Day 1: Mangroves and Archbold
humidity:40%
The effects of the hurricane were clear to the whole group. Having set off in Naples Bay at 8am we drove past piles of wood and rubble. In many buildings along the coastal drive there were gaping holes and sections missing.
Hurricane Ian hit Florida on the 28th of September 2022, almost exactly a month before us fieldtrip students arrived. It was a category four storm, taking down whole houses close to shorelines and flattening the Florida Gulf Coast University`s vester. We were initially planning to stay at this vester, and had to change plans last minute.
Exploring the Mangroves
We drove up and down San Marco road three times before stopping. Either side of the banks in Rookery Bay National Estuarine Research Reserve in Florida thick mangrove forests were growing.
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| San Marco Road |
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| White ibis were spotted on the border, later a roseate spoonbill flew overhead |
Dr Li Zhang is waiting for us on the path running alongside the road.
Zhang, who researches wetlands for FGCU, begins to tell us about the mangroves around us and her project.
Mangroves are evergreen trees with broad leaves. There are around thirty different species of true mangroves in the world, but only three of these grow in Florida: red, black and white mangroves.
Rhizophora mangle (red mangroves) will grow the furthest outshore, termed ‘walking plants’ their prop roots grow from further up their trunk, spreading like a skirt round them. Through seeds germinating and stemming off from the plant red mangroves encroach into the sea, building up sediment between their roots.
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| Red Mangrove |
Avicennia germinans or black mangroves are characterised by their pneumatophores, which point needle-like out of the anoxic tidal areas mangroves inhabit. These pneumatophores draw oxygen in through lenticules in the bark from the air into the root system.
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| Black Mangrove |
All of these three species are beautiful and highly adapted for growing in saline areas. Mangroves are described as halophiles but can grow in freshwater where they are often outcompeted. White and black mangroves flourish in 60-65 ppt salinity where red mangroves prefer 90 ppt. One such adaptation is that white mangroves, for example, have two glands at the bases of their leaves which they excrete salt from.
Mangroves are delicate though in the fact that four days of frost are all it takes to kill a mangrove tree. But because of climate change, the plants have been able to move further North from their normal distribution around the equator.
Because of this spread, throughout the USA, such as in Louisiana, mangroves are seen as invasive when they dominate former salt marsh grassland habitat.
But mangroves should not be seen in this way, as Dr Li zhang explains, the habitats they create are vital both to wildlife and humanity.
-Mangroves are key nurseries for fish, 30% of commercial fish use mangroves to rear their young.
-The trees filter water, preventing pollution from reaching the oceans
-They will sequester carbon, fast tree growth and slow decomposition of dead foliage in oxygen-poor sediment means carbon is locked away in mud. This is blue carbon. Businesses will often invest in building and maintaining mangrove habitats because of blue carbon stored on land that has less commercial uses then terrestrial.
-Additionally, unlike freshwater wetlands, mangroves release very little methane.
-Land is protected when hurricanes, like hurricane Ian, and natural disasters hit, mangroves can weather these storms well and minimise wave hights.
Threats:
Dr Li Zhang gestured towards empty water, punctuated by the black trunks of dead mangroves.
There are many threats to mangroves, primarily water pollution, coastal development and deforestation for reasons such as agriculture.
San Marco Road in this case is the killer, built in 1938 it cut off water flow to 223 hectares of mangroves.
I looked around at the green around me. Thankfully, starting in 2012 the Fruit Farm Creek Mangrove Restoration project is underway working towards fully restoring the flow of water back through the habitat.
Water flow brings in nutrients and sediment to the mangroves. The sediment builds up around the trees, caught by their root systems. This accretion prevents mangroves from drowning as a result of re-suspension of mud and rising sea levels.
“Getting Our Feet Wet”
We all wade in the mangroves, simply stepping off the bank of the road.
The mud released trickles of bubbles as I sunk in, it was soft and thinner than I expected and of course very warm. Pits of deeper water tripped up lots of laughing students.
Following behind the fieldtrip group the water was murky, but ahead it was crystal clear.
Around 15m in, the trees thinned out revealing clearings harbouring small schools of fish. There were also small fish that would lie camouflaged on top of the mud. A wasp darted past my ear.
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| Propagules |
One of my fellow students found a propagule, propagules are viviparous and drop into the water to be washed away and eventually set root.
The Journey
We then all pilled back into the minibus for the two hour drive to Archbold Biological Center where we would be staying.
Along the drive what was instantly obvious as we traveled out of urban areas was the huge wealth of vivid plant life. Small canals had been dug by the sides of most of these long straight motor ways and were teeming with wildlife.
Seen enjoying the canals there were stunning wealths of birds. Snowy and great egrets with Blue herons and anhingas fishing or perched in undergrowth....
Along electrical cables birds of prey and banded kingfishers perched.
The whole minibus erupted into noise when, as we were coming close to Archbold, vultures were feeding off a carcass of what looked like a deer.
I briefly caught site of an American alligator, Alligator mississippiensis, pulled up vertically on a grassy bank in front of a house. It`s incredibly hard to wrap my mind around how these huge reptiles, coming from the UK where in all my years I have seen a few small snakes and lizards, are thriving wild in Florida.
I did not see as many alligators as I thought I would though. I had a preconception that their presence would be more felt. This could be because of the media circulating crocodilians, in which situations like huge alligators are seen in swimming pools and crossing golf courts on youtube.
We stopped of at a swamp at one point, but found it to be closed due to hurricane damage. We did see a juvenile alligator in a small lake and a monarch butterfly.
Archbold Biological Center
We arrived late afternoon and dispersed to look around the center,
After going from forests to passing fields of green ranches more frequently on the journey, what was immediately obvious was the change in plant life in around the centre.
Archbold is scrubland characterised by large pine trees punctuating xeromorphic shrubs on white sand.
Next to the car park a flock of Quiscalus quiscula or common Grackles were gathered calling.
Brown anoles ran over pavements and curbs, speeding into cracks and undergrowth at our approach.
Approximately 7cm long anisomorpha burprestoides, southern two-striped walkingsticks, were tracked walking across the drive in. Two out of the four on the road had been ran over by vehicles. Lots were found as mating pairs, with tiny males on the females` backs.
Classified as stick insects, southern two-striped walkingsticks excrete defensive dolichodial from glands on the front of its thorax.
At around seven in the evening dusk began to fall. While the group headed out to supermarkets a student and me went walking with torches.
We walked up and down the long drive into the station.
As the sun was setting two black vultures flew up from vegetation, most likely spooked, up into a dead tree where they preened themselves before flying away.
Many more southern striped stickwalks came out onto the road as night fell.
Crashing in the undergrowth, at around 9pm, made us freeze. A nine banded armidillo, Dasypus novemcinctus, trotted up by the roadside sniffing at shrubs and burrowing its head into leaf litter frequently, taking it back out again without burrying under.
It did not seem to notice the light on it or hear our presence. Only when we got too loud (shouting in excitement) did it bolt off noisily. Over the course of the night we saw three amidillos, they would come towards us and get close most times.
When the two of us returned towards the lab buildings we observed various geckos on the walls and in the lamps. There were two species but we only saw one species once. Insects teemed around these lamps.
A southern toad froze when we approached. It was situated on the matt in front of the door, where insects had fallen. After ten minutes it resumed hunting, and caught a small fly on the ground close to it with its tongue.
The walk ended at 10pm and we headed to bed.
useful links
on sediment flow: http://www.mangrovealliance.org/wp-content/uploads/2020/01/WWF-MCR-Sediment-Flow-in-the-Context-of-Mangrove-Restoration-and-Conservation-v6.5-WEB.pdf
Grackle sounds: https://www.allaboutbirds.org/guide/Common_Grackle/sounds#
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