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Salt marshes as unsung heroes

Clubhead creek, photo credit:  Sarah Wilkins

Clubhead creek, photo credit: Sarah Wilkins

Marshes are quiet, unassuming ecosystems that do a lot for us. They provide protection from storms, they produce animals that we like to eat or watch, and they give us wonderful places to look out upon while watching the sunrise (or set on the West Coast). WCAI, the Cape and Islands NPR station, highlighted salt marshes last week in their Living Lab segment. Linda Deegan, the lead Principal Investigator was a part of the discussion. If you want to learn about salt marshes, this is a good place to start so give a listen.


The TIDE does not ebb

An intern leaps for joy on the TIDE Project. Photo: DS Johnson

An intern leaps for joy on the TIDE Project. Photo: DS Johnson

It’s official: The TIDE Project has been re-funded by the National Science Foundation until 2016.

The TIDE Project will continue its fertilization experiments to look at the effect of chronic nutrient enrichment of salt marshes. We will focus on our most compelling finding to date: nutrients can lead to marsh loss. This result is compelling because while scientists have identified a number of causes of marsh loss, nutrients had never been identified until now. In that vein, we will focus on three major questions going forward:

The author contemplates, what's causing the marsh to fall apart? What will it look like in the future? How will that affect marsh benefits to humans?

The author contemplates, what’s causing the marsh to fall apart? What will it look like in the future? How will that affect marsh benefits to humans? Photo: Konner Lockfield

1) What are the biological mechanisms leading to marsh loss?
We hypothesize that changes in microbial activity (leading to increased decomposition) and reductions in root biomass have led to less cohesive creek banks, thus making them susceptible to physical forces and slumping. We will test our biological hypotheses to understand how nutrients can lead to marsh loss.

2) How does marsh loss affect ecosystem services?
All ecosystems provide benefits to humans and those benefits are called ‘ecosystem services’ by scientists. Two services provided by marshes include fisheries support and pollution control (i.e., nutrient removal). We will test the hypothesis that marsh loss reduces marsh ecosystem services by reducing the ability of the marsh to produce forage fish (the mummichog Fundulus heteroclitus) and to remove nutrients. 

3) What is the eventual shape of the marsh with chronic nutrient enrichment?
What we have seen in the short-term is marsh loss that has led to sharp scarps (walls) which can affect a number of marsh functions (and in turn marsh services). It is unknown, however, if the marsh edge will continue to erode or stabilize in a different configuration (say, a low sloping edge). We will monitor changes in the geomorphology of the tidal creeks to predict the trajectory of these changes. 

Collectively, the TIDE Project will answer interesting scientific questions while simultaneously addressing the critically important issue of the loss of marshes and the benefits they provide to humans (storm protection, pollution control, fisheries production, beauty).

The TIDE Project is led by Dr. Linda Deegan of the Marine Biological Laboratory (MBL). The team includes Dr. Sergio Fagherazzi (Boston University), Dr. Jen Bowen (UMASS-Boston), Dr. Tom Mozdzer (Bryn Mawr), Dr. Bruce Peterson (MBL), Dr. Anne Giblin (MBL), Dr. Jimmy Nelson (MBL) and Dr. David Johnson (MBL).

Like the salt marsh itself, the TIDE Project has been productive hosting almost 150 scientists, 70% of which have been young scientists, publishing over 40 scientific articles, and contributing to numerous outreach activities. We look forward to another set of productive years. 

Thank you to the readers for all of your support. To learn more about the TIDE Project, go to our project site:

David Samuel Johnson is a scientist at the Marine Biological Laboratory and loves spineless animals.

TIDE Scientists inducted into AAAS – Part II

From L to R: Jane Tucker, Anne Giblin, and Sam Kelsey

From L to R: Jane Tucker, Anne Giblin, and Sam Kelsey

Anne’s recent election into AAAS is well-deserved, and if there were a companion award for outstanding achievements in kindness, generosity, and commitment to others, she would rightfully be awarded that, too.   I have had the privilege of working closely with Anne for over 20 years, and I should know.

Anne Giblin “speaks “ biogeochemistry, thermodynamics, biology, physical chemistry… really all the “hard” sciences…as a first language.  They seem to be part of her innate intelligence.     But she is not a desk scientist.   She loves to be in the lab, or even better, out in the field conducting experiments or collecting samples.   Adverse field conditions are her forte!    She is not stopped by freezing temperatures or clouds of mosquitoes on the North Slope of Alaska, nor by tropical heat, “no-see-ums” or scorpion stings in Panama.   She does not let little things like utter darkness in the cold depths  of Adirondack  lakes  or a blanket of sewage sludge on the bottom of Boston Harbor dampen her enthusiasm for collecting more mud and adding dives to her SCUBA log.   She does not send her students or employees out to do this work for her….she jumps in first.   All of this to keep adding pieces to the puzzle of element cycling in sediments, particularly with respect to nitrogen, carbon, and her first love, sulfur.  

Hard work is often matched by good cheer. A long day with the PIE-LTER team in the marsh at Plum Island, in itself fun, is routinely followed by a good meal (often prepared by Anne),   a good local brew (often provided by Anne), and good stories (often told by Anne).   Over the years, these days and stories and Anne’s optimism have become encapsulated by some memorable lines, now used affectionately by the team.  Three of the classics are:  “Done by noon!” (as in, “It won’t take long, we’ll be ….”), “That’s not thunder, those are jets!” (at next occurrence, accompanied by a bright flash of light) , and “No herics!” (i.e. heroics… I mentioned Anne’s first language is science, not English, didn’t I? It’s really the only thing I can help her with!).  

Sure, Anne has the necessary stats on her CV that attest to her accomplishments as a scientist.  But the best testament of her success may be that, in an increasingly difficult funding climate, and at an all soft-money, independent research laboratory, Anne has kept herself and her team funded for over 25 years.  It is tribute to Anne as a mentor, colleague, and friend, that we have all wanted to stay.

Jane Tucker is a Research Assistant at the Marine Biological Laboratory.

TIDE Scientists inducted into AAAS

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This weekend, Dr. John Fleeger, a former TIDE Principal Investigator (PI), and Dr. Anne Giblin, a current TIDE PI are being inducted as a member of the American Association of the Advancement of Science (AAAS), known to us scientists as Triple-A S, because we’re too busy for real words.  AAAS is like the Hall of Fame for scientists and it’s a big deal.  We at the TIDE Project are incredibly proud of John and Anne’s accomplishment.  It is well-deserved.

In this post I will highlight John.  In the next, Anne.  

I could list many of John’s accolades including his 150 publications in the scientific literature including topics from the Gulf of Mexico oil spill to carbon sequestration in the deep ocean to community ecology of very small crustacean in the dirty, dirty mud to studying the Plum Island marshes here on the TIDE Project.  I could highlight his wonderful teaching career at Louisiana State University spanning over 30 years.  But what I’d rather do is talk about John as a mentor.  My mentor, who guided me to my Ph.D.  

John’s mentoring style can be summed up easily: his door was always literally open.  And no matter the crazy nattering that spewed from my lips, he looked at the floor while nodding and waiting for me to finish.  Then we would discuss.  He never said my ideas were stupid, though he gently said they needed more ‘development.’  

And he was patient.  I can’t tell you how many times I heard him say without annoyance “Again David…” meaning that he already told what he was about to say and he was gently reminding me.  

I appreciated how quickly he made comments on my scientific manuscripts.  Well, how quickly he massacred them.  My words were slain without mercy for their wrongness and their bodies littered the battlefield of my manuscript.  It frustrated me because I prided myself as an excellent writer.  But academic writing has its own style and language and John was teaching. Today I’m a better writer because of the time he took.    

One Saturday morning in Baton Rouge I was at the scope sorting samples.  John came in with a draft of my research proposal that he massacred.  He asked me, “David, what are you trying to say here?”  Then before I had a chance to answer, he looked at the draft and said with rare exasperation, “Do you even know what you’re trying to say?”  I started to say something, but said, “Well no.”  And then he took the time to help me start over. 

I still seek John’s advice today on my manuscripts.    

The following is from the Acknowledgements of my dissertation:  “In 2003, the brave or foolhardy Dr. John Fleeger, with his nodding head and seemingly infinite patience that I tested more than once took in my independent and sometimes irascible spirit and navigated it down a tortuous, yet productive path.  I thank him for reading (and re-reading and re-reading) every word I’ve written as a graduate student, for swatting and cursing mosquitoes with me in the marsh, and for always having his door and mind open.”  

Five years later, those words, unmassacred by John’s pen, still ring true. 

Congratulations John.  Your induction into AAAS is well-deserved on many levels.  


 David Samuel Johnson is a Principal Investigator on the TIDE Project.  A version of this blog post first appeared on David’s blog, New Leaf.

A student of the marsh

There are so many stories of science from the Plum Island marshes and it’s wonderful when they are written down.  The one below is from Harriet Booth, a recent graduate of Brown University, who was also anTIDE Project intern working with me on the idea of a trophic bottleneck (that snails could gobble up a lot of energy and store it and choke off energy flow to fish).   And bless her heart, not only did she survive a summer in the boot-sucking mud and pain-in-the arm, face, and leg flies, but she went on to write an honors thesis.  Recently, she wrote a wonderful blog post about her experience, some of which is excerpted below.  I particularly like “…a small snail, muddy-colored and roughly the size of a peanut, emerged from the edge of the plastic, making a bid for freedom across the mudflat.”  I encourage you to read the entire essay here.   

Harriet is currently a Research Fellow at the Atlantic Ecology Division of the EPA in Narragansett, RI.  She is looking at the effect of ocean acidification on bivalves.  Way to go, Harriet!   

“The square, plastic quadrat slapped down where I tossed it, splattering me with little droplets of mud.  As I bent down to examine the sampling area, I noticed one side of the small quadrat seemed to be moving slightly, lifted by some tiny but determined force.  I looked closer and watched as a small snail, muddy-colored and roughly the size of a peanut, emerged from the edge of the plastic, making a bid for freedom across the mudflat.  I watched this little guy trundle resolutely away from me, making slow but steady progress across what must have seemed to him, a vast expanse of mud.  His tiny antenna occasionally appeared from beneath the front of his shell, wiggling about and seeming to wave at me as I crouched in the creekbed.  Eventually, I picked the snail up and placed him back inside the quadrat, counting the rest of the remaining snails at the same time.  However enjoyable it was to watch these little creatures bumble around, I had many more quadrats to toss before making my own escape out of the sucking mud of the salt marsh.”

David Samuel Johnson is a TIDE Project principle investigator from the Marine Biological Laboratory.  He writes about marshes at his New Leaf blog.

Acid plus middle school equals outreach

Dr. Johnson is fixin' to learn you some chemistry!

Dr. Johnson is fixin’ to learn you some chemistry!

Twenty-four pairs of eyes are upon me.  These eyes, these critical eyes, belong to 12-year-olds.  Twelve-year-olds who expect this real-life scientist standing in front of them to teach them about ocean acidification (OA).  They’ve had no chemistry and I’ve never taught middle-schoolers.  Do they know about pH?  What makes an acid?  Calcium carbonate?  No?  I’ve got 50 minutes?  Deep-breath.  Okay.  Go! 

Over two days last week I taught OA to 200 7th graders at the Rupert Nock Middle School in Newburyport, Massachusetts.  We tested household solutions (e.g., milk, lemon, spit) with pH strips.  We learned how added CO2 lowers pH.  We learned about chemistry through role playing as elements and compounds.  We learned how the loneliness of H+ ions (lonely ions like to bond) make them highly reactive and how that loneliness can steal the bricks (carbonate) needed to build the shells of marine organisms (Thanks to science teacher John Reynolds for a wonderful Home Depot metaphor that I will blatantly steal).  We developed hypotheses about the consequences for marine life and conducted a multi-day experiment on the effects of an acid (dilute vinegar) on mass loss of bivalve shells. 

While OA is not a current focus of the TIDE Project, it is a major concern for marine ecosystems.  Outreach is a supporting pillar of the TIDE Project’s scientific philosophy (as well as the larger group of Plum Island-LTER scientists) and one goal is to strengthen coastal education by working with young scientists and K-12 students. 

My classroom demonstrations also emphasize the important presence the TIDE Project has in the communities local to the marshes we study.  The OA module germinated from a conversation I had when John Reynolds brought a dozen of his students to the marsh as part of his outdoor curriculum.     

From middle-school students peering through refractometers while standing on the marsh to undergraduates publishing papers, the TIDE Project has engaged at over 1000 middle-school, high-school, undergraduate, and graduate students combined through its outreach activities.  Whether standing at a white board or knee-deep in marsh mud, we hope to engage thousands more.

David Samuel Johnson is a principal investigator on the TIDE Project.  He is particularly fond of invertebrates.  All photos courtesy of Lisa Furlong.

Here a snail but not there a snail?

by forest, a research assistant

Though unnoticed on my first visit to the Rowley marshes, I soon became well acquainted with Melampus bidentatus, or the coffee bean snail, during subsequent stem counting, transplant planting, and genetic sampling ventures. While working in close proximity with the coffee bean snails, I began to notice trends in their distribution across the high marsh. Coffee bean snails appear more abundant but smaller in Spartina patens dominated high marsh, less abundant but larger in short form S. alterniflora dominated high marsh, and conspicuously absent from the tall form S. alterniflora where the high marsh boarders the creek bank. The question is: what factors are determining the distribution of coffee bean snails on the high marsh at Plumb Island? I needed to know more about the snails.

Coffee beans snails are pulmonate (air-breathing) as adults but are tied to the sea by a planktonic larval stage. Snail spats settle into the high marsh at the size of 690 um and do not reach their adult size of ~12 mm until over a year of growth (Apley, 1970). Coffee bean snails feed mainly on decaying plant mater and algae (Graca et al., 2000). A number of marsh predators prey on coffee bean snails such as the ubiquitous mummichog, many different marsh birds (Hausman, 1932), and green crabs (David Johnson, pers. comm.).

Could predation be the key to snail distribution? A 1976 study by Vince et al. supports the predation hypothesis. This study shows that the high stem density of S. patens acts as a natural ‘fence,’ excluding predators from eating palatable snails. Thus, small snails, which make up the majority of the population, are confined to S. patens by predation pressure, while larger snails inhabit the low stem density, ‘un-fenced,’ S. alterniflora habitat because their size protects them from most predation. Vince et al. (1975) hypothesizes that larger snails are drawn into the higher risk habitat because the lower snail density in S. alterniflora may lead to greater resources per snail. This study may explain the difference in snail sizes and abundance I observed between S. Paten habitat and short form S. alterniflora habitat on the high marsh. But what about the complete absence of snails in the tall form S. alterniflora on the creek bank edges at the Rowley Marshes?


Dr. David Johnson (aka Mr. Marsh to the Marshview House faithful) posited an alternate hypothesis. He suggests that physiological limitations are the primary driver of coffee bean snail distributions. Because coffee bean snails are air breathing, they do not thrive in areas with a high frequency of tidal inundation. S. patens occurs at higher elevations on the marsh platform (wet only during spring tides). Conversely, the tall form S. alterniflora dominated habitats on creek bank edges are likely the lowest areas of the high marsh (wet at almost every high tide). Differences in the frequency of tidal inundation across habitats could influence the abundance of coffee bean snails on the high marsh. Just as too much water can drown snails at high tide, too much sunlight can cause desiccation at low tide. As a result, coffee bean snails avoid direct sunlight (Hausman, 1932). Larger snails may be more resistant to desiccation than their smaller counterparts. High marsh short form S. alterniflora seems to provide less percent cover than S. patens and this difference in shading could influence the abundance and size of coffee bean snails in these habitats.

I cannot test these competing snail hypotheses at the moment due to the frozen creeks and snowy peat of the winter marsh. Indeed the short days and cold weather has put an end to most marsh fieldwork and I have been effectively exiled to the lab until spring. For now, I am stuck with many questions, some guesses, and no answers. However, the New England winter gives me time to hone my knowledge and plan my approach so that when I get the chance, I can pursue informative questions in an efficient manner. In a way, by taking a step out of the marsh, I am gaining a better understanding what I want to do on the marsh and how I want to do it.

Forest Schenck is a Research Technician at Northeastern University Marine Science Center in Nahant, Mass.  He works with TIDE collaborators Drs. David Kimbro and Randall Hughes of Northeastern.