Monthly Archives: August 2014

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Scalloping Saint Joseph Bay Seagrass Beds: Video

Rob Diaz de Villegas WFSU-TV

Double Rainbow

I figured it was a good sign that our first glimpse of Saint Joseph Bay was of it under a double rainbow.  Of course, that required me to ignore all of the rain clouds that caused the rainbows, and some of the far off lightning I saw on our drive to Port Saint Joe.  But why head into my shoot with a negative attitude?  It didn’t take long for the sun to come out after we got on Captain Bobby Guilford’s boat.  I can’t control the weather, but if I could, I’d have arranged it like it turned out.  First, some clouds and precipitation for the rainbow shot, and then the sun we needed to shoot in seagrass beds and, more importantly, to see the scallops we were there to find.  Florida weather is just as often a friend to my shoots as it is a nasty nemesis.

This was a segment I’d been wanting to do since the first summer of the In the Grass, On the Reef project.  I spent a lot of time in Saint Joseph Bay following Dr. Randall Hughes’ salt marsh research, and when scallop season started I would see people head into the bay with buckets, kayaking out with buckets, or zipping by on boats.  Scallops are some of my favorite food.   In the Grass, On the Reef could just as easily have been called Getting to Know the Places Where the Food I Like Lives.  And I did get to know about seagrass beds, and snorkel in Saint Joe Bay looking for shots of horse conchs, sea stars, and even scallops.  What I learned in my time with Randall and her colleague, Dr. David Kimbro, is that seagrass beds are really cool!

Seagrass beds are remarkable ecosystems, and they’re a big part of why I love going back to Saint Joseph Bay as well as other locations on the Forgotten Coast.  Here are some of the cool things I learned about them from my collaborators’ research:

Seagrasses and Blue Carbon

Dr. Macreadie looks through seagrass bedIn 2012, Dr. Peter MacReadie visited Randall in Saint Joseph Bay from the University of Technology in Sydney.  We talked to he and Randall about ecosystem services provided by seagrass beds, and Peter talked to us about the surprising ability of seagrass beds to store carbon from the atmosphere.  As Randall points out in a 2012 post, their storage ability is on par with forests.

Robert Paine/ Keystone Species

Horse Conch on Bay Mouth Bar

Horse Conch (Pleuroploca gigantea)

Our local seagrass beds house a wealth of diversity.  Dr. Robert Paine studied Bay Mouth Bar, just off of Alligator Point, over fifty years ago.  The bar may have the greatest diversity of predatory snails in the world. His observations of the top predator- the horse conch- and the rest of the animals on the bar when the horse conch was present versus when it left in the winter, were influential in Paine’s pioneering of the keystone species concept. The horse conch consumes other snails, keeping their numbers in check so that those snails don’t in turn consume too many clams. The clams benefit the seagrass by filtering water, and so the horse conch is of vital importance to clams and to the habitat. As we know, David Kimbro is very much interested in predators, and so it is natural that he would spend years following up on Paine’s work, even unfunded.

(The one clam that horse conchs eat is the largest you can find in our seagrass beds, the pen shell. That’s what we see Bobby and Adrianne eating in the video above.)

Predator Diversity Loss

True Tulip Snail eating a Banded Tulip Snail

True tulip (Fasciolaria tulipa) eating a banded tulip (Fasciolaria hunteria).

While it’s great that seagrass beds help combat global climate change, provide habitat for scallops and other seafood species, and help filter water, they unfortunately are a habitat on the decline. As seagrass beds shrink, they tend to house a less diverse assemblage of animals. David Kimbro’s graduate student, Tanya Rogers, used a local seagrass habitat to look at the effects of losing diversity. Specifically, the loss of a top predator. David and Tanya have been conducting a follow up to Robert Paine’s Bay Mouth Bar research in the early 1960s. Five decades later, they found that the seagrass beds there are shrinking, and certain snail species have disappeared. This includes the true tulip snail and murex, which are still plentiful in Saint Joseph Bay. The true tulip was a major predator on Bay Mouth Bar. Tanya conducted an experiment to determine how the loss of this predator would affect the clams in the sediment, and how those clams in turn affected the sediment where the seagrass grows. Did the loss of habitat force the tulip off of the bar, or did the loss of tulip (which eats clam consuming snails) help cause the seagrass habitat to shrink?

Ocean Acidification

As global temperatures rise, the ocean is acidifying. This will have increasing ramifications for the plants and animals living in saltwater ecosystems, such as the oysters, clams, and scallops whose shells will weaken. However, recent research shows that seagrass beds might fight that acidification.  Good news for the clams and scallops that live there!

Seagrass bed in St. Joseph Bay, FL

Music in the video by pitx.

marsh-sunrise

Does Diversity Matter in the Salt Marsh? A Look Back

Dr. Randall Hughes has collaborated with WFSU on this blog since 2010. We have spent years visiting her research sites in Saint Joseph Bay, where Randall conducted a multi-year study on salt marsh biodiversity funded by the National Science Foundation. The study has concluded, and Randall has published several papers on her findings. Here is what she has found.

This is Saint Joe Bay week on the Ecology Blog.  Wednesday, August 20th, at 7:30 pm ET: WFSU premieres the eighth season of Dimensions, and our Saint Joseph Bay scalloping EcoAdventure. 

Dr. Randall Hughes Northeastern University
Just a bunch of grass?  Not to the larval shrimp, juvenile mullet, pinfish, fiddler crabs, mussels, periwinkle snails, and blue crabs that make use of the habitat, or the birds and sea turtles that go hunting there.

Just a bunch of grass? Not to the larval shrimp, juvenile mullet, pinfish, fiddler crabs, mussels, periwinkle snails, and blue crabs that make use of the habitat, or the birds and sea turtles that go hunting there.

As you drive along Highway 98 towards St. Joseph Bay (SJB), one of the most common views outside your window is of the salt marsh.  From the car, it looks like a beautiful but monotonous meadow of green and/or brown, depending on the season, often intersected by tidal channels. So I won’t blame you if “diversity” is not the first word that comes to your mind as you gaze out the window. But diversity is exactly what I set out to find out about when this project first started – how much diversity is there in the marshes of St. Joe Bay, and what (if any) effects does it have? And now, several years later, I finally have answers to share!

First, let’s revisit what I mean about diversity. There are 2 main types that I have focused on for my research:

Species diversity, or the number of different species in an area. If you garden, you can think of it as the number of different vegetables or flowers you plant.

Genetic diversity, or the number of different genetic individuals (or genetic variants) in an area. Using the garden example, this would be similar to the number of different tomato varieties you plant in your garden.

Randall Hughes and Ryan Coker in an FSUCML Greenhouse

Randall and technician Ryan Coker tend to plants in an FSU Coastal & Marine Lab greenhouse. Before Randall and her team could begin to test their theories about marshes and marsh grass, they needed to create controlled marsh units of a comparable size, and needed to know the genetic identity of the grass in their plots.  Randall grew this grass for two years before conducting those experiments.

Wait – why so much talk about plants? Don’t animals have diversity too? Animals do have diversity, and this diversity matters – for one, having more species of fish on a coral reef means the corals grow better. But plants are the foundation of the marsh – if you have no plants, you have no marsh. So I have focused on the species and genetic diversity of the plants and tested how it affects the number and diversity of animals that live there (which includes animals that we like to eat, such as blue crabs). The dominant marsh plant species in many areas is cordgrass (Spartina alterniflora), and we created a greenhouse full of known genetic individuals to use in many of our experiments. Here are some of the highlights of what we have learned, with a little background on each, and links to the published articles where you can learn more if you’re interested:

1. Increasing the number of plant species in the marsh, even just from one species to two, can reduce the negative effects of a hungry periwinkle snail.

Periwinkles are really common in the marsh, and when conditions line up just right (the periwinkles are hungry, the cordgrass is already stressed from something like drought) they can mow down the cordgrass. We don’t see this happen very often in SJB, and I wondered if that was because there’s another really common plant species – needlerush – that often grows with the cordgrass, that the periwinkles also seem to like, at least for climbing on to stay out of the water and away from their predators. So we did an experiment where we planted cordgrass with and without needlerush and with and without periwinkles, and we found what I had expected: having needlerush neighbors around means the periwinkles don’t mow down the cordgrass!

Randall published these findings in the Ecological Society of America Journal.

2. Contrary to conventional wisdom that a few cordgrass individuals (also known as “clones”) rule the marsh, genetic diversity can be quite high, with as many as 9 distinct individuals living together in an area the size of a hula hoop.

periwinkles on cordgrass

Smooth cordgrass (Spartina alterniflora), the foundation species of a coastal salt marsh. Before she could understand how the genetic diversity of this species affects the health of a marsh, Randall needed to know how many genetic individuals were present within the ecosystem.

Genetic diversity is really important for the ability of plants and animals to respond to stress or change, and so it’s something we often want to know, but the bummer about it is that it’s not nearly as easy to measure as species diversity. You can’t just look at two cordgrass plants and tell whether they are the same or different genotypes! I teamed up with Dr. Katie Lotterhos to use little snippets of DNA to tell us whether the cordgrass plants we collected from the marshes around SJB were all a few closely related individuals, or whether there were lots of different individuals around. It turns out that even though they all look pretty much the same, there is a lot of genetic diversity in our marshes.

Randall and Katie published these findings in the Inter-Research Science Center’s Marine Ecology Progress Series (link is a PDF).

Monoculture plot- four genetically identical cordgrass individuals.  In this specific experiment, plots are composed off one, two, or four separate individuals.  Do plots with higher diversity fare better?

A monoculture plot of four genetically identical cordgrass individuals. In this experiment, similar to the one described to the right, plots were composed of one, two, or four separate individuals. Did plots with higher diversity fare better?

3. Changing the number of cordgrass clones living together in an area the size of a hula hoop affects how well the plants grow, as well as how many animals share that space. These effects of diversity may be particularly important when plants are first colonizing an area, such as in restoration efforts.

Once we knew how many different genetic individuals shared a hula hoop-sized area in natural marshes, we did an experiment to see how changing that number affects how well the plants grow. This experiment took a long time to prep, because we first had to grow a bunch of plants in the greenhouse so that we could keep track of who was who. After that, the experiment itself was pretty simple: plant 1, 3, or 6 different clones inside a hula hoop (well, in this case it was a modified hula hoop made of less expensive irrigation tubing) at the edge of the marsh, and watch them grow over time.

Randall published these findings in the British Ecological Society’s Journal of Ecology.

4. Just like you and me, different cordgrass clones have unique characteristics – some are tall, some are short, some do well in a crowd, and some like a little breathing room. And the animals that live amongst these plants, such as mussels and fiddler crabs, can go from being friends to enemies depending on which clone they are interacting with.

Even though I said before that all cordgrass plants look similar, it just so happens that when you grow the same clones in the greenhouse for a few years, you start to see slight differences among them. And these differences that seem pretty minor to us are really important to the small animals like fiddler crabs and mussels that live on and around the plants. So, in part to test this idea that different clones have different relationships with fiddler crabs and mussels, and in part just to do an experiment with fiddler crabs because I think they are cool, we set up an experiment using different cordgrass clones growing with just fiddlers, just mussels, or both. And although typically mussels and fiddlers are both “friends” with cordgrass (in that they provide it with nutrients and oxygen in the sediment to help it grow), that is not a universal truth – some cordgrass clones did not benefit (or even were harmed) by having mussels and fiddlers around.

Randall, her graduate student Althea Moore (whose investigation of a similar relationship between mussels and another marsh plant we covered in 2013), and Randall’s oyster collaborator Mike Piehler published their findings in the journal Oikos.

It’s a little disconcerting that ~ 4 years of work can be boiled down into these 4 highlights. Of course there are loads of details I’m leaving out, as well as other ongoing projects that will tell us even more about the effects of diversity in the salt marsh. That’s how the scientific process works – you gain some answers, and those answers lead to new questions! Job security for a curious mind…

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.

Keep up with the latest posts, environmental coverage from the WFSU News department and more at @wfsuIGOR.

Saint Joseph Bay scallop, shucked and ready to eat

Shucking a Saint Joseph Bay Scallop: Video

Wednesday, August 20th, at 7:30 pm ET: WFSU premieres the eighth season of Dimensions.  Tune in to watch our Saint Joseph Bay scalloping EcoAdventure.  We snorkel  seagrass beds, see some fun critters, and breathe underwater with the Snuba.  We also eat some tasty scallops.  But you can’t taste these guys if they’re still in their shells.  Below, Captain Bobby Guilford of Break-A-Way Charters shows us how to shuck our catch.  Captain Bobby took us out on the water in July, and he gave us this quick demo:

Rob Diaz de Villegas WFSU-TV

Another season of EcoAdventures is so close we can almost taste it.  Next week, it’ll taste like bay scallops as we return to Saint Joseph Bay not for science, but to enjoy the products of the seagrass bed ecosystem.  Saint Joe Bay is of course where we’ve been partnering with Dr. Randall Hughes to explore the inner workings of salt marshes and seagrass beds.  Just a bunch of grass?  Not if you like seafood.  Randall will have more about what she’s learned from Saint Joe Bay next week.

P1060980This summer we also spent some time with the WFSU/ FSU Mag Lab SciGirls.  Their annual two week whirlwind through the many aspects of science takes them on a few choice EcoAdventures of their own.  We accompany them to Tall Timbers Research Station as they get to know pine flatwoods ecology in the best way possible- by trapping birds and handling snakes, of course!  Our area is blessed with some of the best examples of longleaf pine forest, an ecosystem that thrives with fire.  We’ll see how various animal species (like those birds and snakes) benefit from burning.

Pied billed grebe at Wakulla SpringsWe also soak the SciGirls in our Water Moves game.  In our last video centering on the game, we followed water from urban Tallahassee to Wakulla Springs, passing through troubled waterways Munson Slough and Lake Munson.  That piece spent most of its time on the game and learning about the Leon County side of the Wakulla Springs watershed.  In our upcoming video, we visit Wakulla Springs itself.  It is an ecological marvel that’s had it’s share of troubles, but can still wow you with impressive sites and an abundance of wildlife.

And there’s more to come.  This year it’s all about connectivity- between lands and waters, between people and the natural spaces around them.  You can see from our new video open that we’ve seen some cool stuff over the last few years.  What would you like to see coming up?

In next week’s video, Captain Bobby also shucks one of these…

Dr. Randall Hughes holds large clam in St. Joe Bay

Keep up with the latest posts, environmental coverage from the WFSU News department and more at @wfsuIGOR.