audio slideshow: summer fieldwork in Everglades National Park
Audio Slideshow: Summer Fieldwork in Everglades National Park: A Pictorial Overview from a USGS Intern
By Paul R. Nelson
"Summer Fieldwork in Everglades National Park: A Pictorial Overview from a USGS Intern" is a seven minute audio slideshow, narrated by Paul R. Nelson. Cruising through tidal creeks, sampling mangrove sites, pulling sediment cores, and avoiding swarms of mosquitoes are all in a day's work for scientists conducting studies in the Everglades. Paul Nelson, a USGS geologist/GIS analyst and former intern for ecologist Tom Smith, put together this audio slideshow that describes the experience of conducting fieldwork in the United State's largest subtropical wilderness.
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[narrator] Interning with the U.S. Geological Survey in St. Petersburg, Florida during the summer of 2009, I accompanied my supervisor Dr. Tom Smith to Everglades National Park for a week of field work.
[narrator] Lodging in Florida City allowed convenient access to the park. The 7:00 am departure was quickly forgotten during the 30 minute drive to the boat launch. Nothing a coffee and some early-morning window gazing can't cure.
[narrator] After meeting with some USGS colleagues at the Beard Center and grabbing our gear for the day, we set out on our somewhat trusty vessel, "Sweetpea".
[narrator] From the docks, we enter a series of mangrove channels. Mangroves and the tidal creeks play an important role in the ecosystem. Their root structures filter debris from the tidal currents and provide a nursery for many species. Mangrove detritus such as leaves, stems and bark provide food for the marine life. Plus they offer a tropical jungle feel on the way out to open water.
[narrator] Then into Buttonwood Canal. Constructed in the 1950's it allowed mariners entry to the bay and safe passage around Cape Sable. Unfortunately the canal allowed salt water to enter eastern Whitewater Bay and raise the salinity to ecosystem-altering levels. It has since been plugged at Flamingo. Here's Gordon at the helm, zooming up the canal towards open water.
[narrator] Tom braces, while Karen sights a channel marker and brings it up on plane. A suitable admiral and captain for the 25 mile journey up to the sampling sites. Hundreds of mangroves islands bespeckle the bays and coastline requiring excellent knowledge of the area, especially during a rainstorm.
[narrator] The sampling sites and hydrostations are located along the river and into the mangrove forests. Here, the plankway requires a fair amount of balance and some nimble footwork. Zonation occurs in mangrove species typically in a red to black to white mangrove as you head inland from the water.
[narrator] Under this canopy of red mangroves the mosquitoes swarm as if the dinner bell was ringing. No joke. Imagine freckles on a child or spots on a cheetah. Now multiply those numbers together and triple it. Start swatting and keep your mouth closed.
[narrator] Or if you're bright, wear one of these. Here Karen sports a Canadian bug shirt and checks the emplaced feldspar horizon; she kind of looks like a snowy Ninja.
[narrator] We create a recognizable horizon in the soil by laying down a thin layer of feldspar, then periodically measuring as sediment accumulates.
[narrator] Karen records sediment elevation data as Tom measures distance to the land surface. We're trying to determine if the rate of sediment accumulation can keep up with expected rise in sea level. Oh yeah, these mudflats are hot and muggy.
[narrator] Here I get a feel for the sampling equipment. These rods slide through a fixed plate of known elevation down to the land surface. Changes in surface elevation are recorded over time. Major storm events can alter the normal accumulation rate by dumping massive quantities of sediments along the shoreline. However, if the trees die, they'll discontinue adding new material to the record and a dip in the overall accumulation rate will begin. And by the way, mosquitoes are biting my hands, my face, and through my pants.
[narrator] The mangrove forests in the Everglades are magnificent. Typically the prop roots on a red mangrove are finger-size or slightly bigger. Here they reach diameters closer to arms, legs, or heads. They provide stabilization for the red mangrove which grows closest to the water-edge, and allow gas exchange to the submerged roots. They also stabilize the underlying sediments giving the island or shore an opportunity to build; a clever adaptation which allows them to occupy a habitat unsuitable for other species.
[narrator] Once through the mixed mangrove forest pictured in the distance, we enter the coastal marsh. Here sawgrass dominates the vegetation, and in this region it is dense, can grow to 9 feet tall, and is serrated like a steak knife or hack-saw blade. However, it is responsible for creating rich organic soils and covers much of the Everglades from Lake Okeechobee to the sea. Additionally the position of the boundary between the mangrove forest and coastal marsh, also known as the ecotone, is important. Fire, freezes, drought and sea level rise cause the ecotone to migrate seaward or landward. Studying this migration helps scientists recreate the past and make predictions for the future.
[narrator] Hydrostations along the rivers provide real-time data for scientists. Temperature, salinity, velocity, dissolved oxygen, rainfall, and water depth are recorded continuously and provide valuable data about the waterway's health. The USGS and other agencies, universities, and researchers rely heavily on these stations.
[narrator] Returning from the Gulf of Mexico to Shark River, we pass vast areas of dead and/or dying trees. These are large mangrove stems. Hurricane Wilma made landfall far north of here in 2005 but the high winds and massive storm surge devastated much of the coastline.
[narrator] The death of these stems and their subsequent removal will alter the coastline in a predictable manner. The destabilized sediments will be carried off by wind and waves and an overall landward migration will occur. In time, the forest will regenerate and begin a seaward trek, but the combination of rising sea level and increased hurricane activity may affect recovery time.
[narrator] Of the many exotic species introduced to the Everglades over the years, none has captured as much publicity as the Burmese Python. Here a 9-plus footer avoids the boat and heads for the safety of the mangrove roots. The python population is estimated to be in the tens of thousands and has a voracious appetite. It is wiping out the small mammal population, an integral part of the ecosystem. Thankfully none of the crew leaped overboard to wrestle the beast into submission, tempting though.
[narrator] Cruising through the island passes, it's typical to see schools of striped mullet. Rather atypical though is for one to jump into the boat like this little feller did. Here I display our diminutive catch before release. Two more and we could have had a sandwich.
[narrator] It is also rather common in the summer months for large convective storms to form over the hot, moist Everglades. A race back to the dock begins in the afternoon to avoid the plunging temperatures and pelting raindrops. Looks like we may get a little wet.
[narrator] Fires are common in the Everglades and play an important role in preventing shrubs and trees from invading the grasslands. Fires are also effective in releasing nutrients from the plant's tissues. History of fires in the park suggests that this area in the slide has not burned, so we are going to pull some sediment cores to determine why.
[narrator] Maya, who works for the National Park Service Fire Cache group, attempts to take a core as Karen and Tom look on. The fire management division of the park controls wildfires as well as planning and implementing prescribed burns. She's just not quite tall enough though.
[narrator] This shallow core helps to determine why this area is not prone to burn. Here calcitic mud, known as marl, lays atop very shallow limestone bedrock.
[narrator] If I still have some energy left, I'll cycle out here in the evenings. This is Biscayne National Park and lies due east about 10 miles from Florida City.
[narrator] 90% of the park is under water and is a haven for scuba divers and snorkelers.
[narrator] Here, a Golden Orb Weaver spider spins up a Cicada for supper.
[narrator] Thanks for watching. Come on down. It's hot, buggy, and delightful.
For more information visit:
SOFIA project: Dynamics of Land Margin Ecosystems: Historical Change, Hydrology, Vegetation, Sediment, and Climate
Paul R. Nelson