PANGATALAN the isle of horseshoe crabs

This first dive ends at night. It isn’t long before we have removed our kit and reached the top of the tiny island of Pangatalan, a small four-hectare rock lost northeast of Palawan in the western Philippines. We are settled in the unexpected comfort of a superb residence. This island is privately owned and managed by a French couple named Fred and Chris Tardieu. They loved the country and wanted to move here. 
Making their dream come true took “only” about 30 years, a healthy dose of determination bordering on stubbornness, along with some serious know-how in the fields of architecture, earthworks, construction and land management. For it was not merely a question of building a large and beautiful house on the top of their land, but also of restoring the island’s entire ecosystem.

For ten years, with the help of all the inhabitants in the region, they patiently replanted 60,000 trees and plants to hold the soil and provide fruit, and almost 10,000 mangroves to replenish the island’s protective swamps. A little later, they began to restore the coral reef that borders the island. Reaching the limit of their competencies, they asked a motivated, willing young marine biologist, Thomas Pavy, to spend two years with them on the tiny islet in order to establish an environmental analysis of the subsea section. After counting and taking an inventory of the fauna and flora, as well as mapping the habitats, he worked on having the island classified as a Nature Reserve. In parallel with this semi-political work, the actual fieldwork continued. In the dead zones, Thomas and Fred patiently installed nearly 300 small, simple, solid, stable concrete components to which they attached broken coral branches found on the seabed, but still alive. Their future growth depends on this beneficial stability. In time, the artificial reefs will disappear under the growth of natural counterparts. Thanks to perseverance, the island was officially declared a marine protected area in 2016 by the local Philippine government.
 

Every morning, from the very first dive, the horseshoe crabs are there. It must be said that Cédric, who helps me in my work, makes it a point of honor to find them. This includes having to abandon his last pair of fins as he searches the mud plain relentlessly until he spots them. He has a trick to avoid searching at random: like a trapper, he reads the prints left by the beast in its path. When the horseshoe crab moves, its rigid tail marks the mud with a slight furrow. The problem is that the mud is light and the track quickly erased. All the more reason to survey the seabed as quickly as possible. Cédric even finds a track that appears to be double. Two tracks, two crabs? Intrigued, he goes back up the track and comes across a pair in the middle of mating, one holding on to the other. The male’s shell has a notch at the front to better fit into his partner’s round carapace. The female thus carries a male on her back, certainly well-adapted to the curves of his bride, but frankly not very expressive and definitely taking his time about the proceedings: mating will continue for 15 days. Fifteen days during which Lady Horseshoe is forced to accept this conjugal burden until her man finally deigns to have had enough.

When this lengthy ordeal is over, the females head back to the shore, climb onto the beaches, and lay thousands of eggs right on the shoreline, where the waves and tide still wet the sand. Finally freed of their reproductive instincts, the horseshoe crabs return to the depths of their mud plains. The largest and most active are escorted by small golden trevallies, opportunistic juveniles always on the lookout for prey buried in the sediment and brutally exposed by the digging of horseshoe crabs serving to plough the terrain. The fish dart and twinkle above the site, flaming beacons of this silent Caterpillar of the seas. And they are not the only ones who benefit from this living vehicle. On closer inspection, under the hood we discover a whole small world, a population of shrimps that live in the very heart of the gears of this organic machine, between the articulated legs of the horseshoe crab.
 

Thus is the life of this imperturbable creature, and one might naively believe that it will last forever, as it seems so solid, Spartan, ascetic. If the guarantee of happiness is to want what you already have, the guarantee of sustainability lies in having capacities superior to your needs. Everything would therefore work out perfectly and forever, had man not discovered that the horseshoe crab is a pharmaceutical treasure. This timeless animal is no longer out of reach. As soon as it becomes desirable, the balance is endangered. The horseshoe crab has blue blood and I am not talking about its nobility, but about its hemoglobin. One should say hemocyanin to be precise because the central atom is not iron, which makes red blood, but copper, which makes blue blood. Blue as sapphire, and even more expensive than gemstones: $14,000 a liter because its plasma contains Amoebocyte Lysate, a molecule that is impossible to synthesize and which can detect the presence of toxic bacteria in human vaccines. More than 500,000 horseshoe crabs are caught each year and 30% of their precious blue blood is extracted. Those who survive are released, but they are weakened, disoriented, and most often die as a result of the process. In Delaware Bay, south of New Jersey, 75% of the horseshoe crabs have already disappeared since the 1980s. As a result, this champion of survival, whose family has been on Earth for 450 million years, is now classified as a vulnerable species. Not so in Pangatalan. The convalescent island is a haven of peace for the horseshoe crab. Protecting this place means protecting human beings. The island, the horseshoe crab, an idyll.