Graduation Year

2021

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Melanie Riedinger-Whitmore, Ph.D.

Co-Major Professor

Melanie Parker, Ph.D.

Committee Member

Alison Gainsbury, Ph.D.

Keywords

Crassostrea virginica, gametogenesis, bivalve, Tampa Bay, Apalachicola Bay, St. Lucie estuary, Loxahatchee River estuary, Lake Worth Lagoon, Caloosahatchee River estuary

Abstract

Oyster populations from six estuaries in Florida were sampled monthly from January to December of 2018 for reproduction and health analysis. Sites were located in Apalachicola Bay, Caloosahatchee River estuary, Lake Worth lagoon, Loxahatchee River estuary, St. Lucie estuary, and Tampa Bay. Oysters monitored for analysis in South Florida (Loxahatchee River estuary, St. Lucie estuary, and Caloosahatchee River estuary) were chosen as they are a part of a monitoring component of the Comprehensive Everglades Restoration Plan. These estuaries are highly influenced by freshwater input from Lake Okeechobee and other river basins. Like the South Florida sites Apalachicola Bay is also influenced by freshwater input from Apalachicola River. Oyster populations can receive detrimental effects from either too much freshwater input as well as a severe reduced flow. Lake Worth lagoon was previously monitored as a site a part of the CERP monitoring program (2004 – 2015) and is now an outlier oyster population along with Tampa Bay. Monitoring oyster reproduction and health can provide a description on the impacts of changes in water quality on organisms that live in these coastal waters.

Water quality (salinity and temperature), gametogenic stage (including average oocyte diameter and gonad percent area), the intensity and prevalence of the pathogen Perkinsus marinus, and Condition Index (CI) were measured on a monthly basis. Water temperatures showed a similar seasonal trend over the sampling period while salinity varied throughout location. Oysters displayed a similar seasonal spawning period from April to October with the majority of the oysters exhibiting female gametes. Parasites were present at all locations with Apalachicola Bay having the highest prevalence of Bucephalus polymorphus. Gonad percent area displayed some bimodality that coincided with the spring and fall spawning events while showing significant differences between sites (p ≤ 0.05). Average oocyte diameters also showed a uniform trend through the spawning season. Comparisons between oocyte diameters did not show significant differences between sites (p > 0.05). P. marinus was prevalent at all sites with varying degrees of intensity. Intensity was generally higher during the dryer months when salinities were also higher. Condition index values were uniformly higher in the spring and then declined towards the fall. These findings provide a better understanding of the reproductive cycle and health of oyster populations from ecologically important estuaries in Florida.

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