Land and sea

ecological links both obvious and obscure

We often think of land and sea as totally separate entities, and this is commonly reflected in separate governmental jurisdictions. But the biological reality is that the two “entities” are very closely linked, and here in Southeast Alaska that connectedness is very evident.

Perhaps the most well-known ecological link between sea and land is told in the story of the ‘salmon forest’. Spawning salmon return to freshwater streams, bringing marine-derived nutrients (and pollutants) in their bodies. The spawners die or are eaten by predators such as bears, wolves, and eagles. Smaller consumers, including mink, otters, and some song birds, also nibble on the carcasses. The fish-eaters sometimes drag the carcasses into the forest and all the consumers deposit digested fish and the contained nutrients on the landscape, sometimes quite far from the streams. Flies and other insects lay eggs on the carcasses and aquatic insects have bountiful dinners; the flourishing abundances of insects are consumed by birds that contribute to the spread of nutrients over the landscape. These animals help fertilize the surrounding land.

Crows catching sand lance in the intertidal. Photo by Bob Armstrong

But there are also many other channels by which marine-derived nutrients reach land. Less spectacular, perhaps, than the salmon runs and the attendant consumers, these other links make their contribution to the connection between sea and land. Lots of critters forage at the edge of the sea and then move up into the forest and meadows, where they deposit their digested dinners. Bears dig clams in muddy intertidal zones and gnaw barnacles off rocks. Bears, geese, and probably our beach marmots graze in the sedge meadows. Deer graze on sedges and intertidal plants. Ravens dig up sand lance and clams from the sediments. Eagles harvest herring and sand lance, and sometimes capture marine birds. Crows and ravens prey on sea urchins and small crabs and, during a eulachon run, these birds are known to store captured fish in grass tussocks and in trees.

Black bear eating mussels and barnacles. Photo by Jos Bakker

It’s not all one-way, of course; it’s a two-way connectedness. The land has some major influences on the sea. Run-off from rain and snow-melt regularly carry the products of erosion, including sediment, fallen trees, and some dissolved nutrients, eventually to the sea. Glacier-fed streams send a rich supply of minerals and organic nutrients to the sea, feeding the plankton that feeds the herring and the whales and lots of other organisms.

Human activity can have some major effects too. A recent excursion to Hawk Inlet on Admiralty Island made this abundantly clear. This was a SEACC cruise, so the emphasis was on what the mining activities near the inlet are probably doing to things in the sea. Waste products from the mine are pumped out into the lower inlet, where some sink to the bottom and some are swirled about by the incoming and outgoing tides. Leachates from the tailings piles ooze downhill toward the beach. The situation there came to our attention when a harbor seal, harvested in that area and eaten by humans, was found to be heavily laden with toxic chemicals. Then the levels of various toxic metals (e.g., lead, selenium, and several others) in blue mussels, shrimp, crabs, clams, and cockles from the inlet were found to be several times higher than in other parts of Alaska. Perhaps not coincidentally, local herring spawning aggregations and littleneck clams have recently disappeared; so has a run of king salmon. The initial concern has been for humans that harvest wild food in this area.

However, if mussels, clams, shrimp, and cockles are picking up high levels of contaminants, it’s a sure thing that many other organisms are too, leading to ramifying consequences throughout the food chains. Contaminants, such as the toxic metals of direct concern here, get passed up the food chain, accumulating at higher and higher levels, until the top predators get really big doses. Even before the contaminant concentrations become lethal, sub-lethal levels (sometimes very small amounts) can change body chemistry in serious ways, including growth rates, behavior, and even the gender of some consumers. Such changes would be reflected in population sizes of the consumers and that, in turn, would affect the populations of their predators.

On this cruise, we saw some of the spectacular wildlife for which Southeast is famous. There were brown bears foraging on sedges in beach-side meadows. Dall’s porpoises dashed past the boat. Humpback whales cruised by and dove. A group of killer whales moseyed back and forth, sometimes making impressive vertical leaps out of the water. All of those species depend on resources that could be affected by contaminants. To take just one example: Killer whales are top predators that could accumulate high levels of contaminants from their prey. Resident killer whales eat fish, those that eat plankton directly and those that eat plankton-eaters, while transient killer whales eat marine mammals that eat fish that…

The other animals we observed could also be exposed to some level of potentially toxic mine effluent. Even though the effluent from the inlet presumably gets diluted in the larger channel, sometimes a little bit can have huge impacts. It is unlikely that anyone will look to see if that occurs, so it would be wiser to prevent it from happening in the first place.


Tidepooling in May

treasures of the seasonal low tide

Mid-May brought some fairly low tides during the daylight hours, so naturally I had to go prowling in the intertidal zone to see what I could see. I like to go with a companion, because the extra eyes greatly help the search. We found lots of things, as expected, but here are a few highlights.

–A gumboot chiton, about five inches long. I seldom see this species, which is often heavily harvested by humans. It’s an unusual chiton in that its dorsal surface is completely covered by the granular mantle, so none of the eight plates or shells is visible. An herbivore, it eats mostly red algae. It’s the largest chiton in the world, sometimes over a foot long, although in our area half that size is more usual. Beginning its life as a larva, after just a few days it settles on a rock and begins to look like a chiton. It can live for forty years or so, growing a few millimeters a year.

–Clinging to the underside of a rock, we found (I think) two long-armed brittlestars (called serpent stars in one field guide). These are said to be quite uncommon around here. The arms are very long relative to the size of the disc or body; they break easily but regenerate. This species eats detritus and can burrow into sediments.

Long-armed brittlestar. Photo by Kerry Howard

–The small sea cucumber known here as the white cucumber is actually the so-called false white cucumber, to distinguish it from the ‘true’ white sea cucumber of the outer coast. This species is extremely numerous in some places, so finding it was no surprise. But it was an occasion for remembering something weird about these critters. Many sea cucumbers breathe by taking in water through the anus into respiratory trees comprised of narrow tubules. Some cucumbers can eviscerate themselves if they are molested, spewing out both the gut and the respiratory trees through the anus, and regenerating them later. We found ejected guts of several false white cucumbers. The thought of regenerating body parts is exciting (and not very common in the animal kingdom); sea stars can regenerate their broken arms, and we often see evidence of this, but regenerating internal organs??!! How long does it take to re-grow these parts and what do the animals do before the missing pieces are replaced? We also found two giant black cucumbers, which were apparently near the upper limit of their tidal range.

–Cucumber suckers are tiny snails, just a few millimeters long, that feed on sea cucumbers. Strangely, they do not have the rasping, file-like radula by which many snails scrape their living. Instead, the somehow stick to a host cucumber, penetrate the skin, and suck its body juices. Although that’s how they feed, and there were many potential hosts close by, I found a cluster of this species just perched under a rock.

–We love to find baby king crabs tucked under the edge of a rock or a sea star but this time we found only three of them. Starting life as larvae in the plankton, they transform into little crabs and move to the intertidal zone. They molt their exoskeleton as they grow and move to deeper waters, eventually maturing at age five or six years.

–Hermit crabs may be everyone’s favorite intertidal beasties, and there are several kinds here. We found a few very tiny hermits wedged nicely into really small periwinkle shells—the ‘big’ claws of these individuals were less than two millimeters long. A small hermit was startled when we picked up a three-inch whelk shell, and it scuttled directly up into the top spirals of that shell and out of sight—clearly, this shell was not to be carried about on the crab’s abdomen! One old, barnacle-covered whelk shell housed a beautifully colorful widehand hermit, whose extra-wide big claw can close the ‘door’ when the hermit retreats into its protective shell.

–Some small rock crabs were inconspicuous in the sediments under loose rocks. I pried one out of its niche, to look more closely. It protested vigorously, nipping me several times—which I ignored. But then it got serious and its pincers opened up the end of my finger, staining red the rocks at my feet. That worked—it was soon back among the cobbles where it belonged.

There were other enjoyable observations, too: a gorgeous, six-inch crescent gunnel, crows harvesting and toting food to their nests, a flotilla of bright harlequin ducks, a whale blowing in the channel. A partially visible sparrow in the bushes above the beach sang an unfamiliar song repeatedly, making it hard to identify, but then it sang the normal song of a song sparrow. Was it just practicing, or do such song variants have another purpose?

Spring happens!

blossoms and pollination, wetland foragers, and sparrows in the grass

The end of April and early May brought signs that our reluctant spring was finally happening, at least at low elevations. The bright yellow display of skunk cabbage made a welcome contrast with the somber greens of conifers and the still-leafless deciduous trees. A close look at the spike-like inflorescence showed that the numerous individual flowers were all still in their female phase, with no signs yet of the pollen that eventually appears around each pointed stigma. The small brown beetles that are the chief pollinators had yet to show up; they prefer inflorescences with pollen. Deer had munched off the tops of many inflorescences, leaving just a stub with a few flowers.

We found several fern-leaf goldthread plants with their wispy, narrow-petalled flowers, which are pollinated by small flies. The early blueberries were in bloom, their pinkish-white flowers waiting for bumblebees to visit. On sun-warmed cliffs along the Perseverance trail, the first purple mountain saxifrage plants made a splendid show; they are pollinated by bumblebees and probably some other insects. And there are reports of yellow violets along some trails.

We enjoy those floral offerings, but they are a dramatic contrast with what happens in early spring in the forests of the Midwest. There, the forest floor is liberally decorated by the early flowers of many species, including bloodroot, spring beauty, dutchman’s breeches, dogtooth “violet”, among others, many of which have showy white petals. Most of these species require an insect pollinator for seed production, and that job is often done by various species of native, non-social, solitary bees and by the non-native honeybee. Here in Southeast, I am told that such solitary bees occur, but almost nothing is known about their ecology.

The avian world was promising, too: Hooters on the hillsides. Kinglets in full song, along with wrens, robins, varied thrushes, and juncos. Fox sparrows starting to tune up. Other sparrows and early warblers arriving but not yet very vocal. Chickadees with nest material and – in some places—eggs in their nests. Sapsuckers excavating nest cavities. The first hermit thrushes skulking in the understory. Hummers zipping to and fro. Flights of violet-green and tree swallows swooping after flying insects. It is always such fun to see and hear the forest awakening each spring.

A few weeks ago I wrote about our local moose population, noting that population growth might be slow, given that only a few moose were known to be in this area. Well, now there are fewer still. A bear reportedly killed one in Cowee Meadows, and I found the remains of one, killed by a human hunter, in another place.

A little walk on the beach along the Mendenhall Peninsula yielded lots of ducks: the usual mallards, plus widgeon, greenwing teal, and shovellers. I was surprised to see hundreds of scoters rafted up in the lower reaches of the river; they are usually out in the bay. Shorebirds were migrating through, with pipits foraging among them.

Ravens had been turned over a cluster of mussels and barnacles, exposing an enormous hairy hermit crab with its abdomen tucked (inadequately) into a moonsnail shell. They were actively foraging on barnacles, nipping and hacking at the shells; we also found several regurgitated deposits of broken barnacle shells, where the birds had jettisoned the undigestible bits. A couple of ravens near a torn-up patch of sand drew our attention. With their powerful bills, they had just excavated three holes, about five inches deep, and extracted the clams that had been buried there, cracking open the clam shells to extract the meaty morsels inside. As we stopped to watch, a raven was just finishing off the last clam.

On my home pond, a few pairs of mallards found peace and quiet, with lots of spilled bird seed on the fast-disappearing ice. But by early May, the ice was gone. The duck crowd had grown, sometimes to twelve or fifteen, now squabbling over the spilled seed. Most of the females probably had a clutch of eggs in progress, but males were largely still in prime breeding dress, no doubt in hopes of some delayed mating opportunities.

Golden-crowned sparrow. Photo by Kerry Howard

A leisurely stroll around the Crow Point/Boy Scout beach area found a flock of golden-crowned sparrows in the woods along the river and a couple of groups of savanna sparrows along the grassy upper edge of the beach. A flock of dunlin (I think) swirled over the sand flats. In the big, broad meadow I call the ‘goose-flats’, several white-fronted geese mingled with the usual gang of Canada geese, all grubbing for tasty greens and roots, while, off to one side and separate, a flock of snow geese also foraging intently. I circled around all of them at a distance, and so disturbed them not at all.

Elderberry and wild currant bushes leafed out ahead of most other deciduous woody plants, but by the end of the first week of May, bits of green were showing also on willows and alders. In the beach meadows, green shoots were popping up everywhere. It’s “green-up” time!