Among vertebrates, whole-body movement is centered around the vertebral column. The bony vertebral column primarily consists of trabecular (spongy) bone that adapts in vivo to support mechanical demands respective to region, ontogeny, ecology, and locomotion. Previous work has extensively investigated the formfunction relationships of vertebral trabecular bone in terrestrial mammals, who use limb contact with a substrate as the primary support against gravity. However, we lack data from obligate swimming mammals whose locomotor ecology diverged from their terrestrial counterparts in two major ways: (1) body mass is supported by water’s uplifting buoyant forces and (2) swimmers power movement through dorsoventral loading of the axial body. This study examined vertebral trabecular bone mechanical properties and micoarchitecture from fully aquatic mammals, specifically sirenians (i.e. manatees) and cetaceans (i.e. dolphins and whales). We compression tested bone from several regions of the vertebral column among developmental stages in Florida manatees (Trichechus manatus latirostris) and among 10 cetacean species (Families Delphinidae and Kogiidae) with various swimming modes and diving behaviors. In addition, we microCT scanned a subset of cetacean vertebrae before subjecting them to mechanical tests. We demonstrated that in precocial manatee calves, vertebrae were the strongest and toughest in the posterior vertebral column, which may support rostrocaudal force propagation and increasing bending amplitudes towards the tail tip during undulatory swimming. Among cetaceans, we showed that greatest strength, stiffness, toughness, bone volume fraction, and degree of anisotropy were in rigidtorso shallow-divers, while properties had the smallest values in flexible-torso deep-divers. We propose that animals swimming in shallower waters actively swim more than species that conduct habitual glides during deep descents in the water column, and place comparatively greater loads on their vertebral columns. We found that cetacean bone volume fraction was the best predictor for mechanical properties. Due to the shared non-weight bearing conditions of water and microgravity, we present these data as a contribution to the body of work investigating bone adaptations in mammals that live in weightless conditions throughout life and evolutionary history. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Bacillus-derived larvicides, which selectively target mosquito (Diptera: Nematocera: Culicidae) populations to reduce nuisance and health risks, were applied in the South March Highlands Conservation Forest near residential neighbourhoods in Ottawa, Ontario. The objective was to assess effects of application on the nontarget mosquito relative, Chironomidae (Diptera: Nematocera: Chironomidae), and other nontarget aquatic taxa captured using emergence traps. A secondary objective was to assess physicochemical variables that influence Chironomidae emergence. Study ponds received an application of Bacillus thuringiensis var. israeliensis, a subset also received an application of Bacillus sphaericus, and a group of control ponds were left untreated over 3 years (2016-2018). Weekly sampling included trap collections and measurements of water temperature, pH, water depth, conductivity, dissolved oxygen, ammonia, nitrate, and sulphate. Drought in 2016, high precipitation throughout 2017, and seasonal precipitation in 2018 influenced variable physicochemical conditions. Principal component analyses identified differences between sampling groups and between years. Redundancy analyses correlated insect emergence with pond pH, average water depth and water temperature and indicated a strong relationship between Chironomidae emergence and average water depth. Although significantly less Chironomidae annual emergence was observed at treated sites in 2017 and 2018, zero-inflated negative binomial generalized linear mixed modelling failed to detect a significant Bti treatment effect when controlling for within group variation. Rather, variations in pH, mean water depth and water temperature were identified as drivers of Chironomidae emergence. Culicidae emergence was reduced to zero briefly following treatment in 2017 and 2018. The model detected a marginal negative treatment effect on Culicidae in 2017 only, and a positive treatment effect in 2018 at the onset of a secondary hydroperiod, in the absence of treatment. Variations in pH and water temperature were also identified to be drivers of Culicidae emergence. Modelling failed to detect treatment effects on any of the nontarget taxa abundance, including Diptera, Lepidoptera, Ephemeroptera, Odonata, Coleoptera, Hymenoptera, and Arachnida. An inverse relationship between insectivore and prey taxa abundance was observed. In 2018, taxa richness increased between years and trended higher at treated sites and a positive relationship between insectivore and prey taxa richness was observed. In 2017, Shannon-Weiner index and Simpson’s index of diversity were higher at untreated sites, and in 2018 diversity indices were higher at treated sites, with taxa richness increasing between years and higher evenness trending at treated sites. Our data suggest that treatment effects were potentially shrouded by natural variability of physicochemical variables, especially due to the varying hydroperiod observed over the three years of sampling. Additional work is needed to capture average conditions and separate confounding variables from treatment effects. This study provides an inventory of the current wetland insect community in the South March Highlands Conservation Forest landscape that offers a reference for ongoing mosquito management.

La gestion de l’eau douce est un problème majeur partout dans le monde. Les activités anthropiques liées à l’industrie, à l’agriculture et à l’implantation humaine sont les principales sources de pollutions de l’eau. Afin mettre en place des politique de prévention de la pollution, de réhabilitation des environnements aquatiques ou de recyclage des eaux usées, il est nécessaire d’acquérir des données massives sur la qualité de l’eau. Or, les méthodes actuelles de suivi des contaminants présentent des coûts élevés et de faibles débits de mesure du fait de leur incompatibilité avec un déploiement sur le terrain. Ces deux freins majeurs ne permettent pas de suivre les concentrations en polluant et notamment en métaux lourds dans les milieux aquatiques à des échelles spatiales et temporelles pertinentes. Plusieurs organisations internationales, dont l’ONU, ont de ce fait recommandé le développement de nouvelles méthodes analytiques plus performantes. Nous proposons ici une technique de mesure des contaminants métalliques lourds basée sur la diffusion Raman exaltée de surface (SERS). Le SERS présente de nombreux avantages pour l’analyse environnementale dont la sensibilité, la spécificité,la rapidité de mesure, l’adaptabilité aux matrices complexes ainsi que le coût modéré d’un instrument portable. Nous détaillerons donc la construction de la sonde SERS dédiée à la quantification de l’ion métallique lourd cible Zn2+, ainsi que les traitements de données nécessaire à l’établissement d’une quantification. Puis, nous examinerons la robustesse de la méthode de quantification vis-à-vis des sources de variabilités qui seront inévitablement rencontrées dans les eaux naturelles. / Freshwater management is a major problem all over the world. Anthropogenic activities related to industry, agriculture and human settlements are the main sources of water pollution. In order to makes policies for pollution prevention, rehabilitation of aquatic environments or waste water recycling, it is necessary to acquire massive data on water quality. Current contaminant monitoring methods have high costs and low frequency of measurement due to the incompatibility with field deployment. These two major brakes do not make it possible to monitor pollutant and especially heavy metal concentrations in aquatic environments at relevant spatial and temporal scales. Several international organizations, including the United Nations, have therefore recommended the development of new and better analytical methods.We propose here a technique for measuring heavy metal contaminants based on Surface Enhanced Raman Spectroscopy (SERS), which would allow a large scale deployment in the field.SERS has many advantages for environmental analysis including sensitivity, specificity, speed of measurement, adaptability to complex matrix and the moderate cost of portable instrument. We will therefore detail the construction of the SERS probe dedicated to the quantification of the target heavy metal ion Zn2+, which is a geochemical marker of anthropogenic contamination, as well as the data processing necessary for the establishment of quantification. Then, we will examine the robustness of the method of quantification with respect to the sources of variability that will inevitably be encountered in natural waters, when used directly in the field

Any marsh is a distinctive land-forrm of varied interest. To the agriculturist it is wasteland to be reclaimed; to the naturalist, a habitat of aesthetic value. To the ecologist, however, a marsh represents a complexity of vegetation under the influences of many and often inseparable factors. It becomes a place of challenging study. There exists a notable lack of information treating the ecology of inland salt-marshes. Still less known are the ecological conditions imposed upon plant life in marshes arising from saline springs. The presence of such a wetland in western Utah afforded the opportunity to study salt-marsh vegetation in a highly specialized habitat. The study had two phases. First was a study of the vegetation. Data were secured from collections and study plots within each of the major marsh communities. General descriptions of other plant life were additionally compiled. It is not within the scope of this paper to discuss or rigidly define the requirements embraced in the use of "community" as a unit of vegetation. Sufficient references are available for those who wish to pursue the point. In this study, a community is a congregation of plants exhibiting differences in appearance and species composition from other plant congregations. Secondly, studies were directed to the influences of soil and water on the ecology of each community. Transects were used to investigate many of these relationships. Transition zones between communities were narrow and usually sharply delineated. Transects intersected ecotones of this sort; environmental differences which may have occurred in the few broader ecotones were assumed to be of equal magnitude but of more gradual rate of change . Relatively short transects thus adequately represented each community yet allowed collection of intensive data. Information and data were collected during a 5-week period in August and September 1959 and a 6-month period beginning in March 1960.

Over the past 100 years, riparian vegetation communities throughout the Southwest United States have been extensively invaded by Tamara spp. (saltcedar). Saltcedar derives its common name from its physiological adaptation to excrete salts. The production of Tamarix detritus with associated secondary chemicals may affect the quality of aquatic invertebrate food and habitat resources. An alteration in food and habitat quality may affect the composition and structure of aquatic invertebrate assemblages. A series of experiments was conducted contrasting aquatic invertebrate assemblage densities, colonization rates, and growth rates associated with Tamarix versus native vegetation, Populus fremontii (cottonwood) and Salix exigua (willow), to determine if aquatic invertebrate assemblages have been altered by the invasion of Tamarix. Results of invertebrate growth rates over 13 weeks indicate that Tamarix is minimally different in food quality to cottonwood and willow. I failed to find differences in invertebrate colonization rates or invertebrate assemblage densities associated with Tamarix compared to cottonwood and willow over two 6-week time periods.

No description available.

No description available.

Since 1961, a fourold increase in application of fertilizers in the United States has helped to double crop yields. Nutrients not used by crops are often transported to aquatic ecosystems adjacent to agricultural fields. In the Lower Mississippi Alluvial Valley, nutrients enter agricultural drainage ditches and are transported to receiving water bodies, eventually reaching the Gulf of Mexico. The annual occurrence of a hypoxic zone in the Gulf of Mexico is caused by nitrogen loads from the Mississippi River Basin. Objectives of these studies were: (1) evaluate how organic carbon amendments affect nitrate-nitrogen removal in agricultural drainage ditch systems, (2) determine effects of organic carbon amendments and flow rate on nitrate-nitrogen removal in a semi-controlled field setting using experimental drainage ditches, and (3) assess relationships between organic carbon and nitrogen content of overlying water, pore water, and sediments of drainage ditches throughout the Lower Mississippi Alluvial Valley. In laboratory experiments, nitrate-nitrogen removal in dissolved and particulate organic carbon treatments was greater than 90% compared to as low as 60% in control treatments. The optimal carbon-to-nitrogen ratio of organic carbon amendments for efficient nitrate-nitrogen removal was 5:1. Studies in experimental drainage ditches revealed that flow substantially lowered the ability of organic carbon amendments to remove nitrate-nitrogen with a maximum percent nitrate-nitrogen reduction of 31.6% in a dissolved organic carbon treatment, although implementation of low-grade weirs in experimental drainage ditches did result in removal of nitrate nitrogen in all treatments and at all flow rates. Examining the nitrogen and organic carbon contents in agricultural drainage ditches throughout the Lower Mississippi Alluvial Valley revealed that organic carbon content in overlying water, pore water, and sediments is lower than observed in other wetland-like ecosystems and indeed may be limiting denitrification and other nitrogen removal processes. Increasing organic carbon content overall could be achieved by using organic carbon amendments, but this body of research highlights that additional studies are necessary to ensure successful implementation of organic carbon amendments that reach their greatest potential as a management practice to effectively remove nitrate-nitrogen in the realistic settings of agricultural drainage ditches.

The Mississippi Alluvial Valley (MAV) contained vast bottomland hardwood forests into the 20th century. Humans cleared forests, and altered hydrology, yet the MAV remains important for North American waterfowl and other wildlife. To estimate standing crops of aquatic invertebrates as food in hardwood bottomlands for wintering waterfowl, I quantified dry mass of invertebrates in naturally flooded forests (NFFs) and greentree reservoirs (GTRs) during winters 2008–2010. The MAV had greater invertebrate mass in NFFs (x̄ = 18.39 kg/ha; SE = 2.815 [CV = 15.3%]) than GTRs (x̄ = 5.16; SE = 0.492 [CV = 9.5%]), compared with lesser masses in Mississippi Interior Flatwoods’ GTR (x̄ = 2.26; SE = 0.320) and NFF (x̄= 1.45; SE = 1.305). Invertebrate diversity was greatest in NFFs and in depths from 10–40 cm. Flooding GTRs ≤ 40 cm and managing naturally dynamic hydrology may benefit invertebrates, ducks, and associated bottomland hardwood communities

Aquatic plants (macrophytes) are important components of freshwater ecosystems and serve numerous purposes, physical and biological, that help to structure aquatic communities. Although macrophytes represent an essential component of stable aquatic communities, invasive macrophytes may negatively alter ecosystem properties. Non-native, invasive species have been identified as a major cause of biodiversity loss and the increasing prevalence of invasive species has prompted studies to help understand their impacts and to conserve biodiversity. Studying mechanisms of invasion also gives insight into how communities are structured and assembled. This study examined mechanisms that contribute to macrophyte invasion. First, I reviewed literature concerning mechanisms of macrophyte invasion. Mechanisms identified with this review were then placed within the context of the invasion process and potential taxonomic biases were discussed. Second, a set of classic invasion hypotheses were tested, including biotic resistance, disturbance, and stress, using mixed-effects models on survey data collected from twenty-nine lakes across the United States. Finally, using the same survey data, I performed an observational test of Darwin’s Naturalization Hypothesis at a small (point) and large (lake) scale for two highly invasive macrophytes, Potamogeton crispus and Myriophyllum spicatum. Results of the first study indicated that many invasion mechanisms have been tested with fully aquatic macrophytes with varied levels of support. In addition, there is likely a taxonomic bias depending on geographic location of the invaded area. The second study indicated that biotic interaction, disturbance, and stress interact, often in non-linear ways to influence probability of an invasive species occurring at a location. However, models containing these variables explained a relatively low percentage of variation in probabilities. Finally, there was no support for Darwin’s naturalization hypothesis at either a point or lake scale. Future research should continue the search for mechanisms that allow introduced species to establish. It is likely that general principles do not exist, at least among comparisons across ecosystem types. However, ecologists should continue to search for general patterns within definable ecosystem units to increase understanding about factors contributing to invasibility.