Last week, we took a good look at the coastal salt marsh- an ecosystem with a lot to offer but that is seeing die-off across the world. Around Choctawhatchee Bay, schoolchildren are doing something about this.
Two “spoonbills” fight for lima bean. Students at the Laurel Hill School did more than plant marsh cordgrass on the coast. At this station, they were given three types of tools to use as beaks: clothespins, spoons, and chopsticks. With those beaks, the “birds” had to forage for food. The exercise taught them about the adaptations that give animals different advantages. The best adapted beaks got the most food.
Finding out about Grasses in Classes was one of the pleasant surprises of the year so far. The Choctawhatchee Basin Alliance and AmeriCorps start with a similar premise to the In the Grass, On the Reef project: to foster appreciation for coastal ecosystems like oyster reefs, seagrass beds, and salt marshes. We write and make videos for a general audience; Grasses in Classes goes into schools. What they do goes beyond lesson plans and worksheets. These kids grow smooth cordgrass (Spartina alterniflora), the foundation species of a coastal salt marsh, in their classrooms. Then they go to Choctawhatchee Bay and plant it. How awesome is that! You can see in the video how much the cordgrass spreads out over the course of the year, a powerful visual affirmation to the Laurel Hill School students that what they’re doing is having an impact and will benefit that coastline for years to come.
A few yards from their marshes are restored oyster reefs like the ones CBA builds in the bay. They’re frequent collaborators, the salt marsh and oyster reef. Marshes, oyster reefs, and seagrass beds join to create an estuary of critical importance to Gulf fisheries, sheltering most seafood species fished there at some point in their life cycles. As was said in both this and the O.Y.S.T.E.R. Recycling video, marshes and oyster reefs fight erosion. Marshes also filter stormwater runoff (check this list of everything that flows off of asphalt). And yet, probably because no amount of horseradish makes Spartina grass palatable, marshes don’t always capture the popular imagination as oyster reefs do. I hope we can change some of that in the coming weeks.
That’s where the CBA might have us beat. Through their work, a generation of schoolchildren is getting that appreciation the wet and dirty way, by actively restoring that habitat where development had removed it. And with the school year recently concluded, CBA and AmeriCorps are gearing up for next year by hiring 13 full time employees to continue to carry the program out. Click here for more information.
Kayla Mitchell helps a Laurel Hill student plant a Spartina plant.
2 Minute Video: Do Marshes Combat Die-Off Through Biodiversity?
Data on “cold” and “warm” episodes compiled by NOAA and the National Weather Service correlate warm episodes with events Randall and David care about: the ruining of oyster reefs south of Saint Augustine by crown conchs in 2005, the Apalachicola oyster fishery crash last year, and the die-off of salt marsh habitats at the turn of the millennium. These episodes are part of a normal climatological cycle, though recent droughts during warm years have been severe.
Dr. Randall Hughes FSU Coastal & Marine Lab/Northeastern University
Mineral Springs Seafood's Dusty Murray empties a crab trap by a salt marsh off of Ochlockonee Bay. Blue crabs are one of the many animals that make use of the salt marsh habitat.
We’re going to shift our attention a bit to another intriguing intertidal habitat – the salt marsh. We’ve focused a lot recently on oysters, and how David is applying what we’ve learnedfrom our oyster research the last few years to try to understand the crash of the Apalachicola oyster fishery. There is something inherently interesting and fascinating about oysters, despite the fact that they look a lot like not much more than really sharp rocks. And of course, there is urgency to understand the oyster problems in Apalachicola because of the very real and immediate human costs associated with the fishery collapse.But now, my goal is to convince you that the salt marsh is just as fascinating as oyster reefs, even if it is not a highly visible fishery in trouble. Think of me as the parent trying to get you to appreciate your broccoli, after David already gave you your chocolate cake. I’m going to get you to LIKE your broccoli.
The “broccoli” in this scenario is none other than salt marsh cordgrass, Spartina alterniflora, a familiar character on this blog. In addition to oysters, cordgrass has been the focus of most of my research in FL. Why, you may ask? Why study broccoli when you could be studying chocolate cake all the time? The parent in me is tempted to use the catch-all phrase “Because it’s good for you!” But I’ll refrain, and instead give you a few actual reasons:
1. Oyster and cordgrass really aren’t all that different.
What do oysters and cordgrass have in common? At first glance, it may not seem like much. Oysters are animals; cordgrass is a plant. Oysters are tasty (depending on your palette); cordgrass is inedible. Oysters support a community of fishermen, at least in better times; cordgrass doesn’t.
Except this last distinction, which may seem intuitive, is not actually true. Cordgrass, and salt marshes more generally, support a wide range of fishery species including blue crabs (as you can see in the video), mullet, and sea trout. Studies in Florida estimate that marshes provide up to nearly $7000 per acre for recreational fishing alone. And like oysters, salt marshes provide more benefits for us than simply what we can eat, including protection from storms, increased water quality, and erosion control.
2. Plants are cool.
I know I don’t have to convince any of you gardeners out there about the beauty of plants. Give them a little sunshine, some nutrients, and a little water, and they do their thing. And cordgrass can even manage in salt water! There’s something to be said for low maintenance study organisms.
A year ago, that full-bodied marsh in the background looked just like the rows of small cordgrass shoots leading up to it. Both were planted by Laurel Hill School students as part of the Choctawhatchee Basin Alliance's Grasses in Classes program.
Not only that, but you can plant a single cordgrass stem, leave it alone for a few months, and return to find that it has expanded to 20 stems, all from the same individual! (Or, if you’re lucky enough to be part of Grasses in Classes, you can admire successive years of growth from single transplants.) This “clonal expansion” is impressive, and it makes answering some of the research questions that I’m interested in pretty easy to address – I can test whether some individuals are better at expanding than others, or whether they withstand stresses like grazing better, or whether having a mix of individuals is better than lots of stems of the same individual. I can ask these questions using oysters too, but it is a lot more difficult. Even we ‘eat your vegetables’ advocates like taking the easy way out sometimes.
3. Marshes are in trouble too.
Although not in the headlines of the local papers at the moment, cordgrass has experienced significant declines in the Gulf of Mexico in the past, and salt marsh loss is a historic and ongoing problem in many parts of the world. And in some cases, the same problem can contribute to the loss of marshes and oysters. For instance, drought has been linked to salt marsh die-off in the Gulf, and drought-induced stress can make the plants more sensitive to other stresses such as grazing by snails. (As we’ve discussed before, drought and increased salinities can also make oysters more sensitive to predators and disease.) Because of the many benefits that marshes provide, it is in our best interest to understand the causes of these losses and try to prevent / counteract them.
Marsh Periwinkle (Littoraria irrotata).
For these reasons and more, I’ve been conducting lots of experiments the past few years to (a) understand what factors increase / decrease how sensitive cordgrass is to it’s major grazer, the marsh periwinkle, and (b) figure out if having more cordgrass individuals (or “genotypes”) makes the marsh less sensitive to change. We’ll highlight these experiments in the coming weeks as part of our quest to spark your fascination with the salt marsh!
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.
For today’s post, we shift our look at the ecology of fear from oyster reefs to the (often) neighboring salt marsh. We know crown conchs are villains on oyster reefs, but might they redeem themselves “in the grass?” If they live on the Forgotten Coast, it depends on what side of Apalachicola they live.
Dr. Randall Hughes FSU Coastal & Marine Lab
The Crown Conch (Melongena corona).
If you’re a fan of oysters and you read David’s previous post, then you probably don’t like crown conchs very much. Why? Because David and Hanna’s work shows that crown conchs may be responsible for eating lots of oysters, turning previously healthy reefs into barren outcrops of dead shell. And we generally prefer that those oysters be left alive to filter water and make more oysters. And, let’s be honest, we would rather eat them ourselves!
But, in something of a Dr. Jekyll and Mr. Hyde act, crown conchs can take on a different persona in the salt marsh. Here, the exact same species acts as the good guy, increasing the abundance of marsh cordgrass. And more abundant marsh plants generally means more benefits for we humans in the form of erosion control, water filtration, and habitat for the fishes and crabs we like to eat. How exactly does that work?
The Marsh Periwinkle (Littoraria irrotata).
If you look out in a salt marsh in much of the Gulf and Southeast Atlantic, I can nearly guarantee that you’ll see a marsh periwinkle snail. Usually, you’ll see lots and lots of them. These marine snails actually don’t like to get wet – they climb up the stems of the marsh grass as the tide comes in. While they are up there, they sometimes decide to nibble on a little live cordgrass, creating a razor blade-like scar on the plant that is then colonized by fungus. The periwinkles really prefer to eat this fungus instead of the cordgrass, but the damage is done – the fungus can kill the entire cordgrass plant! So these seemingly benign and harmless periwinkles can sometimes wreak havoc on a marsh.
But wait a minute – if periwinkles cause all the cordgrass to die, then why do you still see so much cordgrass (and so many snails) in the marsh? That’s where the crown conch comes in.
At the edge of a marsh at high tide, a crown conch approaches a periwinkle snail. As shown in the video above, the conch was soon to make contact with the smaller snail and send it racing (relative term- the video is of course sped up) up a Spartina shoot.
In marshes along the Gulf coast, there are also lots of crown conchs cruising around in the marsh (albeit slowly), and they like to eat periwinkles. Unlike other periwinkle predators such as blue crabs, the crown conchs stick around even at low tide. So when the periwinkles come down for a snack of benthic algae or dead plant material at low tide, the crown conchs are able to nab a few, reducing snail numbers. And fewer snails generally means more cordgrass.
Of course, the periwinkles aren’t dumb, and they often try to “race” away (again, these are snails!) when they realize a crown conch is in the neighborhood. One escape route is back up the cordgrass stems, or even better, up the stems of the taller needlerush that is often nearby. By causing periwinkles to spend time on the needlerush instead of grazing on cordgrass, or by making the periwinkles too scared to eat regardless of where they are sitting, the crown conch offers a second “non-consumptive” benefit for cordgrass. One of our recent experiments found that cordgrass biomass is much higher when crown conchs and periwinkles are present compared to when just periwinkles are present, even though not many periwinkles were actually eaten.
On the other hand, if the periwinkles decide to climb up on the cordgrass when they sense a crown conch, and if they aren’t too scared to eat, then crown conchs can actually have a negative effect on the plants. This is exactly what David found in one of his experiments. In this case, the tides play an important role – west of Apalachicola, where there is 1 high and 1 low tide per day, each tide naturally lasts longer than east of Apalachicola, where there are 2 high tides and 2 low tides per day. The longer tides west of Apalach appear to encourage the snails not only to stay on the cordgrass, but also to eat like crazy, and the plants bear the brunt of this particular case of the munchies.
So even in the marsh, it turns out that crown conchs can be both a friend and a foe to marsh cordgrass, depending on how the periwinkles respond to them. And figuring out what makes periwinkles respond differently in different situations just gives us more work to do!
Music in the piece by Revolution Void.
In the Grass, On the Reef is funded by a grant from the National Science Foundation.
Much like David finds it hard to distill why the oysters that he studies are so intriguing, I often struggle to convey the charisma of the salt marshes and seagrass beds where I spend so much of my time. At least people like to eat oysters! It can be harder for people to find a connection with the plants that form so many of the critical habitats along our coast (unless of course people misunderstand the meaning of “In the Grass” and think I study a VERY different type of plant!). But even if it is not recognized, there is a connection between the salt marsh and our everyday lives. Like oyster reefs, salt marshes provide many benefits to society, particularly along the coast:
1. A place to live (for marine and terrestrial animals)
Periwinkle snails are among the many animals that make use of the salt marsh habitat.
Even if you’re one of those folks who find it hard to get excited about a bunch of plants, don’t tune out – the salt marsh is teeming with animals! Snails, fiddler crabs, mussels, grasshoppers, dragonflies, and snakes (!) are all critters that we encounter regularly when the tide is out. And there’s always a bit of an adrenaline rush when you see an alligator hauled out nearby. Even better, when the tide comes in, there are lots of animals that you and I (or at least, I) like to eat. Think blue crabs, mullet, and sea trout, for starters. Studies in Florida estimate that marshes provide up to nearly $7000 per acre for recreational fishing alone. Not bad.
2. A safer place to live (for people)
Although it’s generally frowned upon to build houses in the marsh (since it makes it hard for all those animals I just mentioned to live there), it’s a great idea to have lots of healthy marshes near your coastal property. Marshes can protect the coastline from waves and storms, leading to less damage in areas with marshes present. One estimate places the dollar value of coastal protection in the U.S. at over $8000 per hectare per year in reduced hurricane damages! Although here’s hoping that we don’t get an opportunity to test that particular benefit this year.
In addition to reducing the size and strength of waves, marshes also prevent coastal erosion. An unfortunate example of the role of marshes in erosion control came following the Deepwater Horizon oil spill – plants in areas of the marsh that were heavily oiled died, leading to greatly increased rates of erosion in those areas (Silliman et al. 2012). Although the benefit of marshes for reducing erosion and combating sea level rise has been recognized for a long time, there are not any good estimates for what this erosion control is worth in $$. Given expectations of sea level rise in the coming years, I think that the motivation to understand the conditions that lead to sediment accumulation in marshes will only get stronger.
3. Clean water (for animals and people)
Because marshes lie at the intersection of the land and the sea, they serve as a filter for things trying to move between the two. When it comes to run-off and pollution from the land, it’s a very good thing that they do. Simply having a marsh present can serve as an effective alternative to traditional waste treatment. Of course, the protection can go the other direction too – marshes played a critical role in keeping oil from the Deepwater Horizon oil spill from getting to higher elevations.
4. A place to graze (for livestock)
Support for livestock grazing is an important role of marshes in some areas, including the U.K. Although it’s not a benefit commonly associated with marshes in this area, the decaying fence posts that extend out into some areas of St. Joe Bay suggest that it wasn’t too long ago that marshes were used for a similar purpose here!
I could go on, but these and other benefits of marshes are described in greater detail in a recent review by Barbier and colleagues (which I referenced on this blog in May of 2011). Here is the table that they put together summarizing the monetary benefits that we derive from intact salt marshes:
Luckily for us, salt marshes keep working their magic even in the absence of accolades or appreciation. But greater appreciation is needed to help curb the decline of salt marshes around the world – estimated to be as much as 2% per year! We hope that this blog will help generate greater understanding and enthusiasm for the incredible coastal habitats that we are lucky enough to work in every day. Let us know how we’re doing!
In the next two weeks, we delve into a habitat that we have only occasionally covered: seagrass beds. Next week we examine, with visiting researcher Dr. Peter MacReadie, seagrass beds’ role in fighting global climate change. The week after that, we head to Bay Mouth Bar, one of the most ecologically unique places in the world. Also, we’ll be look at the failure of the Apachicola Bay oyster reefs from a biological perspective. Here are a few images of our visit to a Saint Joseph Bay seagrass bed and of Bay Mouth Bar at low tide, when you see all kinds of strange and interesting creatures:
In the Grass, On the Reef is funded by a grant from the National Science Foundation.
Episode 3: Studying Nature Involves Visiting and Standing in Nature
In a couple of weeks we’ll dive right in and look at oyster reefs and their surprising value. In the weeks following, we’ll do the same with salt marshes, seagrass beds, and with the unique diversity of Bay Mouth Bar. Right now, we hope you enjoy watching the WFSU/ Mag Lab SciGirls get their footing in the intertidal zone.
The first question I was asked when I became involved in the In the Grass, On the Reef project was if I was afraid to go out in the field and get a little dirty. “Of course not!” was my response. I have always been a fan of the outdoors and love scalloping and kayaking, so of course I would love this. I guess I was expecting to be in the water more than anything. After all, we couldn’t really be going out into anything too messy, right?
The first few shoots I went on were great and went about how I expected they would. But after a few weeks we went to Wakulla Beach, where I discovered exactly why I was asked that particular question when I was hired. Not fully prepared for my experience that day, I had quite a time trying to walk through the mud without getting sucked in knee-deep and losing my shoes, causing others to slow down and get stuck as well while they were trying to help me out. After clawing my way out and finally escaping the mud, I walked on an oyster reef for the first time. While the mud was not nearly as bad at this point, I am a terribly clumsy person. Luckily, I was able to keep my footing and avoid falling on top of oyster shells.
Although it was exhausting, I still enjoyed my Wakulla Beach experience, as I’ve come to call it. It was definitely a learning experience for me and I loved being able to see the sunset over the reefs. I have yet to master the “quick, light steps” needed to defeat the mud, but I definitely have an appreciation for what our scientists, and many others, go through to set up experiments and collect their data. I also love that getting out in the water (and mud) are a part of my job, not to mention that we get to see some really cool things. Every shoot is a new experience and I notice more about the environment and the animals each time I go out.
And Also, the Animal Experience
Rob Diaz de VillegasWFSU-TV
Animals with claws suited to tearing through oyster shell can, unsurprisingly, injure you.
One thing we didn’t mention in the video above or in Rebecca’s post are the animals at the sites, which you definitely have to keep an eye out for. Members of the Hughes and Kimbro labs have been pinched by blue crabs and have encountered the occasional snake in the marsh. There are small sharks, the possibility of alligators, and the sting rays that we see and shuffle our feet to avoid stepping on and startling. You keep an eye out for those knowing that they’re a potential danger, though not a pressing threat. During last week’s shoots in Saint Augustine, however, events in the news had us paying serious attention to the smallest animals that are also the ones that attack us most relentlessly. Our country is in the midst of perhaps its worst ever outbreak of West Nile virus. Mosquitos are a fact of the coast. During the day, there is usually enough of a breeze to keep them off you; but since the work we follow is tidally based, activities can occur before sunrise or after sunset, when mosquitos are at their worst. Alligators may look scarier, but it pays to know what the most pressing threat is.