Standard Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Rare opportunity to compare krill assemblages 60 years apart in the eastern Indian Ocean (#10)

Alicia L Sutton 1 , Lynnath E Beckley 2
  1. Carijoa Marine Consulting, Rockingham, WA, Australia
  2. Murdoch University, Murdoch, WA, Australia

The collection of in situ biological and oceanographic data in the open ocean does not readily occur, let alone the opportunity to compare data decades apart and across thousands of kilometres. Two large scale studies allowed for the comparison of krill assemblages along the 110°E meridian, namely, the first International Indian Ocean Expedition (IIOE-1) in 1962–1963 and the second IIOE (IIOE-2) in 2019. Despite absence of the raw data on krill from IIOE-1 prohibiting comprehensive analyses, from published work (McWilliam 1977) comparisons could still be made on species occurrence, life stage composition and abundance, and preferred distributions of selected species. Given the patchy nature of zooplankton and the reduced temporal scope of plankton samples collected during the IIOE-2, historical data from IIOE-1 has provided important context for current krill findings, such as the importance of seasonality and the seemingly stable distributions of dominant krill species in the eastern Indian Ocean. To inform future distribution shifts under ecosystem change for a group of species close to the base of the marine food web, a concerted effort to publish biodiversity and oceanographic data in journals and online repositories is needed, particularly for open ocean regions where access is infrequent and challenging.