Spatial and Temporal Abundance of Synechococcus Clades in the San Diego Bay

The marine cyanobacterial genus Synechococcus makes up a major percentage of global phytoplankton abundance and contributes to Earth’s oceanic primary productivity and carbon cycling. Different oceanic regimes are occupied by various co-occurring clades of Synechococcus dependent on depth, temperature, and nutrient availability. Synechococcus clades I and IV are more often in nutrient rich environments, and are often the clades seen from the coastal monitoring site at the Scripps Institution of Oceanography. Clades II and III are found in more oligotrophic waters and are rarely detected from the Scripps pier. Recently, clade II Synechococcus has been detected thirty miles south of the pier, in the warmer more nutrient rich San Diego Bay. Samples were taken from three different sites (varying in temperature, depth, and distance from the mouth of the bay) and analyzed to determine the abundance and diversity of Synechococcus. We examined amplicon sequence variants (ASVs) to analyze community composition at these sites and found a higher amount of clade II Synechococcus near the back of the bay. With this information, Synechococcus was used to track the movement of water in and out of the bay during a twelve hour tidal cycle. Clade II isolates from the bay are currently being obtained and characterized to determine their ecological strategies for growth in the distinct San Diego Bay environment.