Factors influencing phytoplankton and dissolved oxygen in San Juan Channel: a spatial and temporal assessment

Abstract

The purpose of study was to investigate how physical and biological factors influence phytoplankton and dissolved oxygen spatially and temporally in San Juan Channel over fall and the annual cycle of 2011. Specific objectives were to 1) Spatially assess differences in the phytoplankton community by analyzing genera abundance over fall 2011 at North and South stations and compare spatial patterns with those found in chlorophyll, 2) temporally evaluate the correlation between chlorophyll and dissolved oxygen levels during fall 2011 at high resolution to infer whether phytoplankton, as indicated by chlorophyll, influences dissolved oxygen more than physical factors and 3) repeat the second analysis over the 2011 annual cycle. Phytoplankton genera in the San Juan Channel were consistently similar across stations and weekly cruises for fall 2011. Differences in phytoplankton genera were a result of single-species dominated periods. Phytoplankton abundance and chlorophyll concentrations were found to decrease as the season progressed to winter, consistent with previous studies. Physical factors dominated the influence on dissolved oxygen both spatially, across North and South stations, and temporally throughout the year with the exception of July. In July, biological factors appeared to be equivalent to physical factors in influencing dissolved oxygen, as a result of high summer productivity.