Spatial Assessment of Antarctic Krill (Euphausia superba) in the Palmer Long-Term Ecological Research (LTER) Study Site using Acoustic Doppler Current Profiler (ADCP) Technology

• Main Author: Alcaraz, Nicholas
• Other Authors: Nowacek, Douglas
• Format: Master Thesis
• Language: English
• Published: 2017
• Subjects: ADCP; Antarctic Krill; LTER; Ecology; Tools; Palmer Station; Antarctic; Antarctic Peninsula; Palmer-Station; Southern Ocean; Antarc*; Euphausia superba
• Online Access: https://hdl.handle.net/10161/14070

Antarctic krill (Euphausia superba) play an integral role in the ecological community of the Southern Ocean. Information to monitor biomass and distribution is extremely important to scientists and managers, particularly due to recent warming trends along the Western Antarctic Peninsula. Active acoustic systems provide a robust, reliable method for measuring krill biomass and distribution. The intent of this project was to develop tools and methodologies in MatLab and ArcGIS to assess variations in krill patch size, latitudinal and longitudinal distribution, as well as depth dependent patterns. Pre-processed acoustic Doppler current profiler (ADCP) backscatter data, from one-month cruises over 5 years, were used as a template to produce maps, tables, and graphs. The standardized output products allow for qualitative comparisons across multiple years within the Palmer Long Term Ecological Research (LTER) study site. Eventually, whale satellite-tag data can be cross-referenced to determine if the spatial scale of whale feeding behavior coincides with the krill patch size or location; which is critical to interpreting changes within the ecosystem and the foraging dynamics of predators. The initial section of the report presents an overview of Antarctic krill behavior and life history, regional warming implications, and the history of the LTER and acoustic biomass surveys. Technical information is presented concerning the operation of an ADCP and data processing; ADCP data require correction and calibration for use in biomass backscatter measurement. A literature review of previous studies provides context of current knowledge within the field, and highlights shortcomings that this project will address. Next, the study site and data collection methods are discussed, including the acquisition, processing, and storage of acoustic data. Two datasets used as templates in script development, from Meng Zhou and the Common Ocean Data Access System (CODAS), are described in Data Analysis. The ArcGIS Data Import, ADCP ...