Coral reefs worldwide are experiencing unprecedented and rapid declines. However, deeper, mesophotic coral ecosystems (MCEs; 30–150 m) may act as refuges for coral species, providing larvae to recolonize degraded shallow reefs. This study assessed the genetic connectivity of shallow and mesophotic Montastraea cavernosa populations on the Belize Barrier Reef and the community structure of their endosymbiotic algae (Family Symbiodiniaceae) across a fine-scale depth gradient (10, 16, 25, 35 m). Evaluation of nine polymorphic microsatellite markers demonstrated that relatively shallow (10 and 16 m) M. cavernosa populations were genetically distinct from relatively deep (25 and 35 m) populations. High throughput sequencing of ribosomal coding DNA from Symbiodiniaceae communities of M. cavernosa revealed differences in community structure across depth, with shallow-specialist and depth-generalist community profiles. This research provides important information for the management of distinct deep and adds to the body of research on the understudied MCEs of the Mesoamerican Reef. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Reef-building corals (Order: Scleractinia) are undergoing rapid taxonomic revision after molecular systematics disputed the relationships at all taxonomic levels within traditional classification. New morphological characters are being used to produce evolutionary relationships supported by molecular phylogenetics. While these characters are providing more congruent taxonomic relationships, their variation has not been fully explored. Additionally, phenotypic plasticity (changes in morphology resulting from environmental factors influencing the expressed phenotype despite a shared genotype) is prevalent amongst Scleractinia. In order to better understand the nature of these characters and explore their variation, I created a series of aquaria-based experiments designed to test the stability of these new morphological characters in response to differing environmental conditions. Light intensity and temperature were chosen as the environmental factors varied in these experiments on the basis of being a known trigger for environmentally-driven plasticity and their importance in calcification rate. In addition to aquaria-based phenotypic plasticity experiments I also examined a group (Family: Euphylliidae) within Scleractinia that had been divided by molecular phylogeny into two disparate groups. My research focused on morphological features viewed at magnifications observable by scanning electron microscopy (SEM) called micromorphology. Although variation in the skeletal micromorphology is observable, the new morphological characters that are used in taxonomy display only small amounts of variation caused by changing environmental conditions and were found to be stable for use in taxonomic studies. Additionally, I found a few micromorphological features distinguishing the two groups previously assigned to Euphylliidae including the shape of the septal margins and the fine-scale skeletal texture.

As technologies advance the study of ocean dynamics, new approaches to vexing problems of scale and process are becoming more widely available. Originally conceived as a tool primarily for indexing the abundance of near-bottom fishes, the Camera-based Assessment and Survey System (C-BASS) may also be an effective tool for monitoring benthic invertebrate resources vulnerable to natural and anthropogenic perturbations, and for characterizing the composition of benthic communities to inform spatial management. Using still images derived from the C-BASS video of benthic transects within the Florida Middle Grounds, I documented the abundance of benthic habitat-forming functional groups—sponges, algae, and corals—and noted taxa that were present in a SCUBA and ROV study conducted a decade earlier. Images were pre-processed using MATLAB computer programming language to correct for light attenuation and scattering in seawater at depth, and examined using ImageJ software and Coral Point Count software or rapid visual assessment methodology to assess image quality and percent cover, respectively. Exploratory data analysis (dissimilarity profile) delineated five habitat types in the northern Florida Middle Grounds, and discriminating benthic cover was identified using similarity percentage analysis: soft corals, fleshy macroalgae, low-relief algae, encrusted rubble, and sand. Hard corals and sponges represented relatively low area cover. A canonical analysis of principle components of in situ environmental measurements, chlorophyll a, turbidity, salinity, slope, and depth highlighted the association of the sand habitat type with greater depths and least amount of slope. Fleshy macroalgae were associated with greater slope, which reflected its presence in transitional areas between sand and reef. Soft coral habitat type was correlated with shallower depths, but also to lower temperature and lower salinity, highlighting the limitations of one-time environmental measurements to the condition of that time and space. A distance-based redundancy analysis of fish species abundance revealed that sponges, soft corals, and hard corals explained some of the variation of Holocentridae spp., angelfishes, and porgy, and that gray snapper appeared to associate with higher measurements of chlorophyll a. A comparison of C-BASS measurements with a coincidental stationary camera survey revealed that a slight shift in view, either from the seafloor to the water column, or from two slightly different positions in the water column, can obscure or reveal benthic cover to varying degrees, suggesting that more imaging could provide more complete representations of the benthic cover. Continued surveys of the benthic composition of the west Florida shelf could elucidate the range of environmental conditions and facilitate further investigations into the fish species associations with biotic cover in these benthic communities.

No description available.

The glass sponge reefs of western Canada are modern analogues to ancient reefs and are unique habitats requiring conservation. However, the patterns and processes of the glass sponges have not been empirically studied. Here, I characterized the biology of the glass sponges in their reefs. I examined the community structure of the sponges at 3 reefs in the Strait of Georgia (SOG), their role in silica cycling, and the stable isotopes (13C and 15N) of the reef forming sponge Aphrocallistes vastus. Sponges are spatially structured in patches which localize the abundance of other animals. Long term dissolution of spicules is negligible and thus a reef can be considered a silica sink. Lastly, isotope compositions can differentiate populations of A. vastus and depleted carbon signatures at 2 reefs suggest a terrestrial component in their diet. My work represents the biological baseline of 3 glass sponge reefs in the SOG. / Ecology

Ocean acidification (OA) refers to the increase in acidity (decrease in pH) of the ocean’s surface waters resulting from oceanic uptake of atmospheric carbon dioxide (CO2). Mounting experimental evidence suggests that OA threatens numerous marine organisms, including reef-building corals; however, few studies have focused on the effects on early life history stages. Coral recruitment is critical to the persistence and resilience of coral reefs and is regulated by several early life processes, including: larval availability (gamete production, fertilization, etc.), larval settlement, post-settlement growth, and survival. Environmental factors that disrupt these early life processes can result in compromised or failed recruitment and profoundly affect future population dynamics. To evaluate the effects of OA on the sexual recruitment of corals, sexual reproduction (including fertilization and sperm swimming speeds) and several critical early life history stages (including larval metabolism, larval settlement, and post-settlement growth) were tested in common Caribbean coral species. Three pCO2 levels were used: ambient seawater (380 µatm) and two pCO2 scenarios that are projected to occur by the middle (560 µatm) and end (800 µatm) of the century as determined by the Intergovermental Panel on Climate Change. Results show that fertilization success, larval metabolic rates, larval settlement rates, and post-settlement growth rates are all compromised with increasing pCO2. This dissertation demonstrates that OA has the potential to negatively impact sexual reproduction and multiple early life history processes of several common Caribbean coral species and may contribute to substantial declines in sexual recruitment that are felt at the community and/or ecosystem scale.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Mark E. Warner, College of Marine and Earth Studies. Includes bibliographical references.

Determining the relative roles of top-down vs. bottom-up forces in controlling the structure of ecological communities is of primary importance because anthropogenic nutrient loading, overharvesting of consumers, and potential interactions of these forces are pervasively changing ecosystems throughout the world. Here I use both field experimentation and meta-analyses to investigate the role of predators in controlling community composition, the relative roles of herbivores vs. nutrient enrichment in controlling the abundance of benthic primary producers, and the influence of herbivore diversity on the community structure of coral reefs. On a coral reef in the Florida Keys, I showed that release from predation by large fishes and invertebrates via exclusion cages allowed population increases in the gorgonian-eating gastropod Cyphoma gibbosum which increased predation rates on gorgonian corals. To directly address the relative roles of top-down and bottom-up forces in controlling primary producers in benthic marine habitats, I used factorial meta-analysis of 54 field experiments that orthogonally manipulated herbivore pressure and nutrient loading to quantify the effects of consumers and nutrient enrichment on community structure. The relative effects of herbivores vs. nutrient enrichment were context dependant, varying with latitude, the type of primary producer, and the nutrient status of the system. To address the influence of herbivore diversity on the community structure of Caribbean coral reefs, I used manipulative field experiments over two years to show that a Caribbean reef changes dramatically as a function of herbivorous fish diversity. The effects of herbivore diversity on community structure were strong in both years of the experiment due to different diet preferences among herbivores. Higher herbivore diversity suppressed macroalgal abundance, increased abundance of crustose coralline algae, reduced coral mortality, and increased coral growth when compared to treatments with lower herbivore diversity. Complementary feeding by different fishes drove these patterns because macroalgae were unable to effectively deter feeding by fishes with different attack strategies. Thus, herbivore diversity appears to play an important role in the healthy function of coral reef ecosystems via complementary feeding of different herbivore species.

The purpose of this study is to investigate the factors that are responsible for the distribution of coral communities in the lagoon of the Dongsha Atoll. Previous surveys proposed that there was significant difference of coral cover between the east and west sides of the lagoon. Two hypotheses, seawater temperature and water depth, were proposed to explain the spatial variation of coral distribution. In addition, the growth rate of poritid corals, coral recruits, sexual reproduction, and the occurrence of coral predators and diseases were also studied. Ten patch reefs 5 on the west and 5 on the east sides in the lagoon were selected and the corals on reef tops (1-3 m) and deep reef bases (10-15 m) were investigated. The growth rates of poritid corals on reef tops were higher on reef bases than those on reef tops, and higher in eastern lagoon than those in western lagoon. On average, the growth rate is 0.9 cm/year. A total of 10 families of small corals were recorded in which Faviidae (61.6%), Fungiidae (16.6%) and Poritidae (9.7%) constituted the majority. Diversity index comparisons indicated that reef bases have higher diversities than reef tops. The densities of small corals, ranging between 0.1-3.0 ind./m2, are higher on reef bases than on reef tops. In fungiids, individuals in the eastern lagoon were larger than those in the western lagoon. Tissues of corals were sampled in June 2009 for examination of gonads. However, no reproductive tissues were found after decalcification and histology. The morphological classes, live-coral coverage, dead-coral coverage and dead-coral ratio among the comparisons of reef bases vs reef tops and western vs eastern lagoons, only dead-coral coverage was found to be higher in eastern than in western lagoon. The live-coral coverage was 0.3-46%, dead-coral coverage was 8%-76% and dead-coral ratio was 10%-100%. Among the 10 patch reefs, patch reefs 6, 7, 9 and 10 are represented by mostly K type competitors and belongs to Conservation Class 2, patch reefs 1, 2 and 3 are presented by mostly S type stress-tolerated corals and belongs to Conservation Class 1. The remaining 3 patch reefs 4, 5 and 8 belong to the highest Conservation Class 4 and are represented by diverse types of corals. The water temperature exceeded 30¢XC in 36% of the time at reef tops, and 13% of the time at reef bases, during the summer period, i.e., between June and September, 2009. And the water temperatures were found in 95% of the time to be ~ 1¢XC higher at reef tops than at reef bases. The water temperatures were also higher in the west than in the east of the lagoon that 29% of the time exceeded 30¢XC in the west and 9% in the east only. No coral diseases or pests were found that may pose a large-scale threat in the near future. The variations of coral fauna found among habitats in the lagoon are consistent with the temperature patterns, i.e., the higher the temperature the poorer the coral condition. To the two hypothesis, in the eastern or western lagoon and the different depth are the factors of coral distribution in the lagoon.

The study of place has been a component of the recreation literature for about three decades. Most researchers have sought to either describe the cognitive and evaluative beliefs (place meaning) recreational visitors ascribe to a setting or identify the intensity of the human-place bond (place attachment). Few have attempted to qualitatively investigate the meanings visitors ascribe to a setting and quantitatively measure the intensity of their attachment to that setting within the same study design. Nor has there been much work aimed at understanding these concepts in marine environments. In this dissertation, I began to fill these gaps in the literature through the use of a three- phase multiple-method research design. In the first phase, I conducted 20 interviews to identify the meanings that recreational visitors ascribe to the Great Barrier Reef Marine Park (GBRMP) and to further explore how the symbolic interactionist framework can be used to understand place meanings. Ten place meaning themes emerged from the informants' statements. The second phase used 34 items developed from the 10 meaning themes that emerged from the previous interviews and a place attachment scale to explore how recreational visitors' attachment to a marine resource was reflected in their depictions of why the resource is meaningful. Three hundred and twenty-four individuals, living in Queensland, Australia, responded to a postal/email survey conducted during January and February of 2009. The results indicated that all the meanings recreational visitors ascribe to the GBRMP provide context for the attachment they hold for the setting, however particular sets of meanings are important in differentiating between attachment intensity levels. The final phase, which also used the postal/email survey described, identified how place attachment affected the relationship, identified by Stern et al. (1995), between the recreational visitors' environmental world view (EWV) and attitudes toward negative impacts on the reef ecosystem. I found that place attachment partially mediated the relationship between EWV and attitudes toward impacts. The conclusions presented in this dissertation filled in gaps in the recreation literature's understanding of place while providing further insight into how place meaning influences other constructs important to natural resource management.