Tag Archives: smooth cordgrass

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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The unsung heroes of the muck

Roberto Diaz de Villegas WFSU-TV
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photo by John Spohrer

Let’s talk about the little guys.

Think a little smaller than this pelican here.  Obviously, pelicans are a symbol of our coastal areas, flying in those long rows as they do while we’re driving down Highway 98.  Pelicans covered in oil have become the poster-species of the environmental toll of the Deepwater Horizon oil spill.  It’s horrifying to think of animals as evolved as dolphins washing up on the shores, and people of course are always concerned about sea turtles.  As they should be.  They are all important parts of the Gulf ecosystem.

But they are not the only important parts.  There are other creatures that probably won’t make it on to that oil spill tragedy poster because, let’s face it, they already live in muck.  Those are the species that we’ve been most concerned with on this site.  They are worth worrying about, and I’ve come to find them cute in their way.  I keep thinking I need to try to get Disney to make a movie based in a salt marsh or oyster reef, where mud crabs and periwinkle snails sing and hide from predatory blue crabs (who, like those sharks in Finding Nemo, might be sympathetic characters themselves).  When kids are carrying plush fiddler crab dolls, maybe the little guys would get some consideration.  As it turns out, however, I have no pull at Disney.  So I’ll just talk about them right here on this blog.

Like the fiddlers.  They eat sand.  They shovel it in their mouths with their smaller claws, while they do the mating dance for which they’re better known with their larger “fiddle” claws.  I see thousands of them at a time in a salt marsh, always scurrying away and making that sound, a little bit like trickling water and a little bit like tiny bubble wrap being popped.  Of what importance are these silly little guys?

Fiddler on marsh 2

Fiddler crabs are crucial to the survival of a salt marsh

Other than being food for blue crabs, their importance has to do with the muck in which they live.  They live in the sediment collected by the cordgrass root system; you can see the holes they call home throughout the marsh.  As Dr. Hughes explained in this video, these burrows provide oxygen to the soil in which the cordgrass grows.  So their presence helps the cordgrass grow, just as the cordgrass provides them shelter.

So maybe the fiddler crab hasn’t found himself at the center of any teary oil spill montage.  But he’s an animal, and a fairly popular pet.  Spartina alterniflora- aka smooth cordgrass- may never gain a foothold in the popular imagination proportionate to its ecological importance.  It is the foundation species of a Gulf salt marsh.  These marshes act as a filter for pollutants flowing into the ocean, protecting important estuaries such as those at the mouth of the Apalachicola River.  Marshes provide shelter to a number of commercially important species (shrimp, mullet, and blue crab, for instance).  And marshes also help absorb storm surges and prevent erosion.

Those are just a couple of examples.  There are, of course, more.  Tasty, tasty oysters filter water and prevent algal blooms lethal to other species.  Toadfish have faces even other toadfish may not love, but they eat animals that would decimate oyster reefs if left unchecked.  Those oyster predators are interesting as well.  Mud crabs might get as large as 4 cm and have these thick little claws which tear through oyster shells.  Oyster drills are small snails whose tongues (radula) are covered with thousands of small razor-like teeth.

As we move forward with this project, we’ll see more and more of all of these coastal denizens.  So far oil has not reached the areas Dr. Hughes and Dr. Kimbro are studying, and so there is always hope that they may be spared.  If oil does arrive, many of these species could be severely affected.  And while some of them may not look like much, the harm that would come to them would have repercussions felt beyond their own habitats.

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This snail lives on an oyster reef

Interested in seeing a fiddler crab plush toy as a WFSU-TV pledge premium?  Well, that isn’t likely to happen. But we will take comments and questions, as usual.

How long will oil effects last?

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150I heard an interesting conversation on the radio Friday, with someone posing the question of how long will recovery from the Deepwater Horizon oil spill take. Months? Years? The answer, though unsatisfying, is largely that it depends. It depends how much oil ultimately is added to the Gulf. It depends what habitat you’re talking about (sandy beach, open water, salt marsh). And it depends how effective clean-up efforts are.

Fiddler crab in St. Joseph Bay.

Fiddler crab on St. Joseph Bay

(Meet the species of a Forgotten Coast salt marsh)

Unfortunately, previous research suggests that in salt marshes, at least, we’re probably talking decades. For instance, studies of a 1969 spill in Massachusetts (three studies: 1-2-3) find that oil can stick around in the marsh sediments for at least 40 years and continue to have negative impacts on marsh residents like fiddler crabs and mussels long after things appear to be “back to normal”. Lower abundances of these important plant associates may contribute to the lower biomass of cordgrass (Spartina alterniflora) in oiled vs. un-oiled areas, even after decades.

Salt marshes provide habitat for lots of animal species in addition to crabs and mussels, and many of these animals are of interest to us because we like to catch and/or eat them. For example, blue crabs, mullet, seatrout, and red drum all spend at least part of their life amongst the grasses of the salt marsh. Lots of snails and bugs also call the marsh home. Some of these critters benefit the marsh, such as the fiddler crabs whose burrows aerate the soil and the mussels that add nutrients to the soil, whereas others like snails and grasshoppers can have negative effects on marsh plants. All will undoubtedly be impacted at least to some degree by the infiltration of oil into their home.

My lab and I are continuing to collect data on pre-spill abundances of marsh plants and animals in the FL Panhandle, and should oil arrive, we plan to examine the immediate and longer-term effects of oil on their abundance. Although we will make sure to learn as much as we can from the Deepwater Horizon spill, I want to emphasize that none of us are excited about the “opportunity” to study oil in our sites. We all view this situation as an absolute disaster.

The music in the video was performed by Sauce Boss.

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

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What we are doing “In the Grass”

Dr. Randall Hughes FSU Coastal & Marine Lab

IGOR chip- biodiversity 150As a marine ecologist at the Florida State University Coastal and Marine Laboratory, my everyday job is to try to understand the plant and animal communities along our coast and then communicate that knowledge to students, other scientists, and the public.  Much of my research focuses on understanding how the biodiversity, or the number of species or genetic individuals, of coastal communities such as salt marshes influences their productivity and ability to respond to disturbances.  Don’t let the terminology scare you – the basic idea is similar to having a diversified stock portfolio: by having a greater variety of species or ‘genotypes,’ aka more diversity, you increase the chances that one of them will grow really well, attract lots of critters, survive a disaster, etc.  Think of it as the spare tire theory of ecology!

I work with undergraduate and graduate students, research assistants, and volunteers to study the marshes and seagrass beds of the FL Panhandle and Big Bend regions.

IMG_0038Because large portions of the Gulf of Mexico are currently threatened by the Deepwater Horizon oil spill, this work suddenly has an increased urgency for me, personally, as well as for many other citizens who are concerned about what this oil may do to the waters, coasts, plants, and animals that we love.  In this blog, I’ll give you an overview of what we’re doing in regards to the oil spill, as well as on a daily basis in the absence of major disasters, to highlight the ups and downs and funny moments associated with being a scientist.

As awareness of the magnitude of the Deepwater Horizon oil spill has increased, my lab and I have focused our efforts on documenting the current state of salt marshes in our area.  This work includes identifying and counting the dominant plant species in the marsh, as well as the many marine critters (crabs or snails, such as the marsh periwinkle, below) and bugs (spiders, grasshoppers, and other insects) that live here.  Bug collecting is perhaps the most attention-grabbing (as you’ll see in the video below), involving the use of a gas-powered vacuum to suck the insects into mesh bags so that we can then preserve and identify them in the lab.

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Because plant genetic diversity can be very important for the ability of these plants to respond to disturbance, we’re also collecting small pieces of plant tissue that can be analyzed in the lab using DNA markers to determine how many different genetic individuals are present.  Finally, we’re collecting samples of dirt to document the amount of hydrocarbons (a signature of oil exposure) in the marsh sediment.  Although we still fervently hope that none of the oil reaches these marshes, such “pre-spill” data will allow us to document as completely as possible the impacts of this spill on our coast, inform the recovery of these areas, and work to prevent similar incidents in the future.

Special thanks to Bill Wharton, who provided music for the video piece.
Randall’s research is funded by the National Science Foundation.
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