Marine Biology Commons^™

Effects Of Environmental And Anthropogenic Factors On Loggerhead Sea Turtle (Caretta Caretta) False Crawl Rates On Jekyll Island, Ga, Brittany Byrd

UNF Graduate Theses and Dissertations

Loggerhead sea turtles (Caretta caretta) are currently listed as “vulnerable” on the IUCN Red List and are experiencing population declines across many parts of their range. These declines are caused by environmental and anthropogenic stressors which impact sea turtle ecology and behavior, including nesting behavior. One nesting behavior sea turtles exhibit is known as “false crawling,” which is when a female sea turtle ascends the beach in an attempt to nest and either abandons the attempt altogether or while in the middle of digging an egg chamber. False crawling, a largely understudied sea turtle behavior, can not only …

An Analysis Of The Spatial Genetic Structure Of A Hybrid Zone Between Two Species Of Killifish, Fundulus Heteroclitus And F. Grandis, Andrew Lee Hardy

UNF Graduate Theses and Dissertations

Hybridization offers unique insight into the evolutionary process of speciation and the forces that maintain barriers to reproduction. In northeast Florida, a hybrid zone between two species of killifish, Fundulus heteroclitus and F. grandis, has been identified near Flagler Beach, FL, although the exact boundaries of the hybrid zone remain unknown (Gonzalez et al. 2009). This study aims to determine the fine-scale spatial genetic patterns of the hybrid zone and test the hypothesis that species ranges are influenced by changes in dominant vegetation. Results from an ADMIXTURE analysis and F_ST data indicated the boundary of the area of …

Histological Comparison Of Shark Dermis Across Various Ecomorphologies, Olivia Schuitema

UNF Graduate Theses and Dissertations

The integument plays essential roles in the structural support, protection, and hydrodynamic capability among fishes. Most shark skin research has been done on the external epidermal layer containing the dermal denticles, while the larger dermis layer has been mostly ignored. The dermis layer in sharks is composed of two layers, the upper stratum laxum and the lower stratum compactum, holding supportive collagen and elastin fibers. There may be morphological and compositional differences in the dermis layers across various species of sharks, although the extent of such is unknown. These potential differences may be represented by various dermal thicknesses and different …

The Relative Contribution Of The Blue Crab (Callinectes Sapidus) To Periwinkle Snail (Littoraria Irrorata) Predation Mortality In The Lower Salt Marsh Intertidal Of Northeast Florida, Amanda Paige Small

UNF Graduate Theses and Dissertations

In top-down regulation of ecological communities, predation of grazers is critical for maintaining the presence and growth of essential vegetation. The periwinkle snail (Littoraria irrorata) is a ubiquitous grazer in Atlantic salt marshes that can defoliate patches of Spartina alterniflora when populations are extremely dense. On the east coast of Florida, multiple predators could contribute to periwinkle population control maintaining this critical habitat. This study aimed to determine if the blue crab (Callinectes sapidus) is the primary predator of periwinkle snails in the salt marsh lower intertidal. Tethering was utilized to assess if periwinkle mortality is …

Benthic Microalgae Response To A Warming Climate And Shift In Foundational Vegetation Species In A Saltmarsh-Mangrove Ecotone, Gabriela Canas

UNF Graduate Theses and Dissertations

The ecotone in Northeast Florida is experiencing rapid change as mangroves begin to encroach northward into saltmarsh dominated coastal wetlands. This is especially prevalent within the boundaries of the Guana Tolomato Matanzas National Estuarine Research Reserve where studies are attempting to understand the consequences of more mangroves. Although we are beginning to understand some of the implications of this shift in dominant vegetation, the true effects and the accompanying sustained climatic warming effects on the resilience of wetland habitats and their associated communities remains unknown. Primary producers such as benthic microalgae (BMA) are important food sources in both mangrove and …

Estimating The Heritability Of Plasticity Of Thermal Tolerance And Its Application In The Restoration Of Endangered Caribbean Coral, Matz O. Indergard

UNF Graduate Theses and Dissertations

Abstract

Over the last two centuries anthropogenic activity has elevated atmospheric CO₂, creating a greenhouse effect that is predicted to elevate global temperatures 1-4^o C within the century. Increases in surface temperature pose a threat to the world’s coral reefs and have been the cause of many mass bleaching events. To combat this new threat, corals must migrate, acclimate, or evolve to rising temperatures. Phenotypic plasticity, or the ability of an individual to express different phenotypes to survive in different environments, is crucial for sessile organisms since it can increase survivability in species incapable of moving to …

Distribution And Community Structure Of First Coast Shark Assemblages And Their Relative Trophic Niche Dynamics, Clark R. Morgan

UNF Graduate Theses and Dissertations

Nearshore marine environments are known to be highly productive systems with relatively high faunal diversity and abundances, but these systems are particularly vulnerable to negative impacts from anthropogenic disturbances that can result in habitat degradation. Despite these challenges, many shark species of various life stages utilize coastal shelf habitats, inshore estuaries, and bays. The inshore habitats of Cumberland and Nassau Sounds in northeast Florida have been proposed as potential nursery grounds by earlier work, but this suggestion did not satisfy all of the standard criteria of shark nursery designation. It has recently been stated that the combination of surveys inside …

The Effects Of The Red Tide Producing Dinoflagellate, Karenia Brevis, And Associated Brevetoxins On Viability And Sublethal Stress Responses In Scleractinian Coral: A Potential Regional Stressor To Coral Reefs, David A. Reynolds

UNF Graduate Theses and Dissertations

Coral cover is in decline on a global scale, with increased mortality events being attributed to a number of global and regional stressors. While the impacts of global stressors (e.g. sea surface temperature rise, ocean acidification) are well documented, there is growing interest in identifying and understanding the impacts of regional stressors. The reason for this change in focus is that regional stressors can often work in combination, sometimes synergistically, with global stressors and that stressors on a regional scale tend to be more easily mitigated by management practices. One regional stressor that impacts a myriad of marine organisms in …

Tests Of Reproductive Isolation Between The Fishes Fundulus Heteroclitus And F. Grandis, Ruthie E. Barbas

UNF Graduate Theses and Dissertations

The closely related killifishes Fundulus heteroclitus and F. grandis hybridize in a small region where their ranges overlap in coastal northeastern Florida. Hybrids of these species are rare in frequency within the contact zone, suggesting the presence of relatively strong reproductive isolation between these species. The objective of this study was to elucidate barriers to reproduction between F. heteroclitus and F. grandis in the lab, as well as to quantify the relative strengths and contributions of various isolating barriers. Pre-zygotic (mating and fertilization) and post-zygotic (hatching) barriers were investigated by performing a variety of choice and no-choice laboratory mating experiments. …

Habitat Value Of Restored Intertidal Shoreline For Fish And Macrobenthic Communities In Northeast Florida, Shannon K. Dunnigan

UNF Graduate Theses and Dissertations

Oyster reefs are declining worldwide, as well as the economic and ecological value of oysters to their respective systems. Numerous restoration efforts have been undertaken in hopes of re-establishing these shellfish populations. This study evaluated a restoration project within the Guana Tolomato Matanzas estuary in northeast Florida, U.S.A., to investigate community structure as well as seasonal patterns in species abundance and diversity of juvenile fish and benthic macrofauna within restored and unrestored intertidal habitats along the Guana Peninsula. The first objective was to determine whether the artificially created reefs provided similar quantity and diversity of benthic macrofauna as adjacent unrestored …

The Effects Of Thermal Stress And Algal Competition On The Early Life-History Stages Of Porites Astreoides And The Development Of Stress-Detecting Biomarkers For Use In Scleractinan Corals, Kevin C. Olsen

UNF Graduate Theses and Dissertations

Scleractinian coral populations are declining worldwide in response to numerous stressors operating on both global and regional scales. Rising sea surface temperatures associated with global climate change and the increasing frequency of coral-macroalgae competitive interactions are two of the gravest ecological drivers facing coral reef ecosystems. However, little is known about how these stressors interact to impact corals, their health, and potential modes of population recovery. These threats also highlight the need to develop reliable techniques that detect stress in multiple life-history stages of hermatypic corals prior to the degradation of coral reef habitats. To address these concerns we evaluated …