Rigs to Reefs Program
Tony.Lowery at noaa.gov
Wed Nov 1 17:02:02 EST 2000
Dear Rigs to Reefers;
I agree with Don McAllister that before and after studies of rigs to reefs
type artificial reefs should be carried out. It is true that most of the
junk thrown overboard as artificial reef materials provide 1) poor
attachment surfaces for biofouling, encrusting, and attachment of sessile
invertebrates, and 2) an insufficient suite of nooks and crannies for the
smaller reef type invertebrates and fishes to harbor into avoid predation.
Therefore without adequate surface area and harborage for the smaller
non-sessile organisms (esp. esp. larvae, post-larvae and pre-juveniles)
these non-engineered materials don't create the conditions needed for the
establishment of a diverse reef ecosystem.
However, there are some engineered artificial reef units that do provide
large amounts of good bio-attachable surface area in very compact units
that incorporate the nooks and crannies to harbor the smaller non-sessile
organisms. These units have been deployed in large numbers off Pensacola,
FL and St. Petersburg, FL by ARCOA (Artificial Reef Company of America) in
the late 80's and early 90's. The Pensacola deployment was studied and
found to be successful, I'm not sure if the St. Petersburg deployment was
studied or not. These units are approximately 2 ft x2 ft x 4 ft with
hundreds of square feet of good clean bio-attachable friendly surface area
that does not break down in seawater. These units work, are cost
effective, and can be tailored to the species groups of interest by
varying the sizes of the nooks and crannies of the units, and deploying
units with different sized nooks and crannies in clusters or array that
could support the earlier life history stages of the species of interest.
However, due to a general lack of funding for the deployment of such
clusters, these engineered units aren't in wide use. Though in my opinion
they should be.
The rigs suffer from the same problems as the non-engineered artificial
reef materials (type of attachment surface is poor, surface area to volume
is low, and nooks & crannies are in short supply). However, if the rigs
were augmented with well engineered artificial reef units similar to the
ARCOA units (e.g., the units could be strapped onto the piles) then the
rigs could possibly function as artificial reef ecosystems. Otherwise, the
huge amount of surface area afforded by the rigs offers limited harborage
for the smaller non-sessile organisms (esp. larvae, post-larvae and
pre-juveniles) which limits the rigs utility as a reef.
In my opinion, these engineered reef units are the artifical reefs of
choice, and it is disappointing that the fishery management community at
large has not embraced them or for that matter even know about them.
Since, MMS has to spend a portion of the oil royalties paid to the U.S. on
programs like the rigs to reefs, I don't see why MMS shouldn't foot the
bill for augmenting the rigs and supporting studies. They've got the money
and I'd think this would be something they'd be interested in. Possibly
MMS could do a couple of test deployments and study the effectiveness of
the units. I'm thinking that augmenting several standing decommisioned
rigs with the engineered units at 30ft, 60ft, 90ft, and 120ft (with enough
units at each level to surround each pile) would be adequate as a test
deployment. If things work out, and the before and after studies indicate
that augmenting the rigs with these units would be desirable, then MMS
would have the option of funding and studying additional deployments or
just augmenting the decommissioned rigs en mass. Conversely, if the units
turn out not to work, the units could be unstrapped from the piles and
removed, or replaced with revised versions.
Anyway, to my thinking these rigs should be used as platforms for
developing reef materials and designs (like the ARCOA reef units) that
provide lots of surface area in a small volume while providing harborage
for the smaller non-sessile organisms from predation. My interest are
focused on supporting the earlier life history stages and the food chain
that ends up supporting the juveniles & adults of the recreationally
important species. Therefore, I believe that strapping some ARCOA units
onto some rigs and studying recruitment would be a good start.
If anyone is interested in more info on the ARCOA reef units contact me at
tony.lowery at noaa.gov.
Don McAllister wrote:
Above all we need some honest and full evaluations of existing
artificial reefs, and some experiments with full before and after
analyses to answer questions
about recruitment to the structures in the long and short-term.
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