'Tiny Monsters' Give Life to Cloudy Waters
"The region . . . seemed nearly destitute of human beings. . . . The brute creation also had deserted the shores. The tracks of deer were no longer to be seen, nor was there an aquatic bird in the whole extent of the canal. Animated nature seemed nearly exhausted, and her awful silence was only now and then interrupted by the croaking of a raven or the scream of an eagle. Even these solitary sounds were so seldom heard that the rustling of the breeze . . . gave rise to ridiculous suspicions in our seamen of hearing rattlesnakes and other hideous monsters. . . ." Capt. George Vancouver, 1792
In the evening shadow of a forested ridge, we steer the sloop Velella into a bay near the Hood Canal floating bridge and drop our anchor, which instantly disappears into a green, unenticing soup. We can hear the rumble and groan of the nearby highway and the shouts of a group of teenagers at a rowdy beach party, complete with firecrackers. It will not be a quiet evening on Hood Canal.
Safely anchored, I settle back with a glass of wine while Keith Benson, skipper and science consultant, talks about the disappearing anchor. Even a century ago, he says, scientists understood that water quality and water clarity are linked. To measure clarity, then and now, they lower a white disk about a size of a long-play phonograph record into the water and note the depth at which it becomes invisible. That link between clarity and quality is complicated, however, Benson warns.
With this in mind I revisit my trusty copy of George Vancouver's journal. In the first week of May 1792, Vancouver and a small company rowed their launch south into Hood Canal, stopping when the tide turned against them, then resuming exploration. It was to be his first experience with the Northwest's glacial fjords, some of which lead somewhere, most of which don't. In his journal, he noted the change in landscape - steep, forested walls plunging into the bottomless channel - and the eerie silence of the place.
The whistle of the wind in the trees frightened the crew, he wrote, conjuring fears of "rattlesnakes" and "hideous monsters." In an odd and accidental way, the superstitious sailors were right. For, unknown to the captain and company, they were floating above a veritable explosion of life forms completely foreign to them, and to most of us today.
Puget Sound's springtime boom begins with untold trillions of microscopic plants and animals collectively called plankton, the primordial soup that is the basis for all life in the oceans. The explosion begins innocently enough with diatoms - microscopic, single-celled plants shaped like aspirin tablets, but so tiny that a million would fit inside a single pill. During the winter, they drift in a state similar to hibernation, deep in the sea.
In April or May increased sunlight and warmer water trigger photosynthesis and the silent explosion begins. Fed by nutrients from decaying plants and animals, the diatoms begin to reproduce. Each divides into two identical offspring, which promptly divide again. If this binary fission occurs daily, which is not uncommon, it will take only a month for one diatom to become one billion. Scientists call this a plankton bloom, and it will be the first of many. The water in channels like Hood Canal, relatively clear during the winter, suddenly turns murky and green and may remain so all summer. The murkiness is an indicator of life. The ecosystem is shifting into a higher gear.
Nobody has ever seen a diatom without the aid of a microscope. Yet their massive blooms can be seen from airplanes and, in at least one case, from the space shuttle. Other phytoplankton - the plantlike organisms that can create oxygen - have similarly dramatic effects, such as the "red tides" and shellfish poisoning that proved fatal to one of Vancouver's crew. Plankton also provide the marvelous bioluminescence that adds sparkle to a moonless night.
Within a few weeks, the initial bloom sets off more biological explosions as all those diatoms become food for larger organisms - especially shrimplike copepods. Copepods are among the zooplankton, tiny animals rather than plants. Viewed through a microscope, copepods, with segmented shells and a dinosaur-like head complete with flailing antenna, resemble the hideous monsters so feared by Vancouver's crew.
As one of the oldest forms of life on Earth, plankton exist in all the world's oceans. But Puget Sound is particularly friendly. In his 1983 book, "The Fertile Fjord: Plankton in Puget Sound," University of Washington oceanographer Richard Strickland wrote: "Puget Sound is to plankton what Florida is to oranges, what Iowa is to corn, and what the Cascades are to Douglas fir." Never mind Boeing 747s and Windows 98. From a biological point of view, at least, plankton is our primary product.
When the UW research ship Thompson cruised around Puget Sound, one of its missions was to test for plankton at each of 39 stations, including places in Hood Canal. To do this, oceanographers lowered a gazebo-shaped frame holding remote-controlled bottles that close at various depths, capturing water samples to return to the ship.
"We're less interested in how much than in where they are - depth and location," explained Jan Newton, a Department of Ecology oceanographer who also teaches at the UW. "We know, for example, that the bloom occurs earlier in Hood Canal and the South Sound, later in the main basin." By early summer, she says, the diatoms will burn themselves out and be replaced by dinoflagellates, smaller plants that use whiplike flagella to propel themselves.
She and others are interested in plankton for a variety of reasons. Phytoplankton produce about half the world's oxygen. They are key players in delivering the sun's energy to virtually every other creature in the sea.
But for Puget Sound, their abundance can become a serious problem. When plankton do well, they tend to overdo it. Eventually the zooplankton prevail, consuming all the available oxygen and ultimately self-destructing. That's where people enter the equation. Phytoplankton mostly subsist on nitrogen and phosphorous, referred to by scientists as nutrients, familiar to the rest of us as, among other things, municipal sewage, farm fertilizers and the leftovers of any number of human enterprises.
"Too much agricultural runoff or undertreated sewage, and we essentially tip the natural system out of balance," Newton says.
Scientists call this eutrophication, or over-enrichment. That is what went wrong 35 years ago in Lake Washington. Sewage, rich in phosphorous and nitrogen, didn't poison the lake; it fertilized it, breeding a phenomenal growth of algae, another form of plankton. The algae consumed too much oxygen in the water, making the lake unhealthy for salmon and other fish.
In the 1980s, concerns about potential over-enrichment prompted Puget Sound cities to spend hundreds of millions of dollars on upgraded sewage treatment. It is also what kept Newton and her colleagues busy in Hood Canal last month. Their method was to take water samples, plankton and all, add small amounts of nutrients to some of the samples, then leave them in a plexiglass tank on the deck of the Thompson. The rate of photosynthesis in the samples would provide a clue as to whether an area faced potential trouble.
There are signs or indications of declining amounts of oxygen in the water in Hood Canal, the kind of dead-end fjord that is a prime candidate for over-enrichment. If the amount of oxygen available in Lower Hood Canal declines dramatically, Newton says, it suggests an overabundance of plankton. That could be a monster of a different order than Vancouver's shipmates feared.
Would too much plankton implicate some human activity ashore? "As scientists, we don't like to say anything until we have proof positive," Newton says.
By the wee small hours, the teenagers across the bay are partied out and Hood Canal falls silent. I lie in my bunk, listening to water lapping rhythmically against the wooden hull of the Velella.
For me, as with most people, Puget Sound has always conjured images of silvery salmon in sparkling water. But inevitably it's more complicated than that. The regional totem is ultimately dependent on invisible organisms in a soupy green sea.
It's time to move on and learn more about the curious link between the two.
