Modelling mesopelagic taxa distribution and trophic linkages at a large scale: combining stable isotope and active-acoustic data

• Main Author: Walters, AR
• Format: Conference Object
• Language: English
• Published: . 2017
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; The Antarctic; Kerguelen; Indian; Banzare Bank; Antarc*
• Online Access: https://www.science.org.au/news-and-events/events/antarctic-frontier-developing-research-extreme-environment; http://ecite.utas.edu.au/128585

Mesopelagic fish form an important yet poorly understood component of the open-ocean ecosystem with very little information about the bio-physical determinants controlling the spatial and temporal distribution of mesopelagic fish in the open ocean regions. Here, we combine natural abundance stable isotope tracers and active acoustic survey data to address key gaps in our knowledge about mesopelagic fish ecology in a large-scale region of particular ecological importance, the Kerguelen Axis in the southern Indian Ocean sector. The trophic niches of key mesopelagic fish assemblages were investigated using bulk and amino acid compound stable isotope tracers. To investigate spatial variation in trophic interactions, fish were collected from the Antarctic continent to the BANZARE Bank and waters to the west and east of the Kerguelen Plateau in Jan-Feb 2016. Mesopelagic fish were sampled using an IYGPT net equipped with a MIDOC multiple-opening cod-end device. Depth stratified net hauls (from the surface to 1000 m) were undertaken concurrently with active acoustics at 36 stations. Integrated acoustic and isotope data will be used to determine factors that differentiate fish assemblages in the region, something that is currently unknown, and to improve our understanding of the structure and function of mesopelagic components of food webs.