Data Trawler - Project details

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Project details

Title: The availability of Antarctic krill to large predators and their role in biogeochemical recycling in the Southern Ocean
Id: 2477
Investigator(s): Michael Double
Australian Antarctic Division [details]

Eleanor Bell
Australian Antarctic Division [details]

Stephen Nicol
University of Tasmania - Institute of Marine and Antarctic Studies [details]

Description: Antarctic krill (Euphausia superba) is the primary prey for many squid, fish, bird, and mammal species but the factors that influence the distribution, density, form and behaviour of krill are not well understood. Equally it is not known how the characteristics of krill swarms affect the availability of krill to foraging predators. To determine whether krill swarm characteristics influence predator distribution and behaviour this project will use the latest active acoustic multibeam technology to describe the density, distribution, and fine-scale 3D structure of krill swarms both within the vicinity of Antarctic blue whales and in control locations that are demonstrably distant from these specialist and extreme krill predators. Antarctic blue whales facilitate this study because their locations can be tracked in real-time from many hundreds of kilometres using passive acoustic technology explicitly developed to detect these whales’ loud, low frequency calls. Within whale aggregations the movement and foraging behaviour of blue whales will be described using tracking technologies. In addition, this project will facilitate the first field-based investigation of the controversial theory of ironfertilisation by whales. Through measurements of the abundance and speciation of whale faecal iron we will establish whether iron concentrations are higher within aggregations of feeding whales than within krill-only aggregations or than in adjacent areas. We will also determine whether whale faeces stimulates local production, alters phytoplankton community structure and growth, and its influence on nutrient cycling, nitrogen-fixation and biogenic climate gas production and the timescale of any effect. This project could not only profoundly influence our view of the role of whales in the Antarctic ecosystem but will describe the potential dependencies of predators on krill in a form that may be limited in space and time. This information will inform the development of management systems for expanding Antarctic krill fisheries.
Years: 2019



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List of surveys that this project was on.

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Survey InvestigatorDescription

Michael Double (AAD) RV Investigator research voyage in2019_v01, titled "The availability of Antarctic krill to large predators and their role in biogeochemical recycling in the Southern Ocean." The voyage is also known as "ENRICH (Euphausiids and Nutrient Recycling in Cetacean Hotspots)". We will operate south of 60°S, northward of the ice edge, and between 140°E and 175°W. The specific study area/s within these boundaries will be determined by the locations of vocalising Antarctic blue whales, krill and sea-ice. The survey design is therefore adaptive in that sites will be chosen in real-time on the voyage according to available information. At the commencement of the voyage we will head straight to the closest group of vocalising Antarctic blue whales (ABWs) within our operational area. Vocalising ABWs are able to be detected through sonobuoys (see below) hundreds of kilometres away. When whales are found we will undertake a series of activities at that site. We will then commence a series of line transects in the same region and remain within the same area for the rest of the voyage. The study is therefore on a mesoscale and we do not aim to cover our entire operational area. The activities required to achieve our voyage objectives are: • Passive Acoustics • Whale observing, video-tracking and biopsy • Active Acoustics • Krill trawls • Unmanned Aerial Systems (UASs) • Biogeochemistry
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