giving coral reefs a future

[20150805 Day 9 Set 1]

[20150805 Day 9 Set 2] 

SECORE: Mark, why did you start working on a system that keeps the fertilized eggs spinning and moving during their first days?

Mark Schick: During our first coral reproduction projects we kept the fertilized eggs in plastic bins filled with sea water and quickly noticed that the eggs tend to get stuck in this little waterline on the edge of the container. You have to stir them constantly to keep them off that barrier. That is hard work, if you have to do that 24 hours for several days. So we developed this idea of a kreisel, in which the eggs are spinning and moving around constantly, just like they would be doing in the ocean, where they are constantly moving in the waves and the tides. So instead of stirring the eggs by hand to keep them off the barrier, we now let them move carefully by a water pump.

Such a system had never been built before – so how did you start off?

The first systems we did based on flat-bottomed pans. Picture them like a tall-sided, flat serving dish with most of the bottom removed. Glued in its place was a mesh much finer than window screening. This device was then placed in a large container of water where a pump could recirculate water through the kreisel. This system worked. However, we quickly realized that getting the eggs out of the container was very difficult, because when it was time to remove them the could easily get stuck to the bottom of this screen.

What did you do?

Over the years we tried several designs to make improvements. The next round the screening was placed on the sides of a large funnel. This left a spot in the bottom where a little bit of water could be left, so we could concentrate all the larvae into that area on the bottom and afterwards carefully pull them out or clean them. The water inputs for each kreisel were in five spots making it hard to run multiple kreisels and keep all the different water lines organized. That is why the latest edition has only one water input from an overhead sprinkler and a water shield that surrounds the bowl and allows the water to wash down the walls and into the bowl. This way the eggs will not stick to the sides. Furthermore, the sprinkler has a little bit of a drip, which is great, because a drop in the center will just break the eggs up in the center.

[20150805 Day 9 Set 3]

[20150805 Day 9 Set 4]

How long do the eggs stay in the kreisel?

It is temperature dependent. The warmer it is the faster the eggs develop into larvae that want to settle. The cooler it is, the longer the eggs stay in the water column. It usually takes about five days, until the larvae start to look for a spot to settle on. You can see this changing behavior very easily. At the beginning the fertilized eggs are just floating, then as they develop, start spinning in tiny circles. As they mature the young corals start diving down in the water column. They are visibly and actively looking for some place to attach to, preferring good, clean substrate that they can stick to for the rest of there life. This is the point we put them together with our SECORE substrates to settle on.

One last question: How many larvae can you keep in one of the SECORE kreisels?

We can get about 100.000 to 150.000 larvae in one of those 15-liter-bowls with the flow through water. That is five times as much as you can keep in a simple clean plastic bin filled with 20 liters of water. However, the kreisels are relatively technical and need proper lab facilities. Right now we are trying to make a bigger, low-tech set-up to be able to raise even more coral larvae, because if you really want to enhance coral cover, we need many more coral recruits out there on the reef and simplified techniques.

Mark Schick is working as collection manager at the Sheed Aquarium in Chicago, Illinois (US). All photos shown in this blog entry were made yesterday at the coral restoration laboratories of Xcaret Eco Park Mexico. The Xcaret team and SECORE are closely cooperating to advance coral sexual reproduction and enhance reef conservation efforts. The photo were made by SECORE photographer Paul Selvaggio.