Tag Archives: bonnethead shark

Reviewing the Oyster Study in 2010


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Dr. David Kimbro FSU Coastal & Marine Lab
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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:

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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?

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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:

Jeb cuts blue crab from shark belly

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.

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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.

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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.

Ciao,

David

David’s research is funded by the National Science Foundation.
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Way Back When On the Reef

IGOR chip- employment 150Along with David’s remembrances of his early life in marine biology, we have a video on one of David’s collaborators in this oyster study, Jeb Byers. Like all of the collaborators on the study, Jeb attended the University of North Carolina, where he overlapped with Jon Grabowski.  Alicia Brown was sent up to help Jeb’s team during the October Oyster Push, so we lent her a Flip camera to document the proceedings.  She got footage of some of the fish they caught, including the sharks that predate their reefs.

Dr. David Kimbro FSU Coastal & Marine Lab

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L to R- Tanya Rogers, Dr. Jon Grabowski, Hanna Garland, and Dr. David Kimbro. Here you have three "generations" of researchers and techs. Just as David was once Jon's lab technician, Hanna and Tanya help David today with his projects.

Burrrrr….it’s cold down here and I love it…a nice break from the no see’ums! We are gearing up to hit the road for some regular sampling (water/sediment sampling and down load instrumentation) as well as to check on the tile experiment that began 6 weeks ago. Props again to Tanya for getting us organized to go! Although, I have some anxiety about what I’ll see on the tiles because the adhesive we used to affix the oysters may not be working as planned; more on that that in the next post after we get a visual on things.

For now, I want to pick up where Randall last left off by reminiscing about how I first got into the research/oyster business and how it’s all Jon’s fault. Like Randall, I graduated from the University of North Carolina at Chapel Hill and was equally clueless about what I wanted to do in life. However, I did know that the coast was where I wanted to be.

While Randall, Jon, and many others where schlepping around tons of oyster shell in the hot North Carolinian summer, I was having a good time surfing by day and waiting tables by night.  All in all, I’d say that my summer was much more relaxing than theirs!

But after spending lots of time enjoying the coastal environment, I realized that I needed to look into this whole marine science thing. So, I began to nose around UNC’s marine lab and volunteered a little bit. By this time, Randall had taken off to teach middle school and Jon just got a prestigious offer to conduct research in Antarctica. But there was one glitch: who was going to run his oyster project in NC? He couldn’t just push the pause button on this research. Luckily, he had one last greater helper (Meg) whom he began training to be the boss. But she needed an underling. Enter me. Because they could not find a qualified research technician within three counties to hire, Jon decided to give ignorant me a shot. I was immediately told that the work was grueling and that the pay was peanuts. But I figured it had to be better than sitting indoors and watching the clock. Plus, Randall had already done the hard work by building all of those reefs; thank goodness I wasn’t on board for that madness!

Reaping the rewards from all the hard work that Randall and Jon exerted to build the oyster reefs, I got the easy work of just monitoring them and it was fun. When Jon returned from Antarctica, he saw that I hadn’t messed up anything too badly. That, coupled with my always asking him research questions made him decide to give me a little project of my own. And it is this experience that really sent me on my way into marine ecology. So, as I paddle my kayak out to the oyster reefs, think about interesting research questions, and enjoy the scenery, I often think back about the wonderful and fortuitous opportunity that Jon first gave me.

mud crab on Alligator Harbor oyster reef

Mud crab (Panopeus herbstrii)

Ok, do I have any stories? Of course. One classic story that seems to get re-told every time Jon and I get together concerns our ripping up his restored oyster reefs to see what critters lived within them. Now, Jon was really interested in mud crabs, how they affected oysters by eating them, and how larger predators affected this dynamic by eating or scaring the mud crabs. So, while I (the rookie) was working through samples, he was a bit concerned that I was missing many of the smaller crabs. Knowing about his concern as well as being a little bit grumpy about being over worked and being a little naughty, I decided to leave about 5 or so pretty large mud crabs in my sieve. I then said, “hey Jon, to make sure I’m doing this correctly, will you check over my sample to see if I missed any crabs?”. By this time, I had already processed many, many hours worth of samples. So, when Jon looked at my sieve, he immediately freaked out and thought about how many of the other samples I must of messed up. Oh, I had such a good laugh. Thirteen years later, I think this story still gets Jon’s blood pressure up.

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Years later, David heads his own team, and he and Randall are colleagues and collaborators with Dr. Grabowski.

What else…well, the winter work was so boring in North Carolina (lots of indoor time spent going through sediment samples) that I had to turn to coffee to help me make it through the late afternoon; with Meg’s persuasion (she was an addict and wanted some company). I stubbornly refused this drug all throughout college because I did not want to be an addict with smelly coffee breathe. But Meg was very persuasive and she started me out with small doses of Dunkin Donuts froofy, flavored coffees. Boy, this and some good 80’s music really helped me survive the late afternoon hours of sorting Jon’s samples in the lab. Next thing you know, I’m asking Jon for a coffee break (“hey man, can I take a quick trip to the Double D?”) every afternoon. Because Jon was a stingy boss (I say this with love), my and Meg’s new afternoon routine really annoyed Jon. But gosh, had I been open-minded about the joys of coffee back in college, I would have graduated with honors! In summary, the boringness of Jon’s project during the winter gave rise to my love of coffee (as Tanya eloquently captured in her last post), and it bugged the crap out of Jon…that and my caffeinated singing of 80’s songs in his lab during the later winter afternoons.

I could keep going with more stories, but I don’t want to give Tanya and Hanna any ideas or ammunition, so I’ll stop here.

Talk soon,
David

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