Theses and Dissertations

Defense Date

1990

Document Type

Dissertation

Degree Name

Ph.D. Oceanography/Marine Biology

Department

Oceanographic Center

First Advisor

Gary L. Hitchcock

Second Advisor

Gary S. Kleppel

Third Advisor

Julian P. McCreary

Fourth Advisor

Peter B. Ortner

Fifth Advisor

William A. Venezia

Abstract

This dissertation consists of three chapters, two of which are presented in manuscript form. Chapter One is an introduction and review of the measurement of phytoplankton chlorophyll a carbon-specific growth rates. Chapter Two consists of the manuscript ASPECTS OF CHLOROPHYLL a CARBONSPECIFIC GROWTH RATE IN THE EASTERN NORTH ATLANTIC OCEAN. It has been formatted in accordance with the specifications of the oceanographic journal Marine Ecology Progress Series. In Chapter Two, an evaluation of the short-term kinetics of the labeling time of natural phytoplankton populations in different oceanic regions showed that chI a labeling varied in relation to both environmental conditions and latitude. At subtropical stations rapid short-term increases in the activity of chI a were coincident with large (> 38%) increases in total photosynthetically available radiation. The rapid short-term increases resulted in overestimates of the growth rate. Overall though, a strong correlation between chI a carbon-specific growth rates and independently-derived assimilation numbers was evident. This strong correlation, particularly with end-of-day samples suggests that the chI a labeling technique for phytoplankton carbon-specific growth rate determination is applicable in different oceanic regions under broadly varying environmental conditions.

Chapter Three consists of the manuscript DISTRIBUTIONS OF CHLOROPHYLL AND PRIMARY PRODUCTIVITY IN RELATION TO WATER COLUMN STRUCTURE IN THE EASTERN NORTH ATLANTIC OCEAN. Chapter Three has been formatted in accordance with specifications of the Journal of Global Biogeochemical Cycles. Chapter Three has been submitted under the co-authorship of G. Berberian for review by the Journal of Biogeochemical Cycles. In Chapter Three latitudinal variations in the megascale (103 km) distribution of biological properties were observed in relation to the water column structure between 60°N and 7°N in the Eastern Atlantic Ocean. High chI a concentrations in the northern latitudes were associated with a shoaling of the pycnocline. A secondary region of high chI a at 7°N was associated with a lens of low salinity Amazon River water. Productivity maxima were located south of Iceland, in the vicinity of the Azores Front, and at the Amazon River water feature.

The research described in Chapters Two and Three was performed during the Eastern North Atlantic section of the 1988 National Oceanic and Atmospheric Administration (NOAA) Global Change Expedition. Two appendices are included in the dissertation which contain pertinent Global Change Expedition data used in the manuscripts. Appendix One contains data relevant to Chapter Two, while Appendix Two contains data relevant to Chapter Three. A NOAA Data Report (Frazel, Berberian and Hitchcock 1989) containing complete data for the Global Change Cruise is also available. Reference lists are included at the end of Chapters Two and Three, while a master reference list is given at the end of the dissertation. Chapter Three has been formatted in accordance with specifications of the Journal of Global Biogeochemical Cycles. Chapter Three has been submitted under the co-authorship of G. Berberian for review by the Journal of Biogeochemical Cycles. In Chapter Three latitudinal variations in the macroscale (103 km) distribution of biological properties were observed in relation to the water column structure between 60°N and 7°N in the Eastern Atlantic Ocean. High chl a concentrations in the northern latitudes were associated with a shoaling of the pycnocline. A secondary region of high chI a at 7°N was associated with a lens of low salinity Amazon River water. Productivity maxima were located south of Iceland, in the vicinity of the Azores Front, and at the Amazon River water feature.

The research described in Chapters Two and Three was performed during the Eastern North Atlantic section of the 1988 National Oceanic and Atmospheric Administration (NOAA) Global Change Expedition. Two appendices are included in the dissertation which contain pertinent Global Change Expedition data used in the manuscripts. Appendix One contains data relevant to Chapter Two, while Appendix Two contains data relevant to Chapter Three. A NOAA Data Report (Frazel, Berberian and Hitchcock 1989) containing complete data for the Global Change Cruise is also available. Reference lists are included at the end of Chapters Two and Three, while a Master Reference List is given at the end of the dissertation.

Comments

This work was supported, in part, by office of Naval Research contract N00014-87-K-0040 awarded to G. Hitchcock

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