Our knowledge of how oil spills affect coastal environments is severely limited by the shortage of research that addresses the impact of these events on phytoplankton, the single most important group of organisms in the marine ecosystem. This scarcity of knowledge is mainly attributed to the absence of baseline data, preventing the comparison of pre- and post-spill populations. This unique study aims to identify how dinoflagellates and diatoms, the two major groups of phytoplankton in coastal marine environments, have been affected by the 1989 Exxon Valdez oil spill in Prince William Sound (PWS), Alaska. To do this, sedimentary records of dinoflagellate cysts, produced during a dinoflagellate's life cycle and preserved in the sediment, and biogenic silica, a proxy for diatom abundance, were analyzed prior to, during and after the oil spill. The analysis of two well-dated cores in PWS reveals marked increases during the oil spill in the concentrations of total cysts of the species Operculodinium centrocarpum sensu Wall and Dale, (1966) and Dubridinium spp. Total cyst concentrations doubled in core P-10 from 362 to 749 per g, while in core P-12 the increase was from 1175 to 1771 cysts g-1. During this peak in cyst concentrations, total concentrations were 3 and 2 standard deviations greater than the mean in cores P-10 and P-12, respectively. Dubridinium spp. showed a five and sevenfold increase in concentrations in cores P-10 (4 to 20 cysts g-1) and P-12 (16 to 110 cysts g-1), respectively, while O. centrocarpum sensu Wall and Dale, (1966) doubled in concentrations in the two cores (P-10: 117 to 276 cysts g-1; P-12: 268 to 495 cysts g-1). Biogenic silica values did not show significant changes throughout the cores, with values varying between 8% and 9% in core P-10 and 9.0% to 10.9% in core P-12. These changes lie within or very close to the standard deviation of the analyzed standards, suggesting that much of the changes could be analytical noise. The dinoflagellate cyst signals seen in this study are comparable to those seen as a result of nutrient enrichment in estuarine systems, suggesting that the 1989 Exxon Valdez oil spill and its remediation had a stimulatory effect on some taxa of cyst- producing dinoflagellates. This impact appears to be short-lived, with cyst concentrations returning to pre-spill levels within two years of the event. The lack of change in diatom abundance, on the other hand, suggest that diatom abundance remained relatively constant during the entirety of the sample period. / Graduate / 2020-07-10

The oil from the Exxon Valdez incident is still observed in different Prince William Sound beaches over two decades. The persisting oil is slightly weathered and highly toxic to the environment. Several studies investigated the reasons for lingering oil. Different remediation techniques were tried and the results were not satisfactory. Recently, it was found that the oil is stranded in a low permeability layer. Detailed explorations showed that the exchange of the nutrients and oxygen is limited in this layer. The main objective of the present study is to explain the effect of oxygen and nutrients on the degradation phenomena in the Alaskan beaches. The general approach for this study is a combination of the field experiments and lab analysis. As it is important to eliminate any cross-layer contamination, a unique sampling method was developed. The applied method involves collecting samples from the oily layer (low permeability layer), measuring oxygen levels in the field and comparing them with the nutrient samples analyzed in the lab. The findings showed that the nutrients levels were low in the beach but the lack of effective electron acceptor is the major factor limiting the biodegradation of the oil. The seawater is responsible for delivering the oxygen and nutrients to the beach during the high tide while during low tide the landward freshwater discharges to the beach. The study of the sulfate and nitrate in the beach revealed that the levels of the alternative electron acceptors were not sufficient to support anaerobic biodegradation. Finally, for successful biodegradation of the Exxon Valdez oil, adequate levels of nutrients (nitrogen and phosphorous) and along with oxygen are required. / Civil Engineering

Ever since humans began using cargo by sea to transport oil, oil spill incidents have occurred on different scales in different environments. Oil leaks by cargo tankers on the high seas have a bigger and more serious impact on the environment. Among the many oil spills in the ocean, the most serious was the Exxon Valdez incident in Alaska¡¦s Prince William Sound (PWS). While it may not have been the largest spill in terms of the volume of oil leaked, its effects were far-reaching; the location of the spill was in the sensitive area between the temperate and subtropical zones, and it was home to many fish, migratory birds, and mammals. Therefore, this location has become an important place for researchers to study the environmental and biological impacts of an oil leak. In the past, there have been several studies conducted from various perspectives and in various stages. In 2001, the Greek oil tanker The Amorgos ran aground near Kenting National Park¡¦s Long-Keng Environmental Protection Zone and seriously damaged the ecological environment. Taiwanese studies on the ecological impacts of oil spills include investigations and evaluations done on a short-term basis, and have been mainly focused on contingency plans and designs, evaluation systems, and handling technology. Thus, the purpose of this paper is to use related studies conducted in Alaska PWS to evaluate the ecological system in the Long-Keng area and to assess the long-term impacts of an oil spill in the ecological sensitive area of Taiwan.

The pigeon guillemot (Cepphus columba) population in Prince William Sound has failed to recover from declines that occurred both before and after the Exxon Valdez Oil Spill (EVOS). Post-spill studies of pigeon guillemot breeding biology have identified three potential factors limiting recovery: (1) predation on eggs and nestlings; (2) declines in the proportion of high-lipid, schooling forage fish (sand lance [Ammodytes hexapterus], herring [Clupea pallasi], and capelin [Mallotus villosus]) in the diet; and (3) continued exposure to residual oil from the spill. This laboratory study with captive-reared pigeon guillemots at the Alaska SeaLife Center investigated two aspects of the species' biology that are relevant to restoration in the aftermath of EVOS. First, we investigated the role of dietary factors (prey type, quantity of food consumed, dietary fat content, and energy intake rate) in limiting the growth, development, survival, and fledging condition of nestling pigeon guillemots. The objective was to understand how changes in prey availability and prey quality might affect pigeon guillemot productivity. Second, we fed nestlings sublethal doses of weathered Prudhoe Bay crude oil (PBCO) and then measured several potential biomarkers of effects from this pollutant. These dose-response experiments were designed to (1) better understand the impact on nestling guillemots of petroleum hydrocarbons in food, (2) calibrate existing and potential biomarkers of exposure to PBCO in pigeon guillemots in a controlled, laboratory setting, and (3) develop better nondestructive biomarkers of exposure to PBCO in pigeon guillemots in particular, and seabirds in general. Results of feeding experiments indicated that most variation in nestling growth rates could be explained by variation in daily energy intake. The type of forage fish consumed, the lipid or protein content of the forage fish, and even the quantity of food consumed daily did not have as strong an effect on nestling guillemot growth as did daily energy intake. The metabolic efficiency and growth performance of nestling guillemots was not enhanced on high-lipid diets, contrary to results with nestlings of some other seabird species. Instead, structural growth (wing length) in nestling guillemots was somewhat stunted on high-lipid diets. These attributes of guillemot nutritional requirements are associated with the guillemots' nearshore foraging niche and high food provisioning rates to nestlings. The average lipid content of sand lance, juvenile herring, and capelin may represent the optimal dietary lipid content for nestling pigeon guillemots. This study supports the hypothesis that guillemot productivity is limited by the availability of these forage fishes through effects on energy provisioning rates to nestling guillemots. Consequently, recovery of pigeon guillemot populations injured by EVOS is likely linked to recovery of these key forage fish stocks. Results of the oil-dosing experiments indicated that nestling guillemots are resistant to small doses of weathered PBCO in their food. No nestlings died or suffered noticeable health effects following dosing. The high dose in this study (0.5 ml kg����� day�����) was sufficient to induce hepatic cytochrome P450A1 (a liver enzyme indicative of contaminant exposure), but growth rate, fledging mass, and blood chemistry were largely unaffected. None of the 12 plasma or hematological markers examined responded in a dose-dependent manner to ingestion of weathered PBCO, except lactate dehydrogenase (LDH). Although baseline stress hormone (corticosterone) levels were not different between oil-dosed and control nestlings, a standardized acute stress protocol revealed that corticosterone was more elevated during stress for oiled nestlings compared to controls. Although we were not successful in identifying a noninvasive biomarker (e.g., growth) or a blood biomarker (e.g., haptoglobin) of crude oil exposure in nestlings, we were able to confirm that levels of hepatic cytochrome P4SO1AI and corticosterone during stress were elevated by the sublethal doses administered during our experiments. Based on this and other studies, it is unlikely that the failure of pigeon guillemots to recover from EVOS is due to effects on nestling health of residual oil in food. / Graduation date: 2003

I investigated the relationship between harlequin duck (Histrionicus histrionicus) behavior and lack of recovery from the Exxon Valdez oil spill in Prince William Sound, Alaska. First, I evaluated the hypothesis that harlequin ducks in winter have little flexibility to increase foraging time in response to disturbance because they are constrained to forage during daylight. Eight radio-tagged harlequin ducks wintering in Resurrection Bay, Alaska were monitored for evidence of dive-feeding at night. Each radio-tagged individual was detected during an average of 19.5 of 22 nocturnal monitoring sessions and signal loss indicative of diving behavior was not detected during a total of 780 minutes of signal monitoring. In contrast, the same 8 radio-tagged birds were detected during an average of 9.1 of 12 daytime signal monitoring sessions and signal loss indicated diving behavior during an average of 62 �� 7% of 5-minute daytime monitoring periods (total of 364 minutes of signal monitoring). Thus the harlequin ducks monitored in this study rarely, if ever, fed by diving at night, possibly due to reduced foraging efficiency and (or) increased predation risk at night. This result suggests that harlequin ducks in mid-winter may be severely time-limited in their foraging, especially in northern parts of their winter range. Therefore, subtle changes in energy requirements and (or) time-activity budgets as a result of continued exposure to residual oil from the Exxon Valdez oil spill may affect the ability of harlequin ducks to meet their daily energy requirements. Second, I tested the hypothesis that exposure to crude oil affects time-activity budgets of harlequin ducks. Controlled oil-dosing and plumage-oiling experiments were conducted using adult female harlequin ducks in captivity. I found no evidence that ingestion of weathered Prudhoe Bay crude oil affected the occurrence of feeding activity during 30-minute observation periods, nor was there evidence of effects on time spent feeding. Effects of crude oil ingestion on maintenance activity were detected, but were neither consistent between the 2 years of the study, nor dose-dependent for the 2 doses administered (2 and 20 mL kg����� wk�����), and therefore did not strongly support an oil-dosing effect on maintenance activity. Consequently, these results provided little support for the hypothesis that oil ingestion affects time-activity budgets of captive harlequin ducks, at least for the doses and conditions of captivity used in this study. Plumage-oiling reduced feeding activity in captive harlequin ducks. The estimated probability of feeding during 30-minute observation periods for birds in the high-exposure oiling group (5 mL of crude oil) was 53% less than that of non-oiled controls. Oiled birds exhibited a trend of reduced time feeding with increasing level of external-oiling; this effect was greatest among birds in the high-exposure oiling group, which spent 43% less time feeding than non-oiled birds. Reduced feeding was associated with less time in the water dive-feeding and presumably lower heat loss. Trends in the occurrence of maintenance activity and time spent in maintenance activity for birds in the high-exposure treatment suggested plumage-oiling increased maintenance activity, but results were not conclusive. The behavioral changes associated with plumage-oiling in captivity would likely reduce fitness in the wild, where a high proportion of time must be spent in the water feeding. If residual Exxon Valdez oil sequestered in beach sediments enters the water column where it may be encountered by harlequin ducks, external exposure may lead to reduced feeding activity. This, in turn, may compromise survival, particularly during mid-winter when the time available for diurnal foraging is low and maintenance energy requirements are high. / Graduation date: 2004