Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Day trip active acoustic surveys were conducted from Palmer Station Field Season aboard RHIB twice weekly from January-March 2020 using a hull-mounted SIMRAD EK80 single-beam, single frequency (120 kHz) echosounder (Kongsberg Maritime) along transects shown in Figure 1A (Veatch et al 2025).

The echosounder was configured with a 1 s ping rate, 512 µs pulse duration, and 24 µs sampling duration. Calibrations of the echosounder were performed in the vicinity of Palmer Deep Canyon using a tungsten sphere (diameter = 38.1 mm) during February, 2020. Acoustic data were processed in Myriax Echoview software version 11.1 following methods from (Tarling, Klevjer et al. 2009) and (Tarling, Thorpe et al. 2018). Raw data were processed to consider the echosounder calibration and in situ ocean acoustic conditions via incorporation of onboard CTD data, and to remove background noise and other interferences via the Background Noise Removal (De Robertis and Higginbottom 2007) and Impulse Noise Removal (Ryan, Downie et al. 2015) algorithms in Echoview. Krill were then detected using a target strength threshold of -70 dB to -30 dB(Tarling, Klevjer et al. 2009, Tarling, Thorpe et al. 2018) in Echoview following similar parameterization and protocols to (Nardelli, Cimino et al. 2021) and (Reiss, Cossio et al. 2021) (Figure 4, Veatch et al 2025).

All acoustically detected krill swarms were manually reviewed before exporting the acoustic data in NASC (Nautical Area Scattering Coefficient) values, a common proxy for organism presence in acoustic measurements. NASC values were calculated per detected swarm and exported along with depth, GPS position (longitude and latitude), swarm height, swarm length, and backscatter (Sv). These methods for acoustic surveys and processing of subsequent acoustic data follow those in (Hann, Bernard et al. 2023).

NSF Award Abstract:
Undersea canyons play disproportionately important roles as oceanic biological hotspots and are critical for our understanding of many coastal ecosystems. Canyon-associated biological hotspots have persisted for thousands of years Along the Western Antarctic Peninsula, despite significant climate variability. Observations of currents over Palmer Deep canyon, a representative hotspot along the Western Antarctic Peninsula, indicate that surface phytoplankton blooms enter and exit the local hotspot on scales of ~1-2 days. This time of residence is in conflict with the prevailing idea that canyon associated hotspots are primarily maintained by phytoplankton that are locally grown in association with these features by the upwelling of deep waters rich with nutrients that fuel the phytoplankton growth. Instead, the implication is that horizontal ocean circulation is likely more important to maintaining these biological hotspots than local upwelling through its physical concentrating effects. This project seeks to better resolve the factors that create and maintain focused areas of biological activity at canyons along the Western Antarctic Peninsula and create local foraging areas for marine mammals and birds. The project focus is in the analysis of the ocean transport and concentration mechanisms that sustain these biological hotspots, connecting oceanography to phytoplankton and krill, up through the food web to one of the resident predators, penguins. In addition, the research will engage with teachers from school districts serving underrepresented and underserved students by integrating the instructors and their students completely with the science team. Students will conduct their own research with the same data over the same time as researchers on the project. Revealing the fundamental mechanisms that sustain these known hotspots will significantly advance our understanding of the observed connection between submarine canyons and persistent penguin population hotspots over ecological time, and provide a new model for how Antarctic hotspots function.

To understand the physical mechanisms that support persistent hotspots along the Western Antarctic Peninsula (WAP), this project will integrate a modeling and field program that will target the processes responsible for transporting and concentrating phytoplankton and krill biomass to known penguin foraging locations. Within the Palmer Deep canyon, a representative hotspot, the team will deploy a High Frequency Radar (HFR) coastal surface current mapping network, uniquely equipped to identify the eddies and frontal regions that concentrate phytoplankton and krill. The field program, centered on surface features identified by the HFR, will include (i) a coordinated fleet of gliders to survey hydrography, chlorophyll fluorescence, optical backscatter, and active acoustics at the scale of the targeted convergent features; (ii) precise penguin tracking with GPS-linked satellite telemetry and time-depth recorders (TDRs); (iii) and weekly small boat surveys that adaptively target and track convergent features to measure phytoplankton, krill, and hydrography. A high resolution physical model will generalize our field measurements to other known hotspots along the WAP through simulation and determine which physical mechanisms lead to the maintenance of these hotspots. The project will also engage educators, students, and members of the general public in Antarctic research and data analysis with an education program that will advance teaching and learning as well as broadening participation of under-represented groups. This engagement includes professional development workshops, live connections to the public and classrooms, student research symposia, and program evaluation. Together the integrated research and engagement will advance our understanding of the role regional transport pathways and local depth dependent concentrating physical mechanisms play in sustaining these biological hotspots.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.