An expectation-setting teaser from the expedition’s first team of divers. (Photo by Rich Mooi)

Editor’s Note: “The Richest Reef” follows members of a scientific dive team as they attempt to pinpoint the center of the most biologically diverse marine ecosystem in the world. Long considered our planet’s most species-rich piece of ocean real estate, the Western Pacific’s “Coral Triangle” is a continent-sized patchwork of habitats, populations, and communities. Expedition scientists are trying to identify exactly which section of this rich mosaic is most diverse, but their effort carries with it far more meaning than a simple dot on a map would suggest. Along the way, they’ll discover dozens of new species, visit dive sites and depths no one has seen before, and gain a better understanding of the factors that promote biodiversity and the role these species-rich areas play in sustaining healthy ecosystems. See below for a list of all posts in the series.

Amidst the logistical details and my ever-evolving to-do list, one question keeps bubbling to the surface: Will I know as soon as I hit the water that I’ve entered the most biologically diverse marine ecosystem on Earth? I suspect not. I imagine the signs, no matter how numerous, are subtler than that. I’m also a hardcore skeptic who leans toward expectation-management at every turn. But growing each day is a hope that the more careful part of my brain is dead wrong.

I should say that I haven’t actually voiced this particular question to anyone who might be able to answer it definitively. To my ear, it sounds far too naïve—the simplistic musing of a Colorado-raised terrestrial ecologist who’s soon to be well out of his depth. I also figure I’ll know soon enough, since I’m just days away from my first dive in the Verde Island Passage.

A dotted nudibranch (Jorunna funebris) feeding on a sponge. (Photo by Rich Mooi)

Although few people have ever heard of the Verde Island Passage (VIP), this narrow stretch of water sandwiched between the Philippine islands of Luzon to the north and Mindoro to the south is considered the most biodiverse marine ecosystem on the planet. That claim to fame was based initially on an assessment published in 2005 in the journal Environmental Biology of Fishes, which estimated the total number of species here at a very precise 1,736.

Impressive as it was, the 2005 estimate of course didn’t account for the countless organisms yet to be discovered in the VIP—and those tallies appear to know no limits. For decades, scientists have been studying this area and discovering new organisms practically wherever they look. Each new discovery provides important information about the makeup of this diverse ecosystem and how that diversity came to be. On a more basic level, a new species also contributes a data point to what’s known as a species-accumulation curve. This is essentially a growth curve that plots the number of known organisms in a given area per unit time. Practically anywhere else in the world, these curves begin to flatten after years of study. With each field season, fewer and fewer new organisms are discovered. But not here. The Verde Island Passage’s accumulation curve is climbing just as steadily now as it was 10 years ago.

A recent addition to the VIP’s new-species list, Odontanthias borbonus, collected at a depth of more than 300 feet. (Photo by Luiz Rocha)

The reasons for this astounding biodiversity are numerous and complex, explained in terms of evolution, biogeography and climate history. And we’ll explore those scientific questions and explanations—as well as the beautiful and bizarre creatures that call the VIP home—throughout this blog series. But first, let’s look at the comprehensive biodiversity studies happening here, research that is fundamental to this and future expeditions and to the protection of this important world resource. Simply put, you can’t understand organisms and ecosystems—or manage them effectively—if you don’t know what’s there. But that task isn’t nearly as straightforward as it might sound.

This is uncharted territory, both geographically and biologically. There are no maps for most of the dive sites we’ll be visiting and there are no field guides describing the sometimes-subtle differences between known species and any number of novel organisms a diver might encounter. It’s the ability to recognize these telling details that a generalist like myself is sorely lacking, and why specialized knowledge and experience are so critical to conducting a thorough biodiversity assessment.

A cuttlefish unsure what all the fuss is about. (Photo by Gary Williams)

This year’s Philippine biodiversity expedition team is a veritable who’s who of marine specialists. Among the two dozen-plus scientists from the U.S. and the Philippines, there are specialists in corals, echinoderms and sea slugs; there are seaweed, tunicate and polychaete worm experts; there are ichthyologists who specialize in butterflyfish and goatfish; and there’s a team of deep-reef specialists trained in techniques of diving and collecting organisms at depths up to 500 feet beneath the surface.

I’ll be following along—albeit not to 500 feet—and introducing you to the dedicated folks doing this work. My hope is to capture just a glimpse of the wealth of information these experts see in the reef organisms and ecosystems that surround them, and to convey some of their deeper insights about what it all means and how these species and habitats can be preserved.

A fire urchin (Asthenosoma varium) looking dangerous. (Photo by Gary Williams)

I truly can’t wait to get started. While I’ve been prepping and packing in California, the first expedition team has been busy setting up the field lab and doing some early explorations. Their initial reports and the photos they provided for this post suggest that there are many spectacular discoveries to come, and lots of questions to be answered—both important scientific questions and my own naïve wonderings. So please, feel free to comment and tell us if there are things you’d like to know more about and we’ll do our best to answer them.

Next up, I’ll take a look at what it takes to prepare for an expedition of this scale and I’ll share some of the stranger items on our collections managers’ packing list.

Other posts in this series:

The Richest Reef: Exploring the Most Diverse Marine Ecosystem on Earth

The Richest Reef: No Such Thing as Packing Light

The Richest Reef: Life in Layers

The Richest Reef: A Symbiotic Society

The Richest Reef: A Bagful of New Species

The Richest Reef: Deep Diving into the Twilight Zone

The Richest Reef: Where Have All the Predators Gone?