|REEFBALLS: Components for Artificial
Golden Bay Cement, a company with a proven commitment to the
environment, is pleased to have its products used for marine
restoration and enhancement in New Zealand; namely an artificial
reef component called a ReefBall.
The use of artificial reefs is hardly a new one. For
decades people have been creating reefs from tyres, sunken ships,
old cars, concrete culverts and assorted rubble. These, however, can
often do more harm than good - leaching harmful chemicals into the
ocean or damaging natural reefs when currents dislodge them and toss
them around the sea floor. ReefBalls on the other hand, have been
designed to emulate natural reef formations and, as most of the
weight is concentrated in their flat bases, will sit on the sea
floor without moving, even in turbulent seas.
The idea for ReefBalls originated with Florida diver Todd Barber.
His company, the ReefBall Development Group, has placed over 100,000
around the globe in the last eight years.
Dave Head of Napier and a group of friends brought ReefBalls to
New Zealand, setting up the company ReefBall NZ Limited and the NZ
ReefBallTrust, which has already been offered substantial financial
help from a large New Zealand charitable organisation. In April
2000, under the guidance of Todd Barber, trial production began at
Firth's Awatoto Readymix Plant in preparation for a proposed
artificial reef at Westshore and Bayview off Napier's northernmost
coastline. Golden Bay Cement's GP was used along with supplementary
cementitious material Microsilica 600, supplied by GBC subsidiary
Microsilica New Zealand Ltd.
GBC's Microsilica 600 is an important supplementary cementitious
material for the blend due to its durability enhancing qualities and
high level of resistance to sulphide and chloride attacks. With
Microsilica 600 used in the concrete, the Reef Balls will have an
expected life of 500 years or more. By then, the build-up of coral
or other marine life attached to the Reef Balls will be substantial,
making the need for the artificial supports redundant.
ReefBalls are made by pouring concrete into a fibreglass mould
containing a central Polyform buoy surrounded by various sized
inflatable balls to make holes. There are six mould sizes to tailor
the units to the size requirements and purpose of the reef. The hole
size is chosen to attract the type of marine life likely to thrive
in the area, be they crayfish, moray eels or a small species of
Before the concrete is poured, the inside of the mould is sprayed
with a sugar solution. This acts as a mould release agent and allows
for a roughened texture by preventing an outer film of concrete from
setting. Hosing down the ReefBall after the mould casing is removed
strips off the unset film of concrete leaving behind a rough stony
texture to which organisms can attach more easily. Rough,
individualised ReefBalls are preferred over the smooth, homogenous
items normally produced from moulds, in order to more effectively
emulate natural reef formations.
Polythene or similar covers are wrapped around the balls for up
to two weeks to allow for a slow curing time. This prevents early
cracking. The extremely durable polyform bladder used in the mould
can be left in the unit to provide flotation, allowing the ReefBall
to be towed behind anyboat. Once at the desired site, the bladder is
deflated and removed. When divers are used to control the descent,
units can be placed precisely on the sea floor so as not to endanger
existing natural reefs that are being extended or repaired.
New Zealand Projects
Project Kaimoana, at Opotiki, has already gained initial approval
from local government bodies and iwi. The artificial reef, aimed to
bring marine diversity back to the area, is being wholly created by
local community education centre Whakatohea Training Unit. Led by
Aquaculture and Fishing Course Tutor Lloyd Hoskins, the project has
already begun trial constructionof ReefBalls and is finalising the
choice of aggregate and supplementary cementitious materials for
strength and performance in a marine environment before beginning
the reef construction.
A surf reef at Opunake, aimed at producing bigger waves, is
another ReefBall project in the pipeline. This is being headed by
Shaw Mead of ASR Limited. Funding for this is expected to come
through before the end of 2001.
Proven Results Overseas
Among the many sites where ReefBalls have been put in place
overseas is Australia's Great Barrier Reef. To protect the area's
fragile coral reefs, which grow at the rate of one inch every 15
years, ReefBalls were used to create artificial snorkelling trails
for tourists. The rapid development of marine life on and around
ReefBalls makes them ideal for this purpose and proves them to be an
ecologically advantageous option for artificial reefs.
Research Backing ReefBalls
According to Shaw Mead, Director of the New Zealand branch of
international artificial reef producers ASR Limited: "Although a
biological investigation is needed for each individual case, past
studies have shown that stable, complex structures such as
artificial reefs have higher bio-diversity and species abundance
than mobile, abrasive substrates (e.g. sand). Artificial reefs can
actually enhance the ecology of an area. In most situations, a reef
is likely to have no significant effect on the ecology of the
Mead points out that a large amount of marine research into the
ecological effects of artificial reefs shows that species abundance
and diversity is enhanced when:
the habitat is more stable
the topography more complex, with more niches and of variable
the reef is larger
Furthermore, the construction of artificial reefs allows the
creation of specific habitats and the cultivation or encouragement
of species of potential commercial or cultural value. This may mean
increased environmental value through biodiversity and abundance,
recreational opportunities in the form of diving, snorkelling or
even surfing, and controlled commercial fishing ventures.
Gaining resource consent for artificial reef projects around New
Zealand's coastline has proved an arduous and detailed task for Dave
Headand others keen to use ReefBalls.
Consultation and application with local and regional council, iwi
and community representatives is important when making changes to
land formations - even those that are underwater. Although ReefBalls
have been proven to enhance marine ecosystems in overseas projects,
there is the immediate disturbance of the habitat on the sea floor,
albeit minimal, to consider so each proposed project must be
scrutinised carefully before getting the go-ahead.
Resource consent for the use of ReefBalls has been a slow
process. Various projects like Hawke's Bay's are being developed
around the country in preparation for the pending approval from
central and local government and local community groups and iwi.