Tag Archives: predator

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.


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.


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.



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

Tanya Rogers FSU Coastal & Marine Lab
Tanya Rogers

Tanya Rogers

IGOR chip- biogeographic 150IGOR chip- habitat 150As Dr. David Kimbro’s research assistant, I help out with all aspects of the biogeographic oyster project in the field and at the lab. David, myself, and Evan Pettis (an intern from FSU) have returned from our big sampling effort to characterize the predator community on the oyster reefs at our chosen field sites. Over the course of a productive yet exhausting week, we successfully deployed and retrieved nets and traps at Alligator Harbor, Cedar Key, and St. Augustine and found very interesting differences in the abundance and diversity of fish species between sites. St. Augustine had by far the greatest diversity of large fish species, including redfish, snapper, toadfish, flounder, jack, ladyfish, bluefish, and menhaden. At Cedar Key and Alligator Harbor we caught longnose gar, a fascinating and very ancient fish with extremely hard scales and a long toothy snout. The largest fish we encountered were black drum, which we only captured at Cedar Key. Pinfish, hardhead catfish, and striped mullet were present at all of our sites, although in varying abundances.

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Rehearsal is Over

Dr. David Kimbro FSU Coastal & Marine Lab

IGOR chip- biogeographic 150Although we’ve busied ourselves this summer by selecting research sites and practicing various aspects of our sampling program, we have still not collected any ‘real’ data concerning the objectives of our biogeographic oyster project.  Well, this post will be short because as I write this we are hectically preparing to begin said research.  Coincidentally, tropical storm Bonnie has also decided to begin her work in the Gulf at the same time!

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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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Nuts and Bolts

Dr. David Kimbro FSU Coastal & Marine Lab

Why is Dr. Kimbro selecting smaller reefs to study?  How big is a mature oyster?  Watch and find out.

IGOR chip- biogeographic 150In my previous post, I outlined my original reasons for being out on the reef. Although I’m still pursuing those goals, my lab is currently busying itself on the reefs with some newly formed research goals. Anticipating the arrival of oil, we’ve scrambled a lot over the last few weeks to come up with questions and methods that will allow us to understand how the oil affects oysters as well as the assemblage of other important species that it supports.


Using kayaks, David and his crew moved more easily about Alligator Harbor

Step number one in gearing up to study the impacts of oil and to launch our original project involved figuring out a better way to transport a lot of people and gear out to the reefs during low tide, where shallow water prevents boating and deep mud prevents walking. My lab now uses a fleet of kayaks to zip around all the oyster reefs within Alligator Harbor, which sure beats sitting in highway traffic.

Now, once you see our study reefs (patchy, small and next to marsh), if you are a local, you must be thinking that we’re crazy for sampling these puny little things instead of the massive mudflat reefs that are more isolated from the marsh. And I wholeheartedly agree. However, my other colleagues studying oysters in VA, NC, SC, and GA don’t have big massive reefs like these anymore thanks to a much longer and more destructive history of harvesting, dredging and disease. So, to complete our original research goals and to compare things among many different estuaries, we are using the lowest-common-denominator reefs among all of our estuaries: hence the small and patchy little reefs we selected.

Ok, now we’ve figured out how to access our sites and we’ve selected our reefs. Although the latter sounds simple, it’s actually been pretty messy: kind of like my first trying to walk out to the oyster reefs in Alligator Harbor! Using global positioning system (GPS) and Google maps, my colleagues and I have been remotely weighing in on which reefs to use based on whether particular reefs are too large, too small, too close to the ocean, too far from the ocean, exposed to too much harvesting pressure, or exposed to too much pollution. Again, in order to learn how similar food webs operate and affect oyster reefs differently over long distances, we need to make sure that we are comparing apples to apples, not apples to oranges or young oyster reefs (nothing but small oysters) to old oyster reefs (nothing but large oysters) or polluted oyster reefs to pristine oyster reefs.

Over the past week, we’ve not only selected oyster reefs within Alligator Harbor to be part of our original oyster study, but we also set up additional oyster reefs to study the impacts of the oil spill. This involves permanently establishing areas within reefs that are censused for the number of dead and living oysters before the oil hits. Then, when the oil hits, we determine if the number of dead oysters increased.

But, even if we see more dead oysters than live oysters in the future, how do we know whether the oil (rather than some other factor) was the cause?


Well, we are also taking water, sediment, and oyster samples to be processed for stable isotopes. In short, chemical elements (e.g., Carbon, Nitrogen) exist in different forms (i.e., isotopes) and oil hydrocarbons have a Carbon isotope that can be used like a fingerprint.

So, we are also sampling the environment (water and sediment) and the whole food web centered on oyster reefs to determine background levels of oil. Then, when the oil hits we should see a tremendous increase in a new oil signature (that from the Deepwater Horizon spill) that coincides with negative impacts on oysters.

But, in addition to oysters themselves, we are also interested in the predators and prey that it supports. Because we do not yet have a lot of data describing when and how many predators and prey are around and because there is no way to get that data in time before the oil arrives, we are using other stable isotopes to quickly describe how predators and prey are organized within the oyster food web: who is eating whom. The isotopes of Nitrogen are good for this because the form of Nitrogen changes as it passes up the food web from things like oysters to things like big crabs and fishes. So, our second new question is… who has been eating what and how does this organization, which took a long time to develop, change immediately and a few years after the oil spill? Pursuing this new goal has involved some pretty fun hunting of all sorts of critters that make up the oyster food web such as amphipods, polychaetes (worms), clams, mussels, mud crabs, snails, blue crabs, stone crabs, and fishes. We just finished sampling Alligator Harbor and are now off to do the same things in Cedar Key, St. Augustine, and Jacksonville.

Because these four sites in Florida will likely experience much different levels of oil, we will be able to learn how much oil is required to negatively impact oyster reefs and the community of animals that they support.

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

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What we are doing on the reefs

Dr. David Kimbro FSU Coastal & Marine Lab

Oyster reef

Why are we on oyster reefs?

IGOR chip_ predators_NCE 150Well, I am broadly interested (and hope to make you interested) in how large predators can help protect important habitats like oyster reefs by preventing smaller animals from eating all the oysters.  I’m sure you can agree that we don’t need anything competing with people to eat oysters! It’s also important to keep enough oysters on the reef to filter water and provide habitat for lots of fishes and invertebrates, because these processes help keep estuaries healthy, and healthy estuaries support critical economic and recreational activities along our coastline.

Because 90% of the oyster reefs in the world were either eaten (they taste really good) or dredged away (they are a pain for boats to get around), we are specifically studying whether predator-prey interactions determine how the remaining 10% of our oyster reefs operate.  For example, it turns out that large predators such as fish and big crabs can protect oysters either by eating the smaller snails and crabs that consume the oysters or by scaring the snails and crabs enough to spoil their appetites for oysters.

Why should it matter whether the large predators eat or frighten the smaller predators, as long as the oysters don’t get eaten?  Since oysters are sessile, they can’t run away from their predators, but they can stop filtering water when predators are around in order to avoid producing a signal that can give away their location.  So if there are lots of oyster predators around, even if they are scared and not actually eating oysters, they may still keep oysters from filtering water.  And, the amount of water oysters filter matters, because filtration can remove excess nutrients from the water, helping to prevent algal blooms and low oxygen conditions in coastal waters (bad for fish and other animals).  This potential link between predators and nutrient cycling and whether it operates the same way in different places is why myself and researchers from the University of Georgia, University of North Carolina at Chapel Hill, and the Gulf of Maine Research Institute are out studying reefs from Florida to Virginia.

gulf oyster reef food web

If we can understand why more oysters survive in certain locations and how these oysters affect nutrient cycling differently in different locations, then we can better target our restoration dollars when trying to recover the other 90% of our oyster reefs, thereby getting the biggest bang for our buck.

We’re just getting started.  And as you can see from the photos and videos, it’s a slow and ungraceful process at first!

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

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