Article
BAMOS October 2021
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Mapping , predicting and monitoring ecological change in the Southern Ocean
The Southern Ocean Observing System
While evidence is unequivocal that the physical environment of the Southern Ocean has changed over the last 30 years , and will continue to change on a time scale of decades , understanding the ecological consequences of these changes will lag behind .
This knowledge-gap has consequences for developing and assessing policy and management actions , now and into the future . Our project aims to address this significant issue by gaining an understanding of whether , how and why entire assemblages of key species have changed in response to environmental and other factors .
We will focus on the Indian Sector of the Southern Ocean and time series datasets of two key assemblages ; demersal fish surrounding the Heard and McDonald Islands on the Southern Kerguelen Plateau and zooplankton collected across East Antarctica using the Continuous Plankton Recorder . These will be coupled with recent advances in ecological statistics to detect and attribute recent change and predict future change in two key Southern Ocean assemblages , demersal fish and zooplankton . This information will then be used as the basis of simulations to provide advice on a broad-scale approach for monitoring zooplankton .
The Kerguelen Plateau is a productivity hotspot , supporting a diversity of marine life , including ecologically important demersal fish and a significant Patagonian Toothfish fishery . In addition , a Marine Protected Area ( MPA ) was declared in 2002 surrounding Heard and McDonald Islands . While key economic species have been well-studied , changes in the distribution and composition of the entire assemblage and implications for management of the region have yet to be evaluated .
Zooplankton are good candidate indicators of change because they have short generation times and are able to respond to environmental forcing at a range of spatial and temporal scales . Shifts in the distribution and composition of zooplankton towards an ecosystem dominated by smaller copepods are thought to have already occurred in East Antarctica , but this is yet to be conclusively demonstrated . Because zooplankton are near the base of the food chain , the consequences of any changes are likely to be significant , cascading throughout the ecosystem .
Complex , multi-species ecological data is challenging to analyse and interpret . Recent developments in model-based statistical approaches , specifically Joint Species Distribution Models ( JSDMs ), can simultaneously analyse the responses of all species in an assemblage to environmental and other factors , while taking into account correlations between taxa in space and time . This method will allow us to directly model long-term assemblage-level data in which different locations are sampled at different times and predict the composition of assemblages at unsampled locations in space and time .
Ultimately this project will provide maps of changes in the distribution of key species and assemblage , identify correlates of change , identify susceptible species and assess current and proposed spatial management scenarios .
Together , these outputs will significantly advance the scientific information available for policy and management to :
• take into account likely impacts of climate change in policy decisions on natural resources
• inform ecosystem monitoring practices , and
• evaluate spatial management arrangements .
This project is a collaboration between the Institute for Marine and Antarctic Studies at the University of Tasmania , the Australian Antarctic Division , CSIRO , the British Antarctic Survey and the University of Helsinki . It is funded by an Australian Antarctic Science Program Grant and the University of Tasmania .