Theses
Permanent URI for this collectionhttps://hdl.handle.net/1969.6/1140
Browse
Browsing Theses by Department "Marine Biology"
Now showing 1 - 6 of 6
- Results Per Page
- Sort Options
Item An assessment of benthic condition in the Matagorda Bay System using a sediment quality triad approach(2023-05) Caillier, Jasmine; Montagna, Paul; DeLorenzo, Marie; Pollack, JenniferThe Matagorda Bay system is one of seven estuaries along the Texas coast. Once known to be an abundant and diverse ecosystem for marine organisms, however, there has been long-term decline in benthic abundance, biomass, and diversity in the Matagorda Bay System. One possible reason is contamination from municipal, agricultural, or industrial sources, which may be toxic to marine organisms. The purpose of this study was to examine sediment contamination to determine if pollution is a possible cause for ecosystem degradation. Degradation can be indicated by a decline in benthic integrity (i.e., diversity), decreased survival rates of organisms exposed to sediments, and sediment chemical contaminant concentrations over threshold limits. These methods form the Sediment Quality Triad (SQT), which is an interdisciplinary approach that includes contaminant concentrations as a measure of dose, a toxicity measure to assess biological effects, and benthic community diversity to indicate ecological effects. Twenty-four stations were sampled including historical, previously studied sites and sites suspected as having pollution induced degradation. The results revealed that there is contamination but only affecting localized areas in the estuary. The average means (ng/ g dry sediment) across all stations for DDT was 0.07, for PAH the average was 211.87, and for PCBs the average was 0.34. There were no contaminants above threshold limits for PCB, DDT and all but one PAH, but 46% of the stations had chemical detections over threshold limits for seven trace metals: arsenic, cadmium, mercury, copper, lead, nickel, silver, and dibenzo (a,h) anthracene. Mostly near river mouths, 16 of the 24 stations had moderate to high toxicity, and 17 out of the 24 stations had fair to low diversity. Toxicity was significantly correlated with diversity, whereas there were no correlations between sediment chemistry and toxicity or benthic metrics, signifying that there is no evidence that pollution is a problem estuary wide, rather it is localized. This indicates that this system is a multiple stressor system due to various natural influences (changes in temperature, dissolved oxygen, freshwater inflow, salinity) and contamination combined that are affecting benthic communities. With climate drastically changing and more industrialization increasing along the bay the benthic community will face constant declines and more salt or temperature tolerant species dominating. Therefore, focusing on the areas of concern with the most contamination and poor survival and diversity management plans (watershed and non-point sources) can be created to protect this regions ecosystem.Item A comparison of hydraulic patent tongs and oyster dredges for monitoring oyster reefs in the mission - Aransas estuary(2023-08) Wheat, Margaret Catherine; Pollack, Jennifer; Olsen, Zachary; Walther, BenjaminThe Texas Parks and Wildlife Department (TPWD) currently uses dredge sampling to monitor oyster reefs open to commercial harvest. However, dredges have been shown to produce biased sampling data with regard to the density and relative sizes of the oysters collected. In this project, we compared the sampling performance of oyster dredges in reference to hydraulic (patent) oyster tongs. The objectives of this project were to: (1) Compare the density (n m-2) and size (shell height, mm) of live oysters, articulated shells of dead oysters (boxes), and disarticulated oyster shells collected using dredges and tongs across varying reef structures (assessed with acoustic mapping procedures). (2) Compare dredge vs. tong-generated metrics and evaluate resulting thresholds for opening and closing oyster harvest areas. (3) Compare the logistics of dredge versus tong sampling methods for oyster monitoring (e.g., cost, gear maintenance and operation, impacts on staff-hours). Results indicate that dredges show a size bias toward larger shells and oysters, while tongs sample a smaller area and may not accurately represent density across the entire reef extent, particularly for reefs with patchy oyster distribution and where sample size is not adequate. Although deployment, retrieval, and processing for one tong sample takes less time than for one dredge sample, tong sampling requires one additional staff member and approximately 2-3x more samples to see stabilized estimates of density, compared to dredge sampling. Based on this study, tongs may be better suited for more focused (spatially or temporally) sampling initiatives where a greater number of samples and staff time are more realistic. This is the first tong and dredge comparison in Texas estuaries that focuses on monitoring commercially harvested oyster reefs and understanding the ability of tongs and dredges to provide management metrics across a range of reef types and oyster abundances.Item Corals in crisis: How temperature and nutrient fluctuations affect physiological responses of corals and their microbiome in K?ne‘ohe Bay, Hawai‘i(2023-05) Ruben, Zoe; Bahr, Keisha; Turner, Jeffrey; Abdulla, HussainCoral reefs are the foundation of the social, cultural, and economic life in Hawai?i; however, these reefs have not escaped the conditions that have ravaged coral reefs in other areas. Along the east coast of O?ahu lies K?ne?ohe Bay, which serves as a living laboratory with distinct differences in environmental gradients due to variations in circulation and residency times. This provides a unique opportunity to explore the impact of water quality and ongoing ocean warming on coral health, susceptibility, and tolerance. Pairs of historically bleached/non-bleached corals were collected at two sites within K?ne?ohe Bay and subjected to experimental treatments varying in temperature and nutrient levels for one month at the Hawai?i Institute of Marine Biology. Biological response variables were measured, and subsamples were taken from the coral fragments at the beginning and end of the experiment for bacterial community analysis. Results demonstrate that coral decline and bleaching susceptibility were least prevalent in the Control and Elevated Nutrient treatments but most prevalent in the Elevated Nutrient + Elevated Temperature treatment, indicating that low-level nutrients may benefit the corals. Still, the combined stressors may have a synergistic, negative effect. Microbial clustering analyses reveal a shift in relative abundances of bacteria before vs. after exposure to stress. These findings may support that coral bleaching susceptibility is manifested throughout the coral holobiont and that physiological response to interactive stressors can be better understood and potentially mitigated.Item Microbial diversity of bleached nurdles in the NorthWest Gulf of Mexico(2023-08) O'Donnell, Colin Andrew; Turner, Jeffrey; Buck, Gregory; Conkle, Jeremy; Tunnell, JaceNurdles are the raw material in the manufacture of plastic products. They are mass produced and transported worldwide, but accidental and negligent spills pollute marine environments. In the Gulf of Mexico (GoM), a citizen science initiative, the Nurdle Patrol, revealed that 20 of the highest nurdle-polluted beaches are found in Texas. Microorganisms, including potentially pathogenic bacteria, rapidly colonize nurdles. The purpose of this study was to broaden the understanding of nurdle-bacterial coupling through the following objectives: 1) characterize the microbial diversity of nurdles on a recreational beach compared to a natural substrate and 2) isolate potentially pathogenic members of the nurdle community and further analyze those isolates through whole-genome sequencing (WGS) and antimicrobial resistome analysis. Results show that the nurdles were colonized by a distinct (Faith’s phylogenetic distance, P < 0.001) and more uniform microbial community than beach sand. The nurdle community was dominated by Proteobacteria (69.5%) and Bacteroidota (21.7%) at the phylum level, and Rhodobacteraceae (26.2%) at the family level. Culturable members of the nurdle community included potentially pathogenic Bacillus licheniformis and Bacillus paralicheniformis. Isolates possessed antimicrobial resistance genes (e.g., ATP-binding cassette (ABC) antibiotic efflux pumps and class A Bacillus cereus Bc beta-lactamases), and two B. paralicheniformis isolates appeared to be multidrug resistant (i.e., peptide, macrolide, and penam resistant). Results demonstrate that nurdles were colonized by a distinct community compared to a natural substrate. Additionally, nurdles supported the growth of potentially pathogenic Bacillus species with the genetic potential for antimicrobial resistance. Overall, these results establish a baseline knowledge of nurdle microbial diversity in the northwest GoM.Item The role of MIR-199A in BAO-induced transgenerational bone deformities in Japanese Medaka(2023-05) Jayarajan, Rijith; Seemann, Frauke; Bird, Christopher; Portnoy, David; Lu, YuanBenzo[a]pyrene (BaP), a ubiquitous environmental pollutant and known carcinogen, has been evidenced to cause bone disorders in a transgenerational manner by altering epigenetic mechanisms like microRNAs (miRNA). Transcriptome analysis of bone tissue in the ancestrally BaP-exposed F3 generation indicated a prominent role of miR-199a in the regulation of significantly enriched molecular pathways for bone formation and oxidative stress. To elucidate the function of miR-199a during bone development wildtype (Orange Red) and transgenic (twist:dsred/col10a1:gfp and col10a1:gfp/osx:mCherry) freshwater medaka (Oryzias latipes) were assessed for calcification and cell-subpopulation level changes in response to miR-199a agonist and antagonist microinjections at the onset of vertebra development. To further characterize the role of miR-199a on bone development, mineralization and osteoblast differentiation, the effects of miR199a-3p agonist and antagonist injections (700 pg) at the beginning of bone formation in medaka embryos 3 days post fertilization (dpf) were studied. The area and intensity of calcification were assessed in wild-type medaka. Medaka transgenic lines - twist:dsred/col10a1:gfp and col10a1:gfp/osx:mCherry were used to assess changes during osteoblast differentiation. No impact on the calcified area and bone thickness upon miR-199a-3p agonist or antagonist injection was identified. The spatial distribution and the cellular density of twist+ mesenchymal stem cells (MSCs) were not affected. A significant reduction upon agonist injection was noted in the cellular density of col10+ osteochondro progenitors (OPCs). No change in spatial distribution and density of osx+ premature osteoblast cells (POCs) was seen upon miR-199a-3p treatment. Assessment of bone gene expression levels in 25 dpf old medaka larvae revealed a potential inhibitory effect of miR-199a-3p on bone development. The tissue, cellular and molecular level experiments confirmed the role of miR-199a-3p in bone maturation and osteoblast differentiation. This study provides a novel understanding of miRNA regulation during two critical windows of bone development. The provided data can be used to delineate the effect of BaP exposure on regulating specific miRNAs. Moreover, developmental levels of miR-199a may be useful as a potential biomarker for later life-stage bone impairment, such as osteoporosis development.Item Understanding nanoplastic particle accumulation and cell response in human skin cells(2023-08) Simpson, Kayla Haylie; Xu, Wei; Turner, Jeffrey; Sheng, Jian; Zhu, LinEnvironmental nanoplastic particles (NPs) are considered hazardous materials that can potentially enter human bodies through various entry pathways due to their sizes (<1µm). Studies over the past few years have produced results showing the capability of nanoplastic particles (NPs) to enter cells. However, the mechanism of NP cellular uptake remains unclear. Furthermore, the internalization and accumulation of NPs by human cells can likely be altered by the various characteristics of NPs, including materials, shapes, and surface properties. This study aimed to understand the mechanisms of NPs internalization and accumulation in skin cells, including keratinocytes, dermal fibroblast cells, and adipocytes, and how those processes can be altered by the surface coating components (surface corona). The study was conducted using fluorescence microscopy and flow cytometry to track NP endocytosis, organelle staining to determine intracellular co-localization patterns, and various assays and genetic analyses to understand how NPs affect cell functions and inflammation. The results of the present study demonstrated different internalization mechanisms of NPs depending on cell type, exposure time, particle size, and surface composition. It was also observed that specific vital organelles were more likely to co-localize with NPs, depending on particle size and exposure time. NP accumulation patterns in skin cells revealed potential mechanisms behind the impaired cellular function of cells exposed to NPs. Therefore, potential risks were determined to be associated with the exposure of human skin cells to NPs.