Tag Archives: Salt marsh

Saltmarsh amphipod (Orchestia grillus) on a Spartina stem. Brown is the normal color morph, compare to the orange, parasitized morphs. Plum Island Estuary, Massachusetts

Amphipods: the new menacing marine menace?

This week a young man in Australia was attacked by something while he was swimming in the ocean. His legs were bloodied and covered with hundreds of small bites. At the hospital, doctors were baffled about what bloodied the young man’s legs. The dad – who rocks in this story – went back into the water with a bloody steak and collected the small, flea-like animals. They were identified as amphipods, which are small crustaceans. If Sharknado has taught us anything, a movie about flesh-eating amphipods can’t be far now. Let’s see what that movie trailer might look like.

************
A young, beautiful mother sits on the beach and watches her charming son, who she can’t believe is growing up so fast, swim in the ocean. Gulls wheel overhead and waves roll gently. The sky blue.

Boy: Mom, watch me swim.
Mom: Okay.

[cue the Jaws-theme music rip-off]

Cello: Duh-nuh

 Boy: You watching?
Mom: Yes, dear.

Cello: Duh-nuh

 Cello: Duh-nuh

 [cue that voiceover guy]

 That Voiceover Guy: Just when you thought it was safe to go back into the water again.

 Cello: Duh-nuh, Duh-nuh, Duh-nuh, etc.

 The boy screams and grabs his leg. His mother runs into the waves and pulls him out. His legs are bleeding but there’s nothing on them. A handsome and rugged marine biologist who looks just a little bit dangerous but you know you’d feel safe in his arms, runs over.

Mom: What did this!?

 Ruggedly handsome marine biologist: They’re amphipods.

 Mom: Oh my go…wait, what the heck are amphipods?

 Director: CUT!!

************

What the heck are amphipods? They are small crustaceans related to shrimp and crabs and lobsters. Typically, they aren’t larger than your thumbnail. If you’ve picked up seaweed on a beach, you’ve probably seen them. They are the small animals flipping and tumbling around like fleas. Those are amphipods. Sometimes called ‘sand fleas.’ Or ‘beach fleas.’ Or ‘beach hoppers.’ Or ‘sea fleas.’ The ‘flea’ name refers to the shape of their body (pressed from the sides) and the fact that they can flip around using their tails.

The media has used the term ‘sea lice’, but that really refers to an isopod, which can be parasitic on fish and look like the rolly-pollies (aka doodle-bugs) you find under logs.

Are amphipods the new marine menace? A pack of ravenous, flesh-eating beasts that roam the oceans looking for prey? Well, no. They do eat flesh, but typically not live flesh. We marine biologists (both the ruggedly handsome and other variety) don’t think of amphipods as predators but as scavengers that eat dead plants and animals. They’re more like tiny vultures swimming through the sea looking for something dead to stick their heads into rather than wild dogs looking to tear apart a baby deer.

I study amphipods in the salt marshes of Massachusetts and Louisiana (you can see pictures of them below). Just like on the beach, if you pick up seaweed in the marsh, hundreds of little crustaceans will flip and spring until they can hide in the grass. Not much of a terror. In terms of diet, these amphipods are more interested in a rotting veggie burger than a hunk of a marine-biologist.   

Then why did they attack the young man’s legs in Australia? We’re not sure. Amphipods can bite humans – sometimes beach runners will have a bite or two – but they have rarely caused such damage. The best guess is that the amphipods were in a feeding frenzy and the young man’s legs happened to get in the way.

While I’ve been playful with this story, as a father, I too would have been worried. As a marine biologist, I am curious. It shows that we still have a lot to learn. The next time I pick up an amphipod I will check to see if it’s wearing a handkerchief and holding a knife and fork.  

 

 

P.S. Now that we have flesh-eating amphipods in the news, soon I will write about zombie amphipods. Stay tuned. Duh-nuh…

P.P.S. If you enjoyed this article then please post it on Facebook, Twitter, or your favorite social media. And don’t forget to follow me. 

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.

 

It’s good to have friends to lean on: how salt hay gets its licks.

The Great Marsh,
Northeast Massachusetts

It’s August and that means the marsh is a sea of cow licks. In a previous post, I’ve written about how cow licks happen. The short version is this: the salt hay grass (Spartina patens) has weak ankles and when it gets pushed around by the bullying tides it leans on its neighbor.

Cow Licks, Sweeney Creek, Ipswich, Massachusetts (9)

Cow Licks, Sweeney Creek, Ipswich, Massachusetts (8)

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 winter sculptress

January 2015, Eastern Virginia

Ice covered marsh elder - Yorktown, VA, Jan 2015 (1)

The icy fog of winter swallows the Mid-Atlantic. The temperatures drop below freezing and weld the fog to all that it touches. Everything – limbs, leaves, porch steps, 1999 Honda Civics – are glazed with an 1/8 inch rime. Were I snail and one who could skate, I would don my snail sweater and skate (having only the one foot) and invite all my snail-skating gastropod-friends to my front steps and glide from one rail to another. Limbs sag heavy under the new weight. I – not wanting to skate on my steps – grab the rail. It too is slick with the icy slobber of a winter fog – and hold both my breath and myself as best I can. Winter redeems itself as an artist – the world now a garden of ice sculptures.

I scrape ice from my windshield with an bottle because apparently owning an ice scraper is much too much of a luxury. THe holes I make in the ice likely are not street legal as most of my view still obscured, but I take my chances and drive of to admire winter’s artistry.

Ice covered marsh elder - Yorktown, VA, Jan 2015 (3)

Of course I stop in the marsh. That is what you do when every surface you touch is lacquered with ice. Here in Virginia the Spartina stems – though dulled and browned with age – still stand. Today they glisten. Each leaf, each stem encased in a crystalline sheath. One that is cracked like, but intact. Like a mosaic of glass pebbles – each magnifying the beauty of which it clings. On the bushy marsh elder, each leaf is a glassy pendant.

Ice-covered Spartina - Yorktown, VA, Jan 2015 (2)

Ice covered marsh elder - Yorktown, VA, Jan 2015 (3)

My hands, without any sheath – glove or ice or otherwise – beg me back to the car. From the comfort of a defroster I admire what is now an icy meadow of marsh. By the weekend, the 50 degree temperatures will strip away the artistry of winter, each glassy sculpture losing its luster yielding to the rough concrete texture of winter’s true self.

A unicorn in the marsh

A fiddler crab, tee hee
A rare species of fiddler crab

In the Great Marsh, he should be a myth, like a unicorn. But there he is. Like a nervous cuckoo clock in the mud, he pops out two or three times before he completely shows himself. A male fiddler crab (Uca pugnax), with a blue burnish to his shell and the characteristic obscenely large claw. I am astonished to see him. Astonished because I am probably the first person to see a fiddler crab pop out of the Great Marsh mud.

The Great Marsh stretches like a verdant yawn in the Gulf of Maine, which is the whole of the ocean from Nova Scotia to Cape Cod. Here the salty waters are chilled by the Labrador Current, a river of sub-arctic seawater that is born between Canada and Greenland and plunges south like a fist. The warmer waters from the south are deflected off the flexed arm of Cape Cod and kept out of the Gulf of Maine by the colder waters of the Labrador Current. As my New Englander friends like to brag, particularly when the snow is deep and the wind biting, this is a place only for the hardiest of souls.

Ovigerous (egg-bearing) fiddler crab, Uca pugnax, caught in a Rowley, Massachusetts, salt marsh
Ovigerous (egg-bearing) fiddler crab, Uca pugnax, caught in a Rowley, Massachusetts, salt marsh. Credit: Ashley Bulseco-McKim

Fiddler crabs are a warm-water species preferring the temperate waters south of Cape Cod. I am of the same opinion. I can snorkel in swim trunks in Buzzards Bay in July, which is on the south side of Cape Cod, but when I try to do the same on Cape Anne and its rocky shores, it’s like an ice cream headache for my entire body. I, too, am a warm-water species.

I search the mudbanks for other crabs, but find only him. Maybe he is a unicorn. An accident of currents and luck. Then I search other tidal creeks. Jericho, West, Clubhead, Nelson. Though their numbers are low, I find more fiddlers. Their burrows, only as wide as my thumbnail, perforate high in the mudbanks near the hairline of the Spartina grass. Many burrows are abandoned. Active burrows are identified by what look like chocolate ice-cream sprinkles – what we locally call ‘jimmies’ – scattered around the burrow entrance. These are fecal pellets from a recently fed crab. A quick probe with my finger (a very scientific technique, I assure you) confirms the fiddler’s residency.

I search beyond the Rowley marshes and find more fiddlers. Directly behind J.T. Farnhams’ in Essex. Off Atlantic Avenue in Gloucester. Chubb’s Point in Manchester-by-the-Sea. Next to the Endicott Square Shopping Plaza in Danvers. Massachusetts indeed has a new resident. So does New Hampshire as the fiddlers have journeyed as far north as Hampton.

Salt marsh fiddler crab, Uca pugnax, Manchester-by-the-Sea, Massachusetts
Salt marsh fiddler crab, Uca pugnax, Manchester-by-the-Sea, Massachusetts. Credit: Jon Whitcomb

How can a warm-water crab invade the province of the cold, a place where it has never before been able to survive? The answer lies in the fact that the province of the cold is becoming warmer. As the climate warms, so too does the ocean as the overburdened atmosphere gives some of its heat to the ocean to hold, an arrangement as old as the Earth. In the summers of 2012 and 2013 the Gulf of Maine waters warmed to 68 degrees Fahrenheit from the typical and chillier 63 degrees of years prior.

Those five degrees may not mean much to those of us who can adjust thermostats, but those five degrees are significant to an animal that uses the environment to regulate its temperature. For fiddler crabs, those five degrees are the difference between scuttling across the marsh and an arctic death.

Fiddler crabs did not arrive in the Great Marsh in the form that we recognize them, with their snapping claws and rounded bodies. They instead arrived as larvae carried by the currents and tides. The larvae are mostly heads, translucent triangles with Pinocchio noses and topped with a single spine, with legs and tails dangling. For fiddler-crab larvae, 64 is the key that unlocks the Gulf of Maine. Below that number in degrees Fahrenheit and these drifting triangles do not metamorphose into the crabs that make thumbnail sized burrows in the marsh. But give that number a degree or five, and those once-thought unicorns of the Great Marsh become a reality.

And so, borne on the currents of climate change, the fiddlers have made a surreptitious arrival to the Gulf of Maine and the Great Marsh.

The consequences of this incipient colony are unknown. As burrowers, fiddler crabs are engineers that re-work the soil and the marsh chemistry. If the effect is positive or negative is not yet known. I can only give you the answer that is common given by scientists that can be utterly frustrating:

It depends.

Too many crabs and the marsh grass cannot establish, which may ultimately lead to marsh loss. Only a few crabs and the marsh grass grows better. What I can tell you for certain is that with the arrival of these new colonists, just as when we arrived in the 1600’s, the Gulf of Maine and the Great Marsh will be changed forever.

Already we have seen marine species such as lobster, flounder and hake shift northward as a result of climate change. Some, however, still consider climate change a myth, like the unicorn. But sometimes seeing is believing. Like a fiddler crab in the Great Marsh.

The science is here: Fiddler on the Roof: A northern range extension for the marsh fiddler crab Uca pugnax