Tag Archives: mud crabs

Days 1 & 2: October Oyster Push- “Just Gun it”

Rob Diaz de Villegas WFSU-TV
Alligator Harbor at sunrise

The sun is about to rise in Alligator Harbor.

IGOR chip- biogeographic 150The first leg of David Kimbro’s Roctober oyster push is now complete.  If you look at the schedule below, you’ll see the first day was intensive, starting in the wee hours and going late into the night.  As David mentioned in his post, the head of the NC team (Jon Grabowski) was along for the fun.  David was Jon’s lab tech once upon a time, as was Dr. Randall Hughes (In the Grass).  So tagging along I definitely got some “family reunion” vibes, with lots of good natured ribbing (let’s just say it was good-natured).

For this October push, David will be breaking in a new boat to help his team cover ground more efficiently while lugging traps and samples around.  In order for the boat to move in shallow water, David replaced the motor with a lawnmower engine.  It worked fine on Thursday, when the water was higher, but it had a few problems Friday morning at low tide:

Jon drags the boat- and Tanya and Alicia

Jon Grabowski drags the boat- along with and Tanya and Alicia- after not being able to drive the boat through shallow waters.

Finally, they were able to get it to go.  The solution?  As David’s tech, Hanna, said- “Just Gun it!”

The catch this time was a little different than the last, with new fish like Red Drum ending up in the gill nets and no juvenile fish being caught in the minnow traps.  They also started looking into the stomachs of some of the predators (they have a permit to do so if the fish die in the net) and are seeing that the catfish here are eating mud crabs.  Mud crabs, of course, are key oyster predators.

Hanna kayaks

Early Friday morning, Hanna Garland kayaks to "site 1" in Alligator Harbor.

We’ll be heading out with David’s crew throughout the week.  On top of all of the other arrangements they have to make to move their crews around multiple sites hundreds of miles apart, they have to accommodate our camera crew.  So thanks for finding a way to drag us along!  Hopefully we can show people the kind of work that goes into making this kind of research happen.  There’s a lot of work to go along with the science, and with every subsequent sweep and new experiment, the patterns will hopefully clarify and our understanding of these ecosystems- and how to best conserve them- will be that much further advanced.

David’s crew has been split into two teams, the Net/Trap team (N/T) and the Tile team (TI).  For a closer look at how David’s team nets and traps larger fish and crabs, click here.  To learn more about what the Tile team will be doing, click here.  And if you click On the Reef under categories in the sidebar, you can track David’s progress over the course of this study.

Thursday, October 21-  Alligator Harbor

8:30 AM- Retrieve tiles, sediment, and spat. (TI)

11:07 AM- Deploy traps (N/T)

5:07 PM- Retrieve traps.  High tide activities: reference water level, water samples, replace spat sticks.  Unlike in the previous sampling done in Alligator Harbor, there were no juvenile pinfish or pigfish.(N/T)

8:00 PM- Deploy nets.  The nets will be retrieved Friday morning to give David an idea about what was swimming around over night.  (N/T)

Tide Times and height (ft.) for Alligator Harbor, October 21, 2010
Low-  8:07 AM (0.2)
High- 2:12 PM (2.7)
Low- 8:07 PM (0.9)

P1010300Friday, October 22-  Alligator Harbor

8:00 AM- Retrieve nets, data logger.  Today there were a lot of red drum (redfish) and of course, catfish (hardhead and sail).  On site dissection reveals that the catfish eat mud crabs, thus serving the same role that toadfish serve in North Carolina reefs. (N/T)

8:30 AM- Return tiles/ oysters.  The tiles for the new spat experiment mentioned by David go out today. (TI)

Tide Times and height (ft.) for Alligator Harbor, October 21, 2010
Low-  8:40 AM (0.1)

David and his team are taking Saturday off.  Bright and early Sunday morning, the Net/ Trap team heads for Cedar Key while the Tile team heads to Saint Augustine.

David’s research is funded by the National Science Foundation.
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This is what an oyster reef looks like…

Rob Diaz de Villegas WFSU-TV

IMG_3499

The photo above is my work computer’s desktop picture. Most of the time, when people see it, I find that they had no idea what an oyster reef looked like.  One coworker thought it was a muddy cabbage patch.  To be honest, until I first stepped on one for this project, I wouldn’t have known a reef from a pile of rocks.  And, like a lot of people, I love eating the things- right out of the shell with a little grit and juice.  That’s the disconnect we sometimes have between the food we eat and from where it comes.  So it occurred to me that, while we’ve been talking these last few months about the complex relationships between predators and prey on the reef, it might be helpful to get back to oyster basics.  Over the following weeks, we’ll cover various topics (like why subtidal oysters are harvested more often than intertidal ones like those up there).  We’ll start with what it’s actually like out on a reef, and what you’d see there.

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A closer look into the reefs

IGOR chip- habitat 150The following photos are of samples taken at each of Dr. Kimbro’s sites, as mentioned in his previous post.  After surveying the reefs to see what large fish and crabs were living in the reefs, he and his team turned to looking at the oysters and the creatures living under them in the mud.  That’s what you’re seeing here.  Click on any photo to make it larger.

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On the Road Again

Dr. David Kimbro FSU Coastal & Marine Lab

IGOR chip- biogeographic 150As my assistant Tanya eloquently wrote in our last post, our July efforts produced interesting data on the predatory fish and crabs that hang around oyster reefs from North Carolina to Florida.

CK_exposed_reef

Cedar Key reefs, like the one above, tended to be sparser with slightly larger oysters than those in Alligator Harbor

After working on our sleep deficits, we dialed up some Willie Nelson on the iPod and were on the road again during the second week of August.  Our goal: to determine if predator patterns on oyster reefs from NC to Florida were associated with any patterns in oysters (e.g., number and size) and smaller animals that both use oyster reefs as habitat (e.g., polychaetes and crabs) and as food (e.g., crabs).

This destructive sampling involved ripping up large sections of our reefs and placing them in large bins while trying to prevent any crabs or other critters from falling out.  Because these are marine organisms, we had to work fast and quickly get them into a temperature-controlled room (50 degrees F) back at FSU’s Marine Lab.  Easy when collecting samples from nearby Alligator Harbor, but not so easy when collecting samples at our other three sites in Florida.

KImbro Team oyster reef sitesBut before dashing back to the lab, we deployed some instrumentation and took lots of sediment and water samples (more about this stuff later).  Then, the race to keep our samples fresh commenced and mostly occurred on I-95 and I-10; I’m still seeing lane dividers and road reflectors when I close my eyes at night.  After a few hours of sleep, we would drive back across the state to another site and start the process all over again.  All of this sleep deprivation and highway racing against biological clocks made me feel like I was Smokey the Bandit boot-legging some Coors Beer across state lines (maybe I’m showing my age here, but a classic movie nonetheless).

Luckily, we had some great volunteers to help process these samples back at the lab while I was out ripping up oyster reefs, because processing each sample took a long, long time.

processing

Liz and Hanna sort the reef samples.

After a week and a half of sample processing, it was really cool (or so I hear, because I was mainly on the road) to see all the animals living within the oyster reefs and how they and the reefs themselves differed from site to site.  For instance, Alligator Harbor seemed to have dense reefs of small oysters while Cedar Key had sparse reefs with slightly larger oysters; both had few mud crabs (maybe due to the abundance of big fish?).  We also noticed that animals north of Jacksonville must be on growth hormone supplements because everything is gigantic (bigger mussels, bigger crabs, and bigger oysters).  Meanwhile, the crown conch population in St. Augustine is huge and appears to be mowing down the oysters.  So, now I have new side-project: why are crown conchs an abundant nuisance for oyster reefs in St. Augustine but not at other sites?

From one week of field work, we now have about a month or so of associated lab work that will involve counting, measuring, and identifying every organism.  I’m really excited to see how all the predator, intermediate consumer, and oyster reef data correlate from estuary to estuary.

Best,

David

David’s research is funded by the National Science Foundation.
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You can’t enjoy watching the game if you don’t know who the players are

Dr. David Kimbro FSU Coastal & Marine Lab

See David and his crew in action, and see what animals are on Alligator Harbor reefs.

IGOR chip- habitat 150The title of this blog (a sports metaphor) is how my teacher first introduced me to marine ecology. For our oyster project, this essentially means that we need to establish who is on the oyster reefs before we can begin to make connections among predators, oysters, and their water filtration services….as well as (unfortunately) the impacts of oil.

So far, we’ve identified the organisms on the bottom rung of our food web (think of it has a pyramid): oysters, clams, amphipods, and polychaetes on the bottom rung of the food web and mud crabs and snapping shrimp on the next higher rung of the food web. Our goal this week was to begin quantifying who is at the top of this food pyramid. To do this, we deployed crab traps, bait-fish pots, and gill nets onto each of our reefs during low tide. Following the ensuing flood tide, we returned the next day to count our catch and then promptly release everyone.

hardheaded catfish

the hardhead catfish was the most abundant species trapped during this survey

Although we caught a couple of interesting things (e.g., adult stone crabs, mullet, spot, as well as juvenile pinfish, pigfish and silver perch), I was surprised by the low abundance and diversity of our catch and that the most abundant species was catfish!

But after running out of fresh water to drink and profusely perspiring all the moisture out of my body while out on the reefs, it dawned on me that nature of this catch is likely an interesting seasonal pattern (again, I’m new here!): only hardy organisms that can tolerate really hot and low oxygen waters are going to be on Florida reefs right now. Once the rest of this research team begins collecting similar data from Virginia to Florida, it will be interesting to see if these low abundance-diversity patterns might last longer in some areas (e.g., Florida with longer summer) than in others (e.g., NC with shorter summer). If that’s the case, then the cascading effects of higher order predators (things at the top of our food web) down to oysters and their water filtration services may be occur more consistently during the summer in northern than in southern estuaries.

Hmmm…..good thing we are conducting a relatively long-term study and will consistently repeat this sampling in the future to rigorously detect interesting patterns like this one.

Until next time…

The Music in the video was by Jim Crozier.  As always, we welcome submissions from local musicians. WFSU’s kayak was provided by Wilderness Way.

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

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