Category Archives: Salt marsh

How to survive winter

41 degrees Fahrenheit
You’re naked. In a salt marsh. With a giant rock on your back. It’s 41 degrees Fahrenheit. A cold that kills comes tonight. You see someone else. They’re naked. In a salt marsh. With a giant rock on their back. They’re covered in a slimy goop that is sticky and slippery at the same time. They have tentacles on their head. That’s weird. Then you remember, “Oh yeah. I’m a snail.”

As a snail, you are cold-blooded (the scientific term is ectotherm), meaning that you can’t regulate your body temperature internally like those uppity warm-blooded animals (endotherms) like mammals and birds. Your outside temperature is your inside temperature. What happens when the temperature drops below freezing? How do you survive if you are no warmer than an icicle?

38 degrees Fahrenheit
Head south to overwinter in Mexico or the American south like the monarch butterflies, green-darner dragonflies, and not-so-hardy New Englanders? No, you are a slow-footed gastropod and travel only as far as the nearest plant.

36 degrees Fahrenheit
Bury yourself under leaves, moss and the soft soil like the forest and garden snails? There is no moss here. And the leaves are few and the mud is as soft as a cinder block.

Other snails join you at the plant. You all huddle into a cuddle puddle.

34 degrees Fahrenheit
Hibernate like a bear in a cave? Marshes, by their geologic definition of having no rock from which to carve a cave, have no caves. Some snails, if lucky, sneak into crab burrows and stowaway in a muddy hibernaculum. But the holes are few and the snails are many. And a burrow is just a hole and holes are cold.

Your heartbeats slow. 

33 degrees Fahrenheit
Fill your blood with antifreeze like some insects? That’s not a trick you can pull off. But you must do something because cold kills. It’s not the cold itself that kills, it’s the stiletto-sharp ice crystals that form inside your cells. Crystals shred the cell’s membrane and the nucleus and mitochondria spill out like guts from a disemboweled goat. A cell freezing is like stabbing a water balloon with a hundred toothpicks from the inside. Frozen cells die. Freeze enough cells and you die. Winter will kill you.

Or will it?       

32 degrees Fahrenheit
Parts of your body start to freeze.

30 degrees Fahrenheit
The water in your body continues to freeze. But not the water inside your cells, the water outside your cells. The water between the cells. Because of osmosis, this pulls water out of your cells, which makes them saltier. Salty cells, like salted roads, lower the freezing point of water and do not freeze.

22 degrees Fahrenheit
It’s midnight. You heart has nearly stopped. Parts of your body have frozen, but your cells have not. You will survive another winter. But you will still be naked, carrying a big rock, and covered in goopy slime.

It could be worse; you could have a fish living inside your anus.  

 

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Saltmarsh periwinkles, Littoraria irrorata, huddled against the stem of needlerush (Juncus romerianus) in Yorktown, Virginia
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Snails huddling for warmth. The smaller snails in the foreground are coffee-bean snails (Melampus bidentatus). The larger snails in the background are periwinkles (Littoraria irrorata)
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Saltmarsh periwinkles, Littoraria irrorata, huddled against stems of needlerush (Juncus romerianus) in Yorktown, Virginia
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A cute cuddle puddle of saltmarsh periwinkles (Littoraria irrorata)

Post-script
Many marine snails use this ‘freeze part of my body’ trick to survive the winter. The snails starring in this essay are the coffee-bean snail, Melampus bidentatus, and the marsh perwinkle, Littoraria irrorata.

Post-post-script
It’s not clear to me why the snails huddle together when it’s cold. I can come up with at least two hypotheses. First, snails huddle together to shelter each other from the wind. Second, they may not be seeking each other, but all seeking a plant to huddle against. Like humans at an airport. You’d like to avoid everyone, but you’re all drawn to the same place and have no choice but to huddle together and try to survive.

The Joker in the Salt Marsh

The Great Marsh, Massachusetts
For C & J.

On a recent sampling trip in the Great Marsh I brought along a new assistant, The Joker. He was done shooting his latest film and needed a break from his general villainy.

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The Joker investigates the mud between the stems.
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Like some new interns, The Joker was easily distracted. Here he mounts a steed, a horseshoe crab (Limulus polyphemus) molt, and wields a mighty blade of grass.
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Come on, Joker! Quit horseshoe-crabbing around and let’s get to work.
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The Joker couldn’t avoid villainy entirely as he tried to recruit a horde of coffee-bean snails (Melampus bidentatus) to join his evil gang of gastropods.
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He got one recruit. And it totally went to his head. 
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As one of the more fashionable villains, he fell in love with a blushing pickleweed (Salicornia europa) that matched his hair and jacket. 
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The Joker came across a ribbed mussel (Geukensia demissa)… 
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and decided he needed more mussel for his next bank heist. 

 

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The Joker learned the different marsh grasses. Here he’s showing a flowering shoot of marsh hay (Spartina patens) that it’s not the only grass in the marsh. 
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After he learned his grasses, we finally got to work. Here The Joker is estimating the percent cover of grass in the marsh. Looks like about 100%, don’t you think, Joker?
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After a while, I was able to trust him to record data. He was a little slow and a lot messy, but that’s field work sometimes.
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As we left the marsh through the woods, The Joker asked for a snack. I said no. 
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But we did have a well-deserved swim in the river.

Ghost Forests of the Chesapeake

Chesapeake Bay, Virginia

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Skeletal trees tower over the salt marsh, their bare arms outstretched like scarecrows. The salty sea wind polishes their chalky bones. The skeletons loiter like teenagers in the middle of the marsh – bored, out of place and suspicious. Trees, whether dead or alive, are not supposed to be in the grassy plains of the salt marsh unless elevated on a hill. Dead trees that appear in the middle of nowhere like fairy rings or Stonehenge hint at the supernatural; but these ghost forests are impeccably natural.

Throughout the Chesapeake ghost forests line the edge of salt marshes or sometimes rise up like specters in the middle of a marsh half a kilometer from the nearest forest. These are corpse-filled forests created by the sea where dead trees mean new life for the salt marsh.

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Salt marshes chose real estate at the edge of the sea. And like any real estate at the ocean’s edge, it has to deal with not only flooding, but also a rising sea. A salt marsh has the same options as a house to deal with a rising sea: build vertically or move to higher ground. But the higher ground is often occupied by forests. A salt marsh wants to invade the forest and take over its land, but the tree is greedy and grabs sunlight by the armloads, leaving little energy for the forest floor. The salt marsh’s advantage is its ability to tolerate salty land and so it stays in the lowlands. In a rapidly rising sea, however, the salt marsh is caught between a woody devil and a not-so-deep-or-blue sea. One key to the marsh’s survival is patience and opportunity.

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The skeletal remains of trees on a muddy beach on the Goodwin Islands, Virginia. Here the sea not only rose to kill the trees, but also eroded the marsh edge exposing trunk and roots alike.
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The same muddy beach, which serves as a tree graveyard.

The sea has no politics. It does not care about borders and territory and competition between bickering ecosystems. As it rises, it slips past the forest boundary to bathe trunks and roots in brine. In time, trees will die, shedding their light-grubbing leaves, bathing the ground in solar energy. Awash in sunlight and without competition with tree roots, the salt marsh grasses march in and encircle woody trunks as bark flecks and falls away. Trees have always been stubborn and don’t easily give in to gravity or mortality and will stand tall over the marsh long after their phloem no longer flows, continuing to stake their claim even in the afterlife.

The movement of marshes into higher ground, especially into forests, is called marsh migration and is an important mechanism for salt marshes to escape a rising sea. Where a forest sees death, a marsh sees life. A salt marsh does not fear a ghost forest; it fears a hill, a seawall, a Food Lion parking lot, and a road – anything that prevents its escape against a rising sea.

Post Script:

Ghost forests can be found anywhere in the world where there are salt marshes, not just in the Chesapeake. There is a great post on saltmarsh migration by Joe Smith from New Jersey. There are also two great scientific publications on saltmarsh migration. One by  Joe Smith and the other by Matt Kirwan at the Virginia Institute of Marine Science.

 

The vanity of fish and snails like underwater ants

A wonderful video taken in a salt marsh ditch in Newbury, Mass. The fish is who wants to make sure the camera gets his good side is the mummichog, Fundulus heteroclitus. For scale, the snails are the size of a BB from a BB gun. In all my time in the salt marsh, I’ve never seen so many! I guess I’ve got to stick my head underwater more often. Thanks to DeRosa Environmental for bringing the video to my attention.

 

Need a new yoga pose? Try the stretch spider!

The still brown grass crunches under my feet as I walk the salt marshes of the Goodwin Islands at the mouth of York River. I stop when when I see a blade of grass scramble across the other grass blades like a panicked airplane passenger who climbs over other passengers trying to get to the evacuation slide first. I snatch the panicked grass blade in my hand and it sprouts eight legs and repels from my hand down a silken thread, dangling for a moment like Christmas ornament before transmogrifying back into a grass blade. My grass blade is a spider in the tetragnatidae family. Tetra means ‘four’ and gnathid means ‘jaw’; it looks like it has four jaws but she doesn’t. See, science isn’t so hard once you crack the code. Tetragnathid (the ‘g’ is silent) spiders are also called ‘stretch’ spiders because they stretch their bodies in their own yoga pose: four legs forward and two to hold on and two legs back (some spiders try other combinations). Make yourself as thin as possible. And try to look like that grass blade or leaf or cattail.

I am amazed by this spider that looks like dead grass. I assume the yoga pose and combined with the drab-colored yoga outfit is to blend in to avoid detection by 1) potential prey and 2) potential predators. If she had not have scrambled, I would have never seen her. Even when I found her and made her pose for me on a blade of grass I still had trouble figuring out where the grass ended and she started. Look at that pose. Incredible strength and limberness. Stretch spiders can be found in your house, your backyard or your garden. So if you’re looking for a new twist for your boring yoga routine, run to the closet tree you can find, stretch out and see if anyone can find you.

This spider reminds me of another cryptic yoga pose: the toothpick grasshopper.

Namaste.

The savory swimmer swims north?

A blue crab (Callinectes sapidus) found north of Cape Cod in 2012. Plum Island Estuary, Massachusetts
A blue crab (Callinectes sapidus) found north of Cape Cod in 2012. Plum Island Estuary, Massachusetts

In the summer of 2012 I was having dinner with colleagues when one offhandedly said that he’d seen a blue crab, Calinectes sapidus in the marsh (the Great Marsh in northeast Mass.). Incredulous, I said a more colorful version of, “Equine feces.” He was claiming that a blue crab was in the Great Marsh, far north of its northern limit of Cape Cod.

Then other sightings of blue crabs in the Great Marsh were reported.

I grabbed a long-handled net and walked the tidal creek bottoms. I saw many green crabs scuttle but then, in a deep pool, I saw a crab swim sideways and instantly knew it was a blue crab (blue crabs are in the family Portunidae which are swimming crabs with flattened back legs). I found three more that summer.

Finding a blue crab in the the Great Marsh was surprising because the marsh lies in the Gulf of Maine which extends from Cape Cod to Canada and is kept cold by cold water currents from Canada. Water too cold for blue crabs.

Using the list-servs, Twitter and colleagues I crowd-sourced information about observations of blue crabs throughout the Gulf of Maine and from 2012 – 2014 these often-called ‘Maryland’ crabs were found as far north as Maine and Nova Scotia. The reason? I hypothesize warming oceans. Water temperatures in 2012 and 2013 were much warmer than the average of the previous decade which may have lowered the temperature barrier. Earlier I reported on a similar range extension for the fiddler crab.

Solid line: historic blue crab distribution. Dashed line: potential new range extension.
Solid line: historic blue crab distribution. Dashed line: potential new range extension. Arrows indicate sightings of crabs from 2012-2014.

It may be a logical fallacy to talk about climate change and warming seas when Boston is undergoing record snows (record-breaking snows are consistent with climate-change theory as warmer air holds more moisture prior to storm events), but we cannot deny that the climate is changing. One prediction of climate change is that as the climate and oceans warm species will start shifting where they are found. We’ve seen this already in many commercial species such as hake, flounder, and lobsters in the northeast where the concentration of their biomass has shifted north. The Connecticut lobster fishery (CT the southern end of the lobster’s distribution) is severely depleted, possibly in part to lobsters moving north.

What makes my observations of blue crabs north of Cape Cod unique is that this is the first time a commercially important species has been reported to potentially expand into the Gulf of Maine. It should be noted that in the past 150 years there have been four other reports of blue crabs in the Gulf of Maine, but none of those populations were permanent. It’s still to be seen if the 2012 blue crab population is a permanent extension of their range. If so, then it means that crab cakes are expanding north thanks to climate change.

The blog’s title? Callinectes sapidus means ‘savory swimmer’.

The article can be found here: The savory swimmer swims north: a northern range extension of the blue crab Callinectes sapidus?