Thesis Project:
Ecological Consequences of Exposure to Natural Oil Contamination
Crude oil is commonly released into the marine environment via natural and anthropogenic sources. Subsequently, bacteria metabolize the component hydrocarbons, which greatly increases their toxicity (Shelton et al. 1999). Specifically, biodegraded water-soluble fractions (BWSF) of crude oil act as substrates of P-glycoprotein (P-gp) transport proteins, which normally function in a multidrug resistance (MDR) capacity. Some organisms enjoy protection from microbially rich habitats via enhanced P-gp expression, relative to organisms from less contaminated environments (Hamdoun et al. 2002). Embryos of a model organism, the sea urchin Strongylocentrotus purpuratus, obtain protective P-gp and multidrug resistance-associated proteins (MRP) maternally (Hamdoun et al. 2004). Therefore, embryos that upregulate MDR transport activity are subject to BWSF-induced competitive inhibition on a similar scale to known P-gp inhibitors (Hamdoun et al. 2002).
The Coal Oil Point seep field (offshore Santa Barbara, CA) is one of the largest marine hydrocarbon seeps in the world, and has been active at least 500,000 years (Hornafius et al. 1999). Given the abundance of life near these sites of natural oil seepage (Steichen et al. 1996, Davis & Spies 1980, Spies & Davis 1979), resident animals are expected to be well-adapted to local conditions (Spies et al. 1996, 1982) by using MDR efflux transporters to suppress the toxicity of BWSF (e.g., Hamdoun et al. 2002). Thus, oil seeps provide an ideal environment in which to examine long-term natural vs. anthropogenically introduced forms of contamination with a similar toxicity mechanism (i.e., efflux inhibition), as well as the population and community-scale effects of long-term natural pollution.Question: How do the molecular defenses of organisms from naturally contaminated habitats translate into population and community-level ecological effects?
1) Do organisms living in the presence of oil (a naturally occurring MDR inhibitor) respond differently than naïve organisms to exposure of a variety of inhibitors?
2) What is the ecological mechanism that allows a population to “adapt” to oil contamination?
3) What are the effects of this phenotypic plasticity or local adaptation on populations and communities?
This research is funded by a UC Toxic Substances Research & Teaching Program Student Fellowship and a UC Natural Reserve System Mildred E. Mathias Research Grant.
Related Project:
Cost-Benefit Analysis of Estuarine Restoration in the Golden Horn, Istanbul, Turkey
Estuarine ecosystems, which join rivers and seas, are critical components of coastal environments, but have been structurally and functionally impacted by anthropogenic stressors world-wide at a rapid pace. This degradation impairs the ability of estuaries to supply primary production, habitat, nursery grounds, and a migratory stage for countless economically and ecologically valuable species. When damaged, important ecosystem services that filter, detoxify, buffer, and stabilize the physical environment also tend to fail. Decreased revenue from tourism, recreation and commercial fishing, as well as property values are often consequences, as is the risk of ill health upon contact with polluted coastlines. As a result, restoration efforts to improve the quality of coastal ecosystems have been increasingly requested.
The Golden Horn estuary in Istanbul, Turkey is an ideal study site for a cost-benefit analysis of restoration efforts. Researchers at the University of Istanbul have maintained a 60 year data set on the abundance and species composition of algal, invertebrate and fish communities in the Golden Horn. Their data has shown a steady decline in estuarine life since the rapid urbanization of the 1950s that peaked in the 1980s with the disappearance of a great majority of species. This was associated with extensive water quality health standard exceedences and noxious odors. However, a sewage treatment system overhaul in the 1980s and a number of measures such as dam removal, industry relocation, and dredging efforts in the 1990s have partially restored the estuary much more quickly than anticipated. I intend to quantify the aforementioned costs to restoration, as well as benefits that are associated with water quality enhancement, potentially including health impacts, recreational and commercial fish harvesting, tourism, and increased property value near the estuary.
This research was funded by EES and the Institute of Turkish Studies' Summer Research Grant.
Committee:
- Hunter Lenihan, Chair
Past Projects:
- Kelp Restoration with Santa Monica Baykeeper (Asst. Director)
º Video, Poster, Presentation
- Biogeochemical Cycling in the Santa Monica Bay with Dr. Nicolas Gruber (Lab Tech)
- Persistence and management of native plant species at Stunt Ranch Reserve, Malibu with Dr. Jonathan Levine (Undergrad Research)
º Publication, Poster
- Coral and sea fan response to nutrient addition in Akumal, Mexico with Dr. John Bruno (Lab tech)
- Behavioral community ecology at the Discovery Bay Marine Laboratory, Jamaica (Undergrad Research)
º Publication about to be submitted, Poster, Presentation