Baldwin, John

Anthropogenic impacts, including urbanization and development of the Greater Everglades ecosystem, have severely reduced and fragmented populations of Bletia purpurea. Differences across populations in Florida, such as habitat preferences, blooming periods, and self-fertilization abilities have been documented. Genetic data is becoming essential for developing effective conservation strategies to prevent the disappearance of threatened orchids from the wild. Using a target capture method with the Orchidaceae963 baitset, we assessed the genetic diversity of eight wild populations and five cultivated sources of B. purpurea. Our findings reveal two areas of concern; S1 which forms a distinct genetic cluster, and E3, where inbreeding rates are notably high. Additionally, three of the five cultivated sources showed significant differentiation from the wild populations, highlighting the need for more diverse maternal lines in cultivation efforts. These results emphasize the critical role of genetic assessments in informing conservation strategies for threatened orchid populations.

After an unexpected displacement of Atlantic spotted dolphins (Stenella frontalis) from Little Bahama Bank (LBB) to Great Bahama Bank (GBB) in 2013, the LBB immigrant and GBB resident spotted dolphins were observed socially merging and initiating courtship despite previous segregation on GBB post-displacement. This project assessed the genetic integration between them. Through microsatellite analyses and genetic differentiation, reciprocal gene flow appears to be occurring between the two communities. One male was confidently assigned paternity and six males were selected as the most likely candidate males of calves. Three mottled males were designated as the most likely candidate males of calves, indicating that younger males may be reproductively successful.

Freshwater harmful algal blooms (HABs) are increasing in severity and frequency. These blooms are devastating to the communities surrounding these bodies of water due to their numerous health, economic, and environmental impacts (Hallegraeff et al. 1995; Smith 2003; O’Neil et al. 2012; Bláha et al. 2009; V. H. Smith et al. 1999). In Florida, runoff containing fertilizers, human wastes, or industrial wastes contribute to the eutrophication in these lakes and contribute to these freshwater blooms (Val H. Smith 2003; Heisler et al. 2008; O’Neil et al. 2012). M. aeruginosa, a toxic cyanobacterium, often devastates Lake Okeechobee. M. aeruginosa die off creates anoxic conditions and produces a toxin that causes major environmental loss. This project is aimed to increase knowledge on how organic phosphorus compounds affect the growth of the axenic M. aeruginosa and investigate the postulated interactome (Cook et al. 2020). Through these experiments, it was shown that axenic M. aeruginosa cannot utilize organic phosphorus compounds and therefore shows no growth when grown in this media. This research is critical to furthering our understanding of the mechanisms behind these blooms and to mitigating them.

Estuarine ecosystems are dynamic habitats, where the convergence of marine and freshwater results in constant fluxes in environmental abiotic parameters. Organisms must balance these variations within their optimal range to minimize physiological costs, often by movement from unsuitable to more suitable areas. Additional disruptions to ecosystem balances, such as anthropogenic hydrologic discharges, further alter environmental conditions and may cause population-wide movement responses of mobile organisms. Responses to anthropogenic and natural fluctuations can differ based on time of year, life history stage, or individual characteristics. These ecologically-balanced dynamics are difficult to model. In this study, I examined variability in estuarine environmental data and common snook (Centropomus undecimalis) movement responses to anthropogenic and natural fluctuations in the environment in a managed waterway. ARIMA time series models were tested as a method of modeling variability in environmental parameters. Monthly variance was well described throughout most of the estuary, especially when the interannual and intra-annual patterns were stable, indicating that these models are a good method for these types of data and could be appropriate for forecasting. Euryhaline sportfish movement responses to high discharge events in a managed waterway were observed with passive acoustic telemetry and did not show large-scale, population-wide consistency. Responses were variable between and within individuals, but individual characteristics appear to have influenced behavior in response to disturbances. Thus, these sportfish populations may be more resilient to this type of disturbance than previously hypothesized. Generalized additive mixed effects models showed that the distribution and movement of individual fishes varied in response to multiple natural and anthropogenic factors, and there was no primary driver. The understanding of the relationships among the distribution and movement of fishes and abiotic and anthropogenic factors can guide management of waterways and provide insight into how changes will affect abiotic factors and communities.

Otolith increment morphology of the protandric hermaphrodite Centropomus undecimalis (snook) was analyzed in relation to age and length for sex specific growth differences to retroactively determine the time of sex change. Growth spurts in the otoliths of female snook, the terminal sex, were identified between ages 4 and 8, corroborating the current understanding of when sex change occurs (between 3 and 8). No such growth increases were identified on the otoliths of male snook, the primary sex. Otolith growth, however, was found to decouple from length, so these growth spurts are not reflected in the length of the fish. This study marks the first time that a distinct growth pattern differentiating the primary and terminal sexes, similar to that seen in the protogynous transitional growth spurt hypothesis, has been identified on the otoliths of a protandric species.

Stable isotope analysis is a powerful tool that can be used to describe a population’s foraging niche by identifying basal resource use, trophic feeding levels, environmental stability, seasonal ecological variation, important shifts in life history, ontogenetic shifts, intraspecific habitat use, and population dynamics. Describing these relationships in endangered marine turtle populations and their critical foraging grounds is essential for determining informed management decisions. This study systematically describes the foraging niche of hawksbills Eretmochelys imbricata, and green turtles, Chelonia mydas in Buck Island Reef National Monument, U.S. Virgin Islands, a critical habitat for nesting and foraging. It assesses the relationships within and between the species in terms of overlap, annual and seasonal variation, and life history and feeding strategies within the community. Most importantly it describes these relationships with metrics that can be used in global comparisons or to measure change in local conditions.