<p> Increased N inputs along with changes in population, land use, and climate have globally altered the N cycle. This alteration has been associated with increased food, energy, and fiber availability, but has also contributed to the degradation of human health conditions and diminishment of expected ecosystem services in many regions throughout the world. In this context, my research explored the impact of shifting anthropogenic N inputs and other environmental drivers on terrestrial N surpluses and linked changes in terrestrial surpluses to observed changes in N loss to aquatic systems. Working in both forested and mixed land use catchments in the eastern USA, I hypothesized that processes that reduced terrestrial N surpluses in catchments by 1) reducing N inputs, 2) increasing plant uptake, and/or 3) increasing gaseous efflux would result in decreased hydrologic N export. Identification of potential processes was accomplished by first generating long-term atmospheric, remote sensing, terrestrial, and hydrologic datasets for individual catchments. The first two components of my dissertation highlighted potential interactions between atmospheric N deposition, acidic deposition, climate, and disturbance in influencing terrestrial N availability, as indicated by N isotopes in tree rings, in forested catchments. Leveraging trend analysis and statistical models, I identified continued long-term declines in terrestrial N availability in forests, but this decline was likely being modified by disturbance and long-term reductions in acidic deposition. The final component of my dissertation involved developing a lumped conceptual model to explain water quality trends in three mixed land use catchments within the Chesapeake Bay watershed. This study assessed the relative influence of point source N loading, agricultural practices, and atmospheric N deposition on long-term trends in riverine N loss. Insights from the simple N loading model strongly suggested that declines in atmospheric N deposition and point source loading were key drivers of historical water quality improvement. Whether relying on quasi-mass balances or dendroisotopic records, findings from this research emphasize the usefulness of constructing proxy datasets of terrestrial N surpluses in identifying likely processes driving changes in hydrologic N loss in forested and mixed land use catchments.</p><p>

<p> Relying on field research to complete the life history for certain fish species can be inadequate, but laboratory research can be used to fill these gaps. These gaps exist for Bonefish (<i>Albula</i> spp.), a tropical marine fish and popular sportfish. In this study, aquaculture techniques were applied to Bonefish in a captive setting at Harbor Branch Oceanographic Institute (HBOI) and Cape Eleuthera Institute (CEI) to induce spawning and describe early ontogeny. Photothermal manipulations and hormone injections were used to induce gonad maturation and spawning, which was achieved once at CEI and is the first record of hormone-induced spawning for Bonefish. From that spawn, egg and larval development were recorded and described through 26 hours and 56 hours respectively, representing the first record of these early life stages for Bonefish. This work expands upon what is known about Bonefish reproductive biology and will be useful for management and future captive research.</p><p>

<p> Mutations are the ultimate source of genetic variation. Understanding the rate and environmental influence on mutation rate is therefore critical for understanding the origin of human disease and all evolutionary change. Environments, including chemical environments, are rapidly changing around the globe. Over the past seven decades, more than 140,000 novel chemicals have introduced into the market. However, less than 2% of these chemicals have been thoroughly characterized with toxicological assays. </p><p> Because the majority of germline mutations have a neutral or negative impact on fitness, pollutant-induced mutagenesis can be devastating for ecosystems and can increase the rate of human disease. However, the influence of chemicals on the rate of germline mutation has been largely ignored. We therefore utilized Daphnia pulex to, (1) characterize the rate and spectrum of genome-wide mutation, (2) measure the influence of chronic, cadmium exposure on the germline mutation rate, and (3) investigate if adaptation protects the germline from mutagenesis. </p><p> The single nucleotide mutation (SNM) rate in <i>D. pulex</i> is similar to other model organisms. However, the rate of large-scale de novo copy number variants is 10 to 100-fold higher than other organismal models and is identical to the estimated rate in humans. Exposure to cadmium was mutagenic in the germline, altering the genome-wide rates and spectra of multiple SNM classes and changing the SNM rates in multiple genome regions. Since drastic, pollutant-induced changes to germline mutation have not previously been described, we developed a quantitative model for predicting population response to mutagenic pollutants. Finally, with a cadmium-adapted genotype we show adaptation protects the germline from cadmium-induced mutagenesis. The knowledge gained through this research stands to have profound implications for society and the long-term health of populations, which are living longer in the presence of a growing diversity of potentially mutagenic chemicals.</p><p>

Evaluation of solid and liquid waste containing heavy metals from industries

Water pollution in two lakes of Mysore city

Ground water pollution

New spectrophotometric reagents

Fresh water

Water Hyacinth

Newer spectrophotometric methods