No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Each data chapter within this dissertation, while distinct in the stressor/combination of stressors, species under examination, and the purpose of the research effort, contributes to the unified objective of the dissertation: answering critical questions regarding the physiological effects of various environmental stressors on freshwater species. Results from data Chapter 2 indicate that adult Daphnia magna are more sensitive to lead exposure when co-exposed to percent air saturation approaching lethal levels of hypoxia. Moreover, increased hypoxia under control (no lead) conditions induced increased hemoglobin protein and mRNA expression, regardless of isoform transcript and typically in a dose-dependent manner for the latter. In Chapter 3 the maximum sustained swimming speeds (Ucrit) of several fish species of greatest conservation need at different temperatures (15, 22.5, and 30 °C) is assessed, providing valuable insights for site-specific calculations of culvert water velocities (Vf). Additional physiological endpoints of relevance to overall swimming performance were also measured, including maximum burst swimming (Umax), aerobic scope and cost of transport (COT). In Chapter 4 ammonia toxicity at different salinities to juvenile Macrobrachium rosenbergii is determined and real-time metabolic assessments as an effective detection method for perturbations in systems such as recirculating aquaculture systems is conducted. Although these chapters address distinct research topics, they collectively demonstrate the pivotal role of physiology in addressing complex issues related to human activity and environmental impacts. The dissertation's findings contribute novel information emphasizing the importance of understanding physiological responses in mitigating the impacts of anthropogenic activities on freshwater ecosystems.

We investigated the modifying effects of ultraviolet (UV) light and chemical dispersant (Corexit 9500A) on crude oil toxicity in juvenile mysids (≤ 24 h) (Americamysis bahia) and larval red drum (24-72 hpf) (Sciaenops ocellatus). These results demonstrate that crude oil toxicity significantly increases with co-exposure to environmentally relevant UV levels in both species, indicating photo-induced toxicity. This toxicity was further exacerbated by the application of chemical dispersants which increased the dissolution and concentration of oil-derived polycyclic aromatic hydrocarbons (PAHs) in test solutions. To better understand the mechanisms and initiating events of this observed photo-induced toxicity, the incidence of apoptotic cell death and global transcriptomic changes were assessed in larval red drum (24-72 hpf) following co-exposure to crude oil and UV. These results showed that co-exposure to UV and low concentrations of crude oil (<1 µg/L ∑PAH50) induced apoptotic cell death in skin and eye tissue and altered transcriptomic pathways related to visual processing and dermatological disease. To link these cellular and molecular impacts of photo-induced toxicity to apical endpoints of ecological performance, sublethal impacts to growth, metabolic rate, and visually mediated behaviors were explored in larval red drum at 2 developmental stages. These results suggested that earlier life stages may be more sensitive to photo-induced toxicity and that growth and development, particularly of sensory systems, can be sensitive targets of photo-induced toxicity. Together, these studies provide novel insights into the photo-induced toxicity of crude oil in aquatic organisms and can be used to inform future ecological risk assessments.

Genomic modifications occur slowly across generations, whereas short-term epigenetic transgenerational inheritance of adaptive phenotypes may be immediately beneficial to large numbers of individuals, acting as a bridge for survival when adverse environments occur. In this study we used dietary exposure to crude oil as an example of an environmental stressor to assess its effects from the molecular to the organismal levels in piscine and avian animal models. In addition, we assessed the role of the parental exposures on their offspring F1 generation. The research developed in this dissertation has contributed to several areas of investigation including molecular biology, animal physiology, and evolutionary biology. The quantitative information from these studies may be utilized to supplement information regarding the proximate and ultimate effects of environmental stressors on fish and bird populations. Furthermore, this information may be used as additional support for understanding the conservation of the responses from the molecular to the whole organismal levels across the vertebrate taxa, as well as their implications for population survival and maintenance. Additionally, the zebrafish (Danio rerio), the Siamese fighting fish (Betta splendens) and the king quail (Coturnix chinensis) have proven to be excellent models to start building a strong basis for understanding the effects of environmental stressors and transgenerational epigenetic phenomena using a multi-level approach. Furthermore, as more raw data and information is discovered, the concatenation of development, organismal variation, epigenetics inheritance, natural selection, speciation and evolution is being slowly decrypted.