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David Johnson was standing in a salt marsh tidal creek north of Boston, Mass., when he scooped up a blue crab, Callinectes sapidus, 80 miles north of its native range. The northern migration of this commercially important species, Johnson says, could be yet another sign of climate change. Johnson, then a scientist at the Marine Biological Laboratory (MBL) Ecosystems Center, recently published his observations in the Journal of Crustacean Biology.

A blue crab, Callinectes sapidus, caught in Ipswich, Mass., 80 miles north of its historical range. Credit: David Samuel Johnson

A blue crab, Callinectes sapidus, caught in Ipswich, Mass., 80 miles north of its historical range. Credit: David Samuel Johnson

The historic northern limit of this species of crab (also called Atlantic blue or Chesapeake blue) is Cape Cod, Mass. They typically weren’t found in the Gulf of Maine due to its cold Canadian waters. From 2012 to 2014, however, scientists and resource managers observed blue crabs as far north as northern Maine and Nova Scotia, Canada. Johnson hypothesizes that warmer ocean temperatures in 2012 and 2013, which were 1.3°C higher than the previous decade’s average, allowed the crabs to move north.

“Climate change is lowering the thermal barriers that kept species from moving toward the poles,” he says. “Climate change presents a challenge not only for ecologists, but for fisheries managers as commercially important species shift their ranges in response to warming oceans.”

Ephemeral populations of blue crabs have been documented previously in the Gulf of Maine. Johnson notes that in the 1950s blue crabs were observed in the gulf during a time of warmer waters. But once the waters returned to average temperatures, the crabs disappeared.

“It’s too early to determine if the current blue crab population in the Gulf of Maine is permanent or ephemeral,” Johnson says. “However, models predict an increasing warming of the world’s oceans and recent observations of blue crabs may be a crystal ball into the future ecology of the Gulf of Maine.”

Other researchers have documented the northern movement of other commercially important species in northeastern United States such as lobsters, hake and flounder. Johnson’s work, however, is the first to document the movement of a commercially important species into the Gulf of Maine.

This is the second crustacean Johnson has documented as expanding into the Gulf of Maine. In 2014 he published his findings on the rapid expansion of the fiddler crab, Uca pugnax, into the gulf. “As the world’s oceans continue to warm, we will continue to see climate-driven range expansions,” he predicts.

Johnson, now an adjunct assistant scientist at the MBL, recently joined the Virginia Institute of Marine Science as an assistant professor.

Citation:

Johnson DS (2015) The savory swimmer swims north: a northern range extension of the blue crab Callinectes sapidus? J. Crustacean Biology 35: 105-110.

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Buzzards Bay, Eel Pond, Great Harbor are in a deep-freeze. Our hardworking MBL grounds crews have been plowing, shoveling, sanding, and carving narrow walkways throughout campus since January. Shoes, cars,and stairwells are filthy, parking lots are flanked by ugly snow mountains, and patience with snow shovels, overcoats, scarves, gloves, boots, ear warmers, etc., is quickly waning. Even the Eel Pond ducks seem to be crying “UNCLE!” And more snow is predicted for this week.

So how are we surviving the tough winter weather?

Woods Hole’s natural, transient beauty (less the parking lots) keeps us charmed and impressed. Gorgeous sunsets, glimmering snowscapes, ice-capped shorelines, and oddly translucent waters make Woods Hole appear extraordinarily shiny and picturesque. It’s cold and inconvenient, but we all agree the village looks pretty darned good in snow.

Along with breathtaking winter views, good old New England fun energizes and entertains us, despite the bitter cold temperatures. Just today, at lunchtime, a hearty handful of ice skaters ventured out onto a solidly frozen Eel Pond. (The last time the pond froze was more than a decade ago, so this was quite a novelty for most.) Colleagues bundled up and headed out to the dock to watch the skaters, or to embark on their own personal historic walk across the water they are used to boating on. (Yes, that is MBL’s Gemma Captain Bill Klimm donning skates and joining in a round of pick-up hockey. No collecting boat trips today!)

Yes, Woods Hole is exceptionally beautiful and interesting under winter’s weight. But, really, spring is welcome anytime now….

— by Beth Liles

Photos by Hunt Willard, Pam Wilmot, and Beth Liles.

 

 

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Contact: Diana Kenney, Marine Biological Laboratory
508-289-7139; dkenney@mbl.edu

WOODS HOLE, Mass.—How a brilliant-green sea slug manages to live for months at a time “feeding” on sunlight, like a plant, is clarified in a recent study published in The Biological Bulletin.

The authors present the first direct evidence that the emerald green sea slug’s chromosomes have some genes that come from the algae it eats.

These genes help sustain photosynthetic processes inside the slug that provide it with all the food it needs.

Importantly, this is one of the only known examples of functional gene transfer from one multicellular species to another, which is the goal of gene therapy to correct genetically based diseases in humans.

“Is a sea slug a good [biological model] for a human therapy? Probably not. But figuring out the mechanism of this naturally occurring gene transfer could be extremely instructive for future medical applications,” says study co-author Sidney K. Pierce, an emeritus professor at University of South Florida and at University of Maryland, College Park.

The rich green color of the photosynthesizing sea slug, Elysia chlorotica, helps to camouflage it on the ocean floor. Credit: Patrick Krug

The rich green color of the photosynthesizing sea slug, Elysia chlorotica, helps to camouflage it on the ocean floor. Credit: Patrick Krug

The team used an advanced imaging technique to confirm that a gene from the alga V. litorea is present on the E. chlorotica slug’s chromosome. This gene makes an enzyme that is critical to the function of photosynthetic “machines” called chloroplasts, which are typically found in plants and algae.

It has been known since the 1970s that E. chloritica “steals” chloroplasts from V. litorea (called “kleptoplasty”) and embeds them into its own digestive cells. Once inside the slug cells, the chloroplasts continue to photosynthesize for up to nine months—much longer than they would perform in the alga. The photosynthesis process produces carbohydrates and lipids, which nourish the slug.

How the slug manages to maintain these photosynthesizing organelles for so long has been the topic of intensive study and a good deal of controversy. “This paper confirms that one of several algal genes needed to repair damage to chloroplasts, and keep them functioning, is present on the slug chromosome,” Pierce says. “The gene is incorporated into the slug chromosome and transmitted to the next generation of slugs.” While the next generation must take up chloroplasts anew from algae, the genes to maintain the chloroplasts are already present in the slug genome, Pierce says.

“There is no way on earth that genes from an alga should work inside an animal cell,” Pierce says. “And yet here, they do. They allow the animal to rely on sunshine for its nutrition. So if something happens to their food source, they have a way of not starving to death until they find more algae to eat.”

This biological adaptation is also a mechanism of rapid evolution, Pierce says. “When a successful transfer of genes between species occurs, evolution can basically happen from one generation to the next,” he notes, rather than over an evolutionary time scale of thousands of years.

Citation:

Schwartz JA, Curtis NE, and Pierce SK (2014) FISH labeling reveals a horizontally transferred algal (Vaucheria litorea) nuclear gene on a sea slug (Elysia chlorotica) chromosome. Biol. Bull. 227: 300-312.

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The Biological Bulletin is a peer-reviewed, trans-disciplinary international journal that publishes outstanding experimental research on a wide range of organisms and biological topics, with a focus on marine models. Published since 1897 by the Marine Biological Laboratory, it is one of America’s oldest and most respected journals.


The Marine Biological Laboratory (MBL) is dedicated to scientific discovery and improving the human condition through research and education in biology, biomedicine, and environmental science. Founded in Woods Hole, Massachusetts, in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

Bill Klimm, captain of the Gemma, the MBL's collecting vessel. Credit: Daniel Cojanu

Bill Klimm, captain of the Gemma, the MBL’s collecting vessel. Credit: Daniel Cojanu

When Nature began pursuing a story on “unsung heroes” in science — the behind-the-scenes staff who make the whole operation happen — it became clear that plenty of people at the MBL fit that bill. One is Bill Klimm, captain of the Gemma, who as a longtime fisherman knows not only how to operate the boat, but where to find the elusive fish and other marine organisms used for MBL research. Nature published a wonderful profile of Klimm this week, including the video below. Thanks to Bill, Dave Remsen, Dan Sullivan, and everyone who works hard every day to make the MBL’s collecting operation succeed!

 

By Jennifer Walton

Would you like to spend part of your summer at the MBLWHOI Library studying or writing?

Karush-photo-for-webThe Fred Karush Endowed Library Readership provides the recipient with a study desk and library services in the MBLWHOI Library for one summer month, with limited funds granted for travel and/or housing. Applications are being accepted now for summer 2015; the deadline to apply is February 15.

The MBLWHOI Library has long been a working home for scholars and researchers in Woods Hole, offering a unique and historic environment for scientific study and writing. A Library Reader desk in the book stacks is a quiet space in the middle of the vibrant MBL community.

Here are a few comments from researchers and scholars on the MBLWHOI Library Reader experience:

“Every time I have a big writing project, grant proposal, or review paper, I try to find an excuse that will allow me to do it at a desk in the MBLWHOI Library. In many ways, the library is the most valuable feature of the MBL. It contains one of the largest, most comprehensive, and most complete collections of biological and oceanographic primary literature in the country, perhaps the world …  Although it comes as a surprise to my students, not everything is available on the Internet or for free—but it is usually in the stacks of the MBLWHOI Library.”

Sidney K. Pierce, Emeritus Professor of Biology, University of Maryland and Emeritus Professor of Biology, University of South Florida

“The MBL journals collection is one of the most inspiring library collections I’ve ever encountered. It’s the perfect source for anyone interested in current biological research and its historical origins, valuable not only to biologists, but also to historians and philosophers of science like me.”

Florian Huber, University of Vienna

Questions? Please contact Jen Walton, Coordinator of Library Services, at 508-289-7452; .

 

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