A VISIT TO AN OAHU CORAL HABITAT
On February 14, 2007, I had an opportunity to visit Thomas Iwai at Anuenue Fishery Research Center in Honolulu and spend a morning with him and Mike Yamamoto. Tom and Mike are part of the Division of Aquatic Resources of the Hawaii State Department of Land and Natural Resources and amongst the most knowledgeable about opae'ula.
current trials are to discover the key to successfully spawn and
survive marine fish larvae that have a potential for Hawaiian
aquaculture. I met him in his lab where various trials that
are his current focus were in progress.
The opae'ula collection from a number of sources are in aquariums in the upper level.
|Anuenue Fishery Research Center is in the forefront of Hawaiian aquaculture research with many of the leaders of different private and public organizations assisting each other and at any one time, there are a huge number of projects going on.|
| Tom and I
are exchanging information on creating an opae'ula captive breeding mass
cultural system and I got to view his initial experimental set-up.
Then it was off to visit an Oahu coral opae'ula habitat!
Most of the opae'ula anchialine ponds are on Maui and the Big Island
in relatively young lava fields where low spots fill with brackish
water. Some shallow ponds may exist only during high tide
periods. Most of the opae'ula ponds are small as larger ponds are
usually used for some form of aquaculture. Some ponds have
openings to allow ocean fish to enter. Other ponds have had
fish introduced and these predators force the opae'ula to retreat to
the cracks in the lava to their underground hypogeal habitat where
they continue to survive.
Oahu is much older geologically than Maui or the Big Island. At one time, the ocean level was much higher than it is today and coral reefs surrounded Oahu including covering the entire Ewa Plains and the low lying areas of the Waianae and windward coasts. As the water level dropped to the current level, these coral reefs became exposed and "solution holes" formed, including interconnecting labyrinths in the watertable that allows opae'ula to travel long distances underground.
Tom wanted me to see this "pond" as it is unique with several
interesting factors. It's located in a secure National
Wildlife Refuge that is also the an area that has a number of
endangered Hawaiian plants. The area is secured and we needed
to get cleared to visit the site.
This habitat was one of three man-made "ponds" created in 2005 using a backhoe. Two of the three ponds were colonized with opae'ula and Tom and Mike have been collecting data from the beginning.
|A plastic pipe has been anchored to take tide readings and temperature data is also collected. Opae'ula specimens have been forwarded to Scott Santos at Auburn University for DNA analysis. To date Scott has found seven different lineages on three different islands. The Big Island has two, Maui has two, and Oahu has three. The DNA research is producing new information and we look forward to release and publication of that information.|
|This is the only pond to date that has two different lineages in the same pond. There seems to be no evidence of hybridizing! Although the "pond" opening is small compared to the Big Island anchialine ponds, it is clear that several feet below the surface, that there is an interconnected labyrinth of passageways that allow the opae'ula to travel long distances through Oahu coral in much the same way as the lava tubes and cracks allow travel through porous Big Island lava.|
|Mike and Tom have their field methodology down pat and collect and record all needed data very efficiently including water temperatures, tide levels, opae'ula counts, etc. By scooping with measuring cups rather than nets, their handling of the opae'ula is far less harmful than using aquarium nets that may tear off legs. If nets are to be used, it should be of the cloth type called "brine shrimp" nets.|
|Tom and Mike (right) had to hurry back to Anuenue to attend a meeting but I learned a lot in just a short time! I learned of ideas they are considering to reverse the decline of opae'ula and ways to get rid of introduced predators that may be more effective with less side effects than using rotenone fish-killer. They are running a lot of trials to assure no unintended consequences. Their efforts and support have been crucial to our progress! In having the ability to interpret the Fuku-Bonsai and associate observations, they help us and may get fresh insights and this is a win-win situation! We're fortunate to have such dedicated people!|
The opae'ula of Oahu are distinctive and have bands. Some are
pale throughout. A few are pale with red heads, others have various
amounts of reddish and pale combinations. The photo is of the
Waianae strain being maintained as part of the Fuku-Bonsai
We are observing different behavior of the Oahu opae'ula compared to the Big Island opae'ula. When fed, the Oahu opae'ula tend to be very slow to filter-feed at the surface even after one year of feeding-training! They are also less active.
The Fuku-Bonsai Micro-Lobster Team is making steady progress as we continue to serve as an informal informational clearinghouse. Customers, researchers, teachers, etc. willing and able to contribute to the body of knowledge are invited to contact David Fukumoto at email@example.com