Unattached benthic algae are a common component of seagrass meadows and other benthic systems. I used a series of field experiments to investigate (1) whether competition by algal mats represents a disturbance force capable of opening gaps in the seagrass canopy, (2) the extent of associated indirect effects on mobile fauna, (3) the extent to which algal patches are isolated epifaunal islands, and (4) whether algal clumps serve as a dispersal mechanism for benthic animals. Algal mats proved to be a powerful disturbance mechanism which killed most of the above-ground and half of the below-ground biomass of seagrass underlying the algae. Total faunal abundance increased on experimental algal plots, although relative dominance of various taxa changed considerably. The algal mats, despite supporting large numbers of animals, should provide a poor substitute for seagrass because of algal ephemerality. In situ staining and mark-recapture techniques showed that algal clumps were not isolated islands; rather, there was extensive exchange of fauna between algal masses and the surrounding habitat, although there was greater insularity for are dispersed by tumbling benthic algae. Transport of animals by algae proved to be considerable, and observations of tagged algae indicated that clumps can tumble up to 0.5 kilometers per day. This dispersal mechanism should be particularly important for species with direct development or abbreviated larval phases and should entail lower risk than other adult dispersal stratagems such as vertical migration or rafting. The pattern of non-shifting mosaic disturbance and mobility present in this system result in unusual patch dynamics and provide some alternative views of plant-plant and plant-animal interactions in the benthos. / Source: Dissertation Abstracts International, Volume: 53-07, Section: B, page: 3267. / Major Professor: Robert J. Livingston. / Thesis (Ph.D.)--The Florida State University, 1992.

Newly settled Caribbean spiny lobsters, Panulirus argus, undergo an ontogenetic habitat shift from vegetation (algal phase) to crevice shelters (postalgal phase). I experimentally observed the nocturnal behavior and diurnal shelter choice of juveniles across this size range in the absence and presence of conspecifics. Activity and shelter choice was not influenced by conspecifics during the algal phase. Postalgal phase juveniles, in the presence of conspecifics, were induced to greater locomotory activity and shelter sharing. Conspecifics influence produced an ontogenetic habitat shift at a smaller size. / Den sharing behavior by postalgal spiny lobsters has been postulated as a form of cooperation. I examined four hypotheses of how lobsters might benefit from sharing dens and/or being gregarious. By sharing dens, lobsters may increase survival (H$\sb{\rm A1})$ through group defense against predators, or (H$\sb{\rm A2})$ through group defense against interspecific competitors. By being gregarious, lobsters may increase survival (H$\sb{\rm B3})$ through the dilution effect, or (H$\sb{\rm B4})$ through decreased exposure while searching for shelter (guidepost effect). The first two hypotheses provide a benefit for den sharing and constitute cooperation. The last two hypotheses suggest that den sharing is a coincidence of congregation. Each hypothesis makes specific predictions which I tested by den monitoring field surveys, field manipulations and mesocosm experiments. / I found (1) lobsters did not consistently utilize the most defensible dens nor occupy dens to capacity. (2) Den sharing was not correlated with predator or competitor density, but was positively correlated with conspecific density. (3) Lobsters were more often aggregated at a spatial scale larger than a single den. (4) Lobsters did not have higher survival when sharing dens. (5) Lobsters were not better competitors when sharing dens. (6) Lobsters did not have higher survival with higher conspecific density, but (7) lobsters were able to find dens twice as often and three times faster when conspecifics were present. These results support only the guidepost effect (H$\sb{\rm B4})$ hypothesis. Den sharing is a non-advantageous outcome of gregariousness but is not cooperation during the ontogenetic phase when the behavior is first observed. / Source: Dissertation Abstracts International, Volume: 56-12, Section: B, page: 6513. / Major Professor: William F. Herrnkind. / Thesis (Ph.D.)--The Florida State University, 1995.

The structural complexity of a habitat dictates the availability of shelter, and shelter may affect population and community structure in many systems. I test a specific hypothesis of the effects of habitat structure, the demographic bottleneck hypothesis, which proposes that shelter limitation can control population size structure and recruitment density by acting strongly on only one size class. To test this hypothesis, I first experimentally manipulated the size-specific availability of shelter for stone crabs in St. Joseph Bay, Florida, and I found evidence for a bottleneck that affects the growth and fecundity of large stone crabs. / These results provide support for the demographic bottleneck hypothesis, but they do not address its generality. It is a common problem in ecology that we rely on singular tests of hypotheses and the scientific generalization of these results. To address this problem, I suggest that we repeat experiments and use random factors more often in experimental designs. The use of random factors can lead to an unbiased estimate of the generality of patterns and to an understanding of the mechanisms that underlie these patterns. / To address these concerns, I repeat the shelter supplementation experiments in St. Joseph Bay and in three additional haphazardly-selected bays in the northeast Gulf of Mexico in a mixed-model experimental design. In addition to the shelter manipulations, which test the bottleneck hypothesis at the individual level, I use observational and experimental techniques to examine five biotic factors (habitat structure, food, predation, settlement, and competition) that may contribute to population-level differences among bays. / I find differences among bays in the natural population-level parameters of stone crab size structure and density and in crab responses to shelter supplementation. The demographic bottleneck hypothesis best accounts for these differences. I show that there are demographic consequences of shelter limitation on stone crab growth and fecundity at the individual level, and that these effects appear to explain population-level differences among bays. However, the demographic bottleneck hypothesis does not explain all the differences in crab populations. The bottleneck effects are mediated by differences in food, competition, and settlement among bays. / Source: Dissertation Abstracts International, Volume: 56-11, Section: B, page: 5894. / Major Professor: Daniel S. Simberloff. / Thesis (Ph.D.)--The Florida State University, 1995.

The promoter of the developmentally regulated sea urchin L. variegatus U1 small nuclear RNA gene has been studied using in vitro protein binding assays. This U1 gene is active in early embryogenesis but is turned off by the gastrula stage. The promoter of this gene shares four regions of homology with the early U1 promoter of the sea urchin S. purpuratus. The L. variegatus gene can be expressed after microinjection into S. purpuratus embryos, so these four regions were investigated as possible protein binding sites using DNase I footprinting and mobility shift assays. The locations in the promoters of four Boxes tested is as follows: Box 4, $-$318 to $-$298; Box 3, $-$269 to $-$251; Box 2, $-$167 to $-$149; and Box 1, $-$35 to $-$13. The developmental regulation was addressed by performing these assays using nuclear extracts from blastula stage, when expression is maximal, and extracts from gastrula stage, when transcription is turned off. / Mobility shift assays detected complexes with proteins from blastula nuclei using each of the four boxes tested. Areas of protection from DNase I cleavage were detected using one of the boxes and with a sequence immediately adjacent to Box 2. Two of the sequences tested possibly could be involved in the developmental regulation of this gene. DNase I footprints of Box 4 using blastula nuclear extract show an area of protection from cleavage from $-$307 to $-$296 nucleotides 5$\sp\prime$ of the start of the RNA. No protection is detected using gastrula nuclear extracts. Mobility shift assays also detect a complex in blastula extracts only. The other developmentally regulated complex involves Box 2. A specific complex is detected using blastula nuclear extract, but no complex is detected using gastrula extracts. / Boxes 1 and 3 form complexes detected in mobility shift assays using both blastula and gastrula extracts, and the sequence immediately 5$\sp\prime$ of Box 2 is protected from DNase I cleavage using both blastula and gastrula extracts. This protected sequence is located between $-$181 to $-$168. These data suggest that the sequence from $-$307 to $-$296, which is required for expression of the gene, binds a critical developmentally regulated protein. / Source: Dissertation Abstracts International, Volume: 52-08, Section: B, page: 4041. / Major Professor: William F. Marzluff. / Thesis (Ph.D.)--The Florida State University, 1991.

Advantages and disadvantages of various radioisotopic methods for measuring bacterial production are reviewed. To unraval the problems of each method, a new technique for measuring bacterial phospholipid-phosphorus (PL-P) production using $\sp{32}$P was developed. The major findings in developing the PL-P method are that: (1) specific activity of the phospholipids is the same as that of the medium, indicating that $\sp{32}$P is incorporated into PL-P at the same rate as the phosphorus in the medium, and (2) the labeling pattern of $\sp{32}$P into the phospholipids follows the macromolecular labeling pattern. / Bacterial production in the hydrocarbon seep area on the Louisiana slope, measured by the PL-P method, was strikingly high with the range from 0.03 to 1.16 g C m$\sp{-3}$ per generation. The methanotrophic or methylotrophic bacterial production related to methane and other hydrocarbon seepage seem to be a major contributing factor for the high bacterial production. Pulse-labeling experiments using size fractionation showed that bacterial growth and relative biomass were associated with particles larger than 64 $\mu$m in the hydrocarbon seep. The large and metabolically active bacterial aggregates suggest that the aggregates may serve as a trophic intermediate between bacterial carbon and seep heterotrophic benthic fauna. / Unrelated to the previous topics, the microbial aspect of polonium-210 solubilization from phosphogypsum, was also studied. Polonium-210, the last $\alpha$ emitting radionuclide in the natural uranium-238 decay series, is toxic when ingested or inhaled. Several laboratory column experiments demonstrated that polonium release in the phosphogypsum was clearly related to the bacterial activity. Sulfate reducing bacteria (SRB) play a significant role in the Po release. However, the accumulation of sulfide caused by the respiration of SRB removed the released Po by forming metal sulfide co-precipitation. Nutrient depletion in the ground water causes a decline of bacterial activity, and therefore the Po release in the ground water is probably controlled by nutrient availability affecting bacterial growth. / Source: Dissertation Abstracts International, Volume: 55-11, Section: B, page: 4736. / Major Professor: Paul A. LaRock. / Thesis (Ph.D.)--The Florida State University, 1994.

This dissertation investigates the evolutionary consequences of three very different behavioral mechanisms by which males may bias female mating decisions in their favor, elaborate male displays (Chapters I and II) and sexual coercion and resource brokering (Chapter III). The results presented here suggest that sexual selection is an important force in evolution. In Chapters I and II, I investigate the relationship between male courtship displays and speciation. Chapter I utilizes the multiple sister-taxa comparison method to test the hypothesis that sexual dimorphism is correlated with increased species diversity in teleost fishes. In 21 of 27 sister-group comparisons, the lineage with the greater degree of sexual dimorphism was more species-rich than its hypothesized sister taxa. The pattern holds across taxonomic levels and sensory modalities, and whether the male, or the female, is the displaying sex. Additional data supporting the sexual selection-diversity hypothesis in other taxa are also discussed. Chapter II investigates how variation in the signals displayed during social and sexual interactions affect reproductive isolation and may facilitate subsequent speciation, utilizing both field and laboratory experiments with the marine fish, Acanthemblemaria crockeri, a chaenopsid blenny endemic to the Gulf of California, Mexico. The anterior portion of the body, the "signal organ", displayed during social interactions, was found not only to be the most variable but was also the most geographically informative. The behavioral responses of the fish themselves, in both male courtship discrimination trials and in female spawning trials, reinforce these geographical differences and results suggest that variation in socially selected traits may accelerate reproductive isolation. In Chapter III, I examine how, if some males in a population use force to bias female mating decisions, protection can become a valuable resource that other males can use to attract females. I term this the bodyguard hypothesis of female mate choice. I present data illustrating the effectiveness of protective males in reducing the probability of aggression from other males and suggest the importance of protective mating alliances in the evolution of a diversity of animal mating systems including mate guarding, leks, "harems", monogamy, polygyny, and pair-bonding in humans.

<p>The destruction of the ozone layer, concomitant with a projected enhancement in ocean stratification, will increase the dosage of ultraviolet radiation (UVR), as well as sea surface temperature and incident light level. The diatom <i> Fragilariopsis cylindrus</i> and other Antarctic phytoplankton will therefore be exposed to, and require protection from, increasing levels of damaging UVR, under elevated temperatures and light conditions. It has been hypothesized that phytoplankton utilize photoprotective pigments and the production of mycosporine-like amino acids as strategies against UVB-induced production of reactive oxygen species (ROS). The goal of this research was to investigate photoprotective mechanisms employed by <i>F. cylindrus</i>, following exposure to enhanced UVB. Interactive effects of temperature and light level were explored, as cultures were subjected to temperatures of 0&deg;C or 4&deg;C and light levels of 15 &micro;E m^&minus;2 s^&minus;1 or 100 &micro;E m^&minus;2 s^&minus;1, in order to approximate current and future Southern Ocean stratification conditions. Growth rate and photosynthesis significantly declined by 40&ndash;80% and 50-90%, respectively, following exposure to high UVB relative to control conditions. This decline in physiological health was accompanied by a 50&ndash;300% increase in photoprotective mechanisms. Exposure to high UVB under current climate conditions resulted in the least amount of photodamage and photoprotection. Conversely, elevated light level resulted in the greatest decrease in growth and photosynthesis, accompanied with the greatest increase in photoprotection when exposed to high UVB. Under both light levels, the elevated temperature appeared to mitigate damage caused by high UVB exposure. The results of this study shed light on the mechanisms utilized by <i>F. cylindrus</i> in response to oxidative stress induced by UVB, and how these mechanisms may be expected to change under future ocean stratification conditions. </p>

<p> Marine Protected Areas (MPAs) are successful place-based management tools in protecting Essential Fish Habitat (EFH) from commercial and recreational fishing pressures. In the southeast Atlantic, the morphometric environment of the seafloor has been found to be a control on Essential Fish Habitat (EFH) (Sedberry and Van Dolah 1984). To this end, modern methods of acoustic data acquisition and morphometric analysis of the seascape are promising oceanographic techniques for identifying and delineating EFH. In July, 2013, the NOAA Ship Pisces collected bathymetric, backscatter and water column data for potential habitat sites along the U.S. Southeast Atlantic continental shelf. A total of 205 km² of seafloor were mapped between Mayport, FL and Wilmington, NC, using the SIMRAD ME70 multibeam echosounder system. In addition, a total of <i>n</i> = 7410 fish presences were recorded within the water column, using the SIMRAD EK 60 split-beam echosounder system. These data were processed in CARIS HIPS, QPS Fledermaus, MATLAB and Echoview. This study provides a morphometric characterization and quantitative assessment of fish present within each survey site and identifies features of the bathymetry that help explain the presence of demersal fish. A total of 106 unique maps were created, illustrating seafloor morphometrics and fish distributions across the seascape. In ArcGIS, 14 morphometrics were generated as candidate explanatory variables for fish abundances in small (5-12 cm), medium (12-29 cm) and large (>29 cm) size classes. We explored fish-seascape interactions at two spatial scales in the GIS using a site-wide and 50 x 50 m grid scale. At the site- wide scale, <i>X&macr;</i> Slope (R² = 0.97), <i> X&macr;</i> Slope of Slope (R² = 0.90) and &sigma; Depth (R² = 0.87) provided the strongest explanatory power in a bivariate analysis and may be used to help identify EFH at a coarse scale. At a 50 x 50 m grid scale, <i>X&macr;</i> Slope, <i>X&macr;</i> Slope of Slope and <i>X&macr;</i> Backscatter emerged as the strongest contributing variables, when combined in a multivariate analysis. Overall, multivariate model R² values were low and not predictive, but allow for the identification of variables contributing to the characterization of fish-seascape interactions at a finer scale.</p>

<p> Although dawn and dusk periods comprise a relatively small part of the day, their importance as key ecological transition periods has been recognized for some time. Previous marine investigations into this transition have focused on tropical locations and have mostly been qualitative in nature. This project focused on the dusk period in sub-tropical reef fish communities off the coasts of North and South Carolina. High-definition underwater video was collected in 2013 and 2014 at a variety of sites featuring natural live-bottom habitat. Independent samples (43 videos) were obtained on 17 sampling dates. Fishes were tallied by time relative to sunset (TRTS) in an effort to identify temporal abundance patterns and categorize taxa by temporal niche. Sufficient data were collected for statistical analysis of 27 taxa, representing 15 families. Analyses explored whether there was a relationship between time and abundance. Of the taxa analyzed, ten showed no temporal pattern during the dusk period, seven showed abundance peaks during dusk, and ten showed declines in abundance during dusk. Patterns were not always consistent within families. In particular, the Serranidae and Sparidae families featured a variety of patterns. Uncommon species and ephemeral behavioral events were also noted and described.</p>

<p> Despite reductions in species diversity, few studies in wetlands investigate the relationship between biodiversity and ecosystem function (BEF). My research explores the BEF relationship in a recently restored salt marsh in Long Beach, California. I hypothesized that: (1) increasing plant diversity would result in higher primary productivity and decreased recruitment of native salt marsh plants, (2) observed variation in responses would be correlated with species-specific variation in individual demographic parameters, and (3) variation in demographic parameters and resulting ecosystem processes would be correlated with functional traits. I found that while survival over one year was correlated with elevation, overall percent cover and recruit species richness were positively affected by diversity. Performance patterns reveal variation by species in photosynthetic rate, leaf mass per area and chlorophyll a/b ratios. After one year, I found that the overall diversity patterns were driven by selection effect compared to complementarity.</p>