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i DISTRIBUTION AND IMPACT OF ALGAL BLOOMS LEADING TO DOMOIC ACID EVENTS IN SOUTHERN CALIFORNIA by Erica Lee Seubert _______________________________________________ A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOLOGICAL SCIENCES) August 2013 Copyright 2013 Erica Lee Seubert
|Title||Distribution and impact of algal blooms leading to domoic acid events in southern California|
|Author||Seubert, Erica Lee|
|Degree||Doctor of Philosophy|
|Degree program||Marine and Environmental Biology|
|School||College of Letters, Arts And Sciences|
|Advisor (committee chair)||Caron, David A.|
|Advisor (committee member)||
Hutchins, David A.
Sanudo-Wilhelmy, Sergio A.
Sañudo-Wilhelmy, Sergio A.
Sukhatme, Gaurav S.
|Abstract||The term harmful algal bloom (HAB) is used to describe any bloom of microalgae that has a detrimental impact to the local ecosystem and/or economy. The impacts of a HAB to an ecosystem can include death or injury to local wildlife through the production of toxins, decreased oxygen concentrations, physical damage, decreased light availability or food web disturbance. The economic impacts can be reduction in tourism, human illness, reduced fishing effort or interruption of desalination plant operations. The occurrence and intensity of HABs have been increasing globally during the past few decades, whether this increase can be attributed to enhanced awareness and monitoring, or to a dramatic upswing in the development of HAB events remains unresolved. ❧ A variety of HAB-forming species of microalgae occur in southern California, and several of these species are known to produce potent neurotoxins. The impact of algal toxin presence on both the intake and reverse osmosis (RO) desalination process and whether or not the naturally occurring algal toxins can pass through the RO membrane and into the desalination product was addressed through bench-scale RO experiments and monitoring for algal toxins at a pilot RO desalination plant. Concentrations exceeding maximal values previously reported during natural blooms were used in the laboratory experiments, with treatments comprised of 50 µg/L of domoic acid (DA), 2 µg/L of saxitoxin (STX) and 20 µg/L of brevetoxin (PbTx). None of the algal toxins used in the bench-scale experiments were detectable in the desalinated product water. Monitoring for intracellular and extracellular toxin concentrations of DA, STX, PbTx and okadaic acid (OA) within the intake and desalinated water from a pilot RO desalination plant in El Segundo, CA, was conducted from 2005 to 2009. During the five-year monitoring period, DA and STX were detected sporadically in the intake waters but never in the desalinated water. PbTx and OA were not detected in either the intake or desalinated water. The results of this study demonstrate the potential for HAB toxins to be inducted into coastal RO intake facilities, and the ability of typical RO operations to effectively remove these toxins. ❧ The ability to accurately and rapidly identify an emerging HAB event is of high importance. Monitoring of HAB species and other pertinent chemical/physical parameters at two piers in southern California, Newport and Redondo Beach, was used to investigate the development of a site-specific bloom definition for identifying emerging DA events. The neurotoxin DA is produced by the chain forming diatom Pseudo-nitzschia, and it is the most common HAB organism in southern California. Emphasis was given to abundances of the P. seriata size category of Pseudo-nitzschia due to the prevalence of this size class in the region. P. seriata bloom thresholds were established for each location based on deviations from their respective long-term mean abundances, allowing the identification of major and minor blooms. Sixty five percent of blooms identified at Newport Beach coincided with measurable DA concentrations, while 36% of blooms at Redondo Beach coincided with measurable DA. Bloom definitions allowed for increased specificity in multiple regression analysis of environmental forcing factors significant to the presence of DA and P. seriata. The strongest relationship identified was between P.seriata abundances two weeks following upwelling events at Newport Beach. ❧ Blooms of Pseudo-nitzschia can develop at depth in offshore waters not encompassed by coastal HAB monitoring programs. California sea lions are predominately associated with DA mortality events on the US west coast undoubtedly due to their large population sizes and overlapping distribution with Pseud-nitzschia. Quantifying the amount of DA in these animals and correlating this information with the presence of DA in phytoplankton and the local food web has become a research focus for many scientists. However differences in materials, equipment, technical capability, budgets and objectives of the various groups and/or agencies involved in this work have influenced the DA quantification platforms employed. The performance of two commercially available enzyme-linked immunosorbent assays for the analysis of DA in a spectrum of California sea lion body fluids was compared to the results obtained with liquid chromatography-mass spectrometry of the same samples. The results indicated differences among these approaches, presumably owing to matrix effects (particularly urine) and antibody reactivities. This information implies that care should be taken in attempting to compare datasets generated using different analytical platforms and interpreting the results of published studies. ❧ The Orange County Sanitation District diverted flow of secondarily treated effluent from a discharge pipe located 8.0 km offshore at 60 m depth to a pipe located 1.6 km from shore at 17 m depth for three weeks in September of 2012. Two incubation experiments were performed to examine the influence of treated effluent at various dilutions on natural, coastal phytoplankton communities, the first initiated a week prior to the diversion ('Pre-Diversion') and the second initiated a week after the start of the diversion ('Mid-Diversion'). The overall community response observed in both experiments following effluent addition was an increase in diatom and picoeukaryote abundances, a decrease in picophotocyanobacteria and a dramatic increase in heterotrophic bacteria abundance. The 1:10 effluent additions yielded significant increases in chlorophyll a concentrations, although the Pre-Diversion 1:10 experiments exhibited a lag in response to effluent addition. The DA producing diatom Pseudo-nitzschia was present throughout both experiments, however DA production was only detected in the Mid-Diversion experiment. The highest concentration of DA measured, 0.42 ± 0.057 µg/L coincided with phosphate and silicate concentrations below the detection limit of the method, suggesting limitation by these macronutrients.|
|Keyword||harmful algal blooms; Pseudo-nitzschia; domoic acid; saxitoxin; HAB monitoring; desalination; okadaic acid; brevetoxin; California sea lion; ELISA|
|Part of collection||University of Southern California dissertations and theses|
|Publisher (of the original version)||University of Southern California|
|Place of publication (of the original version)||Los Angeles, California|
|Publisher (of the digital version)||University of Southern California. Libraries|
|Provenance||Electronically uploaded by the author|
|Legacy record ID||usctheses-m|
|Contributing entity||University of Southern California|
|Rights||Seubert, Erica Lee|
|Physical access||The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given.|
|Repository name||University of Southern California Digital Library|
|Repository address||USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA|
|Contributing entity||University of Southern California|
|Full text||i DISTRIBUTION AND IMPACT OF ALGAL BLOOMS LEADING TO DOMOIC ACID EVENTS IN SOUTHERN CALIFORNIA by Erica Lee Seubert _______________________________________________ A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOLOGICAL SCIENCES) August 2013 Copyright 2013 Erica Lee Seubert|