When my children were small, I took them to the shore. It would be low tide, and we walked over the pebbly mud and parted the seaweed strands, the bladder wracks and the knotted wracks attached to the big rocks that the glacier had dragged with it from miles away. We peered beneath the seaweeds. The outer layers had dried in the air, but the under layers held a briny wetness that made the creatures we found within especially bright: starfish; the egg capsules of the dog whelks, small sea snails whose eggs look like tiny Greek amphora; green crabs as new and small as my children’s fingernails; young green sea urchins; limpets; sideways-swimming scuds; yellow periwinkles; sometimes a hermit crab or a sea anemone.
It seemed right somehow to be bringing young and growing children to the edge of the bay where life had evolved so far back in time that it was hardly imaginable, as if this place with its seaweeds were the proof we needed that we had come from a world of water, and that everything might have looked, at one time, something like this.
When we are children, our psyches tend to become imprinted on the places we know and love, and for many of us, that edge where water and land meet is one that stays with us all our lives. I didn’t think of it then, but now I believe I was offering them exactly this: their home place to imprint upon so that they might go into the larger world with a sense of where they come from, and thus a sense of who they are.
Lifting the seaweeds and finding life beneath them reminded me of the crepe paper balls my sister and I used to find in our Easter baskets when we were young. We would unroll them across the floor of our New York City apartment, where they spilled out treasures wrapped in tissue paper: tin rings with glass stones, and little metal animals that clicked. But these saltwater surprises, sheltering beneath the seaweed at low tide, were better. They were alive. My children and I gazed into a forest, not a tree forest that stretched its branches into the air, but a forest of overlapping, protective fronds, resting like sheaves against the rocks. We were looking for treasures, not noticing then that the real treasure was probably the seaweed itself.
After we left, the tide came back and the various species of seaweeds lifted into the water. The long fronds of the knotted wrack stood at full length in a high tide. The ribbon weeds and the sea lettuce would bend in the water’s pulse. The purple laver and the Irish moss would start to glow as the sun reached them through the polish of the rising water. And the lives within them began to stir. Fish moved over them and into them, feeding. The crabs skimmed down from their low-tide hiding places and scuttled across the bottom. The ducks would come, the mergansers hunting fish and crabs, the black ducks puddle-dunking in the shallows for snails and clam worms, and the elegant female eider ducks escorting their buoyant ducklings.
Seaweeds are algae, a word of Latin origin that once implied a primal ooze, a genesis of original and elemental stuff. They are not plants, in the strict sense. They have no roots, no leaves, no stems. Not really. Only a few species have developed vascular tissues, and these are only sieve tubes that transport nutrients between them, not like the vascular tissues of land plants, with their complex transport of sugars from the leaves down, and water and minerals from the ground up. Essential to land plants is a sophisticated coordination between specialized cells that have distinct jobs to do. When cooperation and distinctions between cells are present in seaweeds, they are much simpler. Each seaweed cell uses the water in which it lives, taking from it the nutrients it needs.
They are called seaweeds, but scientists still can’t pin them down with a satisfactory all-encompassing definition because species keep slipping in or out of the categories we have constructed for them. The ancient fossil record is sparse, and little can be done to bring to the fore a clear image of their history.
Sometimes, casting a look back, it is difficult to distinguish a single-celled alga from a bacterium. That’s because they both speak to beginnings, when first things—experimental, most of them evanescent—merged and separated and borrowed from one another.
Cyanobacteria were the first living things. They exist today much like their fossil ancestors: they live in water, and manufacture their own food from sunlight. Some species are toxic and dangerous.
They used to be called blue-green algae because of this miraculous ability to turn sunlight, mixed with carbon dioxide and water, into food, which is the prime occupation of algae and land plants. Over time, these photosynthetic creatures floating in prehistoric seas created the biggest revolution on earth. Nothing matches it, not the Chicxulub asteroid plunging into the Yucatán Peninsula and upending the age of dinosaurs, not the wrenching apart of Pangaea, the Paleozoic megacontinent that fractured into the continents we know today.
Minute though they are, cyanobacteria changed the earth’s atmosphere by adding one ingredient: oxygen. And here’s the marvel: they floated for a few billion years, then were joined on the water’s surface by a floating one-celled alga. Two tiny, astonishing beings floating around together for another billion years or so, as the algae and the cyanobacteria took the energy from the sun to make food and dispersed into the air their tiny gifts of oxygen, which, over huge amounts of time, grew into the matrix of all life to follow.
Marine algae, both the one-celled phytoplankton floating in the oceans today and the seaweeds anchored to our shores, and also seaweeds that float free, such as some species of Sargassum, supply the atmosphere of the earth with at least half its oxygen, which is the air we breathe. In the process of photosynthesizing, algae also disperse oxygen within the water to aquatic animals, including fish: the air they breathe.
We find one-celled algae in fresh water, on the damp trunks of trees, on wet rocks, on snow, in rain pools, and in the ocean. The phytoplankton that floats on the surface of the Gulf of Maine and all other saltwater bodies, a soup of many different species of one-celled algal life, are called microalgae because they are very small. The seaweeds that rim our shores to form underwater forests, or grow untethered and floating in deeper water, are the macroalgae. They are multicellular and gigantic by comparison.
Because seaweeds look much like land plants, one might assume that the hostas and lilies and such that we grow in our gardens evolved from them, that red, green, and brown seaweeds slowly made their way out of the sea and onto the land. That is not so. Land plants and particular green and red seaweed groups may share a possible evolutionary point of origin, but what we are witnessing in most of them is an example of parallel evolution: land plants and seaweeds came up with similar shapes as the best way to live.
They both need to anchor. Land plants have roots. A seaweed has a holdfast. Some holdfasts are shaped like disks, but others form a fist with many fingers called haptera. Holdfasts attach to rocks, wharf pilings, breakwaters, clamshells, anything rigid and stable. They are made up of thick tissue and fine hairs and a glue-like substance that sticks them in place. Seaweeds that anchor to corals secrete an acid that wears away a little carbonate chink of the coral into which they insert their attachment filaments.
While holdfasts anchor as roots do, they don’t transport water or minerals up into the algae they anchor. What they do is set the seaweed in one place and keep it there through tides and currents and storms, as water bathes the porous cells with the nutrients they need. The few seaweed species that grow in a hard sand or clay bottom use a rootlike structure called a rhizoid to penetrate the substrate. These seaweeds with rhizoids are in the green algae group and are probably distantly related to land plants.
The simple parts of seaweeds begin with the stipe, a stalk that lifts up from the holdfast. It looks much like the thin trunk of a young sapling, or the stem of a large grass plant. It takes the seaweed into the light. The blade or frond or thallus (often more than one word in the seaweed lexicon can be used for the same thing) is what the stipe brings to the light. The blade is the equivalent of branches and leaves on a tree. A seaweed blade may branch, and air bladders may punctuate it, especially in seaweeds that are long or that grow in quiet waters where currents may not lift it high enough to the surface and into the light. The bladders are simple buoys carrying the blades aloft. Bathed in water and sunlight, the blades have two important jobs: photosynthesis and reproduction.
Some Sargassum species can reproduce by fragmentation, but most species of seaweed reproduce by alternating generations. They have a sporophyte phase, which sends out a drift of tiny spores, as mushrooms and ferns do. And they have a phase of sexual reproduction, as flowers do. With the diploid form of reproduction—the spore phase—a seaweed can replicate itself, but this allows for no genetic variation. Sexual reproduction—the haploid form—introduces the possibility of a genetic mix, but it’s extravagant because the microscopic male and female reproductive cells are dispersed into the tide and swept into the enormity of turbulent currents. Most of them never find each other, never join. As a result, the solution for most, but not all, seaweed species is to depend on both means, which allows for genetic change as well as a chance at abundance.
Ascophyllum nodosum, or knotted wrack, is the tough, familiar seaweed along our shore. It reproduces only through the haploid form. Its blade is multibranched, shaped like a hardwood tree. At the tips of all these “branches” it begins its period of reproduction by growing receptacles, egg-shaped pouches that mature over the winter into male and female gametes, and when the water warms to the temperature the seaweed requires, it will release eggs and sperm in a cloudy mix into an incoming tide.
If you go to a shore with a marked incline, you will find that the native seaweeds arrange themselves neatly into bands. The green algae live closest to shore, the brown seaweeds inhabit the inshore waters and can also thrive in subtidal depths where sunlight reaches, but it is the red seaweeds that can live in the deepest water with the least light.
The bull kelp, a brown seaweed of the eastern Pacific, found in inshore waters from Baja California to southeast Alaska, can grow ten inches a day and up to sixty feet in a season. Buoyed by a single fist-size air bladder on a bare stipe, it lifts from its holdfast and spreads wide blades out across the top of the water, maximizing its exposure to sunlight. Another brown seaweed of that same coast, the giant Pacific kelp, is called the sequoia of the sea, a perennial, fast-growing canopy species that can reach 148 feet. Along with bull kelp, it creates forests of unparalleled ecological value. Kept afloat by numerous delicate air bladders, the giant kelp puts forth side blades from the stipe, like the branches and leaves of a tree, creating dense underwater habitat.
Sea otters require this gargantuan forest to survive. There are two subspecies of sea otter, one along the California coast, another along the coasts of British Columbia and Alaska and out to the Aleutian Islands. Sea urchins, the spiny, slow-moving grazers related to starfish, also depend on kelps. And this is how this particular wild system works: Urchins graze kelps near their holdfasts. They also feed on young, tender kelps newly attached to rocks. The sea otters eat the urchins. At the water’s surface, the otters float on their backs and socialize and consume what they’ve caught, draping the long blades of the kelps around their bodies to anchor themselves.
It’s a life-sustaining relationship, kept in balance by the otters: the sea urchins feed on the kelps; the otters feed on the urchins, preventing the kelps from being overgrazed and the underwater forests from becoming decimated. As with the old-growth forests on land, these spectacular Pacific kelps have created a habitat that has supported communities of many lives—many species—for thousands of years, protected by the appetites of the otters, the equivalent of swimming Loraxes.
Sea otters, members of the weasel family, grow coats the thickest of any mammal in the world, which led to their near extinction by the early 1900s. When hunting them for their luxurious pelts was finally outlawed, they began to rebound. As they rebounded, the kelp forests, devastated by urchin grazing, grew back. But recently, and at first mysteriously, sea otters have declined again along the northern Pacific coast and out into the Aleutian Islands. Why? It was a scientific puzzle. Not only were their populations dropping, but in some places they had disappeared, especially along the Aleutians, and the Steller sea lions, the fur seals, and the harbor seals were disappearing, too. First guess was that the sea lions and the seals were being outcompeted for fish by human fishermen. And that may have been true, or partially true, and laws were made to keep trawlers away from areas where the seals and sea lions haul out.
Otters were a more complicated puzzle. They had reached near extinction before laws to protect them led to their steady comeback. But during the years of exploitation, other changes had occurred in the ocean, changes that were offshore, away from the home territories of the otters. Those changes didn’t seem relevant to sea otter numbers. But one was.
In the aftermath of World War II, hunger in Europe, Russia, and Japan drove a frantic increase in the hunting and rendering of whales for human food consumption. We know that our oceans have yet to recover from the devastation of the whale hunt, but for a long time no one connected that fact to otters or to seaweed. It was primarily the baleen whales that were hunted (they feed by filtering water through a series of horny plates that are like huge sieves arranged in their upper jaw, snagging krill and plankton and small fish). Factory ships ranged from the Arctic to the Antarctic hunting the blues, the grays, the sei whales, and the humpbacks. But what does this have to do with Pacific sea otters and giant kelps?
A few biologists began to hear reports of orcas, otherwise known as killer whales, hunting the otters. These attacks were made by the transient orcas, a separate grouping from the resident orca populations. The transients migrate up and down the coast from Southern California to southeast Alaska. The reports seemed an exception to the rule, because otters are low in body fat, much too small a prey item for a six- to ten-ton whale, and the information was new, unevaluated, and therefore suspect. But reports of attacks continued, and after a while, scientists connected the loss of baleen whale populations, primarily the gray whale, to the deaths of the otters: these transient orcas had shifted their diet from whales to concentrate more fully on, first, harbor seals, then fur seals, and then the mighty and aggressive Steller sea lions. The sea otters as prey item came last. They were snacks, but the hungry whales needed snacks, the more the better.
Orcas are the largest species of dolphin in the world. They’ve been called killer whales forever, but that’s not quite correct: the transients are whale killers. Unlike other whale and dolphin species that feed primarily on fish, krill, jellyfish, and squid, and unlike the resident coastal populations of orcas that feed primarily on salmon, these transients are more like wolves. They can take down animals much larger than themselves by overcoming them with coordinated pack work. The historic numbers of baleen whales were missing along the coast, and the seal and sea lion populations in the Aleutians were also dropping for a number of reasons. The otters were left, and the hungry orcas turned to them. In some places, the transient orcas cleaned out entire bays. With the loss of otters in the bays, the sea urchins quickly tore away at the kelps.
Jim Estes, one of the scientists who made the connection between the otters and the baleen whales and the orcas, has made a further connection: “What we’ve seen is that the kelp forest ecosystem in South Western Alaska went from being robust to being . . . gone. It’s staggering that it occurred over such a large area in such a short time—just a few years. The food web interconnectivity—that urchin explosions could be linked to whaling 50 years ago—is amazing.”
Who knew that sea otters need baleen whales to survive, and that those missing whales had helped keep the great kelp forests alive?
One of the most elaborate wild systems in the world we call the Sargasso Sea. The seaweeds that make up the Sargasso are two species, Sargassum natans and Sargassum fluitans, both of which can propagate themselves by fragmentation and spend their lives unanchored and floating in the North Atlantic subtropical gyre, a circular system of ocean currents that press in on every side. Although these Sargassum species probably originated long ago in the Caribbean, close to shore, with holdfasts, they have adapted themselves to living here now in open water. They can do this because their cells are “totipotent,” meaning that any cell within them is capable of making an entire new individual.
This peculiar sea of seaweed is about two million square miles in size, located in the North Atlantic off the coast of Bermuda. An archipelago of drifts and porous islands sometimes twelve feet deep, the Sargasso carries within its lacy fronds ten species found nowhere else in the world, including fish, mollusks, and crustaceans, all adapted to the sea’s being neither land nor open water but a bit of both. The current at the sea’s western edge is the Gulf Stream, flowing north.
These seaweed islands are also hosts to fish, crabs, worms, and other tiny lives found elsewhere on seaweeds by the shore, but out here they are part of a biome uniquely its own. Not only do young sea turtles seek refuge and food here, but to it come many other species, among them humpback whales, basking sharks, dolphinfish, and bluefin tuna. And this is where the young of the American and European eels can be found freshly hatched.
Mature American eels live in our freshwater lakes and rivers for as long as twenty years. Eventually they begin their journey to salt water. They are females. On their way down they meet the males that live in rivers and streams closer to the coast. As they go, both males and females are transformed, becoming what we call silver eels. They stop eating, their eyes enlarge so that they can see in the dark, the pectoral fins at their sides widen, and a muscular blue-silver gloss shines through the skin of their backs as their bellies turn an eerie white. Just on the lip of winter, in the cold nights of autumn rains, they begin their journey. When they reach deep water, they turn south toward the Sargasso Sea, the only place in the world where they spawn. After they spawn, they die.
We know they do this, and it must be deep beneath the floating seaweed beds, though no one has found a single eel egg stuck in the Sargassum, nor a single body of a spent spawner. But odd little fish shaped like tiny elm leaves with pointed snouts have been found in and around the seaweed. They are the larvae of both the American and the European eels that will eventually wend their way into the Gulf Stream to drift north, the American eels dropping out along our eastern seaboard, as the European eels continue, circling below Iceland and then down along Scotland and south.
All along the eastern coast of the United States, they turn inshore in springtime, seeking fresh water, moving between underwater cobbles and through the sheltering seaweeds in our bays, heading toward our streams and rivers as they change first into what we call glass eels, which look like transparent spaghetti pieces, each with a beating red heart and two black dots for eyes, and then into the thin, dark baby eels we call elvers.
Eel populations along the US and Canadian coast and in Europe are near historic lows owing to years of overfishing, dams that block their access to upstream waters, turbines set into dams that chew them up, and contaminates. Individuals and conservation groups have pressured the US Fish and Wildlife Service to list the American eel as endangered, but there is a problem: managing eels is about as hard as holding on to one because they swim long distances across state and international boundaries. And there is much about them we don’t know. Although biologists who study these eels will tell you that they are threatened and, yes, endangered, a federal protection plan for them has not been written.
With over nine hundred licensed elver fishermen, Maine is the only state on the Eastern Seaboard to maintain an elver and glass eel fishery except for South Carolina, which issues a few licenses each year. Canada prohibits catching glass eels and elvers. Europe has closed all selling of young eels outside its territory. Within its territory, it does allow catches for restocking programs.
Those caught here in fyke nets as they come to our freshwater streams and rivers get packed up and shipped to China. There they are fattened in tubs and, when grown, sold to Japan for unagi. The Maine fishermen who net them have made spectacular, jaw-dropping windfalls. They are the same people who have been sidelined by the closing of other fisheries because of overharvesting, and they need this work. But one must ask: What’s wrong with this picture?
At the Sargasso Sea, boats come to harvest the floating mats of seaweed, and trawlers pull their fishing gear through it, cargo ships regularly traverse it, and within its slow, continuous gyre, plastic trash is collected and held—forever. There is no other sea like the Sargasso, and there are no other eels like the American and European eels. They are bound together and irreplaceable. To work to protect one, we need to extend protection to the other. In 2014, five governments, including that of the United States, came together in Bermuda to see if they could begin to work on conservation for the Sargasso Sea. It’s a small start.
For most of us, the Sargasso is a dreamlike place. It is vulnerable precisely because it is far away and such a strange, wild world of its own.
Close by, our pebble beaches are edged with storm-tossed windrows of seaweed, knotted wrack and bladder wrack, that lie in a long, narrow fringe at the tide line. And before you know it, still in the heat of summer, the shorebirds have come back from their nesting grounds in the Far North. Peter Matthiessen called them the wind birds. Swift in flight, the various species funnel down in their migrations to hunt small crustaceans and other creatures that populate the high-tide line within the tossed-ashore seaweeds. These birds are urgent feeders, feasting at shorelines that must supply them quickly with what they need for the huge metabolic task of flying long distances.
Late one afternoon, at the end of summer, my neighbor and I lay on the thin strip of gravel beach in our town, chatting and watching as the bay water, heading for low tide, inched down the shore. It was the end of August, and we’d both stopped work for the day. Just beyond our toes ran a narrow twist of seaweeds, a curled combination of bladder wracks and knotted wracks that the receding water had left behind. Its colors were dull green and mustard and dark brown, and the sunlight gave it a shiny garland look that made me think it would make a lovely Christmas decoration, hung above a doorway, festooned with tiny lights. I was thinking about the feasibility of seaweed garlands when suddenly two birds, as if they were made out of the weed itself, appeared in front of us. They were smaller than the length of my hand, one slighter than the other, and they seemed to pay us no attention as they worked the briny weed, walking daintily ahead and plucking so fast that even though we could have reached and brushed the crisp feathers of their backs with our hands if they had allowed it, we couldn’t see what they were eating. They were finding food, but whatever was keeping them going at such a pace was invisible to us.
Perhaps they had been here for some time, checkered birds, the color of rust and black pepper and tortoiseshell. They were so much the color of the wrack that we noticed them only because they moved in quick, short thrusts as they fed.
They were least sandpipers, Calidris minutilla, the young of the year, down from the sedge-rimmed bogs of the North, where they nest beside cold-water pools in the tundra and the taiga forests. At most, they are only six inches in length, and a well-fed one weighs about an ounce. These tiniest of all shorebirds appear on our coast both coming and going to summer nesting grounds, to wintering grounds, from the Ungava Peninsula and Newfoundland to North Carolina, Mexico, and Brazil. They count on these shorelines for food.
It was a moment you can’t force—an abrupt epiphany. But epiphanies such as this need an open beach, a drift of damp seaweeds, plentiful critters that live within and around those seaweeds, a withdrawing tide, and a good nesting season so far north that most of us will never visit that soggy, wild landscape where these sandpipers brood their buff-colored, spotted eggs, and where the parents, not long after the young have learned to fly, leave them to the insect-rich pools and head south.
The young before us are on their own, moving down with others of their species, feeding on beaches, in marshes, in the coves between ledges. They know how to find food and to find one another. Gathered in tight, white-flashing flocks in flight, they know how to make their way to places they have never seen before with no one to show them how to get there.