Night Life — On the Beach at Maple Hollow

It is past midnight, barely above freezing. A full moon struggles to cut through the mist that rises from Henderson Bay. The night’s work has just wrapped, and though we are stiff and chilled to the core, a little jackknife clam has the naturalists I’m with in stitches.

We’re at Maple Hollow Park. Twice a year, summer and winter, a team of volunteers led by Stena Troyer of Harbor WildWatch and Michael Behrens of Pacific Lutheran University comes here during the lowest tides of the year to document the beach and its inhabitants. In winter, when low tides are at night, that means special permission from Key Pen Parks to hike in after hours. I have a new appreciation for the park having passed among the twisted forms of its trees rising into the moon mist light.

The project has been running for ten years and includes eight beaches in Gig Harbor and on the Key Peninsula. When we arrive at the beach, Behrens finds a certain bolt in a rock and runs a tape measure down to the water line. This is our transect. He will spend the first half of the night using surveyor’s equipment to measure precise elevations along the transect, allowing him to see over time how the beach’s angle and topography shifts.

Meanwhile, Troyer leads the rest of us in our first survey of life along the transect. Every three meters we huddle and note every category of life we see. At the top of the beach the list is short: unattached sea lettuce, amphipods, shell debris. As we move down the transect and sand turns to cobbles, which then give way to larger rocks sunk in mud, creatures appear and drop out: periwinkles, barnacles, limpets, red algae, shore crabs, hermit crabs, tubeworms, sand dollars, the odd chiton or gunnel.

“Any flatworms?” Troyer asks halfway down the beach. “I want a flatworm. It’ll be under a rock, but they need a little more water than this.”

A few meters later she sings out, “Flatworm!”

Reaching the low tide line and entering the eelgrass beds beyond. knic Pfost

This simple presence-absence survey warms our eyes for a more intensive survey.

At the zero-foot, minus-one-foot, plus-one-foot, and plus-five-foot tide levels, we lay out a series of quarter-meter squares and, inside each one, count every living thing. Barnacles and sea lettuce get an estimate of percent cover, but otherwise we must tally snails into the hundreds, limpets and tubeworms in the dozens, crabs that won’t stay put, tiny hidden mussels, and so on, finishing by dragging our fingers through sandy areas to count sand dollars.

As we move from square to square it is impossible not to wonder why creatures cluster where they do. One square will be filled with sand dollars; the next empty of them. It reminds me of the microhabitats in forests: loose troops of fungi, rare mosses. The differences become especially clear when you compare between beaches. Narrows Beach in Gig Harbor is steeper than Maple Hollow, rockier, with more anemones and chitons and no sand dollars. As we crouch and count, my eyes open to factors that might affect seashore life. What about beach orientation? Geology? Current? Wave shock?

Then, of course, doing this work over decades will reveal how things change over time.

Square by square by square. Stena Troyer

When we finally finish with the squares, the tide is as low as it will go. A volunteer finds a bay pipefish in the shallows. Moon snails are everywhere.

“Time for the hypothermia dance?” asks Troyer.

Behrens laughs and says the water is warmer than the air. He takes a close look at a moon snail on land. “That has cold invertebrate look,” he says. The edges of its mantle are curled up, almost stiff.

This kind of cold will greatly slow clams, snails, and sea stars, he explains, but it will not harm them. It was a much different story when he rushed to the tide flats after the heat dome in 2021, when low tides were mid afternoon. Heat cooks these creatures alive.

The tragedy tonight is that Troyer has left the Reese’s peanut butter cups in the car. We go on. Kelp crabs stalk the night. Krangon shrimp glow in a black light. Troyer explains that the beauty of gathering data in this way is that as soon as something strange happens, she can expand the protocol to include it. Case in point? Sea star wasting syndrome. As we wander she measures each sea star we come across. Tonight there is no evidence of the disease. Some species of sea stars have begun to rebound while others remain absent. Troyer has a record.

Later, Behrens speculates that these long-term whole-beach surveys might prove potent in a few ways. First, they will show how animal communities react to a major change, an oil spill or, as is happening at a survey site on Fox Island, the removal of a crumbling seawall.

Second, the work helps the team tune in when a certain organism’s life changes. Like oysters. In 2015, when the Blob greatly warmed Pacific Northwest waters, the cultivated Pacific oyster had, as Behrens calls it, a stunning recruitment event. A species chosen for farming because the water here is too cold for it to reproduce in the wild suddenly reproduced like mad and Pacific oysters littered every beach. Big ones can still be found. Subsequent years had smaller recruitment pulses. For several years, on nights like these, Behrens and his volunteers measured oysters. A scientific paper based on the record he has assembled is forthcoming.

The cadence of these surveys means that naturalists are on our beaches, paying attention, at least twice a year. That is no minor thing.

A moon snail (Neverita lewisii) plowing through eelgrass, looking for clam snacks. Can you spy evidence of tubeworms as well? Stena Troyer

We are talking, telling stories in the shallows, swallowed up by mist, when a shape pops out of the sand and madly swims away from our boots. Maybe jets is a better word. It is a clam, a narrow jackknife clam, yet it moves like a squid, shooting its siphon forward on one side then its foot on the other and somehow propelling itself with what must be jets of water from within its shell.

“I had no idea they could do that,” Troyer exclaims.

The clam drifts for a moment. Then, amazing these seasoned naturalists, it reaches out its milky foot and grabs the sand so that its shell spins and straightens. After standing for a moment, with a few quick strokes it pulls itself back underground, completely out of sight.

We are left to wonder.

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