The nutrient supply driving pelagic and benthic productivity over the whole Great Barrier Reef and Lagoon system is quantified using a shelf scale 3D hydrodynamic, sediment and biogeochemical model. The (eReefs) model is based on the CSIRO Environmental Modelling Suite augmented with key tropical marine processes modules including coral and seagrass growth, carbon chemistry, Trichodesmium nitrogen fixation, phytoplankton pigment synthesis and a spectral optical model for accurate representation of the in-water light field. Nutrient forcing at the ocean boundary was derived from climatology, along the coast from 22 major river systems and atmospheric supply was included via rain. The model was validated against observations over a 4 year hind-cast simulation and reproduced the observed nutrient climatology, spatial gradients in ocean colour chlorophyll and in situ sensor and water quality observations. Results from the 3D model show the dynamic nature of episodic (< 1 week) subsurface upwelling events along the shelf edge that channel nutrient rich water through gaps in the reef to boosting local productivity. Results are consistent with sparse continuous nutrient observations from moorings and gliders and the model provides significant insight into the interpretation of these observations and the design of observing programs in complex reef topography. Budget analysis for subregions of the shelf quantify the primary nutrient sources in wet- and dry-seasons and identify the relative impact of coastal, ocean and atmospheric supply relevant to water quality management of the reef.



Wild-Allen, K., CSIRO Oceans & Atmosphere, Australia, karen.wild-allen@csiro.au

Furnas, M. J., AIMS, Australia, m.furnas@aims.gov.au

Mongin, M., CSIRO Oceans & Atmosphere, Australia, mathieu.mongin@csiro.au

Baird, M., CSIRO Oceans & Atmosphere, Australia, mark.baird@csiro.au

Skerratt, J., CSIRO Oceans & Atmosphere, Australia, jenny.skerratt@csiro.au

Robson, B., CSIRO Oceans & Atmosphere, Australia, barbara.robson@csiro.au


Oral presentation

Session #:50
Date: 06/23/2016
Time: 15:00
Location: 312

Presentation is given by student: No