One of the most fascinating aspects of the field of science is the unpredictable patterns and directions that certain communities can take over a period of time. Whether the change in a habitat occurs due a spontaneous event such as a devastating hurricane or a longer, more gradual event such as climate change; it is important to understand the impacts these changes may have on the resident organisms as well as the future of the community. Studying how organisms respond to each other and their environment are key principles of ecology.
As David mentioned in the previous post, I have recently begun my graduate student work in St. Augustine, where I hope to gain a better understanding of the unique observations we have made while working in the area for the NSF oyster project.
Other than being the nation’s oldest city, St. Augustine is a very dynamic place. From condominiums and restaurants to historic landmarks and beautiful beaches; the area is flooded with snow-birds during this time of year. More notably, St. Augustine has countless state parks, wildlife preserves, and protected habitats; which allow for not only attractions for tourists but areas of research for scientists and most importantly, shelter and nurseries for the resident wildlife. Continue reading →
Scanning the photo, you can see crown conchs crawling about this Saint Augustine reef. Crown conchs are a normal sight on Florida reefs, but not to the extent seen here. David has tasked Hanna Garland with looking into this very localized phenomenon and its relationship with increasing reef failures.
Dr. David KimbroFSU Coastal & Marine Lab
Last week I detailed a recent trip to St. Augustine, ending the post with a mention of a side project being embarked upon by my lab there. Throughout the past year, we’ve noticed that our St. Augustine study site was loaded with tons of crown conchs. Although crown conchs are ubiquitous in Florida, they are abnormally abundant on our St. Augustine reefs and our St. Augustine reefs are mostly dead. All our other sites have relatively healthy looking oyster reefs and few crown conchs.
But a few miles north of our monitoring reefs, we find absolutely no crown conchs and the health of the oysters is great. Because crown conchs, as has been shown by the research of our very own Doc Herrnkind, love eating oysters, it’s easy to conclude that crown conchs have mowed down all the oysters on our monitoring reefs. But why are they restricted only to our monitoring reefs? Is there a predator of conchs present north of reefs but that is absent on our monitoring reefs? Perhaps the environment has changed in a way that killed all of the oysters and the crown conchs are just cleaning up the mess.
Proboscis out (protruding from the bottom of the snail), a crown conch heads towards a clump of oysters. The conch will use its proboscis to pry open the oyster shell and suck out the meat.
Luckily, Hanna has agreed to enter my lab as a graduate student to tackle this research project. So, she spent a number of days collecting coarse-scale data on the spatial extent of this conch-oyster pattern, consulting with locals about when this pattern developed, and talking with an oceanographer about how to learn whether and how the physical environment has lead to this pattern. In a forthcoming post, I’ll let Hanna fill you in on the details of this new project, which we will be implementing quickly. This is really important to the local community because our monitoring reefs and the conch infested area used to be the most productive area in St. Augustine for harvesting oysters and rearing clams. But now, aquaculture leases here have been abandoned and a very large population of crown conchs appears to have taken up residence.
Stay tuned for Hanna’s post later this week, she’ll go into a little more detail on what we’re doing.
David’s research is funded by the National Science Foundation.
On Wednesday, June 29 at 7:30 PM/ET, WFSU-TV premieres the In the Grass, On the Reef full length documentary. David and Randall guide us through the world of coastal predators (like crown conchs). Top predators maintain important ecosystems like salt marshes and oyster reefs- but the manner in which they do this may not be confined to eating prey. Tune in to find out more!
Where did my winter of catching up on work go? And why is spring quickly hurtling into summer? YIKES!
…Okay, I feel better. All of us here feel a little behind on things, because this past winter and spring have been full of other projects (in addition to the oyster one) such as investigating how the oil spill affected marshes throughout the west coast of Florida and examining what all of those snails are up to out on Bay Mouth Bar. But now that summer is almost upon us, it’s time to move all hands on deck back towards the ambitious summer oyster goals.
Environmental vs. Predator Effects.
To lay the ground work for this summer’s oyster research, I spent a few days in St. Augustine, Florida, which is where we will conduct our colossal field experiment. As a recap of the oyster objectives, we spent year 1 monitoring the oyster food web at 12 estuaries between Florida to North Carolina. Well, we found some cool patterns regarding the food web and water-filtration/ nutrient cycling services on oyster reefs (see the 2010 wrap-up). So, now we want to know what’s causing those patterns. Are differences in oyster reefs between NC to FL due purely to differences in water temperature, salinity, or food for oysters (phytoplankton)? Or, do we have a higher diversity of predators down south that are exerting more “top-down” pressure on the southern reefs? Or, is it a combination of the environment and predators? Continue reading →
Michael Harrell is a local artist, brought to WFSU-TV’s attention by one of our viewers. Michael paints in both oils and watercolors and among his nautical themes are depictions of the oystermen of Florida and South Carolina. This video looks at that series of paintings. The thing that I found so beautiful about his work is his ability to capture a sense of time with his portrayal of light. You can find additional information about the artist at MichaelHarrellArt.com.
Our local oystermen, as you see in this video, typically harvest subtidal oyster reefs like those in the Apalachicola Bay. Michael Harrell also shows South Carolina oystermen harvesting intertidal reefs like those covered in this blog (i.e. Alligator Harbor). The South Carolina sites of the biogeographic oyster study are sampled by Jeb Byers’ group.
This week’s videos look at Dr. David’s Kimbro’s collaborators in the NSF funded biogeographic oyster study. While he has been the face of the study for On the Reef, he is one member of a team of scientists. Today’s videos feature Dr. Randall Hughes (In the Grass) and Dr. Jon Grabowski. Later this week, we’ll have a short video with Dr. Jeb Byers. Randall and David’s posts accompanying the videos are reminiscences on their early days in marine ecology in North Carolina, where they and their fellow team members met while in school.
Dr. Randall Hughes FSU Coastal & Marine Lab
Getting my first taste of marine ecology.
In my last semester as an undergraduate at the University of North Carolina-Chapel Hill, I took a class in marine ecology from Dr. Charles (Pete) Peterson and Dr. Mark Hay.
At the time, I was a double major in biology and public policy analysis, and despite being just a few months from graduation, I was still very uncertain what I was going to do next. So when Pete asked me if I would like to work as a summer research assistant at UNC’s Institute of Marine Sciences for his graduate student, Jon Grabowski, I accepted with little idea of what I was getting myself into.
Jon’s project involved comparing the value of restored oyster reefs in different locations in the marsh (next to marsh edges, sandwiched between marsh edges and seagrass beds, or isolated on sand flats) as habitat for important fishes and crabs. What that meant in reality was that in the summer of 1997, we used ~2 tons of dead oyster shell to create 12 intertidal oyster reefs in Middle Marsh, NC – largely by carrying the shell in orange baskets from one big pile to the specific places where we needed it.
One of the reefs we built in 1997 on a sand flat, pictured here in 2002.
In the process, I learned to trailer and drive a boat, build 30+ fish traps that involved welding rebar together and dipping the whole contraption in “net dip” (the most disgusting substance known to man), deploy and retrieve those traps and happily (well, at least begrudgingly) handle the blue crabs, toadfish, and other critters that we caught, and various other tasks that made my parents wonder why I needed a B.A. degree for this job. But by the end of the summer, I was hooked!
Jon, before he was Dr. Grabowski.
After that first summer, I returned to work with Jon for 3 more field seasons until starting graduate school myself in 2000. (David and my paths crossed at IMS, working for Jon together in 1999.) During the “off-season” I taught school, first in Mexico and then in NC, because I wanted to be sure that becoming an ecologist was really the thing for me. I love teaching, but I love research even more, and so going to graduate school seemed the logical way to combine the two.
Much like the no-see-um story from Jacksonville, the long hours and hard work involved with Jon’s project generated a lore surrounding that first (and subsequent) years. Here’s just one of my favorite stories from the summer of 1997 –
Dr. Pete Peterson in Middle Marsh, NC.
Once the reefs were created (and lots of stories could be told about that process), the plan was to sample them once a month over consecutive daytime and nighttime high tides. Because we couldn’t sample all of the sites at the same time, this involved 48 hours of effort with only short breaks in between times in the field. The first time attempting this sampling happened to fall the 2 days before I was scheduled to leave to start my job teaching in Mexico – oh, and on my birthday. After day 1, we realized that returning to the lab from our field sites and then going home to get cleaned up before getting some rest was burning lots of valuable sleep time, so we decided that the second night we would camp on one of the barrier islands close to our sites. Jon packed most of the gear, including a giant and heavy cooler, and off we went. Of course, it was the middle of the night when we finished up in the field and drove the boat over to Shackelford Island, and we hadn’t bothered to set up camp earlier in the day. Jon thought he knew of a shortcut to cross over to the ocean side, which had a nice breeze and far fewer mosquitos. Unfortunately, we didn’t find the shortcut immediately, and we ended up carrying the heavy cooler and all of our other gear while swatting and cursing mosquitos for quite a while. About 5 minutes from the beach side of the island (though we didn’t know that at the time), I snapped, announcing to Jon that I was NOT walking any farther and so we better set up camp in that spot. (I had maintained a fairly mild-mannered and easy-going persona all summer, but there was nothing mild about my ultimatum that we stop walking.) I was in better spirits after a few hours of sleep, feeling more than a little chagrined at my outburst when I realized how close we were to the beach, and especially when learned that the primary object in that heavy cooler was a chocolate birthday cake for me! I have since apologized many times, and Jon and I laugh and re-tell that story virtually every time we get together.
Of course, beyond the friendships, funny stories, hard work, and good food, we also learned a heck of a lot about oyster reefs and the animals that live on and around them. That’s why our current collaboration “On the Reef” is so satisfying – it’s a way to return to our roots scientifically, professionally, and personally.
The biogeographic oyster study is funded by the National Science Foundation.
(Editor’s Note. Although David refers to Randall’s participation on this study, her role was not elaborated upon in this video. That will be a part of the next video, on David’s collaborators, as Randall is David’s Co-PI- or Primary Investigator)
Tanya measures a fish caught in a gill net.
It’s been said that research techs are those who do the dirty work in science. Although true in many ways, I love being where the action is, collecting the data, turning ideas into reality. That said, here is some of my perspective on what went into our October trip and what days in the field were like.
A busy field trip like our October sampling push typically takes at least as many days to prepare for as the length of the trip itself. Although the daily blog posts covered our time in action, David and I spent most of the previous couple weeks just planning for this trip so that it could run as smoothly as it did. I feel it worth mentioning the many hours I spent pouring over tide charts and editing and re-editing our complicated schedule so that we could accomplish everything as efficiently as possible, factoring in all manner of time and tidal constraints, travel time, land and sea transportation, overnight stays, and numerous other variables, plus designing it with enough flexibility that we could adjust our plans in the field at a moments notice (and indeed we did). In addition to scheduling I also had to make sure we had all the materials we needed to for our trip, that those materials were all in working order, and that they are all packaged up accordingly and conveniently in our two vehicles. The last thing you want is to be out in the field and realize you’re missing some critical piece of equipment.
As they conduct these initial sampling trips every few months, they keep finding new and interesting species living in and around the reefs. Here, Tanya is taking measurement of one of her favorite finds of this last trip, a striped burrfish.
Out in the field, going to retrieve our traps and nets is always the most exciting for me, since you never know what we’re going to catch, and I was interested to see how the October fish community compared with that of July. We caught a few new fish species in our traps this round, including a beautiful spotfin butterflyfish (Chaetodon ocellatus), juvenile snapper (Lutjanus sp.), and a couple tiny pufferfish (technically striped burrfish, Chilomycterus schoepfi – they were very adorable). Equally exciting was getting to use the new motor on our skiff for the first time at our sites. Although noisy and bizarre-looking, it performed admirably in shallow water, as it was designed to. At least in terms of temperature and humidity, conditions on the reefs were considerably more pleasant for us than during the summer. It was wonderful not to be wiping sweat from your face every 10 minutes. The dramatic increase in the no-see-um population at dawn and dusk was not so pleasant however, as David has duly noted. The dawn low tide at Jacksonville brought the worst swarms we’d ever encountered in the field. Incredibly irritating both physically and mentally, they made work nearly impossible, and forced me to spend the subsequent week covered in uncountable numbers of ravenously itchy welts.
Despite its exotic look, the spotfin butterfly fish is a native of both the Gulf and Atlantic coasts of Florida.
When not out on the reefs, there was rarely a moment when something didn’t need to be done – whether filtering water samples, rinsing gear, or (most frequently) extracting spat. Our only breaks seemed to be for the necessities of eating, showering, sleeping, and making coffee. (For David, coffee appears to rank just below data and samples in terms of his most valued possessions in the field.) Our biggest and most time-consuming challenge was whether we could get all of the spat extracted and tiles made for our predator-exclusion experiment in the time allotted between netting and trapping. The process of isolating spat was incredibly tedious to say the least, and particularly frustrating when, after you’ve been working on a spat for several minutes, your tool slips and the spat gets crushed, or it flies across the patio, never to be seen again. You couldn’t help but feel the spat always picked the most inconvenient places to settle. It was also quite a messy process, with water and oyster bits flying everywhere and various crabs skittering across the counter. The oysters also love to slice your fingers open during the few moments when you neglect to wear gloves. Yet in spite of the tedium, we couldn’t help noticing new and interesting critters living amongst the oysters as we broke them apart. For instance, we noticed considerably more porcelain crabs (Petrolisthes sp.) and Boonea impressa (a small, white snail that parasitizes oysters) than we’d seen in previously collected oyster samples. We also found an oyster pea crab (Pinnotheres ostreum), which lives on and steals food from the gills of oysters, and a number of dark brown cylindrical mussels (Lithophaga bisulcata) that bore into the calcareous shells of oysters. It always amazes me how many different animals can be found living within the structurally complex habitat created by species like oysters.
Young oyster spat, beginning their new careers in science.
I remember on one of the last days of our trip, I kayaked out to our St. Augustine reefs for a final service and check while David finished up the dremeling. I remember looking upon reef #5, seeing our newly deployed, spat-covered tiles and cages, our cleaned tidal data logger housing, and our newly replaced spat stick, arranged so neatly on our marked reef, and feeling delighted at our accomplishment, knowing how much effort has gone into this setup. I remembered that in my position it’s easy to get sucked into the details, but it’s equally important to remember the big picture, and how this research will contribute to our greater understanding of oyster reef ecology.
After our field trip, as we recover from battle wounds and wait for the mud to work its way out from under our fingernails, work on the oyster project continues at the lab. For me this has meant entering lots of data and starting to process our many samples. Before you know it though, it’s time to start to preparing for our next journey onto the reefs and the adventures that await.
The Kimbro, Hughes, et al. biogeographic oyster study is funded by the National Science Foundation.
(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.
A 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.
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.
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.
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.
We’d love to hear from you! Leave your comments and questions below:
David Kimbro’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.
Monday, October 25- Both teams in Saint Augustine
That grey spot (dead center) on the shell is spat. After landing on existing shells, they'll build their own and expand the clump.
When I got to St. Augustine, David was chiseling out shards of shell containing oyster spat (baby oysters) from clumps so that he could glue them onto tiles, as he described in Friday’s post. I got a good look at what spat actually was. You can see it in the photo here, basically a small oyster with no shell, seeking out a hard surface (often another oyster’s shell) upon which to settle. David stayed behind doing that as the rest of his crew, and our crew, piled into the boat for this evening’s activities.
This new experiment- placing tiles with the same number of oyster recruits at all sites on every reef across the study- will give them a more precise picture of how young oysters survive at each site. It also means a lot of extra work, as the spat that goes on the tiles has to be from the specific location to be entirely accurate- spat is harvested one day, immediately chiseled off and made into tiles and placed on the reef, in the span of about two days. And this is in addition to the other sampling and trapping. The previous tile method worked fairly well for the NC and SC/GA teams, but for the sake of being consistent, they’ve also had to adapt this method (while cursing David Kimbro’s name).
Crown conchs in St. Augustine making a snack of an oyster.
As previously noted on this blog, the reefs did have plenty of crown conchs crawling on them. David and Tanya have also started noticing Atlantic Oyster Drills, a smaller snail we don’t see in the Gulf. I’ll look for some tomorrow and get a photo or two up.
8:00 AM- Hanna and Randall (N/T team) retrieved the nets that they set last night in Cedar Key. This is low tide work, as that’s when it’s best to empty the nets. They got to their first reef after the vultures did, losing a bit of their catch but still able to identify some species from the fish heads left behind.
1:00 PM- Hanna headed to Saint Augustine and Randall headed home. As Hanna was gassing up the truck and boat, an elderly gentlemen circled the boat, in awe of David’s creation. Eventually, he said, “sweet boat.”
A sweet boat.
5:00 PM- Deploy nets, take water samples, and reference water level. The two teams combined activities that would have kept them out past dark, and finished just as the sun was setting. They then helped David glue spat onto tiles for another hour or so before heading out to dinner.
That was the day. As you see, field work involves a lot of rethinking (as in the tile experiment), thinking on your feet, dealing with circumstances (vultures eating your catch), and coming up with unusual solutions (refitting your boat in a way some might find strange). It’s pretty late now (as I type this, even though I plan to post this in the morning). Time to head to bed so that I can get up and shoot that sunrise.
Tide Times and height (ft.) for Cedar Key, October 24, 2010
Low- 10:oo AM (-0.3)
Tide Times and height (ft.) for Saint Augustine, October 25, 2010
High- 1:35 PM (5.3)
Low- 8:41 PM (0.6)
We’d love to hear from you! Leave your comments and questions below:
I 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.
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…
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.
David’s research is funded by the National Science Foundation.
In my previous post, I described how tides could influence the oyster patterns that we are observing throughout the Atlantic and Gulf coast. But throughout the Gulf coast, can tides explain why most of the oysters sold in restaurants come from subtidal reefs? Are subtidal oysters healthier, happier and thus more abundant?
Well, before I attempt to address this issue, let’s first talk about the difference between subtidal and intertidal oyster reefs. The term intertidal refers to a habitat that spends part of the day submerged by water and the other part of the day out of the water. In contrast, the term subtidal refers to habitats that are constantly submerged by water. Interestingly, along the NW coast of Florida, oyster reefs are subtidal from Pensacola to Apalachicola Bay. And east of Apalachicola, oyster reefs become intertidal.
Fouling organisms grow on hard surfaces under water.
Now back to the second question above: are subtidal oysters happier and healthier than intertidal oysters? Research by Dr. Charles Peterson at the University of North Carolina at Chapel Hill suggests the answer is no because both reef types have different costs and benefits that keep growth and health roughly the same. For example, subtidal reefs may get the benefits of being inundated all the time by food-rich water, but this constant submergence also has costs that include: getting covered by fouling invertebrates (i.e., animals commonly found on the bottom of boats that look like silly puddy) that compete with oyster for food and being exposed to more marine parasites and disease. In contrast, the harsh sun baking that intertidal oysters receive during every low tide can be painful and they may also get exposed to less food, but the sun baking also cooks off the silly-puddy competitors and it also keeps the parasites away. In the end, these different costs keep growth rates about the same between subtidal and intertidal oyster reefs. This is why intertidal oysters from Cedar Key, Florida can be just as big and delicious as subtidal oysters from Apalachicola.
Now I’m ready to tackle the first question from above: why do so many more oysters come from subtidal reefs in Apalachicola than from the intertidal reefs to the east and why aren’t intertidal oysters always equally as large and tasty as subtidal oysters? After talking with an extremely knowledgeable biologist who has been studying and working with Gulf coast oysters for nearly thirty years (John Gunter), I can fairly confidently say that the answer deals with the size of the fresh water input entering an estuary and diversity. This is because good oyster production requires a tricky balance between fresh and salty water that keeps marine predators/disease at bay and fuels phytoplankton for growth and reproduction. So, a larger source of fresh water input creates a larger portion of an estuary suitable for oysters to achieve this delicate balance. But the amount and timing of fresh water input, along with the weather, varies from year to year. As a result, one set of fresh-water input and weather conditions may be good for one portion of the estuary and not so good for the other portion of the estuary. But the next year, this situation could become reversed, maintaining a constant level of production through varying levels of fresh water input and climate. In other words, Apalachicola has a relatively large and diverse oyster portfolio.
Without a steady influx of freshwater, intertidal reefs have no assurance of being consistently healthy and abundant.
In contrast to the subtidal oyster reefs in Apalachicola, the size of fresh water sources that influence intertidal oyster reefs to the east are significantly smaller. Consequently, there are only a few spots where oysters can thrive. When conditions are just right, these intertidal reefs produce oysters just as tasty and large as the subtidal ones form Apalachicola. But when conditions are sub-par, those intertidal oyster reefs shut down and there are no other reefs to make up for this loss in production; these estuaries have small and non-diverse oyster portfolios.
Ok, now that I waved my arms about the difference between subtidal and intertidal oyster reefs and why restaurants mostly serve subtidal oysters, I need to go get ready for our next big outing onto the oyster reefs, which should be extremely busy, but fun.
David’s research is funded by the National Science Foundation.
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