Naturalist's Notebook

Nightlife — The Beach at Maple Hollow

Into the Wild - Exploring with the KP Nature Guide


It is past midnight. 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 half-frozen, 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 visits during the lowest of the low tides to document the beach and its inhabitants. In winter, when low tides are at night, the team has 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 10 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 shift.

Meanwhile, Troyer leads the rest of us in our first survey of life along the transect. Every three meters we huddle and note each 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 sand turns to cobbles, then gives 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!”

This simple presence-absence exercise 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 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? Wave shock? Current?

Then, of course, doing this work over decades will reveal how things change over time. 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 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. This has been a promising year for sea stars.

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 well-documented “blob” 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. Pacific oysters littered every beach. 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. It shows that subsequent years had smaller recruitment pulses.

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

We are in the shallows telling stories, swallowed up by mist when a shape pops out of the sand and swims madly 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 and 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 says.

The clam drifts for a moment. Then 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.

Amazed, these seasoned naturalists are left to wonder.