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?
Dozens of different mollusk species interact within a relatively small area at Bay Mouth Bar, from all manner of bivalves to the predatory snails that eat them (and each other).
As soon as you arrive to BMB, it is easy to imagine and feel the same curiosity and fascination that Robert Paine brimmed with when he first immersed himself in the sand bar fifty years ago.
If someday you have the opportunity to visit BMB at low tide, then you would receive much pleasure in looking at 40000 m2 of sand, full of awesome critters! Twenty minutes by kayak, that’s it!
Since I started working at FSU’s marine lab, I have frequently cast longing looks at a local study system that hasn’t been examined in over 50 years. Back in the 1960s, the world’s most famous ecologist (Bob Paine) was a post-doctoral researcher working at FSU’s Marine Lab. It was at this time and place where he began developing some of the concepts that would transform the field of ecology. Continue reading →
The lab bench set up with all of the molluscan specimens for the students to study this week.
These lyrics are from Mr. Ray’s teaching song in Finding Nemo. It’s too bad that I can’t sing all of my lessons!
I’m teaching Animal Diversity lab to undergrads on campus this semester. This is a “survey” course, meaning that we go over the major phyla in the animal kingdom, learning one to three phyla each week. The students get to look at preserved specimens and do their own dissections. It’s so rewarding to hear a “that is so cool” reaction to whatever a student is looking at.
A few weeks ago, the students designed their own small experiments using planarians (small flatworms, see photo below). It was great to see them think creatively and analytically in formulating their question and experimental design. As with any set of experiments, some worked and some didn’t. The strangest results we got were with two separate regeneration experiments: two different groups each cut a planarian in half, and somehow ended up with three planarians a week later! Spontaneous generation, anyone? (What probably happened was either that the dish wasn’t sealed well and another planarian moved over from another experiment, or that the students accidentally made two cuts instead of one. But it was still pretty surprising!)
One of the planarians used in Animal Diversity lab. Isn't it cute?
One of the most direct benefits of teaching for me is that learning about biology in the classroom motivates students to learn more through field research. The past two months I’ve been fortunate enough to have many eager undergraduates volunteer to help with my field surveys. Thanks to the awesome waders Randall bought for the lab, we all managed to stay warm through the cold weather. I’m very glad the weather is improving though. This past weekend getting sunburned was more of a concern than staying warm! I think the undergrads appreciate the change in weather even more than I do, since for some reason most of them are from south Florida. In January, one of the students said he could tell I was from Maine when I zipped the fleece liner into the windproof shell of my field jacket. I never knew you could identify where someone was from by their outerwear! While admittedly surveying the first site with a group of new helpers takes a long time as they learn how to identify species, use the sweep nets, etc., it is great how quickly they pick it up. On Sunday, two new helpers (Austin and Chris) and I surveyed four sites (compared to our usual maximum of 3 per day), and we were done before 5pm! It wasn’t very long ago that I was an eager undergrad helping a grad student with her research, so I’ve been on both sides of the table. I think it’s a great example of mutualism: grad students need help to realize their lofty research objectives, and undergrads need research experience. At least I hope that they’re getting useful experience out of it! I know I’m indebted to them for their help.
Collecting algae in the rocky intertidal zone in Rhode Island. Photo by Carol Thornber.
My favorite part of teaching (in the field or in a classroom) is when students ask a bunch of questions. That way I know they’re not bored! This is particularly gratifying in the classroom. I teach on Fridays, and at the beginning of the semester I was worried that I was going to end up with students who were unwillingly stuck with a Friday lab and would therefore be uninterested and lethargic. But my students are great! Sometimes they ask questions that really show they’re thinking critically and making connections. I doubt they realize how clever their questions are, but they definitely make me think!
At one of Randall's genetic diversity sites the first summer I worked for her.
Of course, there are frustrating parts of teaching. In the classroom, you have to worry about how to prevent cheating, there are students whose main goal is to get out of lab as fast as possible and do the minimal amount of work required, and sometimes you’re not sure if you’re getting through to the students at all. In the field, whether or not students understand your instructions has major implications on the reliability of the data they collect. In both cases, it falls to you as the teacher to make sure your students are actively involved and fully comprehend both the instructions and the theory behind what you’re studying. And the current climate for teachers isn’t particularly sunny in the states. Rather depressingly grey, really. But I still think getting one excited reaction or clever question makes dealing with the frustrations worth it. I bet many teachers would agree with me. So thanks to all of the teachers out there who work so hard and don’t get acknowledged often enough!
Emily is a graduate student in the Hughes Lab at the FSU Coastal & Marine Laboratory. She is studying the effects of seagrass wrack that washes into salt marshes
Although the oyster project’s fieldwork has attracted most of the attention on this blog (indeed, it is where most of the action happens), our time at the lab deserves a bit of discussion as well, as much progress on the oyster project also happens behind walls. This is especially the case nowadays, in the winter, when fieldwork is kept to a minimum on account of weather and the general inactivity of animals on the reefs. What better time to catch up on processing the zillions of samples we’d collected over the past many months, but never quite had time to get to.
Labwork is a whole different beast than the energetically-demanding, volatile nature of fieldwork – I wouldn’t go so far as to call labwork boring, but it is often incredibly repetitive, time-consuming, and demanding of extreme patience. It’s certainly not as exciting, sensational, or enjoyable as fieldwork (in my opinion), but it is just as much an integral part of the science, and anyone who goes into research will probably spend much of their time sitting at a bench, repeating the same procedure twenty-thousand times in pursuit of the great dataset (that is, until you hire techs and grad students to do it for you). Yet labwork has an appeal and mystique all of its own that’s not to be overlooked.
Certain tasks in marine biology necessitate learning skills used in commercial seafood. Here, Tanya shucks an oyster to remove the meat and weigh it.
So while David retires to his office and catches up on the uncountable tasks at hand there, I’ve holed up in the lab and plodded steadily through the several hundred samples of ours waiting patiently in the freezer. Lately, this has involved two major tasks. The first was to process the sediment organic matter (SOM) samples from our (and Jeb Byers’s) oyster reefs collected every 6 weeks since August. A total of 640 samples needed to be transferred from bags to aluminum dishes, dried for 3 hours at 105°C to evaporate any water, weighed, combusted for 3 hours at 525°C to incinerate and volatilize any organic material, and reweighed to determine the percent of the sediment composed of organic material. This analysis will allow us to compare how oysters affect the amount of organic material in the sediment across latitude. In case you ever wanted to know, 525°C (977°F) is pretty dang hot, and the smell of burning sediment that wafts down the hall during the first half hour or so in the furnace apparently smells exactly like an electrical fire.
Mmmm... oyster jerky!
My second task was to process samples of oysters we’d collected from our reefs during our intensive August surveys. After thawing them out, this involved measuring the total weight, wet and dry tissue weight, and various shell dimensions of 400 individual oysters. From these data we’ll be able to calculate an oyster condition index (health indicator), which we’ll be able to compare across sites. Obtaining wet and dry tissue mass required removing and weighing the meat (my oyster shucking skills increased greatly after this exercise), and reweighing it after drying for 48 hours at 70°C (this generated some quite odorous and not-all-too-appetizing looking oyster jerky). Between the sediment and oyster samples, I admit I had a monopoly of the marine lab’s drying ovens for a short while. I can say though that sticking your face in a drying oven is a great way to warm up on a cold winter’s day.
There are a variety of ways researchers try to liven up the tedious nature of labwork. Many listen to music or books on tape, or play movies in the background, or chat with labmates if others are around. Sometimes I’ll do these things, but other times I find the quiet monotony of labwork to be rather peaceful. There’s no stress or distractions or real need for thinking – just you, the calipers, the oysters, the datasheet. You kind of get in “the mode” and it can be rather, I don’t know… zen? At least for a little while. It’s a nice contrast to the intensive and unpredictable nature of science in the field.
David Kimbro’s research is funded by the National Science Foundation.
David's collaborators, from left to right- Dr. Jeb Byers, Dr. Mike Piehler, Dr. Jon Grabowski, and Dr. Randall Hughes.
As you can see from the video that summarized our efforts over 2010, it was a busy 6 months of research. After taking a great break during the holidays, the entire oyster team (Jon = Gulf of Maine Research Institute, Mike = University of North Carolina at Chapel Hill, Jeb = University of Georgia, Randall = Florida State University and me) met for a long weekend to figure out what we accomplished and where we are going in the future.
You might think that our 2011 research plans should already be set given that we received funding. Well, we did receive funding to carry out some outlandish field experiments in 2011, but these experiments were dreamed up in our offices and may not address the most ecologically relevant questions for our system. Checking in with the monitoring data is probably the best way to determine if our planned experiments were on target or if they needed to be adjusted and hopefully simplified!
Prior to the oyster summit last weekend, I hounded all of the research teams for all of their data. Given the huge volume of data and everyone’s busy schedules with teaching classes and other research projects, this was quite the task. Once Tanya meshed all the data together (also not a simple task), I then moved on to the next task of analyzing our data.
Well, the initial excitement quickly turned into a stomach churning feeling of….where the heck do I begin? Similar to the way that too many prey can reduce the effectiveness of predators, the data were swamping me…I was overwhelmed and the draining hourglass wasn’t helping (people were flying into town in two days…yikes!).
After multiple cups of coffee, the anxiety passed and I decided to revisit some basic questions:
David's team used gill nets to catch the larger fish around the reefs, many of which are top predators in that habitat.
(1) With the gill nets, we obtained predatory fish data. So how do the abundance and biomass of these fishes vary across latitude? And does this pattern change with season (i.e., summer versus fall)?
(2) Then I thought back to the fond memories of ripping up oyster habitat to check out the abundance of things that consume oysters (e.g., mud crabs). Oh…the memory of that work gives me a warm and fuzzy feeling; I bet Tanya, Hanna, Linda and everyone else that helped feel the same way! How do the abundances of these things change across latitude? Are there larger crabs up north or down south? How does the mud crab picture mesh with the predatory fish picture?
This spat stick is made of calcium carbonate, the same substance as oyster shell, and is ridged to simulate the ridges in those shells. That makes it an attractive landing spot for oyster spat (larval oysters), which tend to settle on oyster shells.
(3) Working our way down the food web and sticking with the oyster samples we ripped up back in August, how do oyster densities and oyster size change across latitude and how do these patterns mesh with the mudcrab and predatory fish data?
(4) Finally, I wanted to revisit the data from our instrumentation to see how temperature and salinity changed across latitude and with season, as well as the data from our spat sticks to see how oyster recruitment differed.
It’s pretty amazing that six months of work can be summarized so quickly into four topics. Well, I kept hitting the coffee and got all of these data worked up in time for the first portion of our oyster summit. Surprisingly, all inbound flights arrived on time and we all assembled last Friday to go over the data. I’ll briefly lift the research curtain to illustrate what our data looked like:
The Georgia reef gill nets trapped a lot of sharks. Here Dr. Jeb Byers is removing blue crabs (also an oyster reef predator) from shark bellies. The trapping done on these reefs is clarifying the food web for these habitats.
(1) Although we predicted predator abundance to increase at lower latitudes, predator abundance and the number of different predators peaked in Georgia/South Carolina. This is because lots of the species we have in Florida were also in Georgia. And, Georgia has lots of sharks! Needless to say, Jeb’s crew has been the busiest during gillnet sampling. Jon and Mike’s crew have had it pretty easy (no offense)! The workload reduced for everyone in the fall, but the differences across latitude stayed relatively the same. The really cool result was the pattern that hardhead catfish are extremely important and the most abundant predatory fish on Florida reefs; I love those slimy things.
(2) Interestingly, mudcrab biomass peaked up north where predatory fishes were less abundant.
(3) And the abundance of large, market size oysters was highest where predatory fish were most abundant (GA/SC).
(4) Amazingly, we all did a good job selecting oyster reefs with equivalent salinities (this can vary a lot just within one estuary) and temperature was the same across all of our sites until December….instrumentation up north got covered in ice! Glad I was assigned the relatively tropical reefs in Florida. Finally, oyster recruitment in NC and Florida appears to proceed at a trickle while that of GA/SC is a flood-like situation during the summer.
A month after first being deployed, Tanya and Hanna inspect an Alligator Harbor tile. You can see that some of the oysters have definitely started growing, but also that some of the spat became unglued. When they run the experiment again, they'll use a different adhesive more suitable for a marine environment.
After we all soaked that in, we then talked about the tile experiment. While these data were really cool (mortality presumably due to mudcrabs was lowest where predatory fish were most abundant = GA), we worried about being able to tease apart the effects of flow, sedimentation, and predation. Unfortunately, this experiment seems to uphold my record with experiments: they never work the first time. We’ll probably repeat this in fall of 2011 with a much better design to account for flow and sedimentation.
Before breaking for a nice communal dinner at my place, Mike summarized the nutrient cycling (sediment) data that we have been collecting. In short, having lots of living oysters really promotes de-nitrification processes and our sampling picked this up.
Putting this all together, it looks like there are latitudinal patterns in fish predators that may result in mudcrab density and size patterns. Together, these may help account for latitudinal patterns in oysters (highest in GA). This all matters because more oysters = more denitrification = healthier estuarine waters.
END DAY 1
On day 2 of the summit, we worked through what made us happy about the monitoring data, what things we could add on to make us happier, and that we should continue this monitoring through the summer of 2011. This actually took all morning.
On day 2, the oyster summit moved into the more comfortable location of the Marine Lab guest house.
After a quick lunch break, we then reconvened in another room with a better view (nice to change up the scenery) to go over how we should experimentally test the linkages I mentioned above. This is where the saw blade of productivity met a strong wood knot. Personally, I became horribly confused, fatigued and was utterly useless. This resulted in lots of disagreement on how to proceed and possibly a few ruffled feathers. But nothing that some good food and NFL playoff football couldn’t cure.
After taking in a beautiful winter sunset over the waters off the lab, we ditched the work and began rehashing old and funny stories about each other.
Amazingly, we awoke the next morning and fashioned together a great experimental design that we will implement beginning June 2011. To Jeb’s disappointment, this will not involve large sharks, but we will get to play with catfish!
But now it’s time to prepare for our winter fish and crab sampling. It will be interesting to see what uses these reefs during the dark and cold of winter!
Thanks for following us during 2010, and please stick around for 2011 as I’m sure things will get really interesting as we prepare for our large field experiment.
David’s research is funded by the National Science Foundation.
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 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.)
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.
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.
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 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.
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.
Emily and Hanna, in matching green waders, vacuum bugs on "Island 4."
It 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!
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!
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.
I 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.
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.
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.
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.
One 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:
Now that I’ve muddied my hands pulling my shoe out, where’s all that water?
Emily and Robyn setting up yet another tank experiment that I've dreamed up. (Thanks to Nancy Smith for the pic!)
Because 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!
Snails climbing on cordgrass reproductive stems in the field.
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?
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!
It’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.