Notes from the field.
Philippines Mesophotic Reef Bio-diversity Survey
We are still searching for deep, clean water, ideally around 100-110m (330-360ft) on a wall or slope. This depth is our ideal target depth for discovering and documenting Mesophotic (low light) coral reef eco-systems. Ideal for us in the fish world, because relatively little is known about these habitats, and uncommon to rare (and possibly new) species are found there. The wall or slope setting is also ideal for a number of reasons; firstly it allows us to explore without committing to a certain depth and time profile, a type of diving that rebreathers systems are perfectly suited for. Secondly, a slope or wall allows us to decompress over the bottom, which has interesting things to look at and take video of, which beats sitting in blue water waiting to clear decompression for two and a half hours.
Our team is once again a multi-disciplinary one, which makes the evenings interesting, as each group reveals the treasures of the day. The Bishop Museum is most focused on fish – documenting which fish are found at what depths and in what habitats, but this trip we have an additional scientist with us, Dr. Sonia Rowley, a sea fan / soft coral specialist (gorgonians). She is documenting and collecting tissue samples of gorgonians on the Mesophotic reef, but also some of the more interesting (less studied) shallow water species.
The University of Hawaii is collecting DNA samples of reef fishes, also both in the deep water and shallow reefs, for later analysis and comparison to local populations, as well as comparison to sites ranging across the entire Pacific ocean.
Finally, the California Academy of Sciences team are collecting fish for several research programs, as wells as for the very cool Steinhart Aquarium that is within their San Francisco facility.
The rebreather units have been performing well so far, and everyone is pretty much set up with their final configuration of gas mixtures, rigging and bail out bottles. The sheer volume of equipment is still astounding to me at times, when compared to a simple SCUBA unit or some of the snorkeling surveys I did this summer in the Marianas. Still, the gear is what allows us to explore these very cool eco-systems, so gear fondle we must.
The past three reconnaissance days of diving have been somewhat murky and barren, but not without reward. The high level of nutrients in the water that clouds up the visibility and makes the deep areas somewhat spooky also attracts high numbers of plankton feeders, so lots of schooling fishes and soft corals and fans feeding. We also did a night dive last night which is not a common event for me on a rebreather. Anilao is famous for it’s “muck” diving, with little creature treasures to be discovered in the apparently barren sandy mud and rubble. We will be doing more as the trip progresses.