That Fish Blog – Aquarium Advice and Information

With this weeks passing of Earth Day 2008, I thought I would write a blog about this great article that I had read recently on www.sciencedaily.com. Some of the darkest days in U.S history involve the nuclear weapons use and testing during and after WWII. Most people learned about the bombs dropped on Japan during WWII in history class, or from family members who lived in that era.

Much less well known nuclear testing was done in the years following WWII as the cold war escalated, and the demand for bigger and bigger bombs grew. From 1946 to 1958 the U.S. Government conducted nuclear bomb tests on the remote Pacific Island Group of Bikini Atoll, which is part of the Marshall Islands. In 1954 the U.S. detonated, what was at the time, the largest hydrogen bomb ever tested. The bomb was code named Castle Bravo, and was 15 megatons (1,000 times more powerful that the bomb dropped on Hiroshima). The blast vaporized 3 islands, raised the water temperature to 55,000 degrees, and left a crater that was over a mile wide and more that 200 feet deep. Needless to say, there was nothing left of what was a thriving tropical island group and surrounding reefs.

Enough of the bad news, this story has a happy ending. Recently a group of international scientists returned to Bikini Atoll to see what was there, almost 50 years later. Plant life on the surface had returned, but is still contaminated with radiation (don’t eat the coconuts). What the group found underwater was truly amazing. As they planned their dive into the Bravo Crater, expectations were running wild. The last time the area was surveyed it looked like part of the moon, and was irradiated.

What they found was a thriving coral reef ecosystem that had completely self seeded itself in the once barren wasteland. Porites corals that reached 25ft in the water, huge formations that looked like trees reaching for the surface. The belief is that water currents from untouched neighboring areas brought larval corals to Bikini, where they settled and matured. The corals had recolonized as much as 80% of the habitat in some of the areas studied.

Compared to studies performed at Bikini prior to the testing, the results show that there has been a serious impact on the diversity of corals to the area. The new study showed that 40 species that were documented to have been there prior to testing, where no longer there, and appear to be locally extinct. I found it amazing that what was there had reclaimed space that had felt the worst of what human kind can offer.

This news shows that, given the chance, reefs can recover from even the most severe destruction. Maybe by looking at the species that are thriving in the Bravo Crater, we can use them to as a guide to recolonizing reefs that have been destroyed by shipping, fishing, and pollution around the world. The main thing that I took from the story is that if we as a society can get our act together as far as protecting our natural resources, that Mother Nature can fight back pretty hard if we let her.

Until Next Blog,

Dave

Most of you have probably heard of the Horse Whisperer, and some of you are familiar with the dog whisperer as well. How about the Coral Whisperer? While he may never get a movie made about him, or his own cable television show, Mitch Carl of the Henry Doorly Zoo in Omaha Nebraska is being recognized for his ability to successfully raise Elkhorn Corals in captivity. I came across an article posted on the Omaha World Review website dubbing Mitch Carl as “The Coral Whisperer” for his ability to raise corals from wild captured eggs and sperm, where many others have had less success.

As part of an international research project which is studying sexual coral reproduction (SECORE), Carl and the Henry Doorly Zoo were one of many facilities that took part in the ongoing project, and received wild harvested Elkhorn coral eggs and sperm to try and raise in captivity. According to the article, 500,000 embryos were collected and distributed, of those only 1,100 were still alive after 3 months; these were Mitch Carl’s corals. As techniques have improved in subsequent harvests, survival rates have dramatically increased since the initial collection. Last year Carl was able to keep 75% on his embryos alive, other facilities involved in the project were still unable to achieve more than a 50% success rate. This is where the legend of the Coral whisperer comes from.

This project is of significance because of the coral species at the heart of the project. Elkhorn Coral is vital to natural reef systems throughout the world. It is not only one of the skeleton building corals that build foundations of the world reefs. The heavily branching Elkhorn coral provides habitat for many fish and other animals, as well as providing shorelines with a barrier from storm and wave action. Some estimates put destruction of the worlds Elkhorn Coral, mostly from human related activities, as high as 90%, and Elkhorn Coral is now an endangered species.

Most coral farming is done using asexual reproduction or cloning, taking small pieces or “frags” from a parent colony and allowing it to grow. This process is repeated time after time, and results in many copies of the original. Coral Farming using this “fraging” method produces coral that is adapted to captive environments, and thrives in aquarium conditions. This process works well for corals that are intended for aquarium or zoo use; however it is not a good method of reproduction for coral that is for reintroduction to the wild. These corals have been in captivity for many generations, and have adapted for unnatural conditions. Asexual reproduction is slow, and there is also the risk of introducing unwanted elements back into natural habitats.

Researchers hope that a viable sexual reproduction strategy can be reached, this will allow for “wild” corals to be grown in captivity in huge numbers, then be reintroduced back to the reefs where the eggs and sperm were collected. The hope is that these corals can be grown in coastal regions, where the eggs were collected, so that conditions can be matched as closely as possible to where they will be “planted” on the reef. Successful sexual reproduction of corals would also be of great value to the aquarium trade, the more captive raised corals become available, the less impact the hobby will have on natural reefs, as well as potentially lowering cost with the ability to mass produce corals sexually.

I hope you enjoyed this story. You can get more inforation about the SECORE project at www.secore.org

Until next blog

Dave

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Since our start in 1973, That Fish Place has seen the aquarium hobby grow in popularity and evolve into an amazing blend of science, nature and technology. Our Marine Biologists blog may cover any topic that relates to the hobby, and will hopefully help whoever reads this blog to become a more successful aquarium keeper, whatever you fancy.