In the Kimberley, the Ecosystem of Montgomery Reef Rides with the Tide
“Get ready to see something really special,” says our Expedition Leader, Brad Siviour, as one-by-one we step down from the gangway into the Zodiac. The sun is high in the cobalt sky on this early April afternoon in the Kimberley region of Western Australia. Dainty White-winged Terns hover overhead, carefully picking out their next meal from the glassy water. There is nothing but open sea visible for miles around, save for a handful of isolated islands to the northeast.
The Zodiacs maneuver away from the ship. Then, in the haze of the afternoon sun, I see something phenomenal: land is rising from the water. “What you are experiencing is not a mirage,” explains Siviour with a beaming smile on his face. He is clearly as thrilled to be here as we are. “It is not land, either. This is Montgomery reef – a 400 square-kilometer marine ecosystem becoming exposed as the tide drops.”
One of the Greatest Natural Wonders of the World
Described by Sir David Attenborough as “one of the greatest natural wonders of the world,” Montgomery Reef is a little-known but huge, spectacular coral reef, situated approximately 9.3 miles (15 kilometers) from the Kimberley coastline.
The Zodiacs continue into a long waterway that Siviour calls “The River“—a channel carved out of the reef over time. As the huge mass becomes more exposed, seawater begins to gush over the sides and into it. The effect is overwhelming—like being surrounded by hundreds of mini-waterfalls. We each look on, awe-struck by the abundance of natural beauty.
We notice gentle ripples appearing in the water around us, then Siviour stops the Zodiac and turns off the engine. The sea is still for a moment. Suddenly, a tiny brown head pops up to take a breath. Then, we see another one. Green sea turtles surround us. We soon realize there are hundreds of bobbing heads along the channel.
On the reef, scores of egrets are poised, ready to grab a mouthful of food. Siviour points out the White-bellied Sea Eagle soaring above us. This magnificent bird of prey is also on the lookout for exposed fish and crustaceans. Besides these avian companions, the whole place feels completely wild and isolated.
The Forceful Power of the Tides
As it’s approaching a full moon in the Kimberley, the tidal variation is significant, just as it is when nearing a new moon. During a full moon, a so-called “spring tide” can rise and fall by nearly 34.5 feet (10.5 meters) in just 12 hours.
In the days between the full and new moon, the tidal change is at its smallest with a difference of approximately 13 feet (4 meters). Regardless of the calendar timing, twice a day at low tide a significant amount of reef is left exposed to the elements, including the scorching hot Australian sun. Today, it means hard and soft corals are out of the water. I wonder what this means for creatures such as sea turtles, epaulette sharks and the migratory birds, who depend on this ecosystem to live and feed?
“It is amazing to see reef animals endure this highly dynamic environment,” says Marine Biologist and Silversea Expedition Team member, Lea McQuillan. “Corals that were once under meters of water are suddenly exposed to the intense tropical sun,” she explains. “As a result, they have evolved to be quite hardy. They have adapted to survive being exposed to the air and the sun’s rays.”
Incredibly, some corals have developed the ability to secrete a mucus-like substance over themselves to prevent drying out when exposed to the air. The substance is also said to act as a natural sunscreen to protect cell membranes within the animal from the harsh ultraviolet radiation. This adaption allows the coral species to thrive in hugely varying tides and a dry, scorching environment where others would perish. As a result, the coral reef stays healthy so wildlife can continue living and feeding successfully.
The Ecosystem of Montgomery Reef in the Kimberley
While Montgomery Reef’s ecosystem can survive the large tidal ranges of the region, it is, like all coral, particularly sensitive to changes in light and temperature that can cause bleaching. This was a reality four years ago while McQuillan was working in the region. “I was under the impression that Montgomery Reef was so isolated and remote, so special that it would never be influenced by anything,” she admits sadly. “You can imagine how disappointed I was to see the soft leather corals bleached.”
Whether affected by climate change or the periodic warming of ocean waters due to El Niño, some corals can recover after bleaching. But many also die, resulting in a loss of habitat for those marine critters living and feeding around it. “At that time we had an El Niño year, and 80 percent of the world’s coral reefs had been bleached,” McQuillan recalls.
As I listen to Expedition Team members talk so passionately about Montgomery Reef, I am increasingly aware of how much of a privilege it is to witness such a unique and diverse marine habitat first-hand. And observing it in person serves to raise awareness about just how fragile it is.
It seems the experts feel the same way. McQuillan sums up my feeling with a nod. “Personally, Montgomery Reef offers me a new experience every time we visit,” she says. “I turn a corner, and I never know what wildlife will be there to greet me.”