proposed artificial reef
riskmj at mcmail.cis.mcmaster.ca
Tue Nov 20 16:00:59 EST 2001
First of all, I would echo John's statements re fish. Be careful about building reefs in heavily-fished areas, because the last thing you need is another FAD.
On the other hand, questions about proper materials etc may readily be answered. These are all in the literature, I could dig the refs out if necesssary.
1. properly-constructed "artificial" reef materials resemble real ones as closely as possible, hence the quotes. In terms of larval success, the best stuff to use is sawn-up or broken-up corals-but we would not wish to make a habit of this. Pleistocene reef rock is abundant in many places in the Caribbean, and that stuff works fine-as do concrete blocks, but they cost more.
2. absolutely to be avoided is the conversion of a terrestrial waste-disposal problem into a reef. Avoid metals, plastics. Fish assemble on spatially-complex metal structures very quickly, but they know naught of heavy metal accumulation, etc. Stick to calcium carbonate.
3. build as much spatial complexity as possible into whatever you do.
The reefs I built 25 years ago in Discovery Bay are still there, now heavily-silted, but with corals and other inverts growing all over them, bioeroders in the reef rock and concrete blocks...but there are lessons. Corals accreted on the blocks only above the substrate, avoiding the lower layer of suspended sediment. And to echo John: local fishermen were potting lobster off these things 6 months after they were built, lobster that may well have survived better on a "real" reef.
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