AIMS
long-term monitoring of the Great Barrier Reef
Report of surveys of the
Whitsunday, Cape Upstart and Townsville sectors of the Great Barrier Reef (GBR)
Dates: 1st – 16th
May, 2001
Vessel: RV
Cape Ferguson
Survey leader: Angus
Thompson
Summary
Manta tow surveys were completed on nine reefs in the Townsville sector, five
reefs in the Cape Upstart sector and five reefs in the Whitsunday sector of the
Great Barrier Reef (GBR). Detailed benthic video, fish visual census and vectors
of coral mortality (SCUBA search) surveys were completed on nine reefs in the
Townsville sector and two reefs in the Whitsunday sector. Preliminary results of
the manta tow and SCUBA search surveys are presented in this report.
Summaries of the results are presented in Tables 1, 2 and 3. A full list of
survey reefs is given in the Long-term Monitoring Status
Report number 4. Details of the manta tow method can be found in the Standard
Operational Procedure number one or in the
Survey Manual for
Tropical Marine Resources (English et. al.1997). For a full explanation of
the COTS outbreak terminology used in this report, refer to COTS
Page.
WHITSUNDAY SECTOR
|
Five
reefs in the Whitsunday sector were surveyed using
manta tow (table 1). There has been no appreciable
trend in reef-wide coral cover on these reefs over the
last 5 to 6 years. Median reef-wide live coral cover
is moderate (10-30%) on all reefs. No COTS were
observed during manta tow, however small scars
consistent with sub-adult COTS feeding were noted on
Reef 19-131, Reef 19-138 and Hayman Island. All reefs
are classified as No Outbreak with the exception of
Reef 19-138, which is classified as Recovering.
Click on
this map for a high resolution image.
|
Data from SCUBA search
transects on Reefs 19-131 and 19-138 show a four-fold increase
of coral scars of uncertain origin compared with surveys a
year ago. The nature of the scarring, combined with finding of
one juvenile COTS on Reef 19-138, suggests that low numbers of
cryptic juvenile COTS may be present on these reefs. Drupella
numbers have remained stable or decreased slightly over the
last three years.
 |
 |
A
Rainfords Butterfly fish cruises over a massive Diploastrea
coral colony. Some corals such as Diploastrea
have a defense against COTS feeding activity. Often
colonies such as these may be the only live coral left
on an area of reef affected by a COTS outbreak.
|
Close
up photograph of a neoplasm (cancer/tumor) on a
branching Acropora colony. One can clearly see
the normal healthy brown coral tissue and polyps
surrounding the adjacent white outgrowth of the tumor.
Still visible within the tumor are a few polyps but the
skeleton generally consists of undifferentiated calcium
carbonate matrix. The causes of coral tumors are
unknown.
|
Table
1. Summary of results of Manta Tow surveys
in the Whitsunday Sector of the Great
Barrier Reef Marine Park.
| Reef |
Shelf
Position |
Tows |
Cots |
Cots
per tow |
Median
% Live Coral Cover |
Median
% Dead Coral Cover |
Median
% Soft Coral Cover |
Reef
Status |
| BORDER
IS (A) |
Inner |
56 |
0 |
0 |
10
to 20 |
0
to 5 |
30
to 40 |
NO |
| HAYMAN
IS |
Inner |
29 |
0 |
0 |
10
to 20 |
0
to 5 |
10
to 20 |
NO |
| LANGFORD
AND BIRD IS'S |
Inner |
26 |
0 |
0 |
10
to 20 |
0
to 5 |
10
to 20 |
NO |
| 19131 |
Mid |
50 |
0 |
0 |
10
to 20 |
0
to 5 |
0
to 5 |
NO |
| 19138 |
Mid |
30 |
0 |
0 |
10
to 20 |
0
to 5 |
0
to 5 |
RE |
CAPE UPSTART SECTOR
Click on this map for a
high resolution image.
|
Five
reefs were surveyed in the Cape Upstart sector (table
2). Jacqueline Reef and Elizabeth Reef have changed
little over the last decade with moderate (10-30%) coral
cover and a No Outbreak classification. Low numbers of
COTS were recorded on Jacqueline during this survey.
Bowden Reef also had low numbers of COTS and there were
numerous feeding scars in some areas. Reef-wide coral
cover has declined slightly on Bowden Reef and is low at
5-10%. Bowden Reef is still classified as Recovering
from a previous COTS outbreak (1988-1992). Reef-wide
coral cover on Reef 19-098 is moderate (20-30%) which is
a slight increase from a low of (10-20%) following
Cyclone Justine in 1997. |
The more inshore Holbourne Island is classified as
Recovering following high COTS numbers in the late
1980’s. The reef-wide coral cover on Holbourne
Island remains low at 5-10%, though it is increasing.
 |
|
This
photo depicts a portion of a stand of branching Acropora
found on the front of Elizabeth Reef. The stand was
approximately 20 metres square and many of the corals
were covered in tumors.
|
Juvenile
crown-of-thorns starfish on John Brewer Reef in the
Townsville sector. The presence of juveniles on a reef
can be difficult to detect, as they usually remain
hidden in the reef matrix during the day. Small feeding
scars alerted the diver to the presence of these
individuals.
|
Table 2.
Summary of Manta Tow survey results for
the Cape Upstart Sector of the Great Barrier
Reef Marine Park.
| Reef |
Shelf
Position |
Tows |
Cots |
Cots
per tow |
Median
% Live Coral Cover |
Median
% Dead Coral Cover |
Median
% Soft Coral Cover |
Reef
Status |
| HOLBOURNE
IS |
Inner |
22 |
0 |
0 |
5
to 10 |
0
to 0 |
5
to 10 |
RE |
| 19098 |
Mid |
55 |
0 |
0 |
20
to 30 |
0
to 5 |
10
to 20 |
NO |
| BOWDEN |
Mid |
69 |
9 |
0.13 |
5
to 10 |
0
to 5 |
0
to 5 |
RE |
| ELIZABETH |
Mid |
34 |
0 |
0 |
10
to 20 |
0
to 5 |
10
to 20 |
NO |
| JACQUELINE |
Outer |
62 |
4 |
0.06 |
10
to 20 |
0
to 5 |
5
to 10 |
NO |
TOWNSVILLE SECTOR
 |
Nine
reefs were surveyed using manta tow (table 3). Seven of
these reefs and a further two reefs (Middle and Pandora)
were also surveyed in detail using SCUBA. On Rib Reef
and John Brewer Reef both manta tow and SCUBA search
surveys revealed large populations of COTS. Rib Reef has
been now been classified as Active Outbreak for three
consecutive years. This is reflected in the continued
decline in reef-wide coral cover from 40-50% in 1998
prior to the outbreak to a current low of 0-10%. The
Active Outbreak recorded on John Brewer is the first on
this reef since 1986.
Click on this map for a
high resolution image. |
The high proportion of sub-adult individuals found on the
SCUBA search transects suggests recent recruitment and we
expect COTS numbers to continue to increase on this reef in
coming years. Reef-wide coral cover on John Brewer Reef has
declined slightly from last year though is still moderate at
10-20%.
No COTS were recorded in manta tow surveys on the other
seven reefs though low levels of scarring (presumably due to
COTS activity) were observed on all the remaining reefs except
for Havannah Island. SCUBA searches revealed low numbers of
small sub-adult COTS on Havannah Island and one individual at
Middle Reef, which is not manta towed. The inshore reefs in
the Townsville sector were severely affected by the
1998-bleaching event. Reef wide coral cover on these reefs has
remained low at 0-5% since. The outer-shelf reefs (Chicken,
Dip and Myrmidon) have all remained stable over the last
decade with reef-wide coral cover at moderate levels (10-30%).
Chicken and Myrmidon Reef remain classified as No Outbreak,
while Dip is still classified as Recovering from a COTS
outbreak in the mid-1980’s.
Davies Reef and Reef 18-099 are classified as Recovering
from COTS outbreaks ending in the early 1990’s. Both
currently have moderate reef-wide coral cover (10-20%). The
coral cover at Davies reef has declined over the last two
years. The cause of this decline is not known.
|
 |
A scene from Rib Reef in the
Townsville sector. The overall dull appearance of the reef
is a direct result of crown-of-thorns starfish (COTS)
feeding activity. Adult COTS leave a white feeding scar
that is subsequently fouled by a thick layer of turf
algae. The only live coral in the photo can be seen in the
bottom left.
|
Porites
Pinking, Myrmidon Reef. The pink band seen in this close
up photo of a massive Porites colony is a reaction
of the coral colony to stress. From our observations the
discolouration appears on scar tissue that forms in
response to a wide variety of factors (e.g. parasites,
predators, commensals, competition for space, fish bite
marks, the margins of damsel fish gardens, persistent
rubbing by other benthic organisms, or margins around turf
alga patches on the colony from unspecific causes). In
this case the pink banding is most likely due to feeding
activity of the corallivorous gastropod Quoyula
madreporarum which can be seen in the bottom right of
the photograph.
|
Table 3.
Summary of Manta Tow survey results for
the
Townsville
Sector of the Great Barrier
Reef Marine Park.
| Reef |
Shelf
Position |
Tows |
Cots |
Cots
per tow |
Median
% Live Coral Cover |
Median
% Dead Coral Cover |
Median
% Soft Coral Cover |
Reef
Status |
| FANTOME
IS |
Inner |
73 |
0 |
0 |
0
to 5 |
0
to 0 |
5
to 10 |
NO |
| HAVANNAH
IS |
Inner |
26 |
0 |
0 |
0
to 5 |
0
to 0 |
0
to 5 |
NO |
| 18099 |
Mid |
55 |
0 |
0 |
10
to 20 |
0
to 5 |
0
to 5 |
RE |
| DAVIES |
Mid |
44 |
0 |
0 |
10
to 20 |
0
to 5 |
0
to 5 |
RE |
| JOHN
BREWER |
Mid |
70 |
117 |
1.67 |
10
to 20 |
0
to 5 |
0
to 5 |
AO |
| RIB |
Mid |
33 |
282 |
8.55 |
0
to 5 |
0
to 5 |
0
to 5 |
AO |
| CHICKEN |
Outer |
43 |
0 |
0 |
10
to 20 |
0
to 5 |
0
to 5 |
NO |
| DIP |
Outer |
45 |
0 |
0 |
10
to 20 |
0
to 5 |
0
to 5 |
RE |
| MYRMIDON |
Outer |
46 |
0 |
0 |
20
to 30 |
0
to 5 |
0
to 5 |
NO |
Reference
English, S., Wilkinson, C. and Baker, V. (1997) Survey
Manual for Tropical Marine Resources (2nd Edition).
Australian Institute of Marine Science. Townsville.
For further information contact
Dr. Hugh Sweatman, AIMS
Telephone: +61 7 4753 4470
Fax: +61 7 4753 4288
e-mail: h.sweatman@aims.gov.au
 AIMS home page
web@aims.gov.au
Last updated - December 18, 2008
Copyright ©1996-2001 Australian Institute of
Marine Science
URL
http://www.aims.gov.au
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