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An Agent Based Model to Evaluate Spatio-Temporal Variability in Oyster Reef Connectivity in the Charlotte Harbor Estuarine System, Florida
Title
An Agent Based Model to Evaluate Spatio-Temporal Variability in Oyster Reef Connectivity in the Charlotte Harbor Estuarine System, Florida.
Creator
Bass, Dye
Abstract / Description
Various physical and biological factors influence the larval dispersal and connectivity of benthic species. Physical processes are the primary driver of larval transport, however biological processes have been found to play an important role as well. In this study, we developed and coupled a 2-D hydrodynamic model with an agent-based model to study Crassostrea virginica, oyster larval transport within the Charlotte Harbor estuarine system in southwest Florida. Freshwater flow entering into...
Show moreVarious physical and biological factors influence the larval dispersal and connectivity of benthic species. Physical processes are the primary driver of larval transport, however biological processes have been found to play an important role as well. In this study, we developed and coupled a 2-D hydrodynamic model with an agent-based model to study Crassostrea virginica, oyster larval transport within the Charlotte Harbor estuarine system in southwest Florida. Freshwater flow entering into the southern region of the system, the Caloosahatchee River Estuary, is highly controlled by a series of lock and dams. As a result, considerable interannual variability exists in the amount of freshwater entering the Caloosahatchee River Estuary and this has been identified as a key stressor to the estuary’s oyster population. Oyster spawning in the estuary occurs throughout the wet season months (June-Oct.). Therefore, model simulations were performed during wet season periods of low, moderate, and high freshwater flow into the estuary to determine the impacts varying flows impose on larval transport and settlement in terms of success and connectivity between oyster reefs. The agent-based model was validated using oyster larval settlement data collected throughout a long-term, 2000-2016 study. The model was able to simulate settlement patterns during periods of low freshwater release which ultimately provided insight into the importance of the furthest upstream oyster reef as a larval source to the downstream reefs.
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Date Issued
2018-08-23
Identifier
fgcu_ETD_0254
Format
Document (PDF)
Bioaccumulation and depuration of brevetoxins in the eastern oyster (Crassostrea virginica) and the Northern Quahog (=Hard Clam, Mercenaria Mercenaria)
Title
Bioaccumulation and depuration of brevetoxins in the eastern oyster (Crassostrea virginica) and the Northern Quahog (=Hard Clam, Mercenaria Mercenaria).
Creator
Griffith, Andrew W.
Abstract / Description
The eastern oyster (Crassostrea virginica) and northern quahog (= hard clam, Mercenaria mercenaria) are two species of economic and ecological significance in coastal areas. Both species because they are filter feeders can have profound effects of water quality. Commercial industries for these species, especially within the state of Florida, are relatively large. Crassostrea virginica is also a keystone species in marine ecosystems because oyster reefs provide habitat for numerous marine...
Show moreThe eastern oyster (Crassostrea virginica) and northern quahog (= hard clam, Mercenaria mercenaria) are two species of economic and ecological significance in coastal areas. Both species because they are filter feeders can have profound effects of water quality. Commercial industries for these species, especially within the state of Florida, are relatively large. Crassostrea virginica is also a keystone species in marine ecosystems because oyster reefs provide habitat for numerous marine organisms. The purpose of this experiment is to build upon the already established body of knowledge surrounding effects of Karenia brevis on species of shellfish and to provide an understanding of the kinetics of brevetoxins within shellfish tissue and give an indication of just how long brevetoxins remain in these organisms after a bloom event. Individuals were exposed to Karenia brevis at a concentration of Sx 105 cells-L-1 for eight days. After exposure samples were transferred into clean water for depuration. Individuals were sampled periodically to determine the rate of depuration. Brevetoxin tissue concentrations were determined using an Enzyme Linked Immunosorbent Assay (ELISA). After five days of exposure both species reached brevetoxin tissue concentrations well above safe limits. Clams averaged tissue concentrations of 1,000 ng g1 while the oysters averaged 1,986 ng g-1. After two weeks of depuration both species yielded tissue concentrations that were below safe limits with clams averaging 204.8 ng g-1 and oysters averaging 437.01 ng g-1. Low levels were present in on both species for the duration of the experiment.
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Date Issued
2011
Identifier
fgcu_ETD_0475
Format
Document (PDF)
EFFECTS OF SALINITY AND OTHER STRESSORS ON EASTERN OYSTER (CRASSOSTREA VIRGINICA) HEALTH AND A DETERMINATION OF RESTORATION POTENTIAL IN NAPLES BAY, FLORIDA
Title
EFFECTS OF SALINITY AND OTHER STRESSORS ON EASTERN OYSTER (CRASSOSTREA VIRGINICA) HEALTH AND A DETERMINATION OF RESTORATION POTENTIAL IN NAPLES BAY, FLORIDA.
Creator
Laakkonen, Katie
Abstract / Description
Naples Bay, a highly urbanized estuary, has lost an estimated 80% of its oyster reefs since the 1950s due to dredging and development activities. Artificial canals, primarily the Golden Gate Canal, have increased freshwater flows into Naples Bay causing extreme swings in salinity. This study characterizes the health of the eastern oyster, Crassostrea virginica, at four sites along a salinity gradient by investigating and correlating various oyster responses to salinity, dissolved oxygen, and...
Show moreNaples Bay, a highly urbanized estuary, has lost an estimated 80% of its oyster reefs since the 1950s due to dredging and development activities. Artificial canals, primarily the Golden Gate Canal, have increased freshwater flows into Naples Bay causing extreme swings in salinity. This study characterizes the health of the eastern oyster, Crassostrea virginica, at four sites along a salinity gradient by investigating and correlating various oyster responses to salinity, dissolved oxygen, and temperature. Prevalence and intensity of Perkinsus marinus infection varied significantly among sites, with the northernmost upstream Site 1 showing the lowest infection. Condition index varied significantly among sampling months and sites, and decreased during the spawning period, April through October. Sites 1 and 2, with more optimal salinities for the first 8 months of the study, had the highest mean condition index. Significant differences were found among sampling months for spat recruitment and sites and peaked in August. Spat recruitment was greatest at the southernmost Site 4 which is located furthest from the freshwater influence and therefore has less extremes in salinity. Living densities (# live oysters m-2) also varied significantly among sampling months and sites, with living densities increasing when moving downstream. Higher living densities were found in the wet season than the dry season reflecting recruitment occurring onto the reefs. The wet season is when extreme swings in salinities result upstream which corresponds with oyster reproduction. Site 1 experienced a 31 ppt drop in salinity within a few days in July when significant rainfall began. This is a tremendous stressor on oysters and could result in mortality of juvenile oysters and the flushing of spat downstream due to high freshwater flows. This study highlights that freshwater flows and resulting salinities are a driving force for oyster reef health and distribution in Naples Bay. It also provides a baseline assessment of the oyster population that will allow for future comparisons when water quality improves due to diversions of freshwater from the Golden Gate Canal. These diversions are planned for the near future by the South Florida Water Management District. This study also assists resource managers in determining potential oyster restoration sites in the bay. Management recommendations include focusing oyster restoration sites at the downstream locations due to less salinity extremes, high oyster living densities, and higher spat recruitment.
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Date Issued
2014
Identifier
Laakonen_fgcu_1743_10075
Format
Document (PDF)
Survival and Growth of Eastern Oyster Spat, Crassostrea virginica, when Exposed to Low Salinity for Prolonged Periods with Short Intervals of Recovery at Higher Salinities
Title
Survival and Growth of Eastern Oyster Spat, Crassostrea virginica, when Exposed to Low Salinity for Prolonged Periods with Short Intervals of Recovery at Higher Salinities.
Creator
Hans, Samuel, College of Arts & Sciences
Abstract / Description
The Caloosahatchee River and Estuary in Southwest Florida has a history of human driven alterations by dredging, channelization, construction of several lock and dams, and an artificial connection to Lake Okeechobee. Water management has changed the quality and quantity of discharges into the river and the ecological health of the estuary. The artificial connection to Lake Okeechobee sometimes requires large freshwater releases into the Caloosahatchee River. The euryhaline species in the...
Show moreThe Caloosahatchee River and Estuary in Southwest Florida has a history of human driven alterations by dredging, channelization, construction of several lock and dams, and an artificial connection to Lake Okeechobee. Water management has changed the quality and quantity of discharges into the river and the ecological health of the estuary. The artificial connection to Lake Okeechobee sometimes requires large freshwater releases into the Caloosahatchee River. The euryhaline species in the Caloosahatchee River face osmotic challenges from these freshwater inputs. The eastern oyster, Crassostrea virginica, is a keystone species that can provide an indication of estuary response to freshwater inflow and the resulting salinity fluctuations. A valued ecosystem component, the eastern oyster, helps sustain the ecological structure and function of the estuary by providing food, living space, and foraging sites for other estuarine species. Oyster spat, newly settled oysters <25mm, have an optimal salinity range of 15‰ to 22.5‰ and exposure to low salinity levels for long periods of time causes mortality. High temperatures (300C), which occur during the summer and rainy season, have a synergistic effect on low salinity stress. As part of a larger study to investigate how to improve water management to sustain oyster reefs in the Caloosahatchee River while managing the lake levels, this project examined oyster spat survival and growth during exposure to low salinity levels with intermittent recovery periods at higher salinity. This study carried out iterative bioassays to determine the longest duration (i.e., consecutive days) that oysters can be exposed to some minimum salinity (0‰-5‰, where valves will likely remain closed) with the shortest periods of recovery (10‰) to survive and grow. The results of this study clearly show that Crassostrea virginica spat exhibited improved survival rates and growth when given periods of recovery at a tolerable salinity after being stressed by prolonged low salinity conditions both with and without thermal stress. Spat reach greater than 50% survival when stressed at 5‰ for less than seven days and are allowed periods of recovery at a salinity of 10‰ or higher under thermal stress. Without thermal stress 50% survival was observed in spat that were stressed for less than 14 days at a salinity of 5‰ and allowed periods of recovery at a salinity of 10‰ or higher. The longer the recovery period at both 25oC and 30oC, the better the results tended to be in matching or exceeding growth in the negative stress controls held at 25‰. A ≥14-day period of recovery should always be targeted regardless of exposure duration in order to ensure oyster spat growth.
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Date Issued
2020-12-08
Identifier
fgcu_ETD_0350
Format
Document (PDF)