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Cold and Wet: Field Research in the Winter

Waves on Cape San Blas rocks

Rob Diaz de Villegas WFSU-TV

IGOR chip- employment 150I was driving to Stump Hole with my production assistant Kevin when we saw these waves crashing on the rocks on the beach side of Cape San Blas.  Like any good production people, we knew the only thing to do was to climb the rocks and get footage and stills of the scene.  The same wind pushing the waves at us rocked us a little bit as we balanced- only slightly precariously- on the big stones.  It was a little after 8:30 AM and we had some time to kill before Randall and her team showed up.  And then we would kayak into the bay just across the street.

In early December I made my first winter forays into coastal environments.  Randall has already written about the seasonal shift from Summer to Autumn, where the flora and fauna are reproducing and animals are abundant in the marshes.  Winter is an entirely different beast, as I would see when we got to their sites.  But first, we actually had to get to these sites.

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After everyone was there, we kayaked east from Stump Hole with a stiff north wind pushing us on our left.  Rowing to the left was like rowing into a wall, and there were a couple of marshes in our way where we had to get out and lug the kayaks to the other side.  Saltwater splashed into my eyes and onto my glasses.  I kept my squinty eyes forward and we got to a site that for the purposes of this study is known as Island 4.

The research crew went about their normal survey work, with Randall taking a quadrat to several specific spots within the marsh to see how much grass and other species were within its PVC boundary, how tall the grass is and how many Spartina shoots were dead.  Using markers and a GPS, they’ll have data from these precise spots over a span of three years.  Emily and Hanna vacuumed bugs out of the grass and surveyed seagrass wrack.  They will, as always, search for patterns over time, and I suspect the data collected in the winter months will quantify some of what we saw with our own eyes.

Sea Urchin shell washed up on marsh

While we didn't see the usual critters swimming and crawling about, some cool stuff washed in from the bay, such as sponges, lightning whelk egg casings, and this sea urchin shell.

Last time I was at this site, some male blue crabs were fighting over a female.  They were so engrossed that I was able to get fairly close without their bolting away.  All manner of predatory snails oozed about, little fish darted in and out of the sparse shoots at the periphery, and a ray laid low in an adjacent seagrass bed.  Today it looked like they had all packed up and left for the season.  And, when it came time to go our next site, so had the water in the bay.

A combination of the tide and the strong wind left the south side of the bay somewhat empty.  Taking a few steps with our kayaks in hand, we decided instead to leave them at the island while we walked our gear over to a mainland marsh known as Wrack 5.

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This was another site where I had always seen an abundance of fauna. Hundreds, sometimes thousands of fiddler crabs would scurry away from me into the grass in this one corner of the marsh.  As Randall explained to me, the fiddlers bury themselves in the winter.  Blue crabs swim into the deeper part of the bay, to the north.  Randall didn’t know exactly what happened to the crown conchs, though when digging cordgrass up for an experiment she had come upon a buried conch.  And with their predators all gone, the marsh periwinkles had descended to the bottom of the spartina plants.

Lightning Whelk shellOne thing I did see a lot of were lightning whelk shells.  I picked them up and looked inside, wondering, are they more cold tolerant than the other species?  They’re not.  But their shells were pretty.

The following Monday I went to Alligator Harbor with Tanya and Hanna, and it was a lot of the same.  We dragged our kayaks from the ramp to the first site and walked between the islands to the second and third sites.  It was a much muckier walk than in St. Joe Bay (the oysters like it mucky), and I was breaking in a new pair of crappy old sneakers to be my oyster reef shoes.  This is how they fared:

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Now that I’ve muddied my hands pulling my shoe out, where’s all that water?

Have any of you trekked out into the cold coastal waters this season? Share your stories!

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!

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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.

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.

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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.

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

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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.

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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.

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

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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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Autumn in the marsh

Dr. Randall Hughes FSU Coastal & Marine Lab

Marsh periwinkles climbing on a cordgrass reproductive stem

A cordgrass reproductive stem stands above the surrounding plants.

IGOR chip- biodiversity 150 One doesn’t need to look at a calendar to realize that fall is upon us – recent cool mornings are a welcome sign. The marsh is also showing signs of change, with cordgrass flowering shoots springing up everywhere.

These stems are quite noticeable – they are taller than non-reproductive plants, and they have a “feathery” appearance due to the reproductive structures at the tops of the stems.

As I’ve mentioned before, cordgrass is one of those plants (like strawberries) that can spread by underground rhizomes, putting up new stems along the way. Alternatively, it can reproduce the “traditional” way, with reproductive stems that broadcast and receive pollen via the wind, ultimately producing seeds that fall to the sediment, get buried, and then germinate to produce new seedlings. Though conventional wisdom is that most new cordgrass stems are produced vegetatively by spreading rhizomes, it’s clear at our sites that these plants are investing a lot of energy in the other form of reproduction! Continue reading

A walk “in the grass”

Rob Diaz de Villegas WFSU-TV

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Last week we had a post on what it was like on an oyster reef, the idea being that many people have never really seen one.  Continuing with that theme, I thought it might be interesting to take a closer look into a salt marsh.  This is a trickier proposition because, well, what is a typical salt marsh?  Some of them grow in muddy waters next to oyster reefs, or they can be found along beaches, in wide expanses or in small islands just off the coast.  I’ll keep today’s imaginary journey confined to marshes in St. Joseph Bay, where Randall Hughes conducts her biodiversity study- that is what I am most familiar with.

Continue reading