My first visit to an atoll did not disappoint. Coral atolls are formed when an extinct seamount or island erodes or subsides beneath sea level. A lagoon forms over the caldera and a coral rim remains above or just below sea level around the edge of the atoll. In the case of Tikehau, the reef around the lagoon is almost continuous, with just one pass, Tuheiava Pass, connecting the open ocean to the inner lagoon on the western side of the atoll. Tikehau is located 340 kilometers northeast of Tahiti, the capital of French Polynesia. The area of the lagoon is 461 square kilometers, while the islands that form the rim consist of two major islands and many small islets. 500 people live on the atoll of Tikehau, with most living in the main village, while 8 families live on the remote islets around the lagoon.
The main village of Tikehau is called Tuherahera, and it takes about 20 minutes to bike from one end of town (and the island) to the other. We stayed on the South end of Tuherahera, at Pension Justine.
Tikehau catches enough fish to feed themselves, tourists, and to export their catch to the capital of Papieete on the island of Tahiti, and other surrounding islands.
Most of the fish are caught in this fish trap at Tueheiava pass. We were able to freedive through the pass and experience the current that these fish feel on the incoming tide. It is STRONG! The trap guides the fish into successively smaller chambers with smaller exits and they are unable to escape. Every fish you can imagine was in these traps, including huge moray eels. A large tiger shark even came up to check us out from behind while we were surveying the traps.
The abandoned pearl farm in the center of the lagoon is a known manta ray cleaning station. The Mantas visit this spot in the early morning to be cleaned by the wrasses at the coral head cleaning stations. It was amazing to see the manta rays during the day, as I have mostly dove with them at night in Hawaii.
The amount of fish at the pass was really remarkable. Schools of fish swam at different depths, so there were layers upon layers of schools with all different colors. Here, my friend Morri Sides swims down into a school of Jacks. Above, you will see a school of barracuda that circled us as we floated through the pass. White tip sharks were shy but flitted in and out of the scene at the deeper edge of the pass, while black tip reef sharks hung out near the surface at the edge of the barrier reef.
So, you may be wondering, what about the algae?! There was not much macroalgae present at the pass, as you may expect with such large herbivore numbers. What was interesting is inside the coral lagoon the sand bottom extends out into the deeper waters of the lagoon. When I swam down just off the edge of the beach within the lagoon, I began to feel a layer of warm water. It seems to me that the marshes that are common across the atoll are discharging water at depth within the lagoon, and I was able to feel the heat signature of this beneath the cooler seawater. All along the rim of the atoll where this warm water discharged was a meadow of seagrass. It seems the seagrass is taking advantage of the nutrients from the marsh ecosystem as it discharges within the lagoon.