Meteorological Satellite Observations Reveal Diurnal Exceedance of Water Quality Guideline Thresholds in the Coastal Great Barrier Reef

• Published in: Remote sensing (Basel, Switzerland) Vol. 15; no. 9; p. 2335
• Main Authors: Patricio-Valerio, Larissa, Schroeder, Thomas, Devlin, Michelle J., Qin, Yi, Smithers, Scott
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 28.04.2023
• Subjects: Acanthaster; Anthropogenic factors; Artificial satellites in remote sensing; backscattering; bio-optics; Biogeochemistry; Coastal plains; Coastal waters; Coasts; Coral reefs; corals; Cyclones; Distribution; Diurnal; diurnal ocean colour; diurnal variation; Dry season; Environmental aspects; Floods; freshwater; Great Barrier Reef; guidelines; heat; Heat waves; Himawari-8; Human influences; Marine ecosystems; Marine protected areas; Measurement; Meteorological satellites; Observations; Observatories; Optical measurement; Optical properties; Protected areas; Rainy season; Remote sensing; Rivers; Satellite observation; satellites; Sea grasses; Seagrasses; Seasons; Sediments; Sensors; Solid suspensions; Synchronous satellites; Thresholds; Total Suspended Solids; Tropical cyclones; Water quality; Water quality measurements; wet season; Australia; Queensland Australia; Great Barrier Reef
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs15092335

The Great Barrier Reef (GBR) is a marine protected area subject to natural and anthropogenic disturbances. Water quality is critical for the health and protecting resilience of GBR coral ecosystems against the synergistic and cumulative pressures of tropical cyclones, marine heat waves, and outbreaks of crown-of-thorns starfish. The concentration of Total Suspended Solids (TSS) is a key water quality parameter measured at multiple spatio-temporal scales from in situ probes to satellite observations. High TSS concentrations can adversely impact coral and seagrasses on the inshore GBR. We present diurnal TSS derived from Himawari-8 Geostationary satellite observations at 10 min frequency and demonstrate its applicability for improved monitoring of GBR water quality. Diurnal TSS obtained from Himawari-8 observations were compared to TSS computed from in situ bio-optical measurements at the Lucinda Jetty Coastal Observatory (LJCO). The coastal waters at LJCO experience diurnal variability of TSS (~7 mg L−1), where magnitude peaks followed the slack tides, and the largest diurnal changes were associated with freshwater discharge residuals from the wet season. Exceedance maps revealed that TSS is above guideline thresholds in the open coastal and mid-shelf waters for ~60% of the valid monthly observations, including during dry season months.