Reasons to Love Knotted Wrack (Ascophyllum nodosum)

Ascophyllum nodosum, AKA rockweed, AKA knotted wrack.  It might seem like a lowly organism, merely a bit player in the drama of Maine's coast.  I mean, aren't seastars and lobsters and anemones so much more glamorous?  But Ascophyllum is one of the stars of the Maine coast, exerting a fundamental influence on the intertidal community around it.  So here, without further ado, are ten reasons we all should love knotted wrack:

1.  Knotted wrack lives a really, really long time.

It's not unusual for knotted wrack fronds to be fifteen or more years old, and for their holdfasts to live for decades, or maybe even centuries.  (A holdfast is where marine algae attaches to the substrate.  Seaweed doesn't have roots; rather, their tough holdfasts grab onto rocks, mussels, or other solid objects.)  When a frond breaks, it regenerates from the holdfast.  Next time you look at a holdfast, realize it might be older than you.  Or your parents.  Or your grandparents!

2.  You can tell how old a knotted wrack frond is just by counting the air bladders.

Knotted wrack lays down one air bladder each growing season.  That makes figuring out how old a frond is easy.

3.  Individual knotted wrack fronds can grow meters long -- but very, very slowly.

See?  (Note, fronds are much smaller at sites with more wave exposure than at wave-protected sites.  This was taken at a site where waves only occur in the worst of storms.)  It's amazing to think knotted wrack grows only about 10 cm a year (two and a half inches) and makes it to these great lengths.

4.  Knotted wrack creates a cooling canopy over the rocky intertidal at low tide.

The intertidal portion of the coast is a very stressful place for ocean organisms.  All of the algae and animals we find in the intertidal are derived from ancestors in the sea.  Emerging out of the sea places great physiological stress on them -- especially thermal stress and desiccation.  Amazingly, the rocky intertidal habitat is a very hot place in summer -- too hot for comfort if you're an intertidal organism.  But Ascophyllum provides cooling shade and a moist canopy, protecting the species under it from overheating. In summer, temperatures under an algal canopy of knotted wrack can be 5-10 degrees (F) lower than without it. (It's also warmer in winter, preventing organisms from freezing.)  This is particularly important in the high intertidal.

5.  Knotted wrack reduces wave impacts on organisms living under the canopy.

The energy required to hold on when a wave hits the beach can be substantial.  Knotted wrack can act as a wave buffer, allowing organisms to put more energy into other activities -- like growing and having babies.

6.  Knotted wrack is an ecosystem engineer that fundamentally influences the community of organisms around it.

Knotted wrack has such a large influence on the community around it that it can be thought of as an ecosystem engineer or foundation species, just like coral reefs or sea otters are.  The habitat around knotted wrack changes fundamentally simply because it is there.  Without knotted wrack, it's a place where the sun bakes the substrate at low tide, the waves wash away organisms at high tide, and space for growing is limited.  With knotted wrack, it's a cool(er), wave-buffered, complex habitat with lots of things to hold onto and grow.  Knotted wrack's long fronds -- that persist for decades -- influence their surroundings greatly. Everything from sponges, crabs, nudibranchs and snails to barnacles, smaller seaweeds adapted to low-light conditions, mussels and limpets find a comfy home under the knotted wrack layer.  Knotted wrack also provides substrate for other organisms to grow on -- other seaweeds, worms and snails all live on the seaweed itself.  Predators like gulls have a harder time finding tasty morsels like crabs when they're hidden in knotted wrack too.  However, knotted wrack isn't all good -- it can easily sweep other organisms away (especially babies just settled out of the plankton).

7.  Knotted wrack spores are wimpy.

Despite the dominance of giant knotted wrack stands all over Maine's coast, their spores (like seeds) aren't very robust. Knotted wrack reproduces by making spores that move with the currents and eventually settle on the best hard substrate they can find.  If this substrate happens to be exposed to waves -- even small ones -- the spores simply can't hold on.  That's why it's common to see vast stretches of protected bays blanketed in knotted wrack, but uncommon to see it on exposed headlands.

8.  Littorina obtusata -- a beautiful little snail -- lives in knotted wrack.

Smooth perwinkles -- Litterina obtusata -- lives exclusively on knotted wrack fronds.  They eat both the knotted wrack itself, and epiphytes that grow on knotted wrack.  Rumor has it they even lay their eggs in the air bladders, but I've never seen it myself.

9.  Eiders forage in knotted wrack, and their babies hide in it.

I've got a soft spot for common eiders.  Kent Island, where I spend my summers, was bought by Sterling Rockefeller in 1930 to save the last known nesting eider population in the Gulf of Maine.  There were less than 30 nesting pairs in the entire Gulf of Maine at the time, almost all of them breeding on Kent Island. Rockefeller sold Kent Island to Bowdoin College for a dollar not long afterwards, with the stipulation it would be used as a wildlife sanctuary and research facility.  You can read about this interesting story here.

Eiders are sea ducks that live in large aggregations during the breeding season, nesting on islands.  During this time they forage in knotted wrack for small invertebrates, like snails (see #8) or mussels.  Baby eiders head out into the ocean very early in their life -- 12 to 48 hours after hatching, and are highly vulnerable to predation by gulls and eagles.  Hiding is an important strategy to survive another day, and baby eiders are pretty good at it, hunkering down in the knotted wrack fronds along the shoreline.

10.  Knotted wrack forms a structurally complex underwater forest at high tide.

It might seem, to terrestrial observers like you and I, that knotted wrack just lays there on the bottom.  But we should remember that what we see of the intertidal is only half the story -- the low tide half.  When the tide is in, knotted wrack is bouyed into a thicket of fronds, nothing like what we expect.

Interested in knotted wrack (who wouldn't be)?  You can find it in almost any coastal site that's protected from waves.  Some good places to investigate it are Bowdoin College's Coastal Studies Center in Harpswell, Ocean Point in East Boothbay, or Wolfe's Neck State Park.  Wear shoes that can get wet and use caution; walking on knotted wrack can be tricky.  But get out there, look under those fronds, and have fun.  Just do it at low tide.

Two Lights, and Two Lights

One of the two lights, as photographed from the Lobster Shack.

While I was home from the island I threw the dog in the car and headed down to Cape Elizabeth for a quick evening outing.  A couple of years ago Damon and I crewed on a offshore sailboat race, a great way to recover from our summer on the island.  We had spectacular weather, and beat down along the Cape Elizabeth coast as night fell.  As we ground winches and trim sails, we tacked just offshore of Two Lights -- both the state park and the lobster shack.  In the evening light they both looked so beautiful.  Now I finally managed to make it back, with a view from land to sea this time!

Two Lights State Park seems to really confuse people, if you read Tripadvisor on a regular basis.  Everyone expects there will be two lighthouses in the park, but nary a lighthouse will be found there.  Rather, you'll find some amazing picnic spots, crashing waves on a rocky outcropping, some lovely upland trail, and old artillery ruins from WWII.  This is the place to be for sunsets, even sans lighthouses.

Crashing surf on the rocks, and someone contemplating the enormity of the ocean.  Or napping, I can't really tell.

A word to the wise:  rocks by the ocean are slippery, and waves are dangerous.  Take heed.

The beast in her natural habitat.

If a lighthouse is what you want to see, get thee to the Lobster Shack, right down the road.  You'll have a great view of one of the two lights, plus enjoy some great seafood in what must be the most spectacular setting in Maine (and that's saying a lot).  The evening I was there, a wedding party was rehearsing on the lawn, tourists from all over were enjoying dinners, and gulls were trying their best to snatch a bite or two from an unsuspecting diner.  I of course had to try a lobster roll; my usual in this situation.  It was fine -- but I have to admit, I was pretty turned off by the big, glistening dollop of mayo they put on it.  Luckily, that was easy to scrape off, so I could enjoy my lobster roll in paradise.

See what I'm saying?

Peaks to Portland

Last week I headed down to Portland to watch the finish of the Peaks to Portland swim.  I am in awe of people who swim in open water.  Many years ago, I completed a sprint triathlon, and learned that training in a pool is oh so different from swimming in the ocean.  Every 2 inch wavelet seemed like it was trying to drown me.  It wasn't a pretty sight.

So my respect for folks who swim competitively in the ocean is great.  The Peaks to Portland, a fundraiser for the Portland YMCA, is 2.4 miles long, from Peaks Island to East End Beach in Portland.  The water was in the high 50's/low 60's; making for a cold swim, even in a wet suit.  It was a great morning; worth an early morning drive to the big city.

Before the race started, an army of volunteers prepped the finish line.  There were water bottles to put out . . .

. . . and oranges to cut up . . . 

. . . and medals to prepare.

Then we waited . . . 

. . . and played with the dogs (it's a dog-friendly beach in the early morning) . . . 

. . . and scanned the horizon for signs of swimmers.

Then far, far on the horizon, we could see tiny specks that grew bigger and bigger.

Until finally the lead swimmer charged through the moored boats and into the finishing chute!

And the leaders' escort kayaks made their way to the boat ramp.

Eventually a huge pack of swimmers and kayaks streamed our way.

The kayaks poured up the boat ramp (I helped carry for awhile).

This must be a dream come true for LL Bean and other outfitters.  This is only a small fraction of the kayaks.

Congrats to the finishers!  Great job.

Guest Bloggers -- Hannah and Josie Go Whalewatching

A humpback whale sounds near the boat.

It's been a busy week for me -- home from the island for some work and pleasure -- so I thought I might trick someone into writing a blog post for me provide an educational opportunity for some young scientists. Yesterday my young friends Hannah and Josie joined me for a whale watch, and here's what they have to say:

Before the whale watch we ate lunch at the Cape Ann Brewing Pub.

As you can see, we didn't like it very much.

Josie:  Today we went on a whale watch.  I loved it so much.  We saw humpback, minke, and fin whales. My favorite of them all was the humpback.  We saw them fluke, breach, and make bubble traps.

When they fluke, they come up to the surface of the water and whip their tails up in the air.

When they breach, they jump up out of the water and their full body comes out of the water and slaps back down on (and into) the water.

When they make bubble traps, one to seven whales blow bubbles out of their blow holes and make bubbles in a circle around prey which are mostly sandlance, which are a type of fish.  The bubbles confuse and trap the sandlance.  Then the whales swim up from below with an open mouth and eat the fish.

Hannah:  The whale jumped.  In what seemed slow motion, the head, speckled with barnacles, rose out of the water.  Following close behind, its great big front flippers whipped wildly next to it, causing ocean water to spray behind.  The heavy tail lifted and the whale leaned back in a big arc.  It plunged into the depths of the deep blue waves, splashing everything in about a seven foot radius.  The very last tip of the tail disappeared.    Ripples filled the water, the last mark of a whale I'd never see again.

We got a great view of all the action.   The whales were EVERYWHERE!

This whale is showing us his fluke pattern.  Every whale has a different pattern, so it's like a fingerprint.

A bubble net, with whales about to surface in the middle.

Whales feeding in the middle of a bubble net.  The birds are all hoping to get some too!

This whale has a full mouth!

Some notes from the Ocean Lover:  Hannah, Josie and I went whale watching out of Gloucester, Mass, on the Seven Seas Whale Watch.  Whale sightings have been excellent in the past few weeks, and we saw a ton of whales -- the first one just outside of the Gloucester Breakwater.  A very large group of feeding humpbacks (~20) crowded on Tilley's Bank, allowing us to observe bubble net feeding, tail slap feeding, and a single breach just feet from the boat.  Our naturalist was kind enough to spend some time with my young friends, and told us she was able to quickly identify three of the whales we'd been watching; Wyoming (sex unknown), first seen in 1988; Cove (male), first seen in 1982; and Lynx (female with seven known calves to her name), first seen in 1981.  

Not all whale watches are created equal.  If you're interested in whale watching, I recommend going with a company that either partners with a conservation or research organization (Seven Seas partners with Ocean Alliance), or one that is a member of Whale Sense (a program that promotes responsible whale watching). Whale watching can be disruptive to whales if not done carefully,and a recent study by the International Whaling Commission showed whale watch boats represent the greatest threat to whales in terms of ship strikes.  Supporting companies that treat whales respectfully is one way you can do your part for the oceans.

The Egg Hunt -- Black Guillemots

Time is passing quickly on the island, and everyone is rushing to complete their research before we all head home.  Luckily, people are all willing to pitch in and help with collect data, especially if it involves a trip to the next island over and a hunt for black guillemot nests.

Black guillemots on Kent Island.

Guillemots (Cepphus grylle) are rather charming little seabirds, not too distantly related to puffins.  These little guys are black and white, with rather striking red feet and mouths (inside their beaks).  They forage along the shoreline, diving for up to two minutes at a time as they use their wings to push them through the water to hunt small fish and invertebrates.  Guillemots lay their eggs ashore, usually under boulders, but sometimes in piles of driftwood or simply in a crevice along the shore.  One of our students is studying the nesting behavior of these cute little birds, and last week a bunch of us went on an expedition to Sheep Island to search for eggs one afternoon.

Before we got started looking, Damon and I got a bit distracted.  A humpback whale washed up on the island last October, and I hadn't gotten a chance to see it yet.  This is a known humpback (they are identifiable from the markings on their tails, which are photographed and cataloged), who was called "Harmonic".  In the cool northern climate, it takes quite a while for a whale to decompose, so here he was more than half a year later, still looking quite intact, although some baleen had been washed further along shore.

Harmonic, decomposing on shore.  He's on his back with his ventral pleats visible in this photo.

A large section of baleen washed up in the bushes. The inside of the baleen, a rough hair-like tangle of keratin, can be seen here.  This is used to capture fish inside the mouth. 

Once we had a good look at the whale, we joined the students and got down to business.  Sheep Island's west side is boulder-strewn, so this was quite an Easter-egg hunt:

Ideal nesting habitat for black guillemots; loads of boulders to hide eggs under.

Any eggs under here?

What about here?

Success!  Two eggs sitting on the ground under this rock.

Collecting data after finding eggs.

Once we got into it, we found a bunch of nests -- too many to process in the time we had ashore.  The curse of success!

This egg was just sitting out in the open.  This is not a very good strategy -- crows and gulls love to eat eggs!

These two eggs (look carefully) were well hidden in a pile of rocks.

This little gal was sitting on her eggs, watching us with suspicion.

Another egg sitting out in the open.  Competition for nest sites must be keen, if some birds resort to this.

Close up of an egg that was preyed on.  The colors are amazing!

Hang on a second -- that's not a guillemot!  (We had to use caution to not step on hidden gull chicks.)

Damon getting the skiff, to take us back to Kent (and a hearty dinner!)