Biogeochemistry

Description

The biological productivity of the Kimberley coast is thought to be fuelled by a combination of oceanic and terrestrially derived nutrients, but little is known about how these nutrient sources vary or interact with the poor light conditions found near the coast. The focus of this project is on the microscopic plants and animals that live in the water-column, known as microbial plankton.

Aims

• To better understand the processes controlling carbon and nutrient flows through pelagic ecosystems in the Kimberley region by linking physical processes and riverine inputs to food web structure and function, improving process understanding of pathways and material flows that connect habitats, populations and bioregions in the Kimberley.
• Define variation in nutrients, light and microbial communities of the Kimberley coast.
• Understand the limiting factors on productivity and trophic pathways.
• Quantify the nutrient pathways to production.

Methods

• Two research surveys on the RV Solander (wet and dry season) collected profiles of physical attributes (e.g. turbidity and total suspended solids), nutrient concentrations, light, chlorophyll-a and pelagic planktonic samples.
• Stable isotope analysis of the samples was undertaken to where they fall in the food web
• A shelf-scale hydrodynamic -biogeochemical model was developed.

Outcomes

• Descriptions of plankton community composition, biomass and biodiversity in Kimberley shelf, coastal and estuarine habitats
• Understanding of relative importance of riverine nutrient and organic matter inputs vs oceanic nutrients in controlling regional phytoplankton (algae) production
• Understanding of food web structure and function
• Models  linking the physical  processes of nutrient  cycling to  biological production of phytoplankton and zooplankton.

Project News 

Phytoplankton Proves its Carbon Capture Capability in Extreme Environments

Kimberley coastal system: links from the land to the deep sea

Reports

McKinnon AD, Doyle J, Duggan S, Logan M, Lønborg C, Brinkman R (2015) Zooplankton Growth, Respiration and Grazing on the Australian Margins of the Tropical Indian and Pacific Oceans. PLoS ONE 10(10): doi: 10.1371/journal.pone.0140012

McLaughlin M.J., Greenwood J.E., Branson P., Lourey M.J., Hanson C. E. (2020) Evidence of phytoplankton light acclimation to periodic turbulent mixing along a tidally dominated tropical coastline. Journal of Geophysical Research – Oceans. doi.org/10.1029/2020JC016615

Jones NJ, Patten N, Krikke D, Lowe R, Waite A, Ivey G (2014) Biophysical characteristics of a morphologically-complex macrotidal tropical coastal system during a dry season. Estuar Coast Shelf Sci 149: 96–108. doi:10.1016/j.ecss.2014.07.01

Media

Presentations

Pathways to production: Biogeochemical processes in Kimberley coastal waters (WAMSI 2017 Research Conference).

Pathways to production – Biogeochemical processes supporting productivity of the Kimberley coast (WAMSI 2015 Research Conference).

Hydrodynamic and Biogeochemical Controls on Productivity in the Kimberley Coast (Parks and Wildlife Lunch and Learn seminar).