Tag Archives: experiments

Shark tooth found in Apalachicola Bay buoy marking oyster reef experiment.

Apalachicola Oyster Research: SHARK WEEK

Since they’ve deployed their experimental cages in Apalachicola Bay, David Kimbro’s crew has had some go missing, while others have been found in this condition.  Missing buoys make potentially unharmed cages nearly impossible to find.  Until just yesterday, there have been no leads as to the identities of possible culprits.

Dr. David Kimbro Northeastern University/ FSU Coastal & Marine Lab
Southern Oyster Drill

Shark week? In Apalachicola Bay, oyster drills like this one are the animals that have inflicted the most damage.

I’ll eventually get to how our research on Apalachicola Bay oysters ties into shark week. But first, let me tell you about my history with the annual Shark Week, which is put on by the Discovery Channel. Growing up as a surfer in North Carolina, the best time to surf was in the late summer and early fall. After many warm months of zero waves in the spring and summer, we lived for tropical storms that would make their way into the south east….but not get too close. I hated those suckers that got too close, because fun waves would quickly turn into pigs being on the roof and lots of misfortune for my fellow North Carolinians.

Getting to the point, every August, I was barraged by the Discovery Channel with interesting stories about sharks. Cool… but as soon as the waves start coming up, I’d have all of these thoughts about sharks circling through my head. In fact, in the line-up the next morning, it was looked down upon to talk about the previous evening’s episode of Shark Week. Now, sharks are awesome and they are critical to the health of our marine environments, but I don’t like to think about them when I’m waiting for a wave.

Okay, enter our research on Apalachicola Bay’s oyster reefs. It has been a very wet summer and the waters are very murky… you can’t see squat under water. But that doesn’t deter us, because we have been full throttle this past year and especially this summer on the monitoring and experiments.

Disclaimer: the pronoun we = Nikkie and Hanna, who have to do all the diving and data collection. To be honest, I couldn’t have asked for a better graduate student and employee to lead this research project.

Nikkie with crown conch (and egg casing), found in Apalachicola Bay.

Nikkie with crown conch (and egg casing), found in Apalachicola Bay. Surveys have found that while southern oyster drills have thrived on commercially harvested reefs on the floor of the bay, conchs have been more numerous on fringe reefs.

Now, another disclaimer is that Nikkie DISLIKES not being able to see under water. So, for all of the sites that I can’t free dive to collect the data (my scientific diver certification expired…next on the to-do list to fix), I would serve as shark/alligator bait by swimming on the surface of the water for 1/2 hour while others collected data below.

To be honest, I’ve skewered Nikkie about her fear and about needing me to serve as bait. BUT… then I got an email today from the crew, which happens to be the first mission since I departed from Florida for Massachussettes. This week, my lab is undergoing a Herculean effort to set up another experiment. In doing so today, they solved mystery of who/what has messed with all of our previous experiments and they simultaneously confirmed Nikkie’s fear. These experiments are protected by welded cages and marked with buoys, which have frequently and unfortunately gone missing. This is bad for our research funds, our time and for the data we need to understand Apalachicola and its oyster reefs.

So, in the spirit of the board game Clue...who dunna it?

Freaking sharks. Given Nikkie’s significant fear and my discounting of that fear, I sure felt bad getting this message from Hanna and Nikkie today. But hey, that’s what team Kimbro does for Apalachicola oysters!

(Edit 8/11/13.  FSU Coastal and Marine Lab’s Dr. Dean Grubbs IDs it as a bull shark.  Read more on this fact sheet from NOAA, from which we leave you with this quote: “Bull sharks are one of the three top sharks implicated in unprovoked fatal attacks throughout the world.”- Rob)

Shark tooth found in Apalachicola Bay buoy marking oyster reef experiment.

Cheers,

David

See more posts and videos on the Apalachicola oyster crisis and this research.

This material is based upon work supported by the National Science Foundation under Grant Number 1161194.  Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

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Notes From the Field, Apalachicola: Measure Twice, Cut Once

Waves and wind can make an underwater experiment challenging. But in Apalachicola Bay, it’s getting to where getting enough oysters to run an experiment is a challenge in itself. On Dimensions tonight (Wednesday, May 8 at 7:30 PM/ ET), get an inside look into what it’s like to go oystering during the oyster fishery crisis. We look at the men and women fighting for the bay, and the evolving alliance between those who work the bay, and those who would study it.

Hanna Garland FSU Coastal & Marine Lab

Hanna Garland and Meagan Murdock, Florida State University Coastal and Marine LabGrowing up, I always loved to help my dad with the never-ending list of house and boat projects, but because being a perfectionist is not one of my attributes, it would bother me when he would remind me to “measure twice, cut once.” However, whether taken literally or figuratively, this saying has had more relevance as I have progressed through college and now my graduate career. Take for example: the Apalachicola Bay oyster experiment.

In January, we conducted habitat surveys in order to assess the condition of oyster reefs throughout Apalachicola Bay by quantifying the oysters themselves as well as the resident crustacean and invertebrate species. We found some interesting patterns, but this survey data is just a “snapshot” in time of the oyster reef communities, so we designed an experiment that will investigate the survivorship and growth of market-size oysters in the presence or absence of predators at 12 reefs across the bay.

Live, market-sized Apalachicola Oysters epoxied to posts for an experiment in Apalachicola Bay.Mimicking the design of most of the oyster experiments in the Hugbro lab, we continue to keep the marine epoxy, mesh, and rebar companies in business by securing oysters into predator-exposed or predator-excluded treatments and then installing them onto reefs. While the habitat surveys were conducted via scuba diving (or sometimes walking because the reefs were so shallow!), we decided to give our free-diving skills a test for the oyster experiment installation in order to reduce gear and research costs. Being primarily intertidal researchers we are not accustomed to all of the logistics for subtidal research, but free diving is mostly a mind game, right?

Scuba and snorkeling gear.

The gear needed for scuba diving (left) versus free diving (right).

Wrong! Meagan and I were reminded that we will never be greater than Mother Nature or “the elements.” We were only able to install the experiment on 10 of the 12 reefs throughout the bay and due to unfavorable weather conditions and diving logistics, we were unable to complete the installation on the remaining 2 reefs or check the status of the oysters that had already been deployed. As a result, we will be restarting this experiment in May, but this time via scuba and with learned knowledge and experience of working in the bay, which will allow us to obtain a more complete and accurate experimental data set.

Buoy marking a submerged experiment in Apalachicola Bay.

These buoys mark experiment sites. Having the experiments submerged makes it otherwise invisible to passing boats and their propellors, and to oystermen and their tongs.

As frustrating as it may be to re-do the experiment, I was reminded at the recent Oyster Task Force meeting in Apalachicola, that the answer to the oyster crisis is going to take time; and in order to identify and quantify the environmental or biological stressors in the bay, research and management must be done correctly and entirely. So stay tuned, as there will need to be a lot more “measuring twice and cutting once” before we will be able to identify the key explanatory variables causing the loss of oyster habitat in Apalachicola Bay!

Music in the video by Nekronomikon Quartett.

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

In the Grass, On the Reef, A World Away

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biogeographic 150IGOR chip- habitat 150David and I are in Sydney, Australia, on visiting research appointments with the University of Technology Sydney. We arrived the first of the year, and after recovering from jet lag and getting our bearings, we embarked this week on setting up a couple of new experiments.  We have great local “guides” – Dr. Peter Macreadie (UTS), Dr. Paul York (UTS), Dr. Paul Gribben (UTS), and Dr. Melanie Bishop (Macquarie University) – to introduce us to the field systems and collaborate with us on these projects.

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Our seagrass and razor clam experiment is set up at Point Wolstoncroft in Lake Macquarie (north of Sydney).

Continue reading

A long time in the making

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150

As I mentioned in my last update, we have been working to set up a new marsh experiment in St. Joe Bay. The goal of the experiment is to see whether the genetic diversity of marsh cordgrass (Spartina alterniflora) affects how quickly or abundantly the plants grow, or influences the number of fiddler crabs, grasshoppers, snails, and other critters (like Ibis??) that call the plants home. But what is genetic diversity, exactly, and why do we think it may be important?

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A flock of Ibis resting among our experimental marsh plots.

Spartina is a clonal plant, which means that a single “individual” or clone made up of many stems can dominate a large area (low diversity), or there can be lots of different individuals mixed together (high diversity). In our surveys of marshes in the northern Gulf of Mexico, we find that there can be as few as 1 and as many as 10 clones in an area of marsh about the size of a hula-hoop. You may notice that our experimental plots are about that same size, though we used irrigation tubing rather than actual hula-hoops (not as fun, but more practical and less expensive!). We’re testing whether the differences in genetic diversity (1 vs. 10 clones) that we see in natural marshes has any influence on the marsh community.

A single experimental plot of Spartina that is 1m in diameter.

But why genetic diversity? We know from experiments by other researchers that Spartina clones grown individually differ in height, how many stems they have, and other characteristics. These same plant traits affect the critters that live in and among the plants – for example, periwinkle snails preferentially climb on the tallest plants. Because different animals may be looking for different plant traits, then having greater diversity (genetic and trait) may lead to a greater number of animal species that live in that patch of marsh. Or, a single clone may be the “best”, leading to higher numbers of animals in lower diversity areas.

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A view of the existing marsh behind our experiment.

As my title alludes, this experiment has taken a long time to come to fruition, in large part because it’s impossible to look at any 2 stems in a marsh and know for certain whether they’re the same individual or not. Unlike some clonal plants such as strawberries, where there are multiple berries connected by a single above-ground “runner”, Spartina has runners (aka, rhizomes) that connect stems of the same genetic individual under the ground, making it difficult to tell which stems are connected to which. We have 2 ways to get around this problem: (1) we use small snippets of DNA (analyzed in the lab) to tell clones apart, and (2) we start with single stems that we know are different clones and then grow them separately in the greenhouse until we have lots of stems of each different clone. It’s this latter part that has delayed this experiment – it has taken much tender loving care from Robyn over the last 2 years to get our Spartina clones to grow in the greenhouse to the point that we have enough of each clone (36 small flowerpots of each, to be exact) to plant in our experiment.

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Emily and Robyn work to remove existing rhizome material from around the plot edges.

But plant we finally did! With lots of help from members of the Hughes and Kimbro labs, we got all the sand in the experimental plots sieved (to remove any existing root material) and all the plants in the ground the Thursday and Friday before Thanksgiving.

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Team Hug-bro (Hughes and Kimbro) helping sieve sand!

 

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Meagan and Randall get the easy job - planting the plants.

Now we get to wait and see (and take data) whether Spartina genetic diversity matters for the marsh plant or animal community. There won’t be any quick answers – the experiment will run for at least 2 years – but we’ll be sure to keep you up-to-date!

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

Spat on a Platter

Tanya Rogers FSU Coastal & Marine Lab

IGOR chip_ predators_NCE 150“Spat tiles” are a tool our lab commonly uses to measure the growth and survivorship of juvenile oysters under different conditions, and we’ve used them with varying degrees of success in many of the experiments chronicled in this blog. What these are essentially (in their final form, after a good degree of troubleshooting), are little oysters glued to a tile, which is glued to a brick, which is glued to a mesh backing, which is zip tied vertically to a post. Rob and I have put together a couple interesting slideshows chronicling the growth of these spat over time from two of those experiments. Ever wonder how fast oysters grow? Observe…

This is a time series from our first spat tile experiment, which you can read about in this post. As you may recall, this experiment was largely a failure because the adhesive we used to adhere the spat was inadequate. However, we decided to keep the fully caged tiles out on the reefs to see how they fared over time in different locations. I photographed the tiles every 6 weeks or so, so that we now have a series showing their growth over time. The slideshow shows one of the tiles from Jacksonville. It starts in October of 2010. You’ll notice that not much growth occurs though the late fall and winter, but the spat start to grow noticeably from April-June 2011. From June-September the spat grow explosively and many new spat settle on the tile from the water column and grow equally rapidly. Just as plants (and algae) have a summer growing season, so too do the oysters that feed on them, when conditions are warm and there is abundant phytoplankton in the water to eat.

Next is a series of images from our caging experiment last summer, which you can read about here. Our large cages contained either:

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no predators (bivalves only),

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spat-consuming mud crabs and oyster drills (consumers),

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or mud crabs and oyster drills plus blue crabs and toadfish (predators).

The spat tiles within the larger cages were placed either exposed to potential predators or protected from them in a smaller subcage. Here are typical examples of what tiles looked like at the end of the experiment (about 2 months after starting). You can see how all the spat on the unprotected tiles were wiped out in the consumer treatments, but a good number survived in the treatments with no predators, as we would predict. In the predator treatments, most of the spat on unprotected tiles were removed, but not as fully or quickly as in the consumer treatments, which we would predict if the predators are inhibiting consumption of spat by the mud crabs and drills through consumptive or non-consumptive effects. You’ll see one tiny spat holding on in the predator tile shown. On the protected tiles, most of the spat survived in all treatments, as expected. We plan to further analyze the photographs from the protected tiles though, to see whether spat growth rates differed between them. We may find that protected spat in the consumer treatments grew slower than in the other treatments because of non-consumptive predator effects.

Currently, we’ve recovered most of our arsenal of spat tiles from the field, and I say we have probably amassed enough bricks to pave an entire driveway! Good thing we can reuse them!

The Biogeographic Oyster Study is funded by the National Science Foundation.