November 22, 2024

Tidal Extremes: Ecological Insights From Australia’s Dynamic Montgomery Reef

Satellite picture of Montgomery Reef around Australias Yawajaba island caught at high tide on April 21, 2024, by the Operational Land Imager-2 on Landsat 9. Satellite image of Montgomery Reef around Australias Yawajaba island captured at low tide on April 29, 2024, by the Operational Land Imager on Landsat 8. Big tidal swings expose a plateau-shaped reef around Australias Yawajaba island at low tide.The Kimberley coast of Western Australia has among the largest tidal varieties in Australia and the world. At Montgomery Reef, in Collier Bay, water levels drop dramatically at low tide, allowing the plateau-shaped reef to emerge several meters above the water level.Tidal shifts are especially noticeable in this area due to the fact that of the flat, shelf-like surface along the Kimberley coast. When the tide was high (left) and low (best) in 2024, this pair of images shows the reef. The high tide image was captured by the OLI-2 (Operational Land Imager-2) on Landsat 9 on April 21; the OLI (Operational Land Imager) on Landsat 8 acquired the low tide image on April 29. Ecological Dynamics at Low TideWhen the tide increases, the sandy islets and primary mangrove-covered island, Yawajaba, within Montgomery Reef show up, but the reef is mostly undersea and out of view. During low tides, the water level can come by as much as 10 meters (33 feet), exposing the extensive terraced structure of the reef and the network of shallow lagoons surrounding Yawajaba.As the tide puts off the structure, the outside circulation of water can grow tumultuous. At times, whitewater cascading off the reef forms dozens of rivulets and small waterfalls that stream into deeper channels within the reef, a phenomenon for travelers and a risk for wildlife. Fish, sea snakes, turtles, blacktop reef sharks, dugongs, and other creatures can be seen thrashing and tumbling off the coral platform as the water drains. Animals are periodically left stranded on exposed reef during low tide.Geological and Biological Features of Montgomery ReefThe structure of Montgomery Reef is not entirely an item of coral. As soon as a flat-topped terrestrial mesa made of dolomite and sandstone that formed some 1.8 billion years back, the function was. More recently, this ancient structure has been encrusted with a veneer of marine life, specifically rhodolith– a free-floating type of coralline algae that adds much of the structure to the border of the reef.Communities of numerous kinds of hard and soft corals cover about 20 percent of the reefs surface area, particularly along the edges of channels and pools where the water is much deeper. Corals along the Kimberley coast, like those found on Montgomery Reef, are known for being unusually resilient compared to corals in other parts of Australia and the world. They have actually adapted to hold up against the swings in temperature that include tidal variations, and to withstand the direct exposure to raised ultraviolet light and winds during low tide.But even these rugged corals are not indestructible. Following a marine heat wave in 2016, which became part of the third international whitening occasion, researchers reported widespread coral lightening at Montgomery Reef and other coral communities on the Kimberley coast.Monitoring and Future ConcernsIn April 2024, the National Oceanic and Atmospheric Administration (NOAA) confirmed the worlds corals were in the midst of a fourth worldwide bleaching occasion, but regional reports of bleaching at Montgomery Reef have not emerged yet. Heat stress maps from NOAAs Coral Reef Watch indicate that corals to the southwest in Western Australia and those closer to the equator faced a greater danger of whitening in mid-May 2024. NASA Earth Observatory images by Lauren Dauphin, utilizing Landsat information from the U.S. Geological Survey.

At Montgomery Reef, in Collier Bay, water levels drop dramatically at low tide, allowing the plateau-shaped reef to emerge several meters above the water level.Tidal shifts are especially obvious in this area since of the flat, shelf-like surface along the Kimberley coast. Animals are periodically left stranded on exposed reef during low tide.Geological and Biological Features of Montgomery ReefThe structure of Montgomery Reef is not completely an item of coral. Following a marine heat wave in 2016, which was part of the 3rd global whitening occasion, scientists reported prevalent coral bleaching at Montgomery Reef and other coral communities on the Kimberley coast.Monitoring and Future ConcernsIn April 2024, the National Oceanic and Atmospheric Administration (NOAA) verified the worlds corals were in the midst of a 4th global lightening occasion, but local reports of whitening at Montgomery Reef have actually not emerged.