Sargassum

Sargassum

Sargassum washed ashore after a storm on Pensacola Beach. Photo credit: Carrie Stevenson, UF IFAS Extension

I am sure it drives the tourists a little crazy. After daydreaming all year of a week relaxing at the beach, they arrive and find the shores covered in leggy brown seaweed for long stretches. It floats in the shallow water, tickling legs and causing a mild panic—was that a fish? A jellyfish? A shark? Then, of course, high tide washes the seaweed up and strands it at the wrack line, shattering the vision of dreamy white sand beaches.

But for those visitors—and locals—willing to take a closer look, the brown algae known as sargassum is one of the most fascinating organisms in the sea. The next time you are at the beach, pick some up and turn it over in your hands. Sargassum is characterized by its bushy, highly branched stems with numerous leafy blades and berry-like, gas-filled structures. The tiny air sacs serve as flotation devices to keep the algae from sinking. This unique adaptation allows it to fulfill a niche at the top of the water column, instead of growing at the bottom or on another organism.

The sargassum fish blends incredibly well into its home within sargassum mats. It uses handlike pectoral fins to move around. Photo credit: Reef Builders

Sargassum tends to accumulate into large mats that drift through the water in response to wind and currents.  These drifting mats create a pelagic habitat that attracts up to 70 species of marine animals.  Several of these organisms are adapted specifically to life within the sargassum, reaching full growth at miniature sizes and camouflaged in shape, pattern, and color to blend in.  These very specialized fauna include the sargassum crab, the sargassum shrimp, sargassum flatworm, sargassum nudibranch, sargassum anemone, and the sargassum fish! The sargassum fish (Histrio histrio) is in the toadfish family, a group of slow-moving reef fish that pick their way through coral and algae by using their pectoral fins like hands. Sea turtle hatchlings will spend their early years feeding and resting within the relative safety of large mid-ocean sargassum mats.

The small air-filled sacs of sargassum allow it to float on the surface, becoming the basis of a teeming ecosystem. Photo credit: Carrie Stevenson, UF IFAS Extension

Over time the air sacs  lose buoyancy and the sargassum sinks, providing an important source of food for bottom-dwelling creatures.  If washed ashore, many of the animals abandon the sargassum or risk drying out and dying.

In general, most of the larger, familiar seaweeds like sargassum are brown algae.  Brown algae (including kelp and rockweed) have colors ranging from brown to brownish yellow-green.  These darker colors result from the brown pigment fucoxanthin, which masks the green color of chlorophyll.  Extractions from brown algae are commonly used in lotions and even heartburn medication!

Ghost Forests

Ghost Forests

A ghost forest forming along the shoreline of Blackwater Bay in Santa Rosa County. Photo credit: Carrie Stevenson, UF IFAS Extension

As the name implies, they are haunting—wide stretches of standing, dead trees with exposed roots. These “ghost forests” are an unsettling scene in unsettling times for the environment. While coastal erosion is a fact of life—incoming waves, hurricanes, longshore drift of beach sand—the rate of its occurrence is startling lately.

Global rises in sea level due to increased atmospheric carbon levels mean more saltwater is moving into flat, coastal habitats that once served as a buffer from the open water. Salt is an exceedingly difficult compound for plants to handle, and only a few species have evolved mechanisms for tolerating it. Low-growing salt marshes and thick mangrove stands have always served as “first line of defense” buffers to take in wave action and absorb saltwater. If shorelines have too much wave action for marshes to form, wide stretches of sandy beach and dunes serve the same function, protecting the inland species of shrubs and trees. Many coastal areas are flat and stay at or just above sea level for thousands of yards, or even miles. This means that even a small increase in sea level can send saltwater deep into previously freshwater systems, drowning the marsh and flooding stands of oak and pine. The salt and sulfate in seawater will kill a tree quickly, although it may remain standing, dead, for months or years. Hurricanes and tropical storms exacerbate that damage, scouring out chunks of shoreline and knocking down already-unstable trees.

This diagram outlines the changes in coastal vegetation and shorelines as sea level rises. With “ghost forests,” the sea level moves into that coastal forest section. Figure credit: W. Gray, IAN Image Library

A slow increase in sea level could be tolerated and adapted to as salt marshes move inland and replace non-salt tolerant species. But this process of ecological succession can be interrupted if erosion and increased water levels occur too quickly. And if there is hard infrastructure inland of the marshes (like roads or buildings), the system experiences “coastal squeeze,” winnowing the marsh to a thin, eventually nonexistent ribbon, with no natural protection for that expensive infrastructure.

Ghost forests are popping up everywhere. Earlier this month, Popular Mechanics magazine reported on a recently published study that used satellite imagery to document how 11% of a previously healthy forest was converted to standing dead trees along the coast of North Carolina. The trees died within a span of just 35 years (1984-2019). During that time frame, this stretch of coastline also experienced an extended drought and Category 3 Hurricane Irene. These impacts sped up the habitat loss, with over 19,000 hectares converted from forest to marsh and 1100 hectares of marsh vegetation gone, becoming open water.

Exposed roots of a ghost forest forming along the Escambia Bay. Photo credit: Deanie Sexton

Due to increased coastal flooding and saltwater standing in forested areas, U.S. Fish and Wildlife Service employees are concerned that the historic Harriett Tubman Byway in Maryland—part of the famed underground railroad of the Civil War era—will soon be gone. Over 5,000 acres of tidal marsh have converted to open water in the area and large stands of trees have died. Even locally, trees along Escambia and Blackwater Bay are dying due to salt damage and heavy erosion. Hurricane Sally delivered a knockout punch to many remaining trees along the scenic bluffs of the bay.

Sea level has risen over 10” in the past 100 years in the Pensacola Bay area, and even mid-range Army Corps of Engineers estimates expect 0.6 to 1.4 feet of rise in the area by 2045. There are some actions we can take to mitigate future damage. Building a “living shoreline” of vegetation along a piece of waterfront property instead of using a seawall can help, especially if the vegetation growth outpaces sea level rise. You can also visit the City of Pensacola’s Climate Task Force report to learn more about climate action recommended (and being taken) locally, such as increasing the use of renewable energy and dedicating staff to sustainability measures.

 

 

Guest Columnist Cathy Hardin: The trials and joys of trees

A healthy and diverse native forest provides many benefits for environmental and human health. Photo credit, Cathy Hardin

Trees often are low on priority lists – unless you had tree damage as a result of Hurricane Sally. However, you might be surprised to learn that trees played a beneficial, if somewhat behind the scenes, role for good this year and every year. And celebrating the good, while not ignoring potential problems, is important when making decisions involving trees.

Often trees are disparaged, especially after a severe storm. Many trees fell during Sally, causing costly clean up and often significant damage. Some trees were damaged: causing hazardous conditions, opportunities for the tree disease and insect infestation, or simply aesthetically unpleasant disfigurement. Even without storms, trees require care, can interfere with utilities and foundations, and require extra clean up certain times of year. Yet, healthy well-maintained trees might reduce wind speeds and damage for property underneath or on the leeward (downwind) side of trees. Trees also significantly reduce erosion and absorb stormwater.

Bald cypress. Photo credit, Cathy Hardin

Trees often give more than they take. Many studies have been done on the effects of green space on a person’s well-being, including lowering blood pressure, speeding up recovery times, and lessening depression and anxiety. Other social benefits include lowering crime rates, increasing property values, creating beauty and space for recreation and relaxation, and lowering cooling bills. They provide habitat for birds and other wildlife. We haven’t even begun to mention the material benefits such as fruit, nuts, wood, and the 5,000 plus commercial products made from trees (wood, roots, leaves, and saps).

Author and county forester Cathy Hardin demonstrates proper tree planting at a past Arbor Day program. Photo credit: Carrie Stevenson, UF IFAS Extension

So, celebrate trees this year! Winter is a great time to improve existing trees and to plant new ones. Florida Arbor Day is celebrated the on the third Friday in January – January 15, 2021. National Arbor Day is the last Friday in April. In Escambia County, the UF IFAS Extension office is holding several Arbor Day related events, including a drive-through tree giveaway on January 23. Even if you are not able to attend a public event in your area, you still can get out and celebrate trees. Below are some ideas.

 

 

Existing Trees
• Care for storm damaged trees.
o Contact an arborist for evaluation of potential hazards
o Properly prune out broken limbs to create a smooth surface
o Some trees may not be able to be successfully treated and need removal
o Most trees will recover, but might need time and/or multiple treatments
• Learn about proper pruning techniques to take care of smaller trees yourself
• When hiring a professional is required, hire a reputable company with a certified arborist on staff. Ensure the company has both Personal and Property Damage Liability Insurance and Worker’s Compensation Insurance. Arborists certified by the International Society of Arboriculture can be found at http://www.isa-arbor.com/findanarborist/arboristsearch.aspx.
• Take care of tree roots. Don’t compact the soil by parking or piling things in the root zone. Use caution
when applying any chemicals (fertilizer, herbicide, pesticides) to the soil or lawn. Read the label to
ensure it will not harm your tree.

Florida yew. Photo credit, Cathy Hardin

New Plantings
• Decide what species of tree is right for you, considering the soil type, size of opening, climate, and eventual size of tree.
• Plant the tree at the right depth, not too deep or too shallow.
• Keep it simple. Soil amendments, fertilizers, and staking are usually unnecessary, especially for small native trees.
• Mulch lightly over the root zone, but not against the trunk.
• Water regularly until the tree is established. (Three gallons per inch of tree diameter weekly – applied slowly at the root ball)
• Celebrate!
• Take a photo of your favorite tree to post on social media. Tag the Florida Forest Service!

Longleaf pine. Photo credit, Cathy Hardin

• Take a hike in the woods or a nearby park.
• Have a picnic with friends or family by a tree.
• Be grateful for your tree and its benefits.
• Teach a child about trees. There are many activities that can be used. Check out Project Learning Tree Activities for Families – Project Learning Tree (plt.org) or the Arbor Day Foundation www.ArborDay.org for a few ideas.
• Plant a new tree.

For more information on the benefits of trees, visit healthytreeshealthylives.org or www.vibrantcitieslab.com. The Florida Forest Service, a division of the Florida Department of Agriculture and Consumer Services, manages more than 1 million acres of state forests and provides forest management assistance on more than 17 million acres of private and community forests. The Florida Forest Service is also responsible for protecting homes, forestland and natural resources from the devastating effects wildfire on more than 26 million acres. Learn more at FDACS.gov/FLForestService.

Cathy Hardin is the Escambia County Forester for the Florida Forest Service and can be reached at Cathy.Hardin@fdacs.gov.

Stormwater Ponds 101

Stormwater Ponds 101

Well-maintained stormwater ponds can become attractive amenities that also improve water quality. Photo credit: Carrie Stevenson, UF IFAS Extension

Prior to joining UF IFAS Extension, I spent three years as a compliance and enforcement field inspector with the local Florida Department of Environmental Protection (FDEP) office. It was a crash course in drinking water regulation, wetlands ecology, stormwater engineering, and human psychology. For about half of that time, I worked in the stormwater section with an engineer, certifying the proper construction and specifications of stormwater treatment ponds built for residential and commercial developments. During a construction boom in 2000-2003, my coworkers and I traversed back roads from Perdido Key to Freeport, trying to catch every new project and make sure it was done right. If they weren’t, it also fell to the 3 of us to make sure mistakes were corrected.

Since 1982, Florida Statutes have required that rainfall landing on newly constructed impervious surfaces (rooftops, streets, parking lots, etc.) must be treated before turning into runoff that leaves the property and ends up in local water bodies. The pollutants in stormwater runoff—heavy metals, fertilizer, pesticides, trash, bacteria, and sediment—are the biggest sources of water quality problems for the state, more so even than industrial and agricultural sources.

The most common stormwater ponds have sandy bottoms, grassed berms, and piped inlets with riprap to slow the influx of water. Photo credit, Michelle Diller

Therefore, new developments are required to treat that runoff. This may be accomplished by several means, including regional stormwater ponds. However, the most common are still curbs and gutters, which drain to an often-rectangular hole in the ground with a chain-link fence around it. Ideally, water pools into these dry ponds while raining, reducing flood risk and holding water long enough to allow it to soak into the soil. Most of the ponds in northwest Florida have sandy bottoms that percolate easily. Maintenance is required, however, and when heavier soils, trash, or muck accumulate they must be cleaned out to function properly. Depending on the geology of any given location, the ponds may need sand filters or “chimneys” added to allow water to soak into the native soil.

Admiral Mason Park, adjacent to the Veterans’ Memorial Park along Pensacola Bay, is an example of a regional City stormwater treatment facility that also serves as a park. Photo credit: Visit Pensacola

If an area is naturally low-lying, close to the water table, or has highly organic, water-holding soils, it may be necessary to construct a “wet” stormwater pond. In these, water stands to a level below an overflow device, and can become a water feature for the development. Many residential developers will sell lots around a stormwater pond as “waterfront property” and a well-maintained one really can be a nice amenity. However, at their core, these are stormwater treatment mechanisms. A wet pond functions differently than a dry one and is dependent on healthy stands of shoreline vegetation to take up extra nutrients, metabolize them, and render them into harmless compounds. Many of these ponds have fountains to aerate the water and keep them from becoming stagnant. The City of Pensacola and Escambia County have several great examples of these types of ponds that serve as regional stormwater detention and community amenities. These were constructed in lower-lying areas to handle chronic problems with stormwater in areas that were built up and paved many decades before stormwater rules came into effect. Many other innovative and newer stormwater treatments exist as well, including bioretention, rainwater harvesting, green roofs, and pervious pavement.

 

Fall Color in Florida Swamps

Fall Color in Florida Swamps

A blackgum/tupelo tree begins changing colors in early fall. Photo credit: Carrie Stevenson, UF IFAS Extension

It’s autumn and images of red, brown, and yellow leaves falling on the forest floor near orange pumpkins enter our minds.  However, Florida isn’t necessarily known for its vibrant fall foliage, but if you know where to look this time of year, you can find some amazing scenery. In late fall, the river swamps can yield beautiful fall leaf color. The shades are unique to species, too, so if you like learning to identify trees this is one of the best times of the year for it. Many of our riparian (river floodplain) areas are dominated by a handful of tree species that thrive in the moist soil of wetlands. Along freshwater creeks and rivers, these tend to be bald cypress, blackgum/tupelo, and red maple. Sweet bay magnolia (Magnolia virginiana) is also common, but its leaves stay green, with a silver-gray underside visible in the wind.

The classic “swamp tree” shape of a cypress tree is due to its buttressed trunk, an adaptation to living in wet soils. Photo credit: Carrie Stevenson, UF IFAS Extension

Bald cypress (Taxodium distichum) is one of the rare conifers that loses its leaves. In the fall, cypress tress will turn a bright rust color, dropping all their needles and leaving a skeletal, upright trunk. Blackgum/tupelo (Nyssa sylvatica) trees have nondescript, almost oval shaped leaves that will turn yellow, orange, red, and even deep purple, then slowly drop to the swamp floor. Blackgums and cypress trees share a characteristic adaptation to living in and near the water—wide, buttressed trunks. This classic “swamp” shape is a way for the trees to stabilize in the mucky, wet soil and moving water. Cypresses have the additional root support of “knees,” structures that grow from the roots and above the water to pull in oxygen and provide even more support.

A red maple leaf displaying its incredible fall colors. Photo credit: Carrie Stevenson, UF IFAS Extension

The queen of native Florida fall foliage, however, is the red maple (Acer rubrum) . Recognizable by its palm-shaped leaves and bright red stem in the growing season, its fall color is remarkable. A blazing bright red, sometimes fading to pink, orange, or streaked yellow, these trees can jump out of the landscape from miles away. A common tree throughout the Appalachian mount range, it thrives in the wetter soils of Florida swamps.

To see these colors, there are numerous beautiful hiking, paddling, and camping locations nearby, particularly throughout Blackwater State Forest and the recreation areas of Eglin Air Force Base. But even if you’re not a hiker, the next time you drive across a bridge spanning a local creek or river, look downstream. I guarantee you’ll be able to see these three tree species in all their fall glory.