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dc.contributor.advisorMoran, Xose Anxelu G.
dc.contributor.authorAl-otaibi, Najwa Aziz
dc.date.accessioned2020-12-01T13:17:11Z
dc.date.available2020-12-01T13:17:11Z
dc.date.issued2020-09
dc.identifier.citationAl-Otaibi, N. A. (2020). Seasonal and diel variability of autotrophic and heterotrophic picoplankton in the central Red Sea: Effects of nutrients and temperature. KAUST Research Repository. https://doi.org/10.25781/KAUST-9476K
dc.identifier.doi10.25781/KAUST-9476K
dc.identifier.urihttp://hdl.handle.net/10754/666202
dc.description.abstractPicoplankton, cells between 0.2 - 2 μm, play a vital role in the carbon flow and nutrient cycling in marine food webs. Auto- and heterotrophic picoplankton dominate the biomass of oligotrophic tropical and subtropical oceans. However, little is known about their vertical distribution, changes in space and time and their relationships with environmental variables in the central Red Sea. The goal of this Ph.D. dissertation is to obtain baseline knowledge about their abundance, cellular characteristics (cell size, relative pigment and nucleic acid content) and biomass at seasonal and high-frequency temporal resolution (every 2 hours). This dissertation also aims at assessing picoplankton responses to separate and joint effects of nutrients additions (inorganic, organic and mixed) and temperature in order to be able to predict the relative contribution of eutrophication and warming in the future standing stocks of picoplankton in the Red Sea. I conducted a total of 63 vertical profiles (15 at around noon plus 48 more from the high-frequency diel samplings) from the surface down to the bottom (ca. 700 m) at a station situated 6 km off the coast of King Abdullah Economic City (KAEC) in the central Red Sea and performed 4 nutrient and temperature experiments lasting each 6 days with surface waters from the harbor of King Abdullah University of Science and Technology (KAUST). Flow cytometry allowed me to consistently identify five groups of autotrophs (Prochlorococcus, two populations of Synechococcus separated by their relative phycoerythrin fluorescence, and two differently-sized groups of picoeukaryotes) and two groups of heterotrophic prokaryotes characterized by their different relative nucleic acid content. One of the most surprising findings is the relatively lower abundances and to a lesser extent also growth rates of picoplankton compared with other tropical and subtropical oceans. Seasonality in environmental conditions emerged as an important factor in the response of picoplankton to nutrient additions and temperature. Picoplankton mostly responded to inorganic and mixed nutrient additions rather than warming. Overall, the information provided in this dissertation fills the gap of a critical component of Red Sea pelagic ecosystems and expands the information available on picoplankton communities in tropical waters.
dc.language.isoen
dc.subjectRed Sea
dc.subjectPicoplankton
dc.subjectHeterotrophic bacteria
dc.subjectProchlorococcus
dc.subjectSynechococcus
dc.subjectFlow cytometry
dc.titleSeasonal and diel variability of autotrophic and heterotrophic picoplankton in the central Red Sea: Effects of nutrients and temperature
dc.typeDissertation
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Division
thesis.degree.grantorKing Abdullah University of Science and Technology
dc.contributor.committeememberDaffonchio, Daniele
dc.contributor.committeememberAgusti, Susana
dc.contributor.committeememberEstrada, Marta
thesis.degree.disciplineBioscience
thesis.degree.nameDoctor of Philosophy
refterms.dateFOA2020-12-01T00:00:00Z
kaust.request.doiyes


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