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On our last afternoon at the Schoodic Institute we were dealing with laundry for our upcoming several days touring in New England. On the way back from the laundry room we came across this little creature waddling towards us. It was a porcupine! It kept coming towards us, even as we were backing away. Clearly it had some place to be.

Small brown mammal walking along a paved pathway towards the camera
Porcupine (Erethizon dorsatus) at the Schoodic Institute in Acadia National Park
2022-06-17
@ Allison J. Gong

I don't know whether or not porcupines are always this nonchalant around humans. This one crossed the road in front of us and headed off into the woods. And look, it's plantigrade!

And then it nibbled on a few leaves and climbed a tree! Note how it uses the tail as a brace, the way woodpeckers do when they're hopping up and down trees.

We had to meet up with the rest of the Earthwatchers for a celebration event in the classroom and didn't get to keep watching this porcupine. However, on our way to the dining hall for dinner, we saw the same animal, on the ground again. And this time she was accompanied by a baby! It was getting dark by then and I didn't want to bother either mama or baby, so didn't take any additional photos or video.

We never did see any moose in New England, despite all the road signs promising "Moose X-ing next <insert positive integer> miles", but seeing a porcupine was pretty dang cool. What a terrific send-off from the Schoodic Institute wildlife!

One of the reasons I selected this particular Earthwatch expedition was that it involved studies of both forest and ocean, which are my two favorite ecosystems here at home. I wanted to compare what I'm familiar with to similar habitats on the opposite coast. Regarding the rocky intertidal, I had been warned not to expect the spectacular biodiversity I'm used to on the Pacific coast, and that warning turned out to be quite a propos.

Along the California coast the rocky intertidal is an explosion of colors and textures, especially during the growing season. See this at Pigeon Point:

Ocean and seaweed-covered rocks
Rocky intertidal at Pigeon Point, San Mateo County, California
2022-06-01
© Allison J. Gong

and this at Asilomar:

Ocean and seaweed-covered rocks
Rocky intertidal at Asilomar, Monterey County, California
2022-06-03
© Allison J. Gong

And this is what you see when you walk—or in the case at Pigeon Point, climb down—to the site. It just is this varied, with several algae that are easily recognizable as being different even if you don't know what their scientific names are.

Contrast that with the rocky intertidal at Frazer Point on the Schoodic Peninsula:

Coastline with small rocks covered with golden-brown seaweed
Mounds of Ascophyllum nodosum at Frazer Point on the Schoodic Peninsula
2022-06-17
© Allison J. Gong

All of the algae covering these rocks are rockweeds, and most of it is Ascophyllum nodosum. One of the projects we worked on was a study measuring the biomass of Ascophyllum on the coast of the Schoodic Peninsula. To do so we sampled along 30-meter transects in the intertidal, counting the number of Ascophyllum thalli in half-meter quadrats, looking for other algae and some key invertebrates, and weighing the Ascophyllum. This last part was new to me, and a lot of fun. It involved dividing the masses of Ascophyllum into as many as three bundles, wrapping it all up in a net like a burrito, and weighing the burrito using a hand-held metric scale.

Three people wearing yellow high-visibility vests kneeling among algae in the intertidal
Left to right: Sally, Alex, and Valerie weighing Ascophyllum at Frazer Point in Acadia National Park
2022-06-17
© Allison J. Gong

Clearly, Ascophyllum nodosum makes up the vast majority of biomass along this coastline. There are some other rockweeds in the genus Fucus, a bit of sea lettuce (Ulva sp.), and that's about it. But the lack of diversity doesn't mean the intertidal doesn't have its own sort of spartan beauty. The lead for this project, Maya, described Ascophyllum as having a Van Gogh effect in the landscape. It didn't take long to see what she meant. Check it out:

Ascophyllum nodosum at Frazer Point in Acadia National Park
2022-06-17
© Allison J. Gong

and

Ascophyllum nodosum at Frazer Point in Acadia National Park
2022-06-17
© Allison J. Gong

There are, of course, many types of beauty in the natural world. What I saw in the intertidal at Acadia wasn't at all like what I'm used to seeing on the Pacific coast, but I wouldn't say it is any less beautiful. The variation in color between new growth and the older parts of the Ascophyllum thalli makes for gorgeous patterns as the thalli drape over cobbles.

Besides, any morning in the intertidal is a good morning! I certainly wasn't going to complain.

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This summer we finally got to take a trip that had originally been scheduled for 2020. It was an Earthwatch expedition to Acadia National Park in Maine. It was also the first time I'd traveled outside the Pacific time zone, flown, and taken public transit since the COVID-19 pandemic began. All of those were stressful. I get that people are "over" the pandemic and tired of taking precautions, but seriously? During our travels before and after the expedition we saw very few other people wearing masks, despite being packed into subway cars, stations, and restaurants. We avoided indoor attractions and spent our time walking around outside.

Cloudy sky over shoreline with water and a cobble beach. Coniferous trees in the background.
Shoreline of Schoodic Peninsula in Acadia National Park, ME
2022-06-13
© Allison J. Gong

This particular Earthwatch expedition is all about climate change. During the week we participated in three different, but related, research projects in the park, mostly on the Schoodic Peninsula. The first was called Refugia. At first I couldn't tell if that was a place name, a project title, or something else. Turns out that it refers to the actual project. The target of this project is a plant called black crowberry, Empetrum nigrum. Black crowberry is a low-growing tundra plant, living near its southern limit at Acadia. This is possible because the Schoodic Peninsula juts down into the Gulf of Maine, a region where cold water from the Arctic—specifically, the Labrador Current—meets warm water from the Gulf Stream. Thus, the Schoodic Peninsula may be indeed be a climate refuge for E. nigrum.

Map showing New England coast and the Gulf of Maine. The Schoodic Peninsula is labelled.

The Gulf of Maine, however, seems to be warming more quickly than other ocean regions, possibly due to northward extensions of the Gulf Stream1. As a result, plants such as E. nigrum may be a bellwether for how the ecology of Acadia will be affected by climate change.

The Refugia study examines abundance of E. nigrum along the coast of Acadia, as well as phenology of flowering and fruiting. Our Earthwatch group sampled at Schoodic Point and Little Moose Island, which is an actual island only at high tide. We were in Acadia during the mid-June spring tide series, which is always one of the most extreme of the year, so Little Moose Island was easily accessible for several hours.

The study itself involved setting up two perpendicular transects and collecting several sets of data:

  • Geographic data—GPS location and direction
  • Photos for iNaturalist
  • Presence/absence of E. nigrum at 10 cm intervals
  • Presence/absence of flowers and fruits
  • Visual estimation of the percent of E. nigrum that is alive vs. dead

We worked in teams of four, with each pair setting up and evaluating one of the transects.

Here's how E. nigrum appears in its natural habitat:

Sloping rocks in foreground and conifers in background. In the midground, a carpet of red-and-green low-lying plants.
Coastline of Schoodic Peninsula in Acadia National Park
2022-06-16
© Allison J. Gong

The crowberry is the red-and-green plant growing low among the rocks. Like all tundra plants, E. nigrum grows low to the ground and doesn't get more than about 15 cm tall. We were told that the red bits were the parts that died back over the winter, and the green was the new spring growth.

Here's a close-up look at the carpet of crowberry:

Carpet of red-and-green low-lying plant on a rocky slope
Black crowberry (Empetrum nigrum) on the Schoodic Peninsula in Acadia National Park
2022-06-16
© Allison J. Gong

We found E. nigrum mostly in open areas, but also occasionally in the spruce forest where there is much less light at ground level. It seemed not to require much soil, and was often found tucked between rocks on the coast above the high tide line.

Black crowberry fruits are small berries, green when unripe and ripening to a blackish purple. The fruits we saw, ripe and unripe, ranged in size from 2 to 8 mm. We were told that they were unpalatable even when ripe.

Plant with short stubby leaves and cluster of small green and larger purplish berries
Cluster of black crowberry (Empetrum nigrum) ripe and unripe fruits
2022-06-13
© Allison J. Gong

The protocol had us setting up a 5-meter transect parallel to the coast, where we saw a patch of E. nigrum, and then a second 5-meter transect perpendicular to the first at its midpoint. The result is a big plus sign draped over or through whatever terrain happened to be there. We had to do quite a bit of climbing up and down rocks and pushing through bushes. If this were in California we'd have to worry about poison oak. Fortunately, they don't have poison oak in Maine, and there was no poison ivy at any of our study sites.

Four people wearing yellow high-visibility vests, standing on a rocky landscape with conifer foliage. Two long yellow measuring tapes lie on the ground and cross at their midpoints.
Transects for black crowberry (Empetrum nigrum) at Schoodic Point, by team members (left to right): Alex, Karin, Sally, and Mara
2022-06-15
© Allison J. Gong

To give you an idea of crowberry habitat, here's some wider context:

Transect pair at Schoodic Point
2022-06-15
© Allison J. Gong

The last part of the protocol was to estimate the percent of E. nigrum that was alive, in a 1-meter belt that straddles each of the transect lines. This is one of those qualitative evaluations that at first would seem to be all over the place, depending on the observer. However, the study takes into account any variation resulting from data collectors' individual estimates by pooling the percentages into bins. So instead of having to agree that 22% of the crowberry in a certain belt transect is alive, we only had to agree on a bin of, say, 20-30%. To give you an example, here's a photo of a patch of crowberry:

Black crowberry (Empetrum nigrum) at Acadia National Park
2022-06-16
© Allison J. Gong

What percentage of this crowberry is alive, in your estimation?

I should mention that we had this glorious sunny weather on only one day that we worked on the Refugia project. The first day it was raining, which was fine because we all had brought rain gear with us. But the rain made it difficult to work with the tablets on which we were recording data. The wet screens didn't want to register our finger taps, but would instead register rain drops as touches. That was incredibly frustrating. We persisted and managed.

Over the summer several other groups of Earthwatch volunteers will collect additional data for the project. I think we set a pretty high standard for the sheer number of transect pairs we completed. I liked working on this project because I got to learn about the ecology of a plant that had been entirely unknown to me. That's always fun!


1Seidov, Dan, et al. 2021. "Recent warming and decadal variability of Gulf of Maine and Slope Water." Limnology and Oceanography Vol. 66: 3472-3488.

One of the many delightful animals in the rocky intertidal is the vermetid snail, Thylacodes squamigerus. Unlike their more typical gastropod relations, the vermetids don't live in a shell, per se. Instead, they live in a calcareous tube, which forms a loose coil draped over the surface of a rock. The tubes can be up to about 12 mm in diameter, and, if straightened out, about 15 cm long. In some locations, Thylacodes can be very abundant. In a recent visit to Point Pinos in Pacific Grove, I saw many of them in the low intertidal. I occasionally see them on the northern end of Monterey Bay and points farther north, but at nowhere near the abundance I see in Pacific Grove. At a larger scale, iNaturalist shows observations of T. squamigerus from northern British Columbia down to southern Mexico.

Three coiled white tubes and one spherical snail on a rock amid greenish seaweed
Trio of vermetid snails (Thylacodes squamigerus) with their more conventional cousin, the black turban snail (Tegula funebralis)
2022-06-03
© Allison J. Gong
Loosely coiled whitish tube on a rock
Thylacodes squamigerus
2022-06-03
© Allison J. Gong

Most snails are either grazers (e.g., abalones, limpets, turban snails) or predators (e.g., whelks, conchs, cone snails). Thylacodes is a bit of an outlier with regards to feeding as well as housing, for it is a suspension feeder. Being entirely sessile, it cannot go out and forage. And unlike its doppelganger, the tubeworms Serpula columbiana and S. vermicularis, Thylacodes does not create a water current to catch food on ciliated tentacles. Instead, it spins threads of sticky mucus that thrash around in the current and capture suspended detritus. When the tide is out the snail hunkers down in its tube, same as any worm. It cannot feed unless it is immersed. Where the worms live in the low intertidal on exposed rocky coasts, the water is moving constantly, and it requires relatively little energy for Thylacodes to feed the way it does. As a bonus, even the calories expended in producing the mucus are recouped, as the snail ingests the mucus strands as well as the food particles they capture.

When the tide came back, I got to watch Thylacodes in action. At Point Pinos there are some areas that form lovely tidepools, deep enough for animals to react to the return of the water and clear enough to make photography and videography possible. So standing knee-deep in a pool I stuck the camera underwater and hoped for the best. And I got lucky—you can see the mucus threads!

See here:

Thylacodes squamigerus
2022-06-03
© Allison J. Gong

and here:

Thylacodes squamigerus
2022-06-03
© Allison J. Gong

And not only that, but I captured some video footage. I use a point-and-shoot for these underwater shots, and usually don't know what or whether I've shot anything good until I download images and video at home. Color me happy to have seen these clips!

Despite the unusual aspects of its biology, Thylacodes is indeed a snail. It has a conventional snail's radula, and uses it the way, say, an owl limpet (Lottia gigantea) uses hers to scrape algae off rocks at Natural Bridges. Only instead of scraping the radula against rocks, Thylacodes uses its radula to reel in the detritus-laden mucus threads. That's what's going on in the second video clip above.

So there you have it, another of my favorite animals. Thylacodes is one of those animals that doesn't look like much when you see it just sitting there. But we get to see it only during the tiny fraction of its life that it spends emersed. As with most inhabitants of the rocky intertidal, much of Thylacodes' life occurs out of sight for human eyes. This makes the occasional sighting of Thylacodes under water especially enlightening. And delightful!

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