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Explorer
Scientist: Dr Pat Hutchings, Australian Museum
The
adventure:
These
are 6 day trips on the ribbon reefs of the northern Great
Barrier Reef and remote Osprey Reef. This includes diving
beautiful coral gardens, the world famous Cod Hole and the
amazing pelagic fish, sharks, walls and visibility of Osprey
Reef. We choose the adventure diving locations to suit the
action of the day while the researchers will be off collecting
the blocks and assessing their study site. Between dives
there will be the opportunity to check the scientists finds
and also to hear presentations from one of Australia's leading
marine invertebrate experts. All the other Undersea Explorer
action will also be happening including the shark research
and nautilus capture programs
About
bioerosion:
Coral
reefs around the world are under threat from a variety of
sources. Erosion and reef building are natural processes
but have a natural balance which must be maintained. This
project aims to assess the rate of erosion versus the rate
of building and colonisation by reef organisms. Reefs may
be degraded by man induced or by natural events but certainly
man is in the process of degrading many of the world's reefs.
The
main problems occur from coastal deforestation and poor
agriculture methods which increase nutrient and sediment
outputs to the reef waters; physical construction and anchor
damage or removing fish populations and other reef animals
to upset the fine balance of the reef. Many of these events
may not show immediate degradation but over the long term
the reef may not recruit new colonies as well, algae may
overgrow corals or the skeletal structure may be weakened.
This may eventually cause a change in the reef and in some
cases it has resulted in a rocky algal reef replacing the
original rich coral reef.
The
research:
Dr
Pat Hutchings has placed coral skeleton blocks at a variety
of reef sites from Port Douglas to Osprey Reef. This gives
the ability to check the rates of bioerosion at similar
reef sites which vary in distance from the coast and human
influence. The sites include reefs across the continental
shelf, Lizard Island reefs, the ribbon reefs and oceanic
Osprey Reef which is 100 miles offshore and in 1000 metre
deep surrounds. Coral blocks (7x5x5cm)were cut from Porites
boulder corals in September 1996 and duplicate grids of
8 blocks each were placed at each site at depths of 7 -
10 metres. Two blocks from each grid are taken for analysis
each year for four years. Slices of the block are analysed
for overall change in mass and the organisms boring into
the corals are identified and quantified. Organisms colonizing
the blocks are also of interest and will be assessed.
Throughout
the year Undersea Explorer crew record digital video footage
and images of the bioerosion grids to assess the finer scale
changes and also the animals which may be grazing on the
blocks. The database constructed by Undersea Explorer and
linked to the various research projects will also be of
value in giving year-round data on water temperature, salinity,
nutrient levels and many other related observations. To
date there has been a range of video data already collected.
The first year's samples have been collected and are being
analysed at present.
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