Simulated nutrient and plankton dynamics in the Great Barrier Reef (2011-2016)

Skerratt, J.H., Mongin, M., Baird, M.E., Wild-Allen, K.A., Robson, Barbara, Schaffelke, Britta, Davies, C.H., Richardson, Anthony, Margvelashvili, N., Soja-Wozniak, M., and Steven, Andrew (2019) Simulated nutrient and plankton dynamics in the Great Barrier Reef (2011-2016). Journal of Marine Systems, 192. pp. 51-74.

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Abstract

The dynamics of nutrients, phytoplankton, zooplankton and water clarity of the iconic Great Barrier Reef World Heritage Area (GBRWHA) are influenced by seasonal variation in coastal and oceanic conditions, and anthropogenic inputs. We use the 3-dimensional coupled catchment-hydrodynamic-sediment-wave-optical-biogeochemical eReefs model to hindcast nutrient and planktonic responses to changes in seasonal and annual variability over a six-year period (2011-2016). In this paper we present a comparison of the eReefs model conducted against a range of in situ observations that included 24 water quality moorings, 2 nutrient sampling programs (with a total of 18 stations) and time-series of taxon-specific plankton abundance. At 14 near-coastal stations the simulated chlorophyll a (Chl a), when compared with chlorophyll extractions from water samples, had an average root mean square (RMS) error of 0.30 mg m(-3) and a Willmott index of 0.59. For the same sites, simulated turbidity, when compared with turbidity sensors, had a Willmott index of 0.58 and simulated nitrate + nitrite had a Willmott index of 0.41 when compared with tri-annual water samples. Comparison with a spatially-resolved statistical model of zooplankton based on > 900 observations in the region showed similarities in the relationship and spatial distribution of simulated and observed biomass, where both show zooplankton biomass is greatest inshore, biomass is highest around shallow reef areas and in the southern and central GBRWHA, and greater in summer than winter. Additionally, we investigate planktonic and nutrient responses to climatic variation. The first two years of the simulation coincided with La Nina events that drive greater than average winds, rainfall and river discharge. Throughout all years, simulated Chl a increases from north to south and from outer to inner coastal regions. Dissolved inorganic nitrogen, primary production and phytoplankton biomass were higher during La Nina in inshore and mid-shelf waters, while offshore regions were similar in all years from 2011 to 2016. Simulated Secchi depth was deeper offshore and decreased from offshore to inner coastal regions and from north to south. The eReefs simulation contributes to the understanding at a high spatial and temporal resolution of where and how nutrients and plankton originate and interact within the Great Barrier Reef.

Item ID: 58787
Item Type: Article (Research - C1)
ISSN: 0924-7963
Copyright Information: Copyright Elsevier 2018
Funders: Australian Government through the National Collaborative Research Infrastructure Strategy, Super Science Initiative, Department of the Environment and Energy, Queensland Department of Natural Resources and Mines 'Queensland Regional Natural Resource Management Investment Program 2013-2018', Department of Science, Information Technology, Innovation and the Arts (DSITIA)
Date Deposited: 08 Jul 2019 03:36
FoR Codes: 04 EARTH SCIENCES > 0405 Oceanography > 040501 Biological Oceanography @ 100%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 50%
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