Follow Nature Conservancy scientists Alison Green and Rod Salm as they blog about their expedition to an unexplored heart of coral biodiversity in Southeast Asia!
Week three started off with a bang! Mark Erdmann, our resident mantis shrimp expert, discovered a species of mantis shrimp on the northeastern side of Halmahera that is completely new to science.
Mantis shrimp come in many shapes and sizes. Some are quite large (about 35cm long), while others are very small (about 1cm). The new species is tiny (about 1cm long), and its amazing Mark could find it among the startling complexity of a coral reef.
Mantis shrimp are crustaceans, like crabs or shrimps. They are carnivores and have specialized raptorial appendages they use to kill their prey. Some species have clubs (smashers), while others have claws (spearers). Despite its small size, the new species is a smasher!
I wonder how many more new species we will find!? (Alison Green)
One of the most interesting fishes we've encountered so far on our expedition is a rare “oddball” anemonefish that has been seen twice over the past week. This fish — the White-bonnet anemone — has a very interesting story.
In 1973, Gerry Allen discovered what appeared to be a new species of anemonefish, which he named Amphiprion leucokranos, commonly known as the white-bonnet anemonefish. The original discovery was made at Madang on the northern coast of Papua New Guinea.
Dr. Allen studied this fish over the next few decades. He noticed that, unlike other anemonefishes, the white-bonnet seldom associated with fish of its own kind. Rather, it was usually found paired up with either the orange anemonefish (Amphiprion sandaracinos) or the orange-finned anemonefish (A. chrysoperus).
A few years ago, Gerry made a shocking discovery that shed light on the mysterious white-bonnet anemonefish. In Kimbe Bay, Papua New Guinea, Gerry found an orange anemonefish and an orange-finned anemonefish tending a nest of eggs together! It became clear to him that the white-bonnet anemonefish was in fact not a unique species but a hybrid product of these two.
The intriguing aspect of this phenomenon is that an apparently large number of the hybrids survive and then mate with each other, producing viable offspring. This state of affairs has persisted over thousands of years to the extent that the hybrid can be predictably found throughout the co-occurring range of the parental species, which includes the Solomon Islands, New Guinea and parts of eastern Indonesia.
Though we have good evidence that the white-bonnet is a hybrid, a strong argument can be made that it is actually a valid species resulting from the hybridization phenomenon. Similar evolution of species via hybridization is known to occur in other groups of organisms, notably plants and reef corals. Dr. Allen is currently conducting genetic studies of this problem with a team from Boston University and the Georgia Aquarium.
So much for what we learned in school! It appears that different species can interbreed and produce viable reproductive offspring. (Alison Green and Gerry Robert Allen)
In October 2006, I visited Buli Bay during a Fisheries Survey in Kabupaten Halmahera Timur, concentrating on the assessment of the coral reef condition in the area. Of 17 diving sites in Buli Bay, most showed good coral cover. Only Gea Island presented a rather depressing site, where corals had been smothered by sedimentation caused by nickel mining on the island.
On 25 April 2008 I revisited the area and dived at Pakal Island as part of this Halmahera expedition. But, due to poor visibility from murky water, we could not see any of the beautiful scenery I had found two years ago. Emre Turak and Lindon Deventier, two coral reef experts, indicated that the coral reef in this area is heavily stressed and releasing some of its burden by exerting mucus to the waters.
If this condition is maintained for a long time it will cause a massive killing of the coral reef. The bagan (lift net) fishermen also reported this mucus-exerting phenomenon. The fishermen experienced difficulties lifting their nets because they were covered with the mucus.
At this point, we think the coral stress conditions were caused by the sedimentation process coming from the mining activities I found two years ago in the eastern part of Gea Island. (Nurhalis Wahidin)
We have now sailed 800 kilometers, and the species count continues to rise.
So far we have recorded: 460 coral species, 975 reef fish species — including new species of dottyback and spinecheek — 147 species of crustaceans (including 26 species of mantis shrimp) and 42 species of echinoderm.
We also had the highest coral species count per site of any reef location ever recorded. Many of the species counts for each site are over 200 species, which is considered excellent on the world scale.
Halmahera is living up to our expectation as one of the most diverse areas on the planet!
But why is Halmahera so diverse? As the real estate agents like to say, it's all about ‘Location, location, location.’
Halmahera is situated in the heart of the Coral Triangle, which has the highest tropical marine diversity on Earth. While it makes up less than 2 percent of the world’s planet's oceans, the Coral Triangle comprises a staggering proportion of biodiversity — approximately 30 percent of the world’s coral reefs, 76 percent of the coral species and almost 40 percent of the world’s coral reef fish species.
This extraordinarily high diversity is due to a number of causes. The Coral Triangle is located equatorially where the Pacific and Indian Oceans meet, and so it comprises species from both oceans. Geological processes, including plate tectonics and sea level changes, have also played important roles, with coral reef species evolving and persisting during low sea level events, while reefs in many other parts of the world were high and dry.
Whatever the reason, it is clear that the large area and extraordinary range of habitats and environmental conditions have played a major role in maintaining the staggering biodiversity of Halmahera and the Coral Triangle. (Ali and the biodiversity team: Indra, Ucu, Emre, Lyndon, Gerry and Mark)
Unfortunately, our excellent adventure has come to an end. Of course we are disappointed, but are counting our blessings. We have had an amazing experience diving on some of the most diverse and spectacular coral reefs in the world — exploring new places, seeing new things and compiling management recommendations that will help the provincial government implement conservation measures to ensure these reefs continue to prosper into the future.
One of the highlights of the trip has been the extraordinary team of experts — among the best in the world. They are extremely knowledgeable about coral reefs, very generous with their skills and knowledge, and are always a pleasure to work with. And the Indonesian team members are a remarkable group of people, each an expert in their chosen fields with valuable local knowledge and experience.
The last few nights we have all sat in the moonlight on the top deck, having detailed discussions about coral reefs — their biodiversity, biogeography, ecology and evolution. The whole team was involved for hours at a time. Lyndon and Emre led a discussion about disturbances, focused on corals and crown-of-thorns starfish, and Gerry led a discussion about biogeography and evolution of coral reef fishes. It was great watching the level of interest and discussion between the groups of scientists, and an excellent way to end the survey.
Great friendships have been made, both personal and professional, which will continue long after this trip is over. Several of the Indonesian participants are interested in studying overseas, and the international scientists will help them with their aspirations. All of the international experts are looking forward to returning to Indonesia, to survey these extraordinary reefs again and spend more time with their Indonesian colleagues in the field.
The survey has been a remarkable experience, and one we will never forget. Halmahera is an extraordinary place — the heart of the Coral Triangle. (Ali and the survey team)
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April 19, 2012