All posts by Randall

About Randall

Dr. Randall Hughes is an ecologist and marine biologist focusing on the causes and consequences of species and genetic diversity in coastal systems. She has conducted experimental work on plants and animals in seagrasses, salt marshes, oyster reefs, and kelp forests. The common thread throughout these activities is a long-standing interest in generating information that can enhance the effectiveness of conservation and management decisions.

What are those new images that are popping up on the blog?

Dr. Randall Hughes FSU Coastal & Marine Lab

If you’re a regular reader of the blog, you’ll realize that we often talk about similar research questions or ideas in the context of different projects. As David mentioned in his description of the Baymouth Bar project, this overlap is usually intentional: as ecologists, we’re interested not only in the specific habitats that we study, but also in the underlying factors that affect these habitats and the valuable services that they provide to we humans.

It may appear at times that we’ve been covering a diverse array of topics, and while this is true, all of these topics are interconnected- a web of topics centered around a couple of central themes. The diagram below is the map that shows where every post-topic fits into these central themes. Even the artists, writers, and photographers we occasionally feature have their place amongst ecological processes like sedimentation and the non-consumptive effects of predators. Every post from here on out will have one of these icons on it- if you don’t know what the icon means, just click on it and you’ll be back at this figure with an explanation:

In the Grass, On the Reef master plan

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What do ecologists do for fun?

Dr. Randall Hughes FSU Coastal & Marine Lab


IGOR chip- employment 150

Last week, David and I (along with all the students and technicians in our labs, and over 500 other ecologists/students) attended the Benthic Ecology Meeting in Mobile, AL. You may well wonder – what goes on at a meeting of ecologists? And what does “benthic” mean anyway?

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Return to the field

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150A sure sign of spring for me is an increase in time in the field. (Robyn and Emily would probably disagree with me, since they have been out in the field regularly throughout the winter!) I have been in the lab or office since December, which feels like a long time, and I’m really looking forward to getting back in the field. I find it is so much easier to come up with new research questions and develop insights into what the animals and plants are doing out there when I’m actually there with them. I guess that makes sense!

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The “In the Grass” Top 10 of 2010

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150IGOR chip- employment 150 In keeping with all of the other end-of-year top 10 lists, I’ll wrap up 2010 with my own observations and highlights from In the Grass

10. No tarballs – yet??
The over-riding event of the 2010 research season was undoubtedly the Deepwater Horizon oil spill. (In fact, that was the impetus for the start of this blog!) Early in the summer, I thought our marsh field sites in St. Joseph Bay were doomed to be covered in oil. I am very relieved to say that is not the case – there are no visible signs of oil at our sites. It’s too soon to say we’re in the clear, because there is still a lot of oil that is unaccounted for, and there could certainly be “invisible” traces only detectable by laboratory analyses. However, we’re in much better shape than I would have predicted back when this all began, and that’s as good a way as any to start a new year!


Members of Team Hughes surveying the marsh.

9. It takes a lot of people to conduct scientific research.
I had a lot of help over the course of the last year – Team Hughes consisted of (in no particular order) Robyn Zerebecki, Ryan Corley, Emily Field, Althea Moore, Liz Hibner, Kristin Berger, Michele Sosa, Prathyusha Pamidi, and AJ Gelin, and we often enlisted members of Team Kimbro as well.

But even that list does not really represent all of the many people who help to get the work done. There are friends and family (thanks, Mom!) that get roped into helping when no one else is available. In addition, there’s an entire staff here at the FSU Coastal and Marine Lab who see to it that we have all the necessary paperwork complete, decks and tables for our experiments at the lab, seawater flowing to our tanks, irrigation systems in the greenhouse, boats and vehicles to get to our sites, and any number of other odd requests that we come up with. They don’t get nearly enough recognition for the critical role that they play!

8. It’s not as scary as I thought to have a camera documenting my every move in the field.
Field work is neither glamorous nor graceful, so I was a bit worried when we started this blog about having goof-ups documented on video. Thanks to the great work of Rob and his team, it’s actually been quite fun!  I hardly even notice their presence when we’re in the field, and I love having so many good photos of critters and field sites, since I’m notoriously bad about taking pictures.  Most importantly from my perspective, Rob has a great eye for what is important to include (the science, and the people and process behind the science) and what is not (my team and me clumsily getting out of our kayaks, which never fails to look silly!).

Lightning Whelk

Lightning whelks grace many of the habitats studied by Randall and David.

7. Marine plants and invertebrates are really cool.
Ok, this observation has nothing in particular to do with 2010, but I have to put in a plug for the amazing critters that don’t immediately come to mind when you think of charismatic marine animals. I’m talking snails, crown conchs, fiddler crabs, sea hares – all the little guys – and the habitats they live in – salt marshes, seagrass beds, and oyster reefs. Even nondescript sand bars are amazing. I was out last week with Cristina, a visiting researcher in David’s lab, on a sand bar near FSUCML. We found all sorts of large predatory snails (horse conchs, tulip snails, lightning whelks) as well as tons of sand dollars, clams, and worms. Just walking around, looking at, and counting these critters made for one of my most fun field excursions in recent memory. (It didn’t hurt that it wasn’t freezing cold.)

Learn more about the predatory snails Randall saw at Baymouth Bar.


Black mangrove (Avicennia) growing in St. Joe Bay

6. Sometimes things are hiding in plain sight.
When Dr. Ed Proffitt visited in the fall, I told him that I thought I may be able to find a spot in St. Joe Bay with 1 or 2 black mangroves for us to look at. Turns out, it’s harder to find a spot that does NOT have 1 or 2 black mangroves! I’m really interested to follow their abundance over the next few years to learn more about their response to climate change and their potential impacts on salt marsh systems in this region.

Read about Randall’s collaboration with Ed.

5. Going out on the reef is pretty fun, too.
Though I spend most of my time in the salt marsh, it was fun to return to oyster reefs this fall to collaborate with David, his team, and our more distant collaborators. A lot of the more mobile animal species in the marsh are also found on the reef (crown conchs, blue crabs), which is a reminder that we shouldn’t treat these different habitats in isolation of one another.

Randall writes about her return to the reef.

More snails climbing on cordgrass reproductive stems

Snails climbing on cordgrass reproductive stems in the field.

4. Snails are more complicated than you think.
It seems pretty straightforward – periwinkle snails climb on cordgrass to escape their predators and consume dead leaves / stems. Except that sometimes they prefer to climb on plants that they apparently don’t eat. And sometimes they create razor-like cuts in live cordgrass and graze the fungus that colonizes the resulting scar. And sometimes they climb up the plant but don’t eat anything, waiting instead until the water retreats and they can return to the sediment surface to consume plant litter…

On a related note, for Christmas my parents gave me the wonderful book The Sound of a Wild Snail Eating. The author, Elisabeth Tova Bailey, provides a compelling account of the delightfulness and intrigue of snails.

grasshopper grazing 3

Grasshopper grazing damage on a cordgrass stem

3. Grasshoppers eat a lot.

Snails are really abundant in the marsh, and because they don’t move very quickly, it’s impossible not to notice them and wonder about their effects. However, there’s a whole suite of bugs that don’t stay put long enough to be counted as easily (unless of course you suck them into a bug vacuum or catch them in a sweep net), grasshoppers being key among them. Our tank experiments show that the grasshoppers can consume lots of living plant material in a short period of time, serving as a useful reminder that I should wonder about the things I don’t see as much as those I do see.

Who can eat more- Grasshoppers or snails?

2. It’s fun to do science with friends.
A recent study indicated that scientific collaborations have a greater impact if the researchers work in close physical proximity to one another. I don’t doubt the results – who doesn’t find it easier to reach a consensus in person than over a Skype conference call? However, I’m happy to be working with David, Jon, Jeb, and Mike “on the reef” despite the geographic distance. Not only are they the right people in terms of research expertise, but our shared history makes it easier to communicate (including to give each other a hard time!).


Rainbow over St. Joe Bay on Christmas Day 2010 (photo credit: L. Hughes)

1. Did I mention that my research sites are not covered in oil?  Hooray!

Best wishes in 2011!

Randall’s research is funded by the National Science Foundation.

Winter in the marsh

Dr. Randall Hughes FSU Coastal & Marine Lab
Vacuuming bugs out of wrack

Emily and Hanna, in matching green waders, vacuum bugs on "Island 4."

IGOR chip- employment 150IGOR chip- biodiversity 150It has been COLD the last few times we’ve been out in the field. The first time (described accurately by Rob), we did not have sufficient cold weather field gear – David lent us some emergency use chest waders that he had on hand, and they were much appreciated despite the fact that we looked really silly and they were all split open at the feet by the end of the day!

Immediately upon my return to the lab, I ordered my team the trusty neoprene chest waders that I used throughout graduate school in northern California. As Emily and I can attest after going out twice more in the cold since then, they make a big difference!

Winter field gear

Newly purchased neoprene waders and fingerless gloves for winter field work.

Aside from the change in attire, what else is different in the cold? Most obvious is that many of the cordgrass stems in our survey plots are dead. In marshes north of here, the above-ground portions of the plant will actually die back completely in the winter, re-sprouting from below-ground reserves in the spring. Here, there are fewer stems overall, and certainly fewer bright green live ones, but the plants will continue to slowly put up new stems throughout the winter.


The photos above are of Island 4 over the course of WFSU's documenting this work. The photo on the left is from May 13. The one in the center was taken at the end of Summer. You can see the grass is taller and more verdant, with cordgrass reproductive shoots popping up over the blades. The last photo is from the first of December.

The cordgrass reproductive stems are also now dead – most of them dropped their seeds in late November / early December, so they have done their job. Emily and I made a special trip to all of our survey sites a week or so ago to set out “seed traps”. And what, exactly, is a seed trap? In this case, it’s a Styrofoam bowl lined with Tanglefoot, the incredibly sticky substance that we use on our mesocosms to keep snails from climbing out.


Any seeds (or seagrass wrack, other plant material, bugs, or anything else, really) that fall into the bowl will stick, allowing us to count the number of seeds that get to each area. We are particularly interested in whether seagrass wrack abundance increases or decreases the number of seeds in an area. We’ll go back in January to pick them up and start counting.

We have some plants in the greenhouse that we’re growing for experiments this spring, and they have been getting a little extra TLC on these cold, cold nights. We cover them with frost blankets at the end of the day, and then uncover them again in the mornings when it’s warmed up a bit. They seem to like the extra warmth!

Frost blankets in the greenhouse

Our greenhouse tables covered in (appropriately) green frost blankets on cold winter nights.

From a logistics perspective, the winter is pretty different for a number of reasons. First, it’s harder to find people available to go in the field. (And on really cold days, it’s not very appealing!) Emily will be back on campus taking and teaching classes next semester, so we’ll probably have to do some portion of the monthly surveys over the weekend, hopefully with the help of some undergraduate interns.


Looks like we're walking.

The second logistical challenge is the change in the tides. For most of the year, the low tide is in the evening / night, so it is easiest to kayak to our sites during the morning and early afternoon. In the winter, the low tide shifts to the middle of the day, and it’s often made even lower by a strong north wind, making it virtually impossible to kayak anywhere during daylight hours!

Our solution is to walk to the sites that we can, and kayak as close as we can to the others before we start walking. It’s a good thing that St. Joe Bay is shallow!

In January, we’ll be sampling fishes and small crabs in the marsh. We do this every couple of months to see how the abundance of the more mobile marsh community members changes seasonally. I don’t expect that we’ll find much, but I’ll let you know!

Randall’s research is funded by the National Science Foundation.

Just one more thing…

Dr. Randall Hughes FSU Coastal & Marine Lab
Setting up a tank experiment

Emily and Robyn setting up yet another tank experiment that I've dreamed up. (Thanks to Nancy Smith for the pic!)

IGOR chip- biodiversity 150Because of the big focus on oysters over the last month, it may seem as if we haven’t been doing anything “In the grass”. We’ve been busy, though, trying to squeeze in a few additional surveys and experiments in November before it gets cold enough that the animals stop eating (or eating very much, I should say) and the plants stop growing. For a while there, I was coming up with so many end of season ideas that I’m pretty sure my crew hated to see me coming!  We just did finish up before the winter weather arrived (early) in December. (More on what it’s like working in this cold weather in future posts.)

We actually missed the opportunity to do one of our planned studies involving grasshoppers – there was a cold snap two nights before we went in the field to get the hoppers, and they were nowhere to be found.   Those data will have to wait until next spring when the grasshoppers turn up again!

We’ve had better luck with two other projects –

1. Do snails prefer to climb on cordgrass reproductive stems?

More snails climbing on cordgrass reproductive stems

Snails climbing on cordgrass reproductive stems in the field.

Spartina reproductive shoot

A tasty snack for a periwinkle snail?

I’ve mentioned before on the blog that we noticed lots of snails climbing on cordgrass reproductive stems this fall. In collaboration with David and his team, we visited marsh sites along the Panhandle to see if our observations would be supported with rigorously collected data. So far, so good!


The trusty tank set-up at FSUCML.

We also started a series of experiments in our trusty tanks at the FSU marine lab to tease apart why snails may have this preference: Do the snails simply like that the reproductive stems are taller than regular stems? Or do the reproductive stems “taste” better because of greater nutrient content? Does it matter if predators are present or not? The preliminary results suggest that they like the reproductive stems, regardless of whether they are taller or not. In January, we’ll head into the lab to do the tests for nutrient content that should help us to tease apart why that may be.

2. Does needlerush provide a better predation refuge than cordgrass?

A patch of needlerush surrounded by cordgrass

Needlerush (center patch) is typically much taller than cordgrass (surrounding area) in St. Joe Bay

Last fall I did a tank experiment to look at whether snails prefer to climb on another marsh plant species, needlerush (Juncus roemerianus), and whether this preference increased snail survival when predators were around. The results were interesting, but as usual, the first round of the experiment created additional questions that required more work. In November we started a similar experiment, again in the tanks at the marine lab, looking at snail climbing behavior on needlerush and cordgrass in the presence and absence of the snail’s nemesis, the blue crab.

Needlerush is naturally taller than cordgrass, so to test if this difference in height can explain snail behavior, we “experimentally manipulated” (in other words, used scissors to cut the needlerush down to a shorter height) needlerush height: some tanks have naturally tall needlerush, some have needlerush that is on average the same height as the cordgrass, and some have needlerush that is shorter than the cordgrass. Add a blue crab to half of the tanks, and voilà, the experiment is underway!

blue crabIt’s a bit ironic that each of the experiments we recently finished converged on a similar idea – snails appear to prefer to climb on taller plants. Considering that the taller the plant, the farther they can climb away from predators in the water, it makes sense. The true question is to figure out whether and why it matters that the snails do this. If they climb on reproductive stems, are fewer cordgrass seeds produced? What will that mean for next year’s crop of cordgrass? Also, if snails spend a lot of time hanging out on needlerush to avoid predators, does that mean they don’t eat as much cordgrass? Knowing things as seemingly arcane as which plant a snail prefers to climb on can help us predict and manage the overall abundance and productivity of cordgrass, and the salt marsh in general. And of course, the field work and experiments are fun! Especially when you get to wrestle with blue crabs…

Here are some photos of periwinkle snails in Randall’s latest tank experiments:

Randall’s research is funded by the National Science Foundation.

Back in the Day

IGOR chip- employment 150This week’s videos look at Dr. David’s Kimbro’s collaborators in the NSF funded biogeographic oyster study. While he has been the face of the study for On the Reef, he is one member of a team of scientists.  Today’s videos feature Dr. Randall Hughes (In the Grass) and Dr. Jon Grabowski.  Later this week, we’ll have a short video with Dr. Jeb Byers.  Randall and David’s posts accompanying the videos are reminiscences on their early days in marine ecology in North Carolina, where they and their fellow team members met while in school.

Dr. Randall Hughes FSU Coastal & Marine Lab

Getting my first taste of marine ecology.

In my last semester as an undergraduate at the University of North Carolina-Chapel Hill, I took a class in marine ecology from Dr. Charles (Pete) Peterson and Dr. Mark Hay.

At the time, I was a double major in biology and public policy analysis, and despite being just a few months from graduation, I was still very uncertain what I was going to do next. So when Pete asked me if I would like to work as a summer research assistant at UNC’s Institute of Marine Sciences for his graduate student, Jon Grabowski, I accepted with little idea of what I was getting myself into.

Jon’s project involved comparing the value of restored oyster reefs in different locations in the marsh (next to marsh edges, sandwiched between marsh edges and seagrass beds, or isolated on sand flats) as habitat for important fishes and crabs. What that meant in reality was that in the summer of 1997, we used ~2 tons of dead oyster shell to create 12 intertidal oyster reefs in Middle Marsh, NC – largely by carrying the shell in orange baskets from one big pile to the specific places where we needed it.

A sand flat oyster reef in 2002

One of the reefs we built in 1997 on a sand flat, pictured here in 2002.

In the process, I learned to trailer and drive a boat, build 30+ fish traps that involved welding rebar together and dipping the whole contraption in “net dip” (the most disgusting substance known to man), deploy and retrieve those traps and happily (well, at least begrudgingly) handle the blue crabs, toadfish, and other critters that we caught, and various other tasks that made my parents wonder why I needed a B.A. degree for this job. But by the end of the summer, I was hooked!

Jon at IMS

Jon, before he was Dr. Grabowski.

After that first summer, I returned to work with Jon for 3 more field seasons until starting graduate school myself in 2000. (David and my paths crossed at IMS, working for Jon together in 1999.) During the “off-season” I taught school, first in Mexico and then in NC, because I wanted to be sure that becoming an ecologist was really the thing for me. I love teaching, but I love research even more, and so going to graduate school seemed the logical way to combine the two.

Much like the no-see-um story from Jacksonville, the long hours and hard work involved with Jon’s project generated a lore surrounding that first (and subsequent) years. Here’s just one of my favorite stories from the summer of 1997 –

Pete in the marsh

Dr. Pete Peterson in Middle Marsh, NC.

Once the reefs were created (and lots of stories could be told about that process), the plan was to sample them once a month over consecutive daytime and nighttime high tides. Because we couldn’t sample all of the sites at the same time, this involved 48 hours of effort with only short breaks in between times in the field. The first time attempting this sampling happened to fall the 2 days before I was scheduled to leave to start my job teaching in Mexico – oh, and on my birthday. After day 1, we realized that returning to the lab from our field sites and then going home to get cleaned up before getting some rest was burning lots of valuable sleep time, so we decided that the second night we would camp on one of the barrier islands close to our sites. Jon packed most of the gear, including a giant and heavy cooler, and off we went. Of course, it was the middle of the night when we finished up in the field and drove the boat over to Shackelford Island, and we hadn’t bothered to set up camp earlier in the day. Jon thought he knew of a shortcut to cross over to the ocean side, which had a nice breeze and far fewer mosquitos. Unfortunately, we didn’t find the shortcut immediately, and we ended up carrying the heavy cooler and all of our other gear while swatting and cursing mosquitos for quite a while. About 5 minutes from the beach side of the island (though we didn’t know that at the time), I snapped, announcing to Jon that I was NOT walking any farther and so we better set up camp in that spot. (I had maintained a fairly mild-mannered and easy-going persona all summer, but there was nothing mild about my ultimatum that we stop walking.) I was in better spirits after a few hours of sleep, feeling more than a little chagrined at my outburst when I realized how close we were to the beach, and especially when learned that the primary object in that heavy cooler was a chocolate birthday cake for me! I have since apologized many times, and Jon and I laugh and re-tell that story virtually every time we get together.

Of course, beyond the friendships, funny stories, hard work, and good food, we also learned a heck of a lot about oyster reefs and the animals that live on and around them. That’s why our current collaboration “On the Reef” is so satisfying – it’s a way to return to our roots scientifically, professionally, and personally.


The biogeographic oyster study is funded by the National Science Foundation.

Did You Say Mangroves?

Dr. Randall Hughes FSU Coastal & Marine Lab

Ed Proffitt and Randall Hughes by a black mangrove

Ed Proffitt with Randall Hughes. If global climate trends continue, mangroves may start to overtake the salt marsh ecosystem along the Gulf coast. What will these new habitats look like?

IGOR chip- biodiversity 150A few weeks ago, Dr. Ed Proffitt from Florida Atlantic University visited FSUCML to give a seminar here and on campus. Ed and I have collaborated on several proposals, so we used the visit as an opportunity to get out in the field and toss around some new ideas.

Ed has done some really interesting work on the interactions between mangroves and salt marsh plants in Tampa Bay and the Indian River Lagoon, and he wanted to see some mangroves in this area. I recalled having seen a few young red mangroves last year at some of our sites, but none of them survived this past winter (which is why we generally don’t find them around here – they can’t withstand the cold temperatures that we get every few years). However, black mangroves do extend into this portion of the Gulf, and I knew of a place where we may find one or two small ones to look at.


Black mangrove (Avicennia) growing in St. Joe Bay

To my surprise, we found a lot more than one or two! And although they are small (think small shrub, rather than tree), some of them, such as the one shown here, had aerial roots extending out 14-15m, suggesting that they have been around at least 5-10 years (by our best guess).

black mangrove flower

Avicennia flower. These mangroves are insect-pollinated, and we saw lots of bees buzzing around.


Avicennia propagules growing on the maternal tree.

Also, most of the larger ones had both flowers and propagules (seedlings that are retained on the tree) on them.


Avicennia propagule that has dropped to the ground and started to take root.

As we looked around, we noticed more and more small mangroves in the marsh – probably the seedlings from some of the nearby larger trees – and we even found some of this year’s propagules that were starting to root in the sediment.

As I mentioned, black mangroves are known to grow in the Panhandle and west into Louisiana and Texas, so it really isn’t that surprising that we found them in St. Joe Bay. What is surprising, at least to me, is that they are as abundant as they are in a site where I previously thought there were only a few. Where else may they be in the bay? And are they increasing in abundance each year? What impact do they have on the marsh plants and animals? The questions abound. With our curiosity and Ed’s insight and experience, we are now starting to pursue the answers.

Randall’s research is funded by the National Science Foundation.
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The Magic

Dr. Randall Hughes FSU Coastal & Marine Lab

Randall gets back to her roots, placing traps on a reef with Hanna.

IGOR chip- biogeographic 150When I worked as a technician for our current collaborator Jon Grabowski back when he was in graduate school, one of his favorite sayings as we headed out to the field was “This is where the magic happens”. Yesterday and today I got to experience that magic again as I made my first visit to our oyster sites in Cedar Key. Though I spend a lot more time with plants these days, I do love oyster reefs. Maybe it’s because the first field research I did was on reefs (with Jon), or maybe it’s because of the mystique they seem to hold for nearly everyone, but it sure was fun to hear those shells crunch as I stepped out of the boat.

Of course, in addition to “the magic”, there’s also the cuts and scrapes, the no see-ums, and frustrating way that nets get caught on every oyster clump within 2 ft. But something about the reefs wins me over every time!

Enough of all the nostalgia – what did we actually accomplish? Hanna and I started about midday on Sunday, deploying traps at each of the sites. We realized as we headed back to the boat ramp that the return trip we were scheduled to make later that evening after deploying nets would have been pretty challenging in the dark, so we spent most of the afternoon seeking out a plan B. Thanks to some wonderful people in Cedar Key, we ended up docking the boat for the night at a home just near our sites! Around 6pm we headed out to pick up the traps. We didn’t find a whole lot – a few speckled seatrout and some killifish – but we were able to deploy our nets without any trouble (other than the previously mentioned no see-ums). By 9:30pm we were back at the rental house eating our frozen pizza dinner.

P1010636This morning we got up and headed back out to see what was in our nets. Somewhat surprisingly, it was all mullet and catfish! Not that we didn’t expect those fish to be there, but we thought we’d get a greater variety of species. There were also 2 red drum, 1 blue crab, and a couple of crown conchs, but mostly it was mullet, mullet, mullet.

After we got turned around heading back to the boat ramp, I was really glad that we hadn’t tried that trip in the dark last night! All in all, it was a trouble-free trip to the field, and a welcome opportunity for me to see some of “the magic” again myself.

David & Randall’s research is funded by the National Science Foundation.
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The search for patterns

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150The end of summer is a good time to pause and think about any general patterns that emerge from observations over the course of the last year(s). Sometimes it is easy to get swept up in the minutiae of individual projects and forget about the big picture. Of course, these patterns aren’t definitive (i.e., don’t quote me on this!), but they can be useful to think about, particularly when considering future avenues of research.


Marsh island in St. Joe Bay viewed from the waterand marshes on the edge of the mainland.

So what sort of patterns can I describe to you after two summers in the marshes of St. Joe Bay? One that doesn’t take a PhD to recognize is that there are two distinct types of marshes that we sample: marsh islands and marshes on the edge of the mainland.

But aside from the obvious fact that one is an island and the other is not, there are some additional interesting differences:

1. The slope of marsh islands is typically greater than mainland marshes, so that you move quickly from plants that can tolerate frequent flooding (cordgrass) to plants that are more “terrestrial” (pickleweed, saltwort, etc.). On islands this transition can occur within a few steps of the water’s edge, whereas mainland marshes typically have a large area (I like to think of it as a football field) dominated by cordgrass.


Elevation on islands changes rapidly compared to the mainland. Even slight differences in height can influence plant communities.


Sampling a mainland marsh in St. Joe Bay.

2. Marsh islands tend to have fewer periwinkle snails than mainland sites, although they are certainly present.


Abundant snails in a mainland marsh.

My guess is that the snail predators (blue crabs, crown conchs) that lurk just at the water’s edge have greater access to snails on the islands at high tide, because they can move in from all sides of the island. In contrast, the predators near mainland sites have only one point of entry into the marsh.

blue crab

Blue crab lurking in the seagrass at the edge of the marsh during low tide.


Crown conch foraging for snails in a lab experiment.

3. Perhaps not surprisingly given that they are surrounded by water, the marsh islands typically have fewer grasshoppers jumping around. We’ve also had far fewer snake encounters on islands, which I consider a good thing. Probably because land-based predators such as snakes, raccoons, etc., are less frequent on islands, we also observe greater numbers of nesting birds on the islands than at mainland sites.

4. One clear difference that I can’t explain but hope to examine in the future is that cordgrass plants collected from the islands (which can only be done with a special permit from the Department of Environmental Protection) survive better in our greenhouse at the lab than those from mainlands. It may simply be the growing conditions, or island plants may be hardier overall. Stay tuned.

As we continue to process, enter, and analyze data, there should be additional trends emerging. And we’ll likely find out that some of the patterns we think we see don’t hold up to the test of actual data. And so goes the process of science!

Randall’s research is funded by the National Science Foundation.
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