Sunday 21 June 2015

Corals



During my most recent visit to London, I took advantage of the wonderful Natural History Museum’s exhibition “Coral Reefs: Secret Cities of the Sea”.

As well as an opportunity to traverse the great hall and it’s ever-popular diplodocus skeleton, this visit had two ulterior motives. Firstly, Micronesia is known to have exquisite coral reefs. They are in particularly good condition due to its isolation and lack of tourists (Kosrae also has stringent laws against boat anchoring on the reef). So I was hoping to become a little more educated prior to going out there.

The second impetus was that my best friend ‘just happens’ to be a tropical marine biologist who’s been teaching me about corals ever since I’ve known her and I thought it might win me some brownie points (!).

For those interested in learning about coral reef facts, read on.


Many people, like myself until recently, think corals are plants. Others might believe they are non-living structures. Some have never really thought about it before. But corals are in fact animals (that happen to look a lot like plants). They are living, breathing, reproducing animals just like us humans. But of course with many differences.

They are made up of lots of little tube-like structures, usually in a hexagonal pattern, that are built up, unit by unit, on reefs (ridges of rock in the ocean) into the large structures we see when snorkelling or diving. They come in all shapes and sizes: a branching tree, a big dish, tubes of rigatoni-esque pasta, and the rather entertaining brain coral. See here for lots of pictures (albeit just of Caribbean corals).
Corals unfortunately cannot make food for themselves, so they live symbiotically (‘in harmony’) with algae called…exciting and complicated word alert…zooxanthellae. The algae live on the coral and make food by photosynthesis which is then shared with the coral so it can live. Happy days. However, if the waters get too warm or there is too much sunlight, the algae pick up sticks and ‘fall off’ the corals. This means the coral won’t last very long (would you, without any food?!) and eventually dies. This is ‘coral bleaching’.

Corals are a safe-haven for fish (refer to the opening 10 minutes of Pixar’s Finding Nemo for evidence of this), a hiding ground for predator species, a filtration service for nearshore waters and generally support a hugely diverse marine ecosystem.

If you’ve ever wondered why you can’t find corals in all the world’s seas and oceans it’s because they like warm water that has fast currents. Those who are more adept at geography will know much more about this than me, but I understand this limits them to places such as Australia (the Great Barrier Reef being the most famous of all reefs in the world), the Indian Ocean, the Red Sea, the Caribbean and, most importantly for this conversation, Polynesia.

 
http://oceanservice.noaa.gov/education/kits/corals/media/supp_coral05a.html

In earlier posts and my video I highlight that FSM (Federal States of Micronesia) is made up of 607 islands. However, a large number of these are things called atolls. At the exhibition, I finally came to understand what exactly one is.
An atoll can be thought of as a ring of reef. Therefore not really being a conventional ‘island’. The reef forms from the sinking of inactive volcanoes over many thousands of years. As the volcano sinks into the ocean, it draws a deep lagoon with it and so a ring of reef remains around a cavernous pool of water.

http://undsci.berkeley.edu/images/us101/atollphoto.jpg 
 
Kosrae island itself has interesting reef structure. It of course is not an atoll but does have a reef that surrounds the island and has an extra outer ‘fringining’ reef. This outer reef protects the inner one from strong sea currents and storms meaning that the ones near shore are in pristine condition.  

Kosrae has many dedicated diving and snorkelling sites, and they take great care in looking after their coral reef and the associated marine life. Apparently the water is exceptionally clear too and you can stumble across WW2 ship and plane wreck remains in some bays (!). Hawksbill turtles, reef sharks (I’m told they’re not scary) and thousands of colourful tropical fish will also be on my list of things to try and catch a glimpse of.

Interestingly, we owe a lot to Mr Charles Darwin, famed for his book The Origin of Species, for coral reef discoveries. It was Darwin who was among the first to detail the locations of coral reefs, particularly those in the Pacific, and explain how they (and atolls) are formed.

What remarkable ecology he must have seen when exploring these previously unseen coral reefs, and I count myself very lucky that I will hopefully get to see a bit of this fascinating and dynamic marine world and follow in his footsteps on the bays of Kosrae.
I’ll be hoping to share what I see, plus lots of pictures, with you while I’m out there.


For more info on corals and the exhibition, check out these websites: 
http://www.coral-reef-info.com/ 

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