Tag Archives: Alligator Harbor

TulipMurex

Predator Diversity Loss and Bay Mouth Bar: The Next Stage

David and Randall’s NSF funded oyster study looks to understand how predators control oyster eating animals such as mud crabs and crown conchs. But this dynamic isn’t exclusive to oyster reefs. They are also investigating how predators might help maintain salt marshes and seagrass beds. In their seagrass bed studies, they have focused on a system loaded with predators: Bay Mouth Bar.
Tanya Rogers FSU Coastal & Marine Lab

Tanya RogersThe very first time I drove from Tallahassee to the FSU Coastal & Marine Lab I saw a black bear crossing the Crawfordville highway. No joke. This was in June of 2010, and I had just driven 5 days and 2800 miles from San Francisco to the Florida panhandle to take up my new job on the Gulf Coast. I had just finished college in Washington state, and I had never before been to the Southeast. What sort of wild place had I ended up in?

IGOR chip_ predators_NCE 150IGOR chip- biodiversity 150A very wild and unique one it turns out, and one I’ve come to know better working for the past few years as a research technician for Dr. David Kimbro in the fascinating coastal habitats of this region. Primarily I’ve been traipsing around oysters reefs across the state for the collaborative biogeographic oyster study (now drawing to a close), but for the past year or so I’ve also been managing our side project in the Bay Mouth Bar system, a sandbar and seagrass bed near the FSU Marine Lab. Bay Mouth Bar is a naturalist’s playground filled with surprises and an astonishing diversity of marine creatures that never ceases to amaze me. It is also a unique study system with an intriguing history out of which we can begin asking many interesting questions. This coming fall I’m excited to be starting as Dr. Kimbro’s Ph.D. student at Northeastern University, and for part of my dissertation I’ve decided to conduct some new experimental research this spring and summer out on Bay Mouth Bar.

Horse conch consuming a banded tulip snail on Bay Mouth Bar.

A horse conch in Tanya’s experiment consuming a banded tulip snail.

Bay Mouth Bar is known for its especially diverse assemblage of large predatory snails, which the ecologist Robert T. Paine conducted a study of in the late 1950′s. In 2010, we began surveying the snail community on the bar, interested in what changes might have occurred in the 50 years since Paine’s time, a period during which very little research had been done in this system. I began synthesizing some of the data we’ve gathered, as well as talking to some of the long-term residents of the area. So what has changed on Bay Mouth Bar since the 1950’s? A number of things in fact:

  • Of the 6 most common predatory snail species, 2 are no longer present: the true tulip and the murex snail.
  • The number of specialist snails (like the murex, which only eats clams) has declined relative to the number of generalist snails (those that eat a variety of prey, like the banded tulip).
  • There has been a drastic reduction in the overall area of the bar and changes in the coverage seagrass, specifically the loss of large meadows turtle grass (Thalassia testudinum).
  • Surface dwelling bivalves (e.g. scallops, cockles), once enormously abundant, are now very rare.
True Tulip and murex Snails (no longer found at Bay Mouth Bar)

The two main snail species no longer found at Bay Mouth Bar, true tulip (The larger snail on the left, eating a banded tulip) and murex (right). The true tulip was, along with the horse conch, a top predator of the ecosystem, while the murex is a specialist snail, eating only clams.

Why is this interesting? Worldwide, we know that species diversity is declining as a result of human activities, that specialists are being increasingly replaced by generalists, and that consumer and predator species often face a disproportionate risk of local extinction. So what are the consequences of realistic losses and changes to biodiversity? Is having a diversity of predators beneficial (e.g. both horse conchs and true tulips) to an ecosystem as a whole? Do some species matter more than others? And how do the effects of predators depend on the type of habitat they’re in, given that habitats (like seagrasses) are also changing in response to the environmental changes? These are some of the questions I’m hoping to address in Bay Mouth Bar system, in which we have documented historical changes in predator diversity.

Tethered community in Tanya's Bay Mouth Bar experiment

One of communities in Tanya’s experiment. At the center are top predators reflecting either the current assemblage (a horse conch alone) or the historic assemblage (the horse conch and true tulip).  The predators are tethered to posts and given enough line to reach the lower level predatory snails (murex, lightning whelks, banded tulips, and Busycon spiratum) on the outside.  Those snails have enough line to get out of the large predator’s reach and forage for food.

This past week, I set up an experiment featuring a menagerie of snails tethered in different assemblages across Bay Mouth Bar. Some assemblages mimic the current assemblage, whereas others mimic the assemblage found on the bar during Paine’s time. These historical assemblages include the snail species no longer found there, which I collected from other locations where they are still abundant. Some assemblages have top predators (e.g. horse conchs) whereas others do not. Some are in turtle grass, others are in shoal grass. We’ll see how, over the course of the summer, these different assemblages affect the prey community (clams, mussels, small snails) and other elements of seagrass ecosystem functioning.

Music in the piece by Donnie Drost.  Theme by Lydell Rawls.

In the Grass, On the Reef is funded by a grant from the National Science Foundation.

 

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Notes From the Field: Horse Conch Honeymoon

Rob Diaz de Villegas WFSU-TV

When we started doing Notes From the Field, the intention was for the researchers and their techs and students to write about interesting things they saw or did while conducting their studies.  But I’m sneaking one in.  A couple of weeks ago I went out to Bay Mouth Bar with David Kimbro and his crew for their monthly sampling of gastropods and bivalves.  Horse conchs were plentiful during the summer months, but as the temperature drops they leave for deeper and warmer waters.  WFSU videographer Dan Peeri and I walked around getting shots of dead turtlegrass, a sign of seasonal change.  Oystercatchers were eating sea urchins; how close would they and the other birds let us get?

It was an interesting but quiet day when we heard a shout at the west end of the bar, facing the open Gulf.  Hanna Garland, newly returned from her graduate study on the crown conch problem south of Saint Augustine, seemed to have found something interesting.  Whenever there’s yelling at Bay Mouth Bar, there’s good footage to be found.  Hanna had found a pair of horse conchs mating.  There were several of the football sized orange snails on this side of the bar, including a second coupled pair.  It seems that they hadn’t quite made it to deeper waters, but were perhaps on the way.  And the behavior we observed got my imagination going.  Do they mate before heading on, laying their eggs in deeper waters?  Is that why they leave in the winter, leaving the door open for increased lightning whelk activity?  We can’t say that based on things we saw one day.  But that is one of the wonderful things about visiting wild habitats: seeing animals behave in different ways and getting glimpses into why things happen the way they do (even if careful study ends up providing an alternate narrative).

Horse conchs make an appearance in my EcoAdventures segment on the Leave No Trace principles on tonight’s episode of Dimensions, at 7:30 PM/ ET.  Part of visiting wild places and witnessing interesting behavior is not influencing it with your own behavior. We go over best practices for not disturbing a habitat and its inhabitants.  And for those who haven’t gotten enough Apalachicola River video, our State Parks One Tank Adventure segment tonight is on Torreya State Park.  Also, you can check out our new Apalachicola River and Bay Basin page, under the EcoAdventures North Florida menu.  From there you’ll have access to all of our videos on the basin (beyond the river and the bay) and play with our interactive photo map.

We want to hear from you! Who has seen any interesting animal behavior based on seasonal change? Add your question or comment.

In the Grass, On the Reef is funded by the National Science Foundation.

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The Combined Benefits of Research and Teaching

Dr. Randall Hughes FSU Coastal & Marine Lab

I recently completed teaching a 2-week course in Field Marine Science at FSUCML. Nine undergraduate students and one graduate teaching assistant lived in housing at the lab for the duration of the course, and we were busy from virtually sun-up to sun-down each weekday with class activities. It was a lot of fun:

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The students of Field Marine Science 2012 inspect what we caught trawling through a local seagrass bed.

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A group of students works to complete our field survey before the sun sets.

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Students hunting for mud crabs for a lab mesocosm experiment.

This year, we focused on oyster reef ecosystems, taking advantage of past and ongoing projects in the Hughes and Kimbro (aka, “Hug-bro”) labs. We conducted a field experiment, field survey, and mesocosm experiment examining sediment accumulation on oyster reefs – and all in just 2 weeks!

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Students quantify sediment accumulation on oyster shells during our field experiment.

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Students process the contents of cages from our field experiment, looking for crabs.

Well, the field experiment and survey were started ahead of time by Hugbro personnel, but the labor-intensive breakdown and sample processing tasks were handled by the class.

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Surveying mud crab abundance on our experimental reefs.

After all that time spent learning about, walking around on, and handling oysters, everyone was ready to eat a few by the end of the second week!

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An underwater camera gave us a great view of the seagrass!

In addition to gaining hands-on research experience, a goal of the class was to become familiar with common coastal habitats in northern FL. So we squeezed in a few trips to seagrass beds and salt marshes as well, enjoying the opportunity to ride on a boat that didn’t require paddles.

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Happily preparing to snorkel in St. Joseph Bay State Park, FL.

We observed lots of sea hares as we snorkeled in St. Joe Bay.

And we were all happy to don snorkels and masks to explore the seagrass instead of gloves and boots for the oysters!

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Results of a study by Feldon and colleagues demonstrating an increase in the quality of hypotheses included in graduate student research proposals when the students had teaching responsibilities.

As I catch up on the research projects that languished a bit while I was teaching, it is reassuring to think about the results of a recent study illustrating that teaching can increase the quality of research. Don’t get me wrong – I enjoy and value teaching for its own sake – but the tasks of teaching and research can often seem in competition with one another when time is limited (and when is time not limited?).

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Additional results from the study by Feldon et al. showing better experimental design in research proposals written by graduate students that teach and do research.

Enter the study by Feldon and colleagues in the journal Science, showing that graduate students with teaching responsibilities formed better hypotheses and generated better experimental designs in their own research proposals than graduate students without teaching responsibilities. This benefit did not result from explicit instruction in hypothesis testing or experimental design geared towards the graduate students themselves – rather, the process of teaching scientific concepts to others made them better able to conduct research. So add to the inherent fun and satisfaction of teaching a boost to my research! Time to write a (better?) research proposal…

 

At high tide, this reef will be covered in turbid water, and large predators like catfish, blue crabs, and red drum move in to eat smaller animals such as mud crabs.

Sounds of the Oyster Reef

Rob Diaz de Villegas WFSU-TV

IGOR chip_ predators_NCE 150Imagine you’re watching a slasher movie starring mud crabs as the protagonists.  A mud crab leaves the party in the muck under the oyster reef, where the other crabs are chomping down juvenile oysters.  As he pokes his head out from between a couple of shells, you hear a drumming sound and you shout at the screen “Don’t go out there!”

It’s fun to anthropomorphize some of the freaky looking residents of an oyster reef.  But these are the realities of living within the ecology of fear.  Predator cues have a definitive impact on how the smaller, intermediate consumers such as mud crabs behave.  That’s what David Kimbro, Randall Hughes & co. are studying in Alligator Harbor and at their sites across the southeast.  Large predators send certain cues to their prey- perhaps a certain way they move in the water, perhaps.  When the prey species sense that the predators are near, they cease activity- including the eating of juvenile oysters.  That is how large predators help maintain a healthy oyster reef- they make intermediate consumers (mud crabs) eat less of the basal species (oysters, the foundation of the oyster reef habitat). Continue reading

Photo Feature: Bedazzled Predator

Rob Diaz de Villegas WFSU-TV

Horse Conch shell covered in bivalves

IGOR chip- habitat 150It kind of looks like one of those vintage ’80′s jackets adorned with mirrors and sequins- mollusk style.  This horse conch’s got a little bit of everything on it, the result of an interesting reversal of roles in this seagrass bed on Bay Mouth Bar.

Continue reading