynamic processes of the estuary ecosystem, within and beyond its boundaries.
A commission appointed by the governor of Oregon oversees the South Slough estuary management, and includes representatives from local interests, including the port, community and research institutions. [EG4]
“Many of the people who were my mentors at OIMB were involved in the development of the proposal to designate the South Slough as a special protected area,” he said. “There was a great deal of interest and enthusiasm about this newly created place, what it would be used for and how to get people involved.”
There was also some controversy, according to Graybill. Because the cities of Coos Bay and North Bend are coastal and inextricably linked to the estuary by the waters of the bay, the cities had to develop comprehensive land use plans and Coos County developed an estuary management plan.
“In 1974 and 75, that was a very controversial and newly instituted practice and, needless to say, there were a lot of skeptics and a fair few opponents,” said Graybill.
Now, the South Slough serves as a living laboratory to a slew of scientists and researchers. It’s part of a network of 28 other reserves around the coastal U.S., the National Estuarine Research Reserve System.
The system preserves estuaries that are representative of the many different types, and designates them for research and education, said Graybill. Its mission is to improve how humans understand and interact with the areas.
The types of wetlands in the reserve system vary, from the mangrove swamps of Florida to the glacier-carved fjords of the Puget Sound.
A Continental Signal
“The natural world and places that are managed to emphasize the natural dynamics of the ecosystem will be the place where the signal of climate change can be measured as much as possible in the absence of other disturbances and activities,” said Graybill
The reserve system has created a web of data, constantly checking the pulse of wetland biomes.
“There's a camera or a recording device on the landscape at the scale of the continent now, that can measure large-scale signals like hurricanes, oil spills, sea level rise and climate change,” said Graybill.
In what they call the System Wide Monitoring Program (SWMP), reserve biologists are partaking in a national data collection system. They’re monitoring short and long-term changes in water quality, species diversity and characteristics of the marshes and lands in the reserves.
In that data, researchers are looking for signals – the signals of climate change.
Climate change is an accelerated warming of the earth’s atmosphere. Over the last 200 years, the burning of fossil fuels like gasoline and oil released vast amounts of stored carbon into the atmosphere.
“We’ve got highly elevated levels – unprecedented elevated levels – of carbon dioxide in the atmosphere in human history,” said Graybill.
When sunlight enters the atmosphere, it becomes infrared light, which warms the earth. It leaves the atmosphere slowly because it’s trapped by greenhouse gasses like carbon dioxide. The more greenhouse gasses in the atmosphere, the warmer the earth becomes.
Certain biomes like forests, marshes, and the ocean help balance warming by pulling carbon out of the atmosphere and storing it through photosynthesis and a process called carbon sequestration. Carbon is one of the major components of organic life on the planet.
In the past, the oceans have absorbed enough carbon dioxide to keep the earth from warming dramatically, said Graybill. The ocean is absorbing about half, but it’s not enough.
One of the most measurable effects of climate change is the increased acidity of the ocean, and it’s been studied with the SWMP.
“It's an important issue,” said Graybill. “It's particularly manifesting itself on the Oregon coast because of the oceanographic conditions that exist here.”
When carbon dioxide in the atmosphere meets the ocean, it dissolves in the water. The more carbon dioxide added to the water, the more acidic it becomes.
“If you think of Pepsi Cola or carbonated soft drinks, the carbonation in soft drinks is the result of the injection of carbon dioxide into the water,” said Graybill. “So, on a much more mellow scale, the same thing is happening in the ocean.”
For shellfish, crabs and tiny foraminifera in the estuary or ocean, and especially as larval young, an acidic ocean makes life conditions difficult.
“Think of a clam; it grabs calcium out of the water and makes its shell with that. That’s a bit of chemistry that the animal undertakes,” said Graybill. “When the PH of the ocean is changed, it’s harder to do that chemistry project.”
Marine biologist Ali Helms is the estuarine monitoring coordinator at the South Slough Reserve. She monitors water quality for the SWMP at six stations set up along the salinity gradient throughout the reserve.
One of the biggest climate change threats to estuaries is sea level rise. But marshes can temper the effects if they are building enough new sediment to keep pace with the rising tides, a process called sediment accretion.
Jenni Schmitt stands in knee-high rubber boots in the tall marsh grasses, water pooling up to her ankles. She’s holding a long, thin silver pole, taller than her head – a Russian peat borer. It is hollow and pointed on the bottom. Using two hands, she slams it into the soggy ground with her body weight, until it slides through the tangled root system of marsh plants and into the sediment below. When Schmitt pulls it up, it is holding a cylindrical sampling of earth in its hollow point.
Schmitt is the watershed monitoring coordinator at the reserve. She’s tracking levels of sediment accretion in the estuary as part of the Sentinel Site Program, a research initiative within the national reserve system to better understand how estuaries are vulnerable to climate change.
“We’re trying to understand how our marshes and our eelgrass beds and our forested swamps are going to be changing as the climate changes,” said Schmitt. “As ocean patterns are changing, as sea levels rise, how is that all going to affect our marsh communities?”
The sentinel site program monitors marsh elevation, tidal range, coverage of the plant communities and the salinity of groundwater.
The Resilience of Rhizomes and the Case of the Disappearing Eelgrass
Plants shape the landscape of a marsh. Their roots create dimension and structure. Long stems trap silt suspended in the water, improving the water’s turbidity. When plant bodies decompose, they accumulate in layers of rich loamy detritus on the marsh floor. Eelgrass beds create shelter beneath the waters of tidal channels for estuarine life.
Rhizome: A continuously growing horizontal underground stem that can produce shoots and roots.
Meter-long pieces of it float through Winchester Creek during high tides. King tides sweep the creek waters so high that the strands become tethered to low hanging branches. In some places, dried-up pieces of it decorates the riparian trees like withering Christmas streamers, rustling and lilting in the breeze above the creek.
In northern parts of the Coos Bay estuary, eelgrass beds are thriving. But in parts of the South Slough, they are vanishing.
Helms has over a decade of data from four eelgrass monitoring sites on the estuary. At Valino Island, near the center of the reserve, eelgrass was growing in abundance. She holds a photo of the site from 2002, filled with eelgrass just beneath the water’s surface.
“At the same site, it’s barren,” says Helms. “There’s a small patch of eelgrass, there’s lots of macroalgae and the rest is just intertidal mudflat. Look at the stark difference. Eelgrass is gone.”
Danger Point, the eelgrass site furthest south on the reserve, used to have 90 percent coverage in eelgrass in the areas she surveyed. Now there is none.
As a scientist, Helms isn’t going to guess why, but she has several hypotheses to research. She knows with certainty that in the fall of 2016, something, or a combination of stressful conditions, caused the eelgrass to disappear.
Fish and Chips
Since the end of the ice age, the South Slough’s shores have been inhabited by humans. Long before its forests were logged, its marshes diked for farm and pasture, and the mouth of the estuary dredged for a shipping lane, the Miluk lived and fished on its shores.
European-American settlers brought an extractive economy to Coos Bay in the 1850s, centered on logging and fishing. It continued into an intensification of economic development that was not sustainable, said Graybill.
“Coho salmon was one of the most important commercial salmon fisheries in our harbor. There has not been a commercial salmon fishery for perhaps the last 15 years in this estuary,” says Graybill.
He tells a similar story about the timber industry.
“We built a timber economy that was scaled larger than trees could grow,” he said. “We’ve conducted land use practices that have impacted fisheries; we’ve built hydroelectric dams.”
Weyerhaeuser, the logging company, exhausted the timber supply in the Millicoma forest, he said.
“We’ve run out of big logs,” said Graybill.
He recalled a story of an afternoon in Coos Bay at lunchtime, when the mill gave sudden notice of its closure and hundreds of people were left out of work.
“So, the economy in this community has gone through some fairly serious ups and downs. It's largely been based on an extractive resource economy – fish and chips,” said Graybill.
Coos Bay is still one of the largest wood chip exporting ports in the world.