Ecosystem Responses

Satellite image of sea surface temperature (left) and ocean colour (right) along the east coast of Australia. The separation of the EAC from the coast is shown clearly, as is the biological response represented by the ocean colour (Courtesy M. Baird).
Satellite image of sea surface temperature (left) and ocean colour (right) along the east coast of Australia. (Courtesy M. Baird)

Ecosystem responses to variability and change also need to be considered at all levels of the food web (trophic levels), from primary producers to apex predators.  An integrated approach seeks to undertake biogeochemical measurements and combine them with biological data, across the base of the food web through to higher trophic levels, to provide information about ocean productivity, organism abundance at a number of spatial and temporal scales. Spatially these may encompass broad/basin-wide and bioregional scales, along shelf scales and regional-across shelf scale.

The east coast of Australia supports a broad range of species-rich and diverse habitats that transition from subtropical to temperate climatic zones. Understanding marine connectivity in this region is a challenge for managers. Knowledge of how habitats along the NSW coast are connected by larval dispersal, whether through existing marine park sanctuary zones acting as larval sources, sinks or neither, and how these locations vary seasonally and inter-annually is unresolved.

The following high-level science questions will guide the NSW-IMOS observing strategy in this area:

Productivity: 

  • What are the key productive regions along the NSW coast and what are the drivers of this productivity? (latitudinal zones, EAC separation zone, frontal zones, shelf zones, mixed layer)
  • How does the ocean pH and carbonate chemistry vary in key ecosystems, and how is it changing over the continental shelf off NSW?
  • How do climate variability and change affect trophic levels and trophic connectivity?
  • What are the effects of climate change on the structure and functioning (i.e., energy, nutrient cycling) of ecosystems and on the processes and phases of life cycles?
  • Can we determine indices for assessing ecosystem health? 
  • What are the most vulnerable ecosystems and species (either particularly sensitive or unable to adapt, such as kelp, Sargassum, etc) to changing environmental factors?

Distribution and Abundance:

  • What is the distribution and abundance of organisms by species/trophic/functional group level, and how does this vary in space and time?
  • How do distributions and abundance of organisms relate to physical oceanography (temperature, circulation), nutrient availability, and population connectivity?

NSW-IMOS aims to integrate the ecosystem response with oceanographic processes:

i) Quantify the daily to decadal variation of planktonic communities in relation to oceanographic and climate-driven changes in physical and chemical ocean properties;

ii) Quantify rocky reef biota variables (kelp distribution and abundance) associated with climate variability, at deep reefs along the NSW to Tasmanian coast;

iii) Relationship of the EAC, its eddies and oceanographic conditions on fisheries, and movements by fish.