Welcome to ‘x-ray vision’: night-time marine wildlife watching on Honduras

From the glossy, polished decks of his blazing yellow catamaran, pilot and environmental biologist and explorer Andres Bautista Rito could not miss the magical light spell in the sky above the bays below. The…

Welcome to ‘x-ray vision’: night-time marine wildlife watching on Honduras

From the glossy, polished decks of his blazing yellow catamaran, pilot and environmental biologist and explorer Andres Bautista Rito could not miss the magical light spell in the sky above the bays below. The light in question seemed to hover over the towering mangroves along the shores of Puerto Rico’s Ceiba Bay.

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Though the bay has about 100 kinds of soft corals, it was the luminescent cystic coral that stood out. It’s one of the bioluminescent creatures that scientists have been studying with interest since the 1960s, when researchers documented the shining water off the Caribbean country’s northeast coast at the University of Puerto Rico, the US-based source of our coral tank. It was one of the few areas in the world with colour.

The year 2016, however, marked a new stage in bioluminescence research, when researchers from the University of Miami and other institutions in Puerto Rico confirmed the first-ever bioluminescence in a salt marsh in the Caribbean, near Wulalonga in the southern part of the island. And that in turn led to the rekindling of interest in the South Florida bioluminescent marsh, Nemo’s Marsh, since it became a lab of sorts for the University of Puerto Rico.

University of Puerto Rico scientist Andres Bautista Rito. Photograph: Dan Comas for the Guardian

Bautista, 47, was leading one of several scientific expeditions aboard his catamaran, the Coyote II, on the evening of 19 July to survey Nemo’s Marsh. Over the past few weeks, the swamp has been draining after a high-tide dam was re-opened to let the waters of Lake Okeechobee flow. It was the same time that lake waters hit a historic high of more than 1,000 feet.

A night of low-light marine wildlife-spotting, when the only light is in the sky above, was the perfect chance to test out some of the rarest and most incredible marine animals in a single night.

“It gives us a chance to see the biological lights in their environment,” Bautista says, “so we don’t get limited to observational studies.”

Late in the evening, the sun was out, burning the water orange, as some of the 90 species of coral that make up the bioluminescent shore are able to derive colour by absorbing light from the sky when the conditions are right.

“This is a new species,” says Bautista, holding aloft a translucent and translucent hooded sea anemone for an insect. “It would probably be extinct if it wasn’t here because it is completely covered with fluorescent tentacles.”

Sea anemones have an 11.9% growth rate and 25 percent chance of reproduction each year. But the only solution now to support this species of algae is habitat destruction. “When we rescue one of these animals, we save a whole community,” Bautista says. “We capture this alga and feed it with nutrients from the water. There are over 5,000 species of algae present in these waters, most of which are vital for ecological success. So when we capture an animal, it builds a community.”

With about 90% of Nemo’s Marsh drained, the causeway only allows through the most frequent water flow, which can last up to 18 hours.

“We are actually bringing in fresh water during the night,” Bautista says, looking up. “With this, I mean, wow! We were expecting the methane bubbles to go away, but they don’t go away.”

“This,” he adds, pointing down, “is algae.”

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