Christina Nau - Coastal Ecology Field Trip Assignment

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2001C

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Oct 30, 2023

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Christina Nau Professor Arellano OCE-2001-650 14 October 2023 Coastal Ecology Virtual Field Trip Assignment (70 points) 1. The three types of mangroves found in the Tampa Bay area are the red, black, and white mangroves. Mangroves are a protected species in Florida that help hold the ground in place, prevent erosion, and are a good habitat for marine and aquatic organisms. They all produce detritus or food for herbivore organisms, and mollusks love them. (Greely 2018) The red mangroves have prop roots that go downward, lush pointy green leaves, and propagules that hang down from the branches which enable them to reproduce. The propagules get about 6 inches in length and once they become too heavy, they break off the branches and fall into the water below to eventually root themselves in the sediment to start the reproduction process, which can start up to a year later. The red mangroves have prop roots and are the only type of mangrove that have yellow leaves, which are called sacrificial leaves, or leaves that have salt secretions on them. When these leaves fall into the water, they become food also known as detritus for the herbivore organisms that reside below. (Greely 2018) The black mangrove roots aerate upwards (pneumatophores), and they have the darkest leaves of the mangroves, dark green, that are a little pointy, but not nearly as pointy as the red

mangrove. Their leaves all secrete salt on the back side of them, and you can actually lick the leaves to taste the salt that the plant secretes onto them if you would like. They also have flowers on their branches for reproduction. (Greely 2018) Lastly are the white mangroves, which usually grow closest to the shore. They have medium-colored green leaves, which are oval-shaped and have two little salt glands at the base of the leaves, where they secrete salt that kind of look like whiteheads or pimples. They have a regular rooting system in the ground like all other trees. (Greely 2018) Some physiological adaptations in the mangroves for water uptake and conservation are through ion compartmentation, osmoregulation, the selective transport of ions, the balance between ion supplies to the shoot, and room for the salt influx from the environment. Mangroves also have salt-excreting leaves, and a thick epidermis to help with the salt and water uptake. Mangrove leaves tend to be more succulent so smaller and thicker allowing for cooling and a bigger retention to conserve water use. This is because they have well- developed large-celled water-storing tissues within them. Many species of mangroves contain salt glands in or on their leaves, which allows salt to be secreted on them. The lower leaf surface is said to have dense covered hairs which raise the secreted saltwater droplets away from the leaves surface to prevent osmotic withdrawal of water. Therefore, the leaves may thicken with high salinity content in the surrounding area. Root elongation and the suberization of cell walls also avoid salt to help maintain water, as root elongation maintains room in the plant. Most mangroves have a thick-walled epidermis alongside a waxy cuticle and sunken stomata, which reduce water loss through the stomata and salt glands. Overall, to regulate water uptake, mangroves have thickening of leaves to have a greater retention time

for leaf nitrogen and to conserve water efficiently, so as saltwater salinity increases, their water conservation rises as well. (Parida and Jha 2010) The three salt-eliminating mechanisms mangroves use to live in saltwater are salt secretion, salt exclusion, and salt accumulation. Salt-excluding mangroves eliminate excess salt by an ultrafiltration mechanism at the root cell membranes. Salt-secreting mangroves regulate internal salt levels by secreting excess salt through glands, which sometimes results in salt deposits on their leaves. Lastly, salt accumulators accumulate high concentrations of salts in their cells and tissues to avoid salt damage by sequestering ions to the vacuoles in the leaf, translocation outside the leaf, cuticular transpiration, and efficient leaf turnover to salt shedding. (Parida and Jha 2010) 2. The mangrove environment consists of mangrove trees that shed salt-covered leaves which become food once broken down for organisms such as decomposers and bacteria that live below. The ground surrounding mangroves is very soft, so soft that your feet may sink, which is common near mangroves that have prop roots, such as the red. Mangroves do not have fast-moving waters or big waves, rather they have stiller water so they can stabilize themselves better. On the other hand, the low-energy beach environments have very little to no vegetation near the water, but some upland a little bit. In mangrove habitats, there are the mangroves themselves, as well as seagrasses in the surrounding area, so a bountiful amount of vegetation. All beaches along the Gulf Coast are considered low energy because of how low their wave heights are. Their waters produce small, ripple-like waves, unlike the beaches on the East Coast of Florida or in California that are high-energy, and you can surf on them. In low-energy beach habitats, there is not much fine mud or silt, but rather coarser, larger

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sand particles and crushed shells, so that is why soft-bodied animals do not reside there since they prefer finer-grained mud and silts like in the mangrove habitat. We would therefore expect less diversity in the low-energy beach environment than in the mangrove or seagrass communities. Both the mangrove and low-energy beach environments contain water that is oxygenated and slow-moving, as well as rich sediments even though their contents differ. (Greely 2018) To test the mangrove core, Dr. Greely took a PVC pipe which she pushed into the sediment to collect a sample right next to the mangroves. The sample was not evenly stratified, as there were a lot of water, different size grains, and difference in coloration, showing lots of inorganic and organic processes. At the surface, where the water meets the sediment, you will expect the highest oxygen concentration. As you go deeper into the core, darker materials and grains occur, which is known as organic composition. A lot of leaf and plant material is directly near mangroves, which creates this organic breakdown. That also means that there is less oxygen as you get deeper into the core, which releases hydrogen sulfide. Bacteria break down the plant material within the sediment which is then reused by the plant again. Once she got this core sample, she moved a couple of yards away from the mangroves to collect another sample. While push-coring, she could immediately smell the release of the hydrogen sulfide gas. Upon examination, the sediments are of a lighter shade and there is not as much dark organic matter and a lot more shell material. She also noticed some worms in the sample. Lastly, she took a final core sample far away from the mangroves near a seagrass bed. Here, there were lots of very dark organic breakdowns, but from seagrass and not mangroves this time. She noticed that the layering was darker and darker as

the sea grass got buried deeper and deeper. There was also an increase in shell material, with larger grain size, and a bit of sand. (Greely 2018) To test the low-energy beach core, she used the push-coring method to collect a sample, and Dr. Greely stated that the area was very crunchy, and not soft and mushy like the mangrove ground. There was also not much organic matter in the sample, so little to no plant material. The water movement contributes to a much higher oxygen concentration in the water than the mangrove core. This provides a healthy habitat for organisms that need more oxygen for swimming. The content of the core was very sandy, but mostly shell hash, with some mineral content. (Greely 2018) Two characteristics that are different between the sediment core in the mangrove environment and at the low-energy beach are the contents of the core itself and the oxygen levels within the core. The core contents in the mangrove environment were soft and mushy and contained mud and silt, while the beach core contained lots of sand and shell materials. Furthermore, the oxygen levels are much higher in the beach core than in the mangrove core because of water movement. In the mangrove environment, the water is still, so oxygen is coming from the mangroves, but it’s not being mixed deep into the core, rather sediment and vegetation are. However, in the beach core, the water is moving the ground constantly so the oxygen is constantly being overturned, so there will be oxygen present throughout the core, not just on the top layer. (Greely 2018) Two differences between the mangrove habitat and the low-energy beach habitat are the amount of vegetation and the variety of species residing in the said habitat. There are tons of vegetation in the mangrove habitat as there is a bountiful amount of mangrove trees and seagrass in some cases. The low-energy beach environment does not have any vegetation at

all near the water, and a little on the ground near the sand at times. Furthermore, there is a wider variety of species that live in the mangrove habitat rather than the low-energy beach habitat. This is because most soft-bodied animals prefer to live in the soft silty mud sediment rather than the coarser larger sandy and shell sediment. There are also not many places for animals to hide in the low-energy beach environment, unlike the mangrove environment that provides tons of shelter. (Greely 2018) The mangrove habitat is better for most juvenile organisms because it provides more shelter and nutrients than the low-energy beach environment. In the mangrove environment, leaves fall from the mangroves that break down and create food that the juvenile organism would be able to feed on. Furthermore, the roots and cover from the mangrove branches provide shelter for the juvenile organisms to hide or rest. (Greely 2018) 3. Three benefits that mangroves and seagrasses provide are ground stabilization, oxygen production, and the production of food for organisms. The roots of the mangrove trees and the seagrasses stabilize and hold the sediment together. This is why they are such a vital species to Florida, so much so that they are protected. In holding the sediment together, they prevent soil erosion and that is a major benefit in itself. Furthermore, mangroves and seagrasses produce oxygen that spreads throughout the water and into our atmosphere so that we can breathe it in. The production of oxygen comes from the photosynthesis process as CO2 is taken from the atmosphere and used to produce O2 or oxygen. Lastly, the trees from the mangroves and the seagrasses eventually break off and decompose and form what we call detritus, or food for the marine and aquatic organisms that live below. This is why the mangrove habitat has a variety of species as a lot of them benefit from the food produced by

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the trees and grasses, as well as the protection they provide and the pollutants they filter out. (Greely 2018) 4. Needlefish live close to the surface and are smooth, slender, and glide through the water. They have a pointy nose, with a lower and upper jaw that is lined with teeth. They have dark blue coloring on their upper side, and a light whitish silver color on their belly. Their dark upper side helps the needlefish disappear from above since the sunlight camouflages them. The only con is that their bellies are very visible underneath, but not from the top down. On the other hand, the toadfish are bottom dwellers that live near the sediment and are round, with a large flat mouth, and have a rigid and rough texture. They are a darkish brown color with a black twisty pattern down their body and fins. Their coloring and texture allow them to blend into the sediment they reside in and near. Both the needlefish and the toadfish use camouflage techniques to survive. (Greely 2018) Both needlefish and toadfish use coloring camouflage techniques, but they are different. The needlefish have a dark bluish dorsal color, which blends them with the water from predators above since they live near the surface of the water. They use this blending-in tactic to feed and live their lives accordingly at the surface. Similarly, the toadfish is a very dark multi-shaded brown color and is textured which helps them blend into the sediment at the bottom where they live, so they use the tactic of blending into the sediment. (Greely 2018). For needlefish, they stay near the surface in open waters and the tactic of blending in with the sunlight gives away where they live. They use the tactic of blending in with the sunlight, which automatically tells you that they live near the surface of the water. Likewise, the toadfish stay near the bottom and blend in with the sediment they live upon. Their coloration

looks exactly like the sediment, which is why their camouflage is so good, and it tells you that they reside on the bottom. (Greely 2018) By looking at the cartoons provided, the needlefish appears to be long and thin, with a pointed tip nose kind of like a swordfish. They are primarily a whitish silver color, with bluish accents to their fins and tails. It appears they are fast swimmers and have an easier time jumping in and out of the water to catch food with the help of their needle-like mouths. They seem like the kind of fish to gain speed to ambush their prey and catch it with their pointy nose. On the other hand, the toadfish appear a little rounder and bulkier, have a dark brown color with black accented patterns and appear to have a texture to them. They appear to have large wide mouths with strong jaws to hunt on shrimp, crabs, and fish that live at the bottom. The body shape and the location of the mouth and tail fin tell you how each fish swim and feed. Having a thin, slender body tells you that the needlefish swim fast, whereas toadfish are flat and compressed letting you know that they just stroll along the bottom. The needlefish have pointy noses that they can use to catch prey in an ambush way, while the toadfish uses their large mouth to capture prey and crush them with their jaws. The needlefish have forked tails to aid in swimming whereas toadfish have little stubby tails to slowly move across the bottom. (Greely 2018) 5. Juvenile gags prefer higher salinity habitats, as that is where they tend to be found in higher numbers. They also like shallow waters, with a large amount of vegetation coverage for them to live in and eat on, with seagrass meadows being the most popular. The seagrass in the shallow waters (coast) acts as a nursery for the juvenile gags. You may also find them in

oyster beds until they venture to offshore reefs. They have declined in population over the years since they are targets of fisheries. (Switzer et al. 2012) These types of habitats are beneficial to gags and other juvenile fish since they provide protection, habitat, and food. The vegetation gives gags and other juvenile fish protection as they can hide in it, but they also consume the seagrass, so it is a food source as well. Lots of small prey live in these coastal nurseries so the gags have plenty of food. The habitat is a breeding ground, or reproductive ground, especially for this species of grouper. A lot of the juveniles will live in the nursery or shallow coast region for a while before venturing into deeper water. (Switzer et al. 2012) The loss or decline of seagrasses can impact local fisheries since these fish depend on seagrass for habitat and food. If there is a loss of seagrass there will be a decline in population due to starvation or predation. This means that there is less productivity for fisheries as there will not be as many fish since there is no habitat or food surrounding them to keep them alive. (Switzer et al. 2012) 6. Two factors that contribute to the seagrass decline in Tampa Bay are algae growth and pollution from runoff and wastewater leaks. Pollution is creating algae blooms which is declining the seagrass population, and the pollution itself is killing the seagrass, so both factors work hand in hand with the decline of the seagrass population in Florida. Florida lost 5,411 acres of seagrass from 2018 to 2020 alone. (Sampson 2021) Three changes in Tampa Bay that have helped to restore seagrass habitats are proposals, seagrass transplanting, and monitoring the seagrass levels (“Seagrass Monitoring”; “Seagrass in Tampa Bay”). The proposal, the Tampa Bay Estuary Program

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was recently enacted to improve the water quality of Tampa Bay, and seagrass beds were chosen to conserve to do this (“Seagrass Monitoring”). Furthermore, seagrass transplanting has been used to help restore seagrass habitats by taking grass from a donor area to a project area to try and maintain roughly 38,000 acres of seagrass in Florida (“Seagrass in Tampa Bay”). The last method is seagrass monitoring where the Tampa Bay Watch acts as a member of the Tampa Bay Interagency Seagrass Monitoring Program to conduct annual seagrass surveys at 60 different transects to ensure a stable about of seagrass communities (“Seagrass in Tampa Bay”). The current state of seagrass coverage in Tampa Bay is estimated at 30,137 acres as of 2022. (“Seagrass Monitoring”)

References Greely, Theresa. “Virtual Coastal Ecology Field Trip - Introduction to Oceanography.” Introduction to Oceanography - Coastal Ecology , University of South Florida, Oct. 2018, http://usfweb.usf.edu/courseresources/ms/oce2001/videos/coastal- ecology/index.html . Parida, Asish Kumar, Bhavanath Jha. “Salt Tolerance Mechanisms in Mangroves: A Review.” Trees, vol. 24, no. 2, 2010, pp. 199-217, https://doi.org/10.1007/s00468-010- 0417-x . Sampson, Zachary T. “Tampa Bay Lost 13 Percent of Its Seagrass in Two Years, Study Shows.” Tampa Bay Times , 30 Apr. 2021, www.tampabay.com/news/environment/2021/04/30/tampa-bay-lost-13-percent-of-its- seagrass-in-two-years-study-shows/. “Seagrass in Tampa Bay.” Seagrass - Tampa Bay Watch , Tampa Bay Watch, tampabaywatch.org/restoration/seagrass/#:~:text=Seagrass%20Restoration&text=Tampa %20Bay%20Watch%20has%20a,into%20the%20permitted%20project%20area. “Seagrass Monitoring in Tampa Bay.” Seagrass Monitoring in Tampa Bay , TampaBayWaterAtlas, tampabay.wateratlas.usf.edu/seagrass-monitoring/. Switzer, Theodore S., et al. “Recruitment of Juvenile Gags in the Eastern Gulf of Mexico and Factors Contributing to Observed Spatial and Temporal Patterns of Estuarine Occupancy.” Tandfonline , 18 May 2012, www.tandfonline.com/doi/full/10.1080/00028487.2012.675913.