Tag Archives: experiments

Day 7: October Oyster Push- Last Day

Rob Diaz de Villegas WFSU-TV

Thursday, October 28- Finish up, head back home

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(Farthest to nearest) Hanna, Tanya, and Cristina perform some of the more glamorous work of this trip- cracking oysters apart and finding spat (oyster babies). David needed everyone on his team to perform, or this week would be wasted.

IGOR chip- biogeographic 150A while back, I was talking to Randall or David, I forget which one, and they were telling me about building a research crew.  Obviously you need people who have the knowledge and skills to do what needs to be done- from identifying fish to driving a boat, or setting a gill net.  But just as important, they said, was that you had people you could get along with, since you practically live with them sometimes.

Weeks like this one are where building the team pays off.  When you’re getting bitten up by gnats on an oyster reef at 6:45 in the morning, you don’t want a crew member sniping at another about losing a fish out of the gill net.  David remarked to me that the morale of this team had stayed strong, despite the schedule always changing and everyone having to shoulder more of the load while David got the tiles ready.  They did a lot of work on their own, and made it possible to get everything done even as plans shifted.

On a day like today, it was good that David has the crew he has.

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A swarm of gnats hovers over the oyster reef water.

6:45 AM- Retrieved fish from nets, deployed traps.

After a night of battling cockroaches in their “haunted” house, they might have been happier to be out on oyster reefs at this early hour.  They might have, had it not been for the no see-ums.  They were getting eaten alive, which made it hard to work.  And it got worse from there, as if the universe decided to pile it on in this last day.

As early as it was, the birds had gotten to their fish before they did and there were no stomachs to examine.  And then there were the injuries.  David cut his finger on a catfish spine, and then, within about ten minutes, a stone crab got a hold of Hanna’s finger and inflicted some pain.  They’re both okay.  Their truck, however, is a little worse off.

Truck accident in Jacksonville

Banged up over the course of the week, the crew- and their truck- are ready to come home.

When they got back, they glued spat onto tiles one more time to deploy this afternoon.

3:00 PM- Tanya, Hanna, and Cristina retrieved the traps and set the tiles.

7:00 PM- The girls headed back to the FSU Coastal & Marine Lab.  When they got there, they cleaned all of their gear, even though it was late.  They figured that it was better to wash the salt off sooner than later.

So that was the week.  They’ll go back to each of the sites about every six weeks, though it won’t always be this intensive.  David, Jeb (SC/ GA), and Jon (NC) will start to see seasonal patterns in the fish that they find- when do certain fish tend to show up on what reef?  They’ll check in on their tiles and take photos, and over the months the photos should play like a flip book in showing the growth of the oysters on each site.  They’ll gain understanding, and they’ll run into more road blocks.  They have about two-and-a-half years left on this study, so while Thursday was the last day of the push, they’re nowhere near the end of the road.

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Assuming no one tampers with them, we should be able to watch these oysters grow up over the next year.

Check back in a couple of weeks for wrap-up posts from David and Tanya.

Tide Times and height (ft.) for Jacksonville, October 28, 2010
Low- 6:44 AM (0.3)

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

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Day 6: October Oyster Push- Home Stretch

Rob Diaz de Villegas WFSU-TV

Wednesday, October 27- Finish tiles, go to Jacksonville

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When not losing sleep over whether the tile experiment will work, David dreams of making the tiles. They'll be back in six weeks to check on the progress of the baby oysters they set upon the reefs.

IGOR chip- biogeographic 150Walking down the hall of our dorm at 7 AM, I heard the familiar sound of the dremel from across the street in the lab area.  This time the whole crew was there- Tanya, Hanna, and Cristina cleaning and separating oysters and David Kimbro slicing shells into similarly sized pieces.  The Jacksonville oysters they’re processing have an entirely different kind of predator than the Marineland oysters have in crown conchs.  The Jax shells were speckled with little greenish spots- these are boring sponges.  They bore holes through the shell and take up residence within it.  The specks were making it harder to spot spat.

I was thinking about predators when I was driving today, in particular the crown conchs here.  A1A runs alongside the intercoastal waterway where the oyster reefs are.  Driving north towards the Matanzas Inlet, which is the northern boundary of the crown conch problem, there is a bridge under construction.  While getting some footage of oyster reefs earlier, I noticed how close many of the reefs are to the road and its runoff.  Overall, the area is more heavily settled than the Forgotten Coast sites where David and Randall do their studies.  This drive I took today put a slightly different light on the work they do.  When I’m shooting on the reefs, or in the salt marshes, it sometimes seem like a different world.  But it isn’t, really.  Not that this sudden and very focused problem may not have an entirely natural cause.  But there are a lot of potential factors in play outside of trophic cascades and water salinity.

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Those innocuous looking spots are trying to kill the oyster and take over its shell.

2:00 PM- Hanna, and Cristina drove to Jacksonville to deploy nets at low tide.  Cristina found a deep spot in the mud and sank in waist deep, which is a concern at this site.  The new boat was purchased specifically for this site, as it’s a long kayak trip in somewhat treacherous waters.

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So far, so good for the Saint Augustine spat tiles.

4:30 PM- David and Tanya finish making the Jacksonville tiles and spend about two hours cleaning up the lab space.  Tanya kayaked out to check on the St. Augustine tiles they deployed yesterday before heading to Jax.  David said he had lost sleep last night over whether the tiles would still be there, or if the glue would even hold the spat onto the tile.  Jon Grabowski (NC team leader) has a site with easy public access.  This morning he showed up to find his sites being harvested, the tiles already removed.  So you can see where David would worry.  But, at least over the first night, the SA tiles were fine.

David and Tanya joined the rest of the team in Jacksonville for another awesome Tanya-cooked meal.  I feel I did her a disservice yesterday by not mentioning the zucchini bread and double chocolate biscotti she made, so I’ll do so now.  Yum!  Perhaps On the Reef needs a cooking segment.  Everyone is now settled into a house they all think is haunted.  Hanna put together a makeshift tub on their screened-in porch to keep the spat alive to deploy tomorrow.  One more day to go…

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On Thursday, the October oyster push concludes and the FL, GA/ SC, and NC teams will start looking at the data and continue establishing patterns.

Tide Times and height (ft.) for Jacksonville, October 27, 2010
Low- 5:56 AM (0.2)
High- 12:25 PM (5.7)
Low- 6:42 PM (0.5)

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

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Roctober!

Dr. David Kimbro FSU Coastal & Marine Lab

IGOR chip- biogeographic 150I went to graduate school in northern California. Locals along the coast of NorCal used to refer to the month of October as Roctober because it was the most beautiful time of the year.  Well, I think the Forgotten Coast should also be privy to this monthly description because things have been beautiful around here this month.  Looking at the oyster reefs, I get the sense that things are really starting to get busy in there.  But I wonder if the ecology on oyster reefs in NC is starting to slow down.  Where are predators really having a big effect? We shall soon see.

For the past week, we have been trying to figure out how to do a lot of ambitious seeing and learning on all of our reefs.  All three teams (i.e., NC, SC/GA, and FL) need to not only sample fish and invertebrate predators on reefs (for the second time and in the dark…all because of the timing of tides in the autumn), but each team also needs to simultaneously squeeze in an experiment.  Oh, I just remembered that we also need to pay attention to other things that can explain oyster patterns: oyster food in the water (phytoplankton), water temperature, tides, and sediment properties.  So, add those to our to-do list as well!

Because this will be a ton of work to do in a short amount of time, we are sending a new crew member of the Florida team (Alicia Brown) up to help out the South Carolina/GA team.  We are going to send her up with a video camera, so it will be fun to get a glimpse into their lives over the next week.

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Jon Grabowski holds up a fish for Tanya to measure. David was Jon's lab tech at UNC.

In addition, one of the leaders from North Carolina (Jon Grabowski) has been down with us in Florida for the past week to help make sure that all three teams are doing the same thing.  While he was here, we also worked with a wonderful assistant up in Georgia (Caitlin Yeager) to figure out how to manufacture our experimental products.  The first part of this experimental puzzle involved figuring out how to remove baby oysters (spat) from oyster clumps in the field and to attach them to a standardized surface (tile).  Across all of our sites, we all want to start out with oysters of roughly the same size and age; otherwise, differences in our experiments among sites could simply be due to differences in starting oyster size or density, rather than to differences in predator diversity etc.   After we get all the spat attached to our tiles, we then built (well Tanya built most of them- thanks Tanya!) structures to put around our tiles, or not…

Tile Experiment

A partially open cage (cage control) that lets predators eat the oyster spat.

Our first structure was built to exclude all predators from munching on our oysters (i.e., predator cage).  Our second structure was a modified exclosure that mimics physical characteristics of the exclosure, but still allows predators to munch oysters (cage-control).  Finally, we have naked tiles that receive no structure or cage.  At 2 sites in NC, 2 in Georgia, and 3 in Florida), we will put each of these ‘treatments’ on all of the reefs (15 tiles/estuary or 105 tiles total).

But why do this crazy experiment thing?  Well, we will come back each month and monitor the traits of oysters and their survivorship.  With these results, we will compare survivorship or oyster traits from cages to that of the naked tile (“control”) to see if excluding predators improved oyster survivorship.  But because any improvement of oyster survivorship by the cage could simply be due to the physical structure (not to predator absence) providing shade during low tide or somehow changing flow (and food delivery), we will then compare cage results to that of the cage-control; now we can tell just how important predators are.

Another cool thing about the cages is that it may exclude predators from eating oysters, but they will not prevent predators from affecting traits of the oysters through intimidation.  So, do the traits of oysters surrounded by cages in Florida (maybe more oyster consumers) differ when compared to caged oysters in NC (maybe fewer oyster consumers).   Or, perhaps it’s that FL has more oyster food this time of year than NC and that better explains trait differences in oysters, not predators.  Or, maybe larger fish predators in Florida means less oyster consumers and less influence of oyster predation in Florida compared to NC, where there may be fewer large fish predators to eat the smaller crabs that love to munch on oysters.

To pull off this extra work, my Florida team will divide and conquer over the next week and a half.  Out of a team of four, 2 people will trap and gill net while the other two folks will set up the experiment.   This will involve ½ the team moving a head of the other team members at certain points.  But we’ll all overlap at each site for at least a few hours, which will then result in interesting stories about what each team has been observing.  Because we want to share this circus show with you over the next week, we’ll post updates every day.  We hope that this gives you a feel of what it’s like to get all of this done (both the good and the bad!).

Well, I need to go stockpile some sleep.

See ya,

David

David’s research is funded by the National Science Foundation.
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Eating contest: grasshoppers vs. snails

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150One of the really interesting aspects of the marsh community is that it is a mix of sea-based and land-based critters. At low tide, insects and rodents move in, whereas at high tide, snails, fish, and crabs dominate. The 2 most common plant grazers at our sites illustrate this dichotomy :

one is a land-based grasshopper(Dicromorpha elegans),

Grasshopper

and the other is a sea-based snail (Littoraria irrorata).

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In addition to being very abundant in our sites, the grasshoppers and snails leave distinctive grazing marks that alert us to their activity. Grasshoppers tend to chew large pieces out of the margin of the leaves, often resulting in the removal of large portions of the upper leaves. Snails, on the other hand, create razor-blade like incisions in the middle of the leaf:

grasshopper grazing 2

spartina with grasshopper grazing damage

Snail grazing scar

periwinkle grazing scars on spartina

We are interested in the potential for interactions between these 2 consumers, because they occur together in abundance at several of our sites. A preliminary experiment last summer suggested that snails somehow deter grasshopper feeding, even though neither animal can directly harm the other. (In fact, as you can see from the video, sometimes the grasshoppers even hang out on the snails’ backs!) However, it is possible that snails leave a “slime” trail that the grasshoppers don’t like, or perhaps snail grazing causes the plants to produce chemicals that make it less likely that grasshoppers will eat them.

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To find out more, we are repeating the same experiment (with some minor modifications) to look more closely at how much snails and grasshoppers eat when they are alone versus how much they eat when they are together. Because it is difficult to make grasshoppers stay where you want them, we are doing the experiment in mesh cages inside “mesocosms” (science-speak for large buckets) at the FSU Coastal and Marine Lab.

The mesocosms are set up to mimic the natural tidal cycle, with both high and low tides on a regular basis. We measured the height and number of stems of all the plants in each mesocosm at the start of the experiment, and we’ll take these same data at the end of a couple of weeks to see which species has the largest effect, and whether their combined effects are different from what we expect based on what they eat alone.

As an aside, this experiment is a good example of one of my ecologist’s rules of thumb: you can never do an experiment just once. There are certainly exceptions to this rule. (For example, when you have lots of experience with the animals you are experimenting with, when the experiment is just too large to repeat, or when the experiment relies on something you can’t manipulate, such as an oil spill.) However, I find that it generally takes one go-around to work out the kinks, figure out the relevant time frame, and discover unanticipated results. Then I can be much more confident the second time around that the patterns I am seeing are real!

The music in the piece was by Ric Edmiston.  We are always looking for local musicians to score our videos.  If you are interested and already have some music recorded, we would love your submission.

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

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Can plant species diversity provide protection against oil?

Dr. Randall Hughes FSU Coastal & Marine Lab

Watch Dr. Hughes’ species diversity experiment.  The results could help determine how best to restore marshes affected by oil.

IGOR chip- biodiversity 150With oil arriving on FL beaches, the race is on. We’ll be out in our sites this week collecting more data. We want to be sure that we know as much as possible about:

(1) the condition of our sites before oil arrives;

(2) the amount and specific location of any oil that does reach our sites; and

(3) the response of the marsh plants and animals to this oil.

We expect that there will be considerable variability in the degree and extent of damage to our sites, both because oil exposure will likely be patchy (at least at first), and because marshes are likely to differ in their ability to either withstand or recover from oil. And this variation in marsh response provides a prime opportunity for us to learn more about the specific marsh characteristics that either hinder or promote recovery, information that could be valuable in the aftermath of this disaster.

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"marsh 2," location of the species diversity experiment

One aspect of marshes that may aid in the response to oil is plant species diversity. A substantial number of scientific studies in the ocean and on land illustrate that having more species in an area can reduce the impacts of disturbance. For example, research by David Tilman and colleagues shows that drought impacts are less severe in Minnesota grasslands with more plant species. A number of different processes can contribute to these positive effects of diversity, but they generally result from the fact that individual species typically differ in their life history (the timing of growth, reproduction, etc.) and in their response to specific disturbances. Thus, if you have more species, you’re more likely to contain one or two that are able to withstand disturbance as it occurs, or that are able to re-grow quickly following the disturbance.

So, back to salt marshes and oil. We know from previous studies that different marsh plants have different tolerances for oil (1,2). Because the chances of a more tolerant plant species being present are greater when there are more plant species around, it seems possible that marsh plant diversity could reduce the negative impacts of oil exposure. We’ll get some idea of whether or not this is the case from our surveys of natural marshes – we know the plant species diversity before oil gets there, and we’ll be able to record the impacts to the marsh once oil arrives to see if the negative effects are reduced in areas with more species. But to get the “real” story (i.e., a story not complicated by characteristics other than plant species diversity that vary from marsh to marsh), we need to do an experiment.

Recently, we did just that – we set up an experiment to test whether marshes (“plots”) with more species (3) are less impacted by oil than marshes with few species (1). 3 species may not seem particularly diverse, but it’s on par with what we find in natural marshes. There’s a chance that our experimental site won’t get any oil, which quite honestly will be fine by me. (In that case, we’ll simply look at how marsh productivity and growth differ due to marsh plant species diversity.) But, if it does, we’ll be positioned to examine how marsh plant species diversity affects the response to oil contamination.

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

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What were we doing before Deepwater Horizon?

Dr. Randall Hughes FSU Coastal & Marine Lab

Watch the “snail experiment.”
Snails in the marsh

Periwinkle snails climbing on cordgrass

IGOR chip- biodiversity 150One of the marsh animals that we have been studying for the last year (in the absence of oil) is the marsh periwinkle, Littoraria irrorata. This snail is very abundant in many marshes and is particularly visible at high tide when it climbs the plant stems to get out of the water and away from its predators, primarily crown conchs and blue crabs.

While hanging out on the cordgrass stems, the snails will often create grazing scars that look much like a razor blade cut through the grass. Even though they don’t remove much plant tissue, they can have a big impact – fungus colonizes their grazing scars, and if the fungus becomes abundant enough, it can kill the entire plant, leading to marsh loss. (See the excellent work done by Brian Silliman at UF on this topic.)

One of the interesting aspects of many Panhandle marshes is that needlerush, a taller plant than cordgrass that usually occurs closer to land, can grow side-by-side with cordgrass at the water’s edge.

When needlerush is there, lots of snails climb on it despite the fact that they don’t eat it. (We think they like needlerush because it is taller and provides a better escape from predators than cordgrass.)

Because we noticed that the cordgrass that occurs with needlerush is taller and healthier than cordgrass that occurs in patches by itself, we are currently conducting an experiment to see if this pattern is due to the snails spending less time on cordgrass when needlerush is around. Each experimental plot is surrounded by a cage that serves to keep snails either in or out so that we can test their effects on the plants. You may notice the snails are very fashionable – we ‘tag’ them with nail polish so that we can differentiate the ones we put in the cages from ones that get in from the surrounding marsh. Some cages contain cordgrass only, whereas others contain a mix of needlerush and cordgrass. Finally, in some of the cages we have clipped the above-ground portions of all of the neighboring plants – this allows us to see whether the cordgrass simply prefers the environment that needlerush grows in, or if the needlerush must be present for the cordgrass to benefit.

As long as our experiment isn’t prematurely interrupted by oil, then we should have an answer to our question by the end of the summer!

Randall’s research is funded by the National Science Foundation. The song used in the video is Florida Breeze, by Craig Reeder.

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