A multi-directional wear apparatus was developed to simulate the kinematic motion of diarthrodial joints. A comprehensive evaluation including biotribological and biomechanical characterization of articular surfaces was performed with concomitant translational and oscillating rotational motion similar to that experienced in vivo. Various system parameters were evaluated in the designed experiments including normal load magnitude (high/low), surface quality (defect/no defect), and wear pattern (with/without rotation). Biomechanical characterization was achieved through stress relaxation and dynamic cyclical testing. Quasi-linear viscoelastic theory was used to curve-fit the stress relaxation data, while the dynamic data was used to determine the dynamic properties through Fast Fourier Transform analysis and verify the assumptions posed with the QLV theory.Overall tissue compression was significantly dependent on load magnitude (pstatic was significantly dependent on surface quality (pinitial was significantly dependent on both surface quality (pComparisons of the curve-fit parameters showed a significant decrease in pre- vs post-wear elastic response, A, and viscous response, c. In addition, the short term relaxation response, τ1, showed a significant decrease between no defect (0.801 ± 0.13 sec) and a defect (0.679 ± 0.16 sec). lGlpost-wear/lGlpre-wear tan δ , was generally greater while lGl was less for those specimens experiencing rotation Qualitatively, SEM photographs revealed the mechanical degradation of the tissue surface due to wear. Surfaces with a defect had increased wear debris, which ultimately contributes to third body wear. Surfaces without a defect had preferentially aligned abrasions, while those surfaces outside the wear path showed no signs of wear.Significant correlation was detected between the μstatic and μinitial for both the nonliner viscous response, B (p2 (p<0.013 and p<0.062). Thus, the comprehensive evaluation of biomechanical and biotribological characteristics suggests the new wear regime and standardization of analysis techniques will aid in the development of functional articular repair and clinical repair techniques.

Rickettsiales-like organisms (RLOs) are thought to be related to bacteria in the order Rickettsiales. They have been reported to occur in the staghorn coral (Acropora cervicornis), and this study investigated trends of infection over time, and in relation to the health of infected corals. This study focuses on tissue samples taken mostly from visibly healthy A. cervicornis thickets in Broward County, Florida, and processed for histological examination. Samples were originally collected and analyzed to document reproduction during years 2001 through 2012, and tissue loss diseases (white-band disease [WBD] types I and II, and rapid tissue loss). The presence of suspect RLOs, the presence of ovoid bacterial aggregates in the basal body wall, and the condition of the coral tissue were examined in hematoxylin and eosin (H&E) and Giemsa-stained sections. Determination was made as to whether suspect RLO infection severity, location, or the presence of bacterial aggregates are correlated with changes in tissue condition associated with WBD. To better understand progression, trends, and periodicity in bacterial presence and coral tissue health, these data were then further analyzed for potential correlation with the month, year, and average monthly nighttime sea surface temperatures (categorized into ranges above, within, or below 24–29°C) when samples were collected. The severity of suspect RLO infections and the presence of bacterial aggregates in A. cervicornis varied over time, with no correlation with the location of suspect RLOs within the polyp. High suspect RLO prevalence was correlated with normal tissue conditions, while low suspect RLO prevalence was correlated with abnormal tissue conditions. However, high prevalence of bacterial aggregates was correlated to abnormal tissue conditions. Epidermal RLO and overall suspect RLO prevalence severity scores were significantly higher among samples collected when monthly average nighttime sea surface temperatures were below 24°C in contrast to samples collected when temperatures were between 24–29°C, suggesting direct or indirect effects of sea surface temperatures on infection severity. The areas of suspect RLO intracellular bodies within infected mucocytes were measured using digital image analysis software and found to be positively correlated with worsening coral tissue condition. Semiquantitative variable scores for histoslides stained with H&E were significantly different from those stained with Giemsa, indicating that these stains cannot be used interchangeably to study the presence of bacteria and the condition of coral tissue. Overall, the results of this study indicate that infection severity of suspect RLOs and the presence of bacterial aggregates are variable and correlated with the incidence of WBD-I in A. cervicornis. However, the exact nature of this relationship remains unclear. Further studies are necessary to interpret trends detected during this analysis to develop a better understanding of what contributes to the severe tissue-loss outbreaks and mortalities of A. cervicornis.

Since the 1970s, loss of herbivores, coral bleaching, pollution, and disease epidemics have reshaped the ecological framework of coral reefs. Staghorn coral, Acropora cervicornis, was a major reef-building scleractinian coral found throughout Florida and the Caribbean that experienced unprecedented population declines primarily due to disease and coral bleaching. These two stressors are coupled; the highest coral disease prevalence occurs after periods of thermal stress caused by increased sea surface temperature. Previous research documented three disease-resistant A. cervicornis genotypes in Panama, but it is unknown if disease-resistant genotypes exist in the Florida Keys. Thermal tolerance has been found to be variable among different species of corals and is relatively unknown in A. cervicornis. To investigate disease resistance and thermal tolerance in corals collected from the Florida Keys, pathogen transmission, thermal tolerance experiments, and coral outplanting studies were conducted, along with histological work to assess the condition of coral tissues. Corals were challenged in situ with exposure to rapid tissue loss (RTL) and bleaching resistance was evaluated ex situ in temperature-controlled seawater tanks, using 39 A. cervicornis genotypes. Disease and bleaching were further characterized in the wild using outplanted colonies. In a pathogen transmission pilot study, 7 out of 39 genotypes developed signs of rapid tissue loss transmission. An expanded transmission experiment that used 12 potentially disease resistant genotypes (based on anecdotal information and results from the pilot study), all genotypes developed signs of RTL transmission. However, susceptibility was variable but not statistically different among genotypes (p>0.05), ranging from 40-100% transmission. Histological analyses revealed significant (p0.05) related to photosynthetic efficiency and tissue condition metrics. No significant differences in mortality, disease, or predation were found between disease resistant and disease susceptible genotypes in outplanting experiments (p>0.05). This study reports the first evidence that disease resistance is present in Florida A. cervicornis genotypes. The variability of disease resistance found within genotypes suggests that genotype is not the only factor influencing disease transmission. Short-term exposure to thermal stress revealed heat tolerant A. cervicornis genotypes, which corroborates with recent published studies. Taken together, these results provide insights into how Caribbean Acropora and other scleractinian species persist through multiple disease and coral bleaching events.

A traumatic skeletal muscle injury that involves the loss of a substantial portion of tissue will not regenerate on its own. Little is understood about the ability of the muscle to recover function after such a defect injury, and few research models exist to further elucidate the repair and regeneration processes of defected skeletal muscle. In the current research, a model of muscle injury was developed in the lateral gastrocnemius (LGAS) of the rat. In this model, the muscle gradually remodels but functional recovery does not occur over 42 days. Repair of the defect with muscle-derived extracellular matrix (ECM), improves the morphology of the LGAS. Blood vessels and myofibers grow into the ECM implant in vivo, but functional recovery does not occur. Addition of bone marrow-derived mesenchymal stem cells (MSCs) to the implanted ECM in the LGAS increases the number of blood vessels and regenerating myofibers within the ECM. Following 42 days of recovery, the cell-seeded ECM implanted LGAS produces significantly higher isometric force than the non-repaired and non-cell seeded ECM muscles. These results suggest that the LGAS muscle defect is a suitable model for the study of traumatic skeletal muscle injury with tissue loss. Additionally, MSCs seeded on an implanted ECM lead to functional restoration of the defected LGAS. / text

Bioerosion is a major process that affects the carbonate balance on coral reefs, and excavating sponges from the genus Cliona are some of the most important bioeroders on Caribbean reefs. The orange boring sponge, Cliona delitrix, is an abundant excavating sponge offshore southeast Florida that frequently colonizes dead portions of live stony corals, killing live coral tissue as it grows. With the recent decline in coral cover attributed to combined environmental and anthropogenic stressors, the increasing abundance of excavating sponges poses yet another threat to the persistence of Caribbean coral reefs. In the first part of this study, I explored distributional patterns of C. delitrix offshore southeast Florida and compared yearly sponge growth/corresponding coral tissue loss rates across habitats of different depths. C. delitrix densities and growth rates were significantly higher on the outer reef, where coral colonies also showed some of the fastest tissue retreat rates. More sponge individuals were found on sites with higher coral densities, likely resulting from the higher availability of preferred coral skeleton substrate. C. delitrix showed a clear preference for boulder stony coral species, which could alter the coral community composition in the future and allow an increase in branching and foliose species. The growth rates of C. delitrix offshore southeast Florida are slower compared to rates from other locations, likely a result of intense fouling of the coral-sponge interface by other spatial reef competitors. These results suggest that outer reef sites with high boulder coral density offshore southeast Florida are most vulnerable to C. delitrix colonization and may continue to suffer the greatest impacts of coral bioerosion. Excavating sponges are also strong competitors for space on coral reefs; able to colonize, excavate, and kill entire live stony corals. Despite the known negative effects of excavating sponges on stony corals very few studies have experimentally tested the competitive nature of this interaction. In the second part of this study, I examined the effect of manual removal of the excavating sponge, Cliona delitrix (Pang 1973), on tissue loss of the stony coral Montastrea cavernosa (Linnaeus 1767), and its possibility as a restoration technique. A total of 33 M. cavernosa colonies colonized by small C. delitrix sponges (up to 10 cm in diameter) were examined. Sponges were removed using a hammer and chisel from 22 of the affected colonies, and 11 colonies were left alone as controls. After sponge removal, the resultant cavities in the coral skeletons were filled to minimize future colonization by other bioeroders and promote coral tissue growth over the excavation. Cement was used as fill material on 11 of the colonies, and the remaining 11 cavities were filled with epoxy. Standardized photos of each colony were taken immediately, at 6 months and 12 months after sponge removal. Results show a significant reduction in coral tissue loss in colonies where sponge was removed, and both fill materials performed similarly reducing coral tissue loss. I also found that a majority of experimental corals showed no return of C. delitrix to the colony surface a year after removal. This study demonstrates that eliminating the bioeroding sponge competitor may promote recovery of the affected stony coral. Additionally, the sponge removal technique can be applied to any stony coral colonized by C. delitrix to preserve, or at least slow the loss of, remaining live tissue.

Les coraux durs font face à des menaces croissantes dues à des facteurs anthropogéniques, les rendant vulnérables à des maladies telles que la maladie de perte de tissu des coraux (MPTC). Découverte en Floride en 2014, la MPTC s'est propagée dans la mer des Caraïbes et a atteint la Grenade en 2018, menaçant les récifs locaux. La relation complexe entre les facteurs environnementaux et la susceptibilité des coraux reste mal comprise. De plus, une hyperpigmentation cutanée a été observée chez divers poissons récifaux en Grenade, avec des causes et liens environnementaux inexplorés. Notre étude explore les corrélations potentielles entre la MPTC et l'hyperpigmentation chez la gorette jaune (Haemulon flavolineatum) et le chirurgien océanique (Acanthurus bahianus) sur 12 sites de plongée de la côte ouest de la Grenade. Nous examinons également les liens entre les scores de pression anthropique et la santé des coraux. Les résultats indiquent une prévalence de la MPTC de 45% à l'ouest de la Grenade en mai 2023, inférieure à celle observée en Floride. La baie de Saint-Georges, soumise à une pression anthropique élevée, montre un taux de mortalité moyen des coraux de 11%, dépassant significativement les sites à faible pression anthropique (P=0,020). De plus, la prévalence des poissons hyperpigmentés est corrélée significativement à celle de la MPTC chez les coraux (P=0.004), et le score de pression anthropique est positivement corrélé aux pourcentages de coraux morts (P=0.001). Cette étude préliminaire pose les bases pour des investigations longitudinales futures, fournissant un aperçu crucial de la MPTC en Grenade. / Hard coral, as vital habitats for reefs organisms, are threatened by anthropogenic factors, making them more susceptible to diseases, including Stony Coral Tissue Loss Disease (SCTLD). First described in Florida in 2014, SCTLD has spread throughout the Caribbean Sea and has been observed in Grenada since 2018, threatening local reefs. The intricate relationship between local environmental factors and coral susceptibility remains poorly understood. Additionally, Grenada's reefs have witnessed skin hyperpigmentation in various fish species, whose etiology and connection to environmental factors remain unexplored. This study investigated potential correlations between SCTLD and hyperpigmentation in French grunt (Haemulon flavolineatum) and ocean surgeonfish (Acanthurus bahianus) across 12 popular dive sites. It also explored potential links between anthropic pressure scores and coral health. The findings revealed a 45% prevalence of SCTLD among hard coral colonies, lower than observed in Florida. Saint George's Bay, subjected to high anthropic pressure, experienced a significant 11% mean coral mortality rate, surpassing sites with minimal anthropic pressure (P=0.020). Furthermore, the prevalence of hyperpigmented fishes significantly correlated with SCTLD prevalence in coral (P=0.004), and anthropic pressure scores exhibited a positive relationship with dead coral percentages (P=0.001). This preliminary study provides crucial insights into SCTLD in Grenada, laying the groundwork for future longitudinal investigations.

Coral nurseries have become a popular and successful method to produce coral fragments for reef-restocking and restoration projects worldwide. Numerous in-situ coral nurseries have been established and many studies have focused on the most effective way to produce coral fragments in offshore nurseries. In contrast, production of coral fragments in land-based nurseries is rarely studied despite a growing knowledge of coral husbandry and coral aquaculture. Little data exist on the success of tank-raised corals when transplanted back into reef environments. This thesis presents the results of a study designed to assess the use of land-based coral nurseries in production of fragments of the Atlantic staghorn coral Acropora cervicornis for the purposes of reef re-stocking and restoration. The first objective of the study was to assess if A. cervicornis fragments can be produced in aquarium conditions at comparable rates to offshore nurseries. Fragments from the same wild donor colonies were placed in an offshore nursery and a land-based nursery and monitored for survival, growth, branch production, and branch thickness for 16 months. Survival was lower in the land-based nursery, largely due to a mechanical failure. Linear extension was lower in the land-based nursery until nursery conditions were evaluated and optimized. The optimization process included changes to water quality, temperature control, and lighting. Post-optimization, linear extension in the land-based nursery exceeded the offshore nursery, with a maximum monthly growth rate of 16.0 ± 5.3 mm month-1. The maximum monthly rate in the offshore nursery was 10.6 ± 4.1 mm month-1. Branch number and thickness were also lower initially in the land-based nursery, however both metrics increased rapidly after optimization. This experiment shows that A. cervicornis can be successfully grown in a land-based nursery, and that linear extension and fragment production can be higher than in offshore nurseries if environmental conditions are maintained within optimum ranges. This experiment highlights some of the conditions that promoted high linear extension rates in this species. The second objective of this study was to examine the success of corals outplanted from land-based nurseries and to determine whether corals reared in a land-based nursery would show the same growth and survival after transplantation as those reared in a traditional offshore nursery. This was examined in two experiments. In the first experiment, small fragments were outplanted from colonies reared offshore and from colonies reared in a land-based system. In the second experiment, larger colonies reared in the two separate land-based systems were outplanted to the same location. All transplanted corals were monitored for survival, growth, branch number, and incidence of predation, breakage, and disease over one year. Two major storm events occurred during this portion of the study, so the potential for differences in breakage or storm damage were also assessed. There were no significant differences in survival or growth of fragments outplanted from a land-based nursery and an offshore nursery. Colony outplants from one land-based location had better survival and growth than colonies from a second land-based location. Tropical storm activity greatly increased the occurrence of breakage and tissue loss in all groups, resulting in decreases in colony volume and additional mortality. Survival ranged from 85% to 100% after six months, and survival ranged from 70% to 89% after one year and the passing of two tropical storms. Small (5 cm) transplants did not have significantly lower survivorship than large transplants. Overall, the transplant of fragments and colonies raised in land-based nurseries was successful, as measured by growth and survival rates that were comparable to or exceeded those observed for corals raised in offshore nurseries. Large colony transplants exhibited the best survivorship and extension rates, but were also highly prone to breakage.

Coral diseases were first noted in the 1960s and 1970s and have had major impacts globally on coral reef community structures. In the Caribbean, a major outbreak of white band disease has been considered responsible for the drastic decline of Caribbean Acroporids since the 1970s. In addition to white band disease, another more recently described condition known as rapid tissue loss (RTL) has had major impacts on Acropora cervicornis populations, specifically offshore Broward County Southeast Florida. While these diseases have contributed to the population decline, determining their etiologies has been elusive. Coral diseases have been characterized by shifts in their microbial counterparts within many levels of the coral host. While some coral diseases have had specific pathogens identified, research has not been able to determine pathogens for most. Evidence points toward bacterial causes for many diseases, but due to the complexity of the coral holobiont and the interaction with the environment, elucidating the causes has proven difficult. Many studies have examined the microbiomes of specific diseases and determined some potential pathogens or at least taxa playing important roles in the disease, although none have looked at RTL. Recognizing the local affect of RTL on A. cervicornis, this study set out to gain a baseline understanding of the healthy and RTL affected microbiome of A. cervicornis. 16S rRNA gene sequencing was used to examine the microbiome of completely healthy colonies, healthy regions of diseased colonies, and the disease margin of diseased colonies. Analysis of four microbial diversity metrics revealed marked increases in diversity with respect to declining health states. Additionally, community dissimilarity analysis and analysis of differentially abundant taxa exhibited distinct microbial community structures due to coral health. Several highly abundant (Rickettsiales, Rhodobacteraceae) and a few low abundance (Bdellovibrionales) taxa were identified as primary drivers of the differences. Additionally, Piscirickettsiaceae, a known fish pathogen, was consistently associated with RTL and warrants further investigation. All of the taxa identified with in RTL have been associated with other Acroporid and non-Acroporid diseases throughout the Caribbean and the rest of the world. The consistent IV association of similar taxa for coral diseases around the world, including those found in this study, supports the recent ideas of non-specific primary pathogens. While most disease studies, coral and otherwise, aim to determine a single pathogen for a single disease, this study and others suggest there could be a multitude of organisms responsible for the disease. Therefore understanding the interactions of the coral holobiont and the environment is important to understanding coral disease. While this study reveals significant changes in the bacterial community associated with RTL as well as some potential pathogens, the relationships appear complex and perhaps at a functional level rather than merely taxonomic. Furthermore, this study did not examine viruses, fungi, or protists, which could be possible pathogens. Therefore, to further develop an understanding of RTL and many other coral diseases it will be necessary to consider additional none-bacterial members of the holobiont as well as the bacterial functions and taxa coupled with the roles of environmental factors.