Award Abstract # 1743035
Using Bio-acoustics on an Autonomous Surveying Platform for the Examination of Phytoplankton-zooplankton and Fish Interactions in the Western Ross Sea

NSF Org: OPP
Office of Polar Programs (OPP)
Recipient: RUTGERS, THE STATE UNIVERSITY
Initial Amendment Date: August 8, 2017
Latest Amendment Date: August 8, 2017
Award Number: 1743035
Award Instrument: Standard Grant
Program Manager: Jennifer Burns
OPP
 Office of Polar Programs (OPP)
GEO
 Directorate for Geosciences
Start Date: August 15, 2017
End Date: July 31, 2019 (Estimated)
Total Intended Award Amount: $299,988.00
Total Awarded Amount to Date: $299,988.00
Funds Obligated to Date: FY 2017 = $299,988.00
History of Investigator:
  • Grace Saba (Principal Investigator)
    saba@marine.rutgers.edu
Recipient Sponsored Research Office: Rutgers University New Brunswick
3 RUTGERS PLZ
NEW BRUNSWICK
NJ  US  08901-8559
(848)932-0150
Sponsor Congressional District: 12
Primary Place of Performance: Rutgers University New Brunswick
33 Knightsbridge Road
Piscataway
NJ  US  08854-3925
Primary Place of Performance
Congressional District:
06
Unique Entity Identifier (UEI): M1LVPE5GLSD9
Parent UEI:
NSF Program(s): ANT Instrum & Facilities,
ANT Organisms & Ecosystems
Primary Program Source: 0100XXXXDB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):
Program Element Code(s): 164700, 511100
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.078

ABSTRACT

The Ross Sea is the one of the most productive regions in Antarctica and supports large populations of several key species in the Ross Sea food web, including copepods, crystal krill (Euphausia crystallorophias), and Antarctic silverfish (Pleuragramma antarcticum). Copepods and crystal krill dominate the diets of Antarctic silverfish, the dominant fish species in the high Antarctic zone, and silverfish are a major link between lower (copepods, krill) and higher (fishes, marine mammals, flighted birds, Adélie and Emperor penguins) trophic levels. Despite the significance of these key species, there is limited understanding of copepod, krill, and silverfish mesoscale distribution, spatial structure of age/maturity classes, and their interactions with physical drivers within the Ross Sea. Autonomous underwater profiling gliders are a developing technology that offers the potential for providing high spatial, temporal, and depth resolution data on regional scales. The project will test the capability of a multi-frequency echo sounder integrated into a Slocum Webb glider with the aim of providing the first glider-based acoustic assessment of simultaneous distributions of three trophic levels in the Ross Sea. Complementary glider sensors measuring physical, chemical, and biological parameters will provide mesoscale and sub-mesoscale hydrographic information from which phytoplankton-zooplankton-fish interactions and the relationships between these organisms and physics drivers (sea ice, circulation features) will be investigated. The approach proposed here, glider acoustics, is relatively new and has the potential to be transformational for investigating food webs and the Ross Sea ecosystem.

Researchers will modify and integrate an Acoustic Zooplankton and Fish Profiler (AZFP) multi-frequency echo sounder into a Slocum Webb G2 glider with the capability to differentiate between krill and other types of zooplankton, including copepods, and different sizes of krill and silverfish. The AZFP will be complemented with the existing glider sensors including a CTD, a WET Labs BB2FL ECO puck configured for simultaneous chlorophyll fluorescence (phytoplankton biomass) and optical backscatter measurements, and an Aanderaa Optode for measuring dissolved oxygen. The new sensor suite will be tested during a four-week glider deployment, where it will conduct acoustic surveys to map distribution and abundance of multiple zooplankton taxa and silverfish during the austral summer along the Terra Nova Bay polynya ice shelf and in adjacent continental shelf waters. The relationships between phytoplankton-zooplankton-fish distributions and the physical drivers of zooplankton and silverfish species and size distributions will be investigated. Coordinated ship-based acoustic sampling and net tows/trawls will be conducted multiple times during the glider deployment to validate glider acoustic-based species, size, and abundance measurements. Open accessible, automated data produced during this project will be made available through RUCOOL (Rutgers University Center for Ocean Observing Leadership) and THREDDS (Thematic Real-time Environmental Data Distribution System). The production of consistent, vertically-resolved, high resolution glider-based acoustic measurements will define a successful outcome of this project that should help in identifying the challenges in their use as a potentially cost-effective, automated examination of food webs in the Antarctic.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

Terra Nova Bay (western Ross Sea, Antarctica) supports dense populations of several key species in the Ross Sea food web, including copepods, crystal krill (Euphausia crystallorophias), Antarctic silverfish (Pleuragramma antarcticum), and colonies of Ad?lie and Emperor penguins that feed primarily on crystal krill and silverfish. Absent from our understanding of the Ross Sea food web is zooplankton and silverfish mesoscale distribution, spatial structure of age/maturity classes, and their interactions with physical drivers and each other. The quantitative linkages between primary producers and the higher trophic levels, specifically, the processes responsible for the regulation of abundance and rates of middle trophic levels dominated by copepods and crystal krill (Euphausia crystallorophias), is virtually unknown. Given that the next century will see extensive changes in the Ross Sea?s ice distributions and oceanography as a result of climate change, understanding the basic controls of zooplankton and silverfish abundance and distribution is essential.

Intellectual Merit: During a January ? March 2018 cruise in the western Ross Sea, we deployed a glider equipped with an echo sounder (Acoustic Zooplankton Fish Profiler) that simultaneously measured depth, temperature, conductivity, chlorophyll fluorescence, and dissolved oxygen. Additionally, net tows, mid-water trawls, and crystal krill grazing experiments were conducted. Our study provided the first glider-based acoustic assessment of simultaneous distributions of multiple trophic levels in the Ross Sea, from which predator-prey interactions and the relationships between organisms and physics drivers (sea ice, circulation features) were investigated. We illustrated high variability in ocean physics, phytoplankton biomass, and crystal krill biomass and aggregation over time and between locations within Terra Nova Bay. Biomass of krill was highest in locations characterized by deeper mixed layers and highest integrated chlorophyll concentrations. Krill aggregations were consistently located at depth well below the mixed layer and chlorophyll maximum. Experiments investigating krill grazing, in combination with krill depth distributions relative to chlorophyll biomass, illuminate high krill grazing rates could be attributed to the occupation of a unique niche whereby they are opportunistically feeding on sinking high concentrations of detritus derived from surface blooms. The information on the abundance, distribution, and interactions of key species in multiple trophic levels resulting from this project provide a conceptual background to understand how this ecosystem might respond to future conditions under climate change.

Broader Impacts: Our project tested the capability of a multi-frequency echo sounder on a glider for the first time. The production of consistent, vertically-resolved, high resolution glider-based acoustic measurements will pave the way for cost-effective, automated examination of entire food webs and ecosystems in regions all over the global ocean. A wide range of users including academic and government scientists, ecosystem-based fisheries managers, and monitoring programs including those conducted by OOI, IOOS, and NOAA will benefit from this project. This project also provided the opportunity to focus on broadening participation in research and articulating the societal benefits through education and innovative outreach programs. A data set from this project is being included in the new NSF-funded Polar CAP initiative, that will be used by a diverse and young audience to increase understanding of the polar system and the ability to reason with data. Finally, this project provided a unique field opportunity and excellent hand-on training for a post-doctoral researcher, a graduate student, and two undergraduate students.


Last Modified: 01/27/2020
Modified by: Grace K Saba

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