Step Reef re-design

Step reef 2.0

Initial design

Here at TRACC we are actively working to restore our marine environment. Around our island there has been catastrophic damage caused by historic dynamite fishing. Due to this destructive fishing practice, the reef slope has been degraded to a mobile rubble slope environment with little 3D complexity. This drastically reduces the biodiversity of the reef crest and provides little shelter to larval fish. It is not all bad news though, the rubble environment often has hard corals try colonize and when successful coral growth is consistent. In 2013 we built trial step reefs, our goal was to build a sturdy 3D artificial reef, on a slope environment. This had the aim to both provide 3D complexity and a stable benthic substrate for corals to attach and grow onto. Upon our return we found that our initial test wasn’t 100% successful. Many had rolled down the reef slope due to turtles using them as scratch posts. 

Itchy turtle making a mess!

Step reef re- design

One of the first things we noticed was that, in general, the trial step reefs which were larger , were more stable. This lead to the idea of interlocking each individual block with the one both its left and right, this in effect makes every layer of the step reef one large stable block. This is achieved by leaving gaps between the individual blocks, with the plan to initially cable tie them and then cement these once the blocks are in place under the water.  Massive and encrusting corals will be put in the unset cement with the hope that they would grow to envelop the two blocks, creating a biological adhesion that will only become stronger over time.

The next area we chose to strengthen was between layers. A simple and effect method of using recycled stakes to hold each step in place was used. There by removing the possibility of shallower step reefs rolling downhill over deeper step reefs.   

Step reef from every angle

interlocking layers

When the step reef is in place we add biscuits (basically a coral plant pot) from our coral nursery.

For more about coral biscuits and nursery, click here

As you can tell from the picture below, he step reefs are strong enough to support the weight of our step reef primary engineer, Kit! Hopefully our new step reefs trials will be totally successful,. [blog posts on this topic to come]. I personally cannot wait to start deploying these.

Nice and Sturdy

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