Phytoplankton are responsible for almost half of the total global primary production, or the uptake of about one hundred million tons of carbon per day (Field et al, 1998) and are, consequently, a major pathway for long term sequestration of carbon.  In Australia there is good evidence of phytoplankton species moving southward and concern where these may be toxic or harmful species.  For example, the red-tide dinoflagellate Noctiluca scintillans has expanded its range from Sydney to southern Tasmanian waters since 1994.  It is suggested that the gradual warming of East Coast Tasmanian waters, associated with a greater influence of the East Australian Current, has paved the way for the apparent range extension of this warm-water organism into Tasmanian waters.  Predicting the response of phytoplankton productivity and community structure to climate change is complicated.

Key Science Questions

Plankton

• How will microbial/phytoplankton components of the marine food web respond to variation in environmental forcing including global change?
• How will zooplankton components of the marine food web respond to variation in environmental forcing including global change?
• What has caused the dramatic decline in silicate concentrations and changes in the phytoplankton community?

Mid-trophic levels

• How will nekton components of the marine food web respond to variation in environmental forcing including global change?
• How will commercial fish stocks respond to variation in environmental forcing including global change?
• What are the relationships among biodiversity, structure, function, and stability of marine ecosystems?
• How does environmental variability affect regional primary, secondary and tertiary productivity?
• What is the role of mesoscale variability in regional and local productivity?
• How interconnected are our populations of mobile species?

Benthos

• How will benthic communities respond to variation in environmental forcing including global change?
• What are the long term impacts of climate variability on benthic ecology?
• What determines the variation in Centrostephanus rodgersii and of Macrosystis pyrifera?

Ocean chemistry - nutrients

• What are the spatial and long term temporal dynamics of mixed layer depth, nutrient resupply, onset of the spring bloom?