The open grasslands of the American west support huge herds of grazing herbivores such as bison, antelope, and deer. These large herds again support populations of hunters such as wolves, coyotes, and – historically – bears. The huge acres of wetland grasses we call marshes are productive as well, with all sorts of grazing creatures that feed on the grass like snails and insects, which in turn support populations of first order carnivores like birds, crabs, and turtles, who then feed larger predators like alligators, otters, and raccoons.
The salt marsh is full of life, if you look close enough. Photo: Rick O’Connor
One would think that the submerged seagrass meadows would work in the same way. But there are no large herds of bison like creatures that graze on the grasses. True, manatees and sea turtles do graze on these, but not in the numbers we see with bison and antelope. There are numerous species of snails and crustaceans that live in seagrass, but it is not the grass they are interested in… it is the epibiota. These epibiota are the key to vast diversity of creatures living in seagrasses. If you snorkel or seine through a submerged grassbed you will notice the majority of creatures are small. This place is a nursery for the estuarine and marine environments. These grasses provide excellent hiding places and the epibiota provide the food they need to grow.
Grassbeds are also full of life, albeit small creatures.
Photo: Virginia Sea Grant
So, what are these epibiota?
The term epibiota means “creatures that live on other creatures”. They can be further broken down into epiphytes (plants that growth on other creatures), and epizoids (animals that grow on other creatures). Spanish moss is a familiar example of an epiphyte most people know. Barnacles growing on a turtle shell, or a whale could be an epizoid you are familiar with. Many epibiota are small, even microscopic. You can see the algae growing on the shells of turtles, or the fur of the sloth. There are also numerous epizoids that are microscopic, and no one sees. It is a whole field of microbiology – the study of the natural history and diversity of this tiny world that, certainly in the case of seagrasses, makes the whole thing work.
The wide blades of turtle grass provide habitat for a variety of epibiota.
Photo: UF IFAS
With the seagrasses you will not always see the epibiota we are talking about. At times, there are mats of algae growing on the grass like Spanish moss on oak trees. We typically see these epibiotic macroalgae growing on seagrasses in the spring and summer. Most of these algal mats are red algae. Studies have shown that they support juvenile animals as hiding habitat and can increase the overall biomass of seagrass meadows. But, like with all things, too much of a good thing can have a negative effect on seagrass meadows as well. The seaweed can smother the grasses, reducing needed sunlight, and enhance the decline of seagrasses in some areas.
Gracilaria is a common epiphytic red algae growing in our seagrass beds. Photo: Rick O’Connor
Most of the epibiota feeding the growing populations of shellfish and finfish using these nurseries are microscopic plants and animals that appear to us as “scum” on the blades of the grass. As you might expect, the wider the blade (in this case turtle grass) can support a higher diversity and abundance of growing grazers than the thinner shoal grass.
A study conducted in 1964 listed 113 species of microscopic algae existing on the blades of seagrasses in Florida. They include such creatures as diatoms, cynobacteria, and bryozoans. We will focus on these.
Diatoms are quite abundant on seagrass blades and provide for microscopic grazers.
Photo: University of New Hampshire
Diatoms are single celled plant-like algae that are encased in a clear silica shell. They are one of the most abundant forms of oxygen producing plant-like creatures found in the sea. Many species drift with the phytoplankton layers of the open ocean. Others are benthic, living on the bottom upon rocks, seawalls, turtle shells, and seagrasses. It has been stated that 50% of the oxygen produced on our plant comes from the diatoms and the dinoflagellates (another microscopic plankton).
Cells of a species of cyanobacteria.
Photo: Florida Atlantic University.
Cyanobacteria are what many call blue-green algae. They produce a darker colored green with their photosynthetic pigments – thus the name blue-green algae – but were not initially identified as a bacteria – which they are now because they lack an organized nucleus. Many have heard of the recent cyanobacteria blooms in central and south Florida in freshwater systems. Some species are toxic and have caused fish kills and even made pets, who drank from water with cynaobacteria, very sick. There hundreds of different species found in marine systems. Like diatoms, some live in the water column, others are attached to an object on the bottom – like seagrasses.
This beautiful matrix was built by a group of microscopic animals known as bryozoans.
Bryozoans are microscopic colonial animals. They act and behave similar to corals, though they are much smaller. Some species appear as a “cast net” over the shell of a snail or clam, and can be seen on blades of turtle grass as well. There are many other species of these colonial creatures that call seagrass home.
We are highlighting these three groups but there are many other forms of epiphytes and epizoids growing on these grass blades. And it is these that the small grazers, like tiny crustaceans, feed upon, which in turn are what the millions of small silver juvenile finfish and crabs are feeding on. The seagrass meadow biodiversity and productivity is dependent on them and most Panhandle folks do not know they are there. Dr. Edward O. Wilson made a comment in his book Half Earth, that we have been focused on conservation of wildlife and habitat for many years now – but we fully do not understand what it is we are trying to conserve. We focus on blue crab and manatee conservation and do not realize that conservation of these micro-communities is essential for conservation, or restoration, success. The first step in conserving such communities is knowing they exist and how they support the system. You now have a little more knowledge of them, but there is SO much more to learn.
Many in the Florida panhandle are aware of the importance of seagrasses to estuarine ecology. They have heard this many times before and have heard how important it is to protect them. Some are aware that they are important as a nursery for many commercial important fin and shellfish. But fewer are aware of the diversity of life that exists in these “fields of grass”. Much of the life there is small and unnoticeable until you don a mask and explore. Even then, you need to slow down and look closely.
In this series on “Sea of Grass” we will be looking at some of the species that reside in these massive meadows expanding the Florida panhandle. We begin with the grasses themselves.
Seagrasses are just that – grasses that grow “under the sea”. They are similar in many ways to the grasses that grow in your yards. Their blades extend above the sediment and are usually all one sees as they are exploring the meadows. Being true plants, they do have stems – but these stems run horizontally beneath the sediments and are called rhizomes. Rhizomes are like “runners” and extend the plants across the landscape. Many have discovered rhizomes in their yards when pulling weeds. You begin to pull and a the runner exposes itself like pulling a thread from a sweater. From these rhizomes extend the small roots. Like lawn grass, seagrass use the roots to help anchor them in place and remove water and nutrients from the environment. But they are immersed in water and, like many marine creatures, have the ability to desalinate it so they have a source of freshwater.
Like all plants, seagrasses require sunlight for photosynthesis. Thus, they must grow in shallow water. In the western panhandle they are limited by the availability of light and are usually found in the estuaries where the water depth is not more than 10 feet. As you move into the eastern panhandle, particularly close to where the Big Bend begins, there are fewer large rivers depositing muddy water, more expanses of salt marsh to remove sediments from runoff, here seagrasses can grow deeper. Here they can expand into the open Gulf of Mexico itself producing hundreds of thousands of acres of these grass meadows.
Seagrass beds have declined over the last half century.
Photo: Rick O’Connor
They are not fond of high energy systems. Large waves can rip seagrasses from the bottom and deposit them onshore. In the western panhandle the Gulf generates larger waves and thus the grasses are found in the protection of the lagoons, sounds, and bayous. Near the Big Bend natural wave energy is low enough to support them in the open Gulf. It has been estimated that Florida has between 2.2 and 2.5 million acres of seagrass. Most of this is along the west coast of the peninsula running from the Florida Keys to the Big Bend1.
There are seven known species of seagrass in the state. Three of these are common in the panhandle and an additional one, Manatee grass (Syringodium filiforme), is beginning to expand its range into our area.
An amazing meadow of turtle grass.
Photo: Virginia Sea Grant
Two of our common species prefer more saline water – water with a salinity at least 20 parts per thousand (ppt). Those are Turtle grass (Thalassia testudinum) and Shoal grass (Halodule wrightii). These grasses both have flat blades but differ in blade width. Turtle grass is wider (4-12mm) and resembles St. Augustine grass from our lawns. Because of the wider blade, they grow in deeper water (not being able to tolerate the break waves and whitecaps near the surface). Shoal grass is very thin (<4mm) and feels more like human hair when you run your toes and fingers through it. Manatee grass resembles shoal grass in size but has a round blade instead of a flat one. In the Pensacola area we are beginning to find patches of it growing in Big Lagoon and Santa Rosa Sound.
Shoal Grass
Photo: Florida Department of Environmental Protection
Widgeon grass (Ruppia martimia) can tolerate the higher salinities of the lower estuary but can also tolerate the lower salinities of the upper estuary. It dominates the lagoons and bayous of the upper Pensacola Bay system. It has a thin flat blade like shoal grass but differs in that it branches as it grows instead of a single blade extending about the surface.
Widgeon Grass
These meadows of seagrass provide food and habitat for a myriad of marine creatures, who we will meet in other posts in this series. In Part 2 we will begin with one that is very important but very few know is even there – the epiphytes.
It is 1922 and you are rowing your wooden skiff from a small beach house near what will become the town of Gulf Breeze Florida across Santa Rosa Sound on your way to Santa Rosa Island. The water is 10-15 feet deep, and you can see the bottom. It is covered with a lush garden of seagrasses with numerous silver fish jutting in and out of the blades. Most are there only for a moment before they are lost again. You notice a brown colored puffer fish hovering over the grass as you past by. Maybe a small sea turtle grazing, or a tannish colored stingray flying over the meadow. As you get closer to the island, which is covered with sand dunes reaching 20-40 feet in height and shrubby live oak and magnolia trees, you begin to see Florida conchs and horseshoe crabs, maybe fields of bay scallops littering the grass in every direction.
An amazing meadow of underwater grass. Photo: Virginia Sea Grant
Sounds amazing, doesn’t it? And it was actually like this once.
What changed?
I asked this question of some ole timers who grew up on Bayou Texar in Pensacola decades ago. You might be surprised to learn that Bayou Texar resembled this scene. They described water that was between 10-15 feet deep, had sand and seagrass on the bottom, and you could catch shrimp the size of your hand by tossing out a cast net. But Bayou Texar no longer looks like this.
Most told me the first thing they remember was a change in the water clarity. The water became more and more turbid. Then the shrimp went away, then some of the fish. They mentioned several species of fish that no longer exist there. The cause of the turbid water? … Development. They were developing all around the Bayou after World War II and that was when things began to change. They mentioned the road going in on the east side of the bayou as the point when turbidity issues began. The houses came later.
With little rain over the last few days the water clarity was excellent and you could see the seagrass very well.
The city of Gulf Breeze was founded in 1935 and was originally called Casablanca because of a white house there that could be seen from Pensacola. As the community grew the waters became more turbid as well, and the amazing underwater garden declined. But this was not just happening in Gulf Breeze and Bayou Texar, it was happening everywhere.
But it was bound to happen. As the human population grows more space is needed for homes, businesses, and schools. More roads are needed to reach these locations and a bridge was placed to reach Santa Rosa Island, so you no longer had to paddle a skiff to reach it. Once on the island, growth continued. More homes, roads, and businesses. With more run-off, turbidity, and the garden continued to decline.
Shoal grass. One of the common seagrasses in Florida. Photo: Leroy Creswell
The thing was we did not know at the time that (a) we were causing this decline and (b) how much we really wanted that garden there. I often hear the question “what happened to all of the blue crabs?” I think they know the answer, but they remember a time when blue crabs were more abundant, can you imagine what it probably was like for our friend paddling across in 1922. And there has been a noticeable difference in crab numbers in their life. There are folks, including myself, who remember bay scallops in the Sound and horseshoe crabs on what they called “Horseshoe Crab Island” in Little Sabine. This is one of the amazing things about this story – how fast the decline was. Now we better understand how important these underwater meadows were to the function of a healthy estuary and there is interest in restoring them.
Bay scallops need turtle grass to survive. Photo: UF IFAS
To restore seagrass, you first have to understand, and mitigate, what is causing the decline. Seagrasses are vascular plants that possess roots, stems, and leaves. They produce flowers and sexually reproduce using seed. This is not the case with seaweeds, which are nonvascular and lack the above, but they often mistakenly called seaweeds. There are three species that dominate our seagrass meadows in the Florida panhandle and a fourth one that is not as common. The uncommon one has a round blade like a pine needle and is called manatee grass (Syringodium filiforme).
The three common species all have flat blades. Widgeon grass (Ruppia maritima) has blades that branch. It tolerates a wide range of salinity and is more abundant in the upper regions of our estuaries. Shoal grass (Halodule wrightii) has a single flat, non-branching, blade that is very narrow (< 3mm) and resembles human hair. Turtle grass (Thalassia testudinum) is also flat, non-branching, but wide (>3mm) and resembles St. Augustine grass.
Like other grasses, these plants require sunlight and nutrients to survive. They also need to grow in the low energy locations of our estuaries. Sunlight, of course, is key for photosynthesis and clear water is the key to getting enough of it. 15-25% of the sunlight reaching the surface of the water must also reach the bottom where the grasses are. Nutrients can be obtained through the water column and sediments. The stems run horizontal beneath the sand and are called rhizomes. They help hold sediments in place increasing the much-needed water clarity as well as reduce shoreline erosion. The blades extend from the substrate up into the water column bathing in the sunlight. They are covered by microscopic plants and animals that resemble scum when you run fingers over them but provide mush of the food for the creatures that live there.
And live there they do.
It has been estimated that it least 80% of the commercial and recreational important shell and finfish spend at least part of their lives in the seagrass meadows. Ducks, manatees, and sea turtles are some of the grazers on these plants and sea horses, pipefish, and pinfish are abundant.
Photo: NOAA
When humans began developing around the Sound in the 1940s and 1950s the sediment run-off decreased water clarity, cutting off the much-needed sunlight, and in some locations covered the grasses. Excessive nutrients from our fertilizers, and detergents increased phytoplankton growth which in turn decreased water clarity more and enhanced the growth of macroalgae which smothered the meadow like a blanket. Hot water discharges from industrial processing along the shores stressed the grasses as did prop and anchor scars from power boat plowing through and anchoring in them. These same boats and jet skis increase wave energy with their wake, as do seawalls when waves reflect off of them. Marinas, bridges, and docks all required dredging in the meadow which not only removed the grasses but increased turbidity even further. All of this triggered the decline of these amazing gardens. And with them the decline of the cherished fisheries as well.
The scarring of seagrass but a propeller.
In recent years the Florida Fish and Wildlife Conservation Commission (FWC) conducted surveys across the state to assess the status of our seagrass beds. They estimated that there was a little over 2 million acres of seagrasses in Florida waters, 39,000 in the western panhandle. Though much of these beds appeared to be stable, or even increasing acreage, those in the panhandle were still in decline and all of Florida’s seagrass gardens were less than the acreage in the 1950s.
In this study they found the Perdido Bay had primarily shoal grass. Big Lagoon and Santa Rosa Sound were a mix of shoal and turtle grass, with some manatee grass reported from Santa Rosa Sound. Aerial imagery found –
Perdido Bay had 642 acres of seagrass in 1987; 125 acres in 2002 for a net loss of 5.4% / year
Pensacola Bay had 892 acres in 1992; 511 acres in 2003 for a net loss of 3.9% / year
Big Lagoon had 538 acres in 1992; 544 acres in 2003 for a net gain of 0.1% / year
Santa Rosa Sound had 2,760 acres in 1992; 3,032 acres in 2003 for a net gain of 0.9% / year
The numbers in the lower portion of the bay are encouraging and suggest some behavior changes we made in recent decades have helped. Both development and monitoring continue. We will see.
What can be done to help restore the garden?
First, reduce run-off into the bay. This can be done by engineering designs with green infrastructure methods but can also be done by the private homeowner as well. Using native plants in your landscape reduces the need to irrigate your property and landscape designs which include rain gardens and rain barrels will also help reduce run-off.
The reduction of nutrients begins with the reduction of fertilizers on the landscape. Using Florida Friendly Landscapingprincipals can lead to a beautiful landscape that does not require fertilizers. If you choose to use nonnative plants that do require fertilizers, use only what the plant needs – do not over do it.
If you live along the waterfront, you can further reduce nutrients by planting a living shoreline. The plants used in living shorelines are known to remove nutrients from run-off from your property, as well as reduce erosion and provide more habitat for fisheries. One living shoreline project in Bayou Grande has seen an increase in shoal grass beds since they planted it.
When boating, be aware where seagrasses exist. Lift your motor when moving through them to avoid prop scarring and anchor in open sandy locations. You can also follow the principals of a Florida Clean Boater to reduce your impact on water quality that could impact the seagrasses.
With a little effort on our part, we can enhance some of the positive numbers we have seen in seagrass assessments and hopefully turn the current negative trends into positives. Maybe the garden will return. For more information on how you can apply any of these principals contact your county Extension office.
Seagrasses have been described as the “nursery of the sea”. Studies show that up to 90% of the commercially valuable fin and shellfish species spend part, or all, of their lives in these submerged meadows. As you can imagine, these grasses must grow in clear, relatively shallow waters – so they are more inshore. You might also imagine that most of the fish living here are going to be small. There are the larger predators in this grassy world, but most are going to be small enough to hide amongst the blades.
These inshore seagrass meadows not only provide hiding places but provide food as well. Interestingly, most do not feed on the grass directly, but rather the tiny plants and animals that are attached to the blades – what are called epiphytes and epizoids. Those that feed on these are then preyed upon by slightly large creatures until we find the larger apex predators – like the speckled trout.
Many of those who reside here are specialist in camouflage and mimicry, and others might be ones who actually live in the sand bordering the edge of the meadows – waiting for a chance to pounce on unsuspecting food. Let’s meet a few of these interesting fish.
Photo: Nicholls State University
Pinfish
You are at the beach for a day of fun and sun. You enter the water of Santa Rosa Sound to play at the edge of the seagrass bed, or maybe to snorkel and explore it. As you stand on the sand you feel little nips at your ankles and immediately think – CRAB! But you would be wrong. As you look closer you will see it came from a small fish – and the more you stir the sand, more of these small fish arrive. They are probably feeding on the small invertebrates that are stirred up from your movement, but they periodically nip at you as well.
This small fish is a very common member of the inshore fish community known as the pinfish. They are members of the Porgy family, related to sheepshead, and have incisor teeth for crushing the shells of their prey. Most locals are first introduced to them as a kid while fishing. They seem to bite, or steal, any bait you put on. Most often used as bait themselves, they are actually edible – but you need one of the large ones to have a meal. They get their common name from the sharp spines of their dorsal fin. When snorkeling in the grassbeds you will find they are the most common fish there.
Photo: USGS
Needlefish
These guys look scarier than they are. Long skinny fish with long skinny snouts that hold long skinny teeth. They resemble barracuda and have the look as if they could attack and do some damage – but they are harmless, unless you catch one in a net, then they will swing their long skinny heads towards your hand for snip.
These small predators travel above the grassbeds looking for potential prey hiding among. Small juvenile fish seem to be what they want. Though often just referred to as “needlefish”, there are actually four species, but they are hard to tell apart.
Photo: NOAA
Seahorses
These are captivating fish, and very hard to find as they blend in so well, but they are there – along with their close cousins the pipefish. It seems hard to call it a fish at all – it certainly does not look like one. Swimming vertically in the water, no tail to speak of, they seem like a creature in their own group. But they are fish. The scales are fused into an armor plating and they do have both gills and fins – characteristics of fish. They will use their prehensile tail to grab onto a grass blade, hanging there waiting for tiny shrimp to swim by which they inhale using a vacuum like motion with their tube-shaped mouths.
Pipefish resemble seahorses but are elongated, with a distinct fin for a tail, and swim horizontally as most fish do. They will turn vertically in the grass to appear to be a blade themselves and hunt similar prey as their seahorse cousins.
A well-known characteristic of this group is the fact that the males carry the fertilized eggs – not the females. Males can be identified by the brood sac on their ventral side and they may carry up to 80 eggs. The eggs hatch within the pouch and the young are born alive.
Photo: NOAA
Puffers
This group of fish are famous for their ability to “blow up”, or inflate like a balloon, when threatened. Kids love to play with them and get a kick out of watching them inflate. These are round bodied – slow moving fish, which is one reason they inflate. It does not matter if you can catch them, you cannot swallow them if you do!
There are actually two different families of “blowfish”. The true puffers are smaller (3-12 inches), have tubercles on their bodies instead of long spines, and the teeth in the upper and lower jaw have a space forming four teeth (two on the top jaw, two on the bottom) – giving them their family name “tetradontidae”. The “burrfish” are larger in size (1-2 feet), have long spines on the body, and no median in the teeth – so only one tooth on the top jaw, one on the bottom – “diodontidae”.
The most common one found is the striped burrfish. The big boy of the group – the 2-foot porcupine fish – is rare in the northern Gulf and prefers the reefs of the open sea to grassbeds.
When threatened they will inflate with water (or air) and try to continue swimming. After the danger has passed, they will deflate and go about their merry way. There are stories about their flesh being poisonous and dangerous to eat – it is true. The compound they produce is one of the more toxic found in the fish world. Though there are certified chefs around the world who can safely clean them, it is not recommended you eat these.
Seagrass meadows are made up of plants that live under water in our local estuaries. Just like the grass and plants in our yards where many types of insects, worms and small animals live, seagrass meadows provide habitat for many types of young fish and invertebrates, such as crabs and shrimp.
Between 70 and 90% of fish, crabs and shrimp that recreational and commercial fishermen catch, spend some time during their life in seagrass beds. In 2014, the commercial fishing industry contributed nearly $140 million, while recreational fishing spending contributed $6 billion to Florida’s Economy. If we did not have healthy seagrasses, we would not have this economic impact on our coastal economies (http://gulffishinfo.org/Gulf-Fisheries-Economics).
In addition:
·As seagrass blades move with the currents and tides, sediments are removed from the water, which contributes to improved water clarity.
·Seagrasses are the same type of plants that grow on land, they produce oxygen for marine life.
·Seagrasses filter excess nutrients from the water.
·Provide food and shelter for juvenile fish, shrimp and crabs.
·Endangered species such as manatees and green sea turtles depend on seagrass beds for food.
·Migratory birds depend on seagrass beds for foraging needs.
What can you do to help protect seagrasses?
While boating:
•Avoid seagrass beds. If you do run aground in a seagrass bed, turn off your engine, tilt up the engine and walk or pole your boat out of the shallow water.
•Be safe and know water depths and locations of seagrass beds by studying navigational charts.
•Seagrasses are usually found in shallow water and appear as dark spots or patches. Wear polarized sunglasses (to reduce glare) to help locate these areas.
•Always choose to use a pump-out station for your marine sanitation device.
•Stay in marked channels.
At home:
•To reduce pollution from entering our waterways, keep a buffer of native plants along your shoreline. This will also help to protect your property from erosion and slow flood waters during storm events.
•To save money, plant native plants that don’t require a lot of fertilizers and pesticides. Avoid seagrass beds when planning for dredging activities or pier construction.
•Comply with Shoreline Protection construction codes
•Maintain septic tanks.
In your community:
•Families and children can get out and snorkel these areas! Many sites are easy to access from public parks.
•Get involved with local organizations that promote nature protection.
•Working together, we can share with community members what we have learned about seagrasses at the 20th annual Seagrass Awareness Celebration, March 6, 2020 from noon until 4 pm at Shoreline Park South in Gulf Breeze Fl.
