The Santa Barbara Channel is embedded within the California current system, which includes the cool nutrient-rich southward-flowing California current to the north west, the warm oligotrophic Southern California Current flowing poleward from the South, and the inshore Southern California Counter Current. Seasonal upwelling in the Santa Barbara Channel provides nutrients that stimulate regular phytoplankton blooms of diatoms and other micro phytoplankton. The upwelling and predictable biological response makes the Santa Barbara Channel a unique location to examine microbial interactions with dissolved and particulate organic matter.
Although the Santa Barbara Channel is a coastal environment the DOM concentrations are generally < 70 µM C and < 6 µM N. These concentrations are typical of oceanic values and are significantly less than concentrations found in systems dominated by estuarine and riverine inputs. This relatively low "background" DOM signal allows us to resolve small temporal and spatial changes in bulk DOM and its chemical constituents rather easily. The diversity in nutrient and trophic states experienced in the Santa Barbara Channel make it an ideal model system for examining the factors that control organic matter partitioning between DOM and POM, the chemical character of each pool and the bioavailability of DOM to microbes during the growth and demise of diatom blooms. Here we examine the production and consumption of DOM and the bacterioplankton communities that respond to these dynamics.