A Tale of Two Winters

From Dec 2010 - Feb 2011, I collected, on average 180 pieces of manmade debris at my beach, Bayview, in Saco, Maine each week.

From Dec 2011 - Feb 2012, that number was an average of 60 pieces each week!

Anyone following my Collection Reports has seen that the amount of debris I'm pulling off the beach has nosedived. It would be very tempting to see this as amazing news. I'd be tempted too, if not for all the research I'm now conducting simultaneously on a second beach further south.*

This, plus 153 individual scraps of fishing rope, came from my
second beach, Curtis Cove in Biddeford, for a total of 249
pieces of junk from 150 ft of shoreline. In one week in Feb.

No, the debris is still swirling in the Gulf of Maine, as fiercely as ever. But for some reason, starting in mid-November, it largely stopped washing up on Bayview beach.

Why?

There are two really intriguing possibilities. The first has to do with a strange phenomenon called internal waves. The ocean isn't one big homogenous lump of water. It is stratified -- often sharply -- with fresh, "light" layers on top and saltier, "dense" layers down below. When the stratification is strong, energy that gets put into the ocean (from storm or surface wind, etc.) can propagate along the boundaries between those layers. It's the cause of what's known as "dead water" -- when, say, a boat propellor that usually pushes the boat forward instead sends all its energy just into creating these underwater waves, and the boat hardly moves at all.

What does this have to do with beach debris? Well if the winter of 2010/11 was a time of high stratification between layers, more ocean energy may have traveled through these undersea conduits, churning up the seabottom and its debris. This huge wrackline from December 2010...

...may have gotten its beginnings from a churned-up seafloor thanks to shallow-water internal waves. Contrast that view with this winter's:

All winter long there has been almost zero seaborne wrack. No wrack = no plastic. Are the internal waves weaker this year, or even shut down? It's been an exceptionally mild winter in Maine. Freakishly mild. Does Saco Bay need bone-chilling air masses to stratify its waters in winter? We've also had fairly little rain or snow all winter long. Does the bay need fresh river runoff to stratify it?

I don't know. But it's one thought, and it's got some support from oceanographers I've spoken with.

The second thought comes from the few curious finds that have surfaced. Twice in the past month, I've pulled from the sands pulltab-era aluminum tops from old rusted-away steel cans.

2/29: Generic style used ~1970-1980

3/12: Coke can used only '71-'72

A third 30+ year-old pulltab aluminum top down in Curtis Cove makes 3 in a month! Which makes me wonder if an offshore sandbar has shifted, revealing 30-year-old flotsam and dampening the energy coming into Bayview. Just this week, at an ultralow low-tide, I snapped this muddy bar which peeked out of the water at the very edge of the tide line:

I've never seen anything like a sandbar exposed out at Bayview before. The ripples show that it's migrating landward. If it has bigger cousins just offshore, and they're steep enough to cut off inflow of seafloor debris, that may be what's stopping the debris from coming in.

As usual, I have more questions than answers. Clearly there's some energy at the beach. I've documented huge sandloads dumped up on the shore this winter, as well as several lobster traps. Yet the stuff that would get whipped up, suspended, and dragged in -- like vinyl, polystyrene, seaweed -- it's just not coming.

Whatever's keeping it from coming in, it's out there. And it will start washing into Bayview again. It's just a question of when. For the moment, it leaves me with the tantalizing question of "Why?"

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* More specifics on this beach, Curtis Cove in Biddeford, in a future post, soon!

Collection Report Feb 21, 2012

Monday, February 20th, 2PM. Hour before low-tide. Bright sun, 40 degrees. A rare brisk Winter '12 seabreeze.

February 20

But on the sands? Nothing. No wrack, rock, shell, paper, metal, or plastic. A void. So, a return Tuesday, February 21st. 1:15PM, a couple hours before high-tide. A repeat of the day before, weatherwise.

February 21, cusps, rocks, and...

And mostly a repeat of conditions on the ground. At least the regular, beautiful cusps are back. Behind, the sand slopes sharply up to the dunes; in front, the sand drops off sharply again to the low-tide terrace. But on either side? Still nothing. Zone N:

16 finds:

• Building materials: 1 (asphalt)
• Foam/Styrofoam: 0
• Fishing misc.: 1
• Food-related plastics: 1 (straw wrapper)
• Food-related metal/glass: 3 (sea glass)
• Nonfood/unknown plastics: 6 (survey flag/marker, tieback, 1 scrap >1", 3 scraps <1")
• Cigarette filters/plastics: 4 (3 filters, 1 filter tip)
• Paper/wood: 0
• Misc./unique: 0

How dull? That dull. Oh, and Zone S? Zip. Not one bit of manmade debris washed in.

Thus ends one of the briefest collection reports I've ever done! I'd love for this to be great news... But at the beginning of the year, I got approval from National Fish & Wildlife Service to work on a second beach about 5 miles south, an untouristed little nook called Curtis Cove.

Yay, I'm official!

After removing, so far, 1000+ feet of fishing rope from the Cove -- plus hundreds of scraps of new washed-in plastic every week -- I know that the Gulf of Maine hasn't miraculously cleaned itself.*

One recent week's haul at Curtis Cove

The junk's just bypassing Bayview's shores. But in a way, this is exciting to me. The debris is out there, yet Bayview this year is monumentally different from last. The question is, why?

I'm working two hypotheses:

(1) A little-known phenomenon called "internal waves," which propagate through the water instead of on the surface. If those waves are missing or weak, seafloor debris may not get churned up enough to move onto land.

(2) Sandbars. If a series of sandbars has moved into the Bay just offshore, it might be blocking debris as well as dampening the energy of the incoming waves. The high-tide swash marks this winter have been pathetic compared to last year. Several yards further down the slope than last year's average. For whatever reason, the energy just isn't there at Bay View this year.

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* I'm keeping track of my Curtis Cove finds too. Soon I'll devote a blog page describing what I'm doing there and will post its collection reports as well. Being a site that gets no tourists, practically everything I find has been washed in. And I'm learning that much of it has really fascinating stories to tell.