Chaetognaths are the second most abundant zooplankton taxa worldwide, are incredibly diverse, and are important for energy transfer in marine food webs, yet little is known about their distribution and predation potential. Because chaetognaths are gelatinous, using traditional sampling methods for collection is difficult, making their biological and ecological attributes relatively unknown. Using the In Situ Ichthyoplankton Imaging System (ISIIS), we mapped the fine-scale distribution and abundance of chaetognaths and two other zooplankton taxa: copepods and larval fishes. ISIIS was used to collect data across two transect lines in the Northern California Current, one of the most productive boundary currents in the world. Each of the two transects experiences different upwelling patterns: the Newport Hydrographic (NH) transect line off the coast of Newport, OR is a seasonal upwelling system and the Trinidad Head (TR) transect line off the coast of Trinidad, CA is a persistent upwelling system. By using environmental data also collected by ISIIS, we contextualized the distribution patterns of zooplankton to not only understand environmental preferences relative to the shelf, but also to the specific oceanographic conditions found in different upwelling systems.
The high-resolution imaging data indicate that the distribution overlap between chaetognaths, copepods, and larval fishes is highly dependent on upwelling conditions. Further, the strength of their connectivity to primary production indicators (dissolved oxygen, chlorophyll a-fluorescence) varies spatially and temporally among all three taxa. We found that upwelling-dependent offshore advection of both chaetognaths and copepods facilitated their strong overlap off the shelf in a persistent upwelling system. In contrast, zooplankton taxa were highly aggregated inshore of the shelf in an intermittent upwelling system. The potential for chaetognath predation was determined to be higher on copepods than on larval fishes based on their physiology, abundance, and realized niche within the two upwelling environments. Continuing to resolve zooplankton distribution patterns and their association with environmental variables is important to deepen our understanding of oceanographic processes associated with the marine food chain.
"},{"label":"Degree","value":["Bachelor of Arts with Departmental Honors"]},{"label":"Author-supplied Keywords","value":["Chaetognatha","California Current","Trophodynamics"]},{"label":"Administrative Note","value":"Drupal Node ID: 33856