Report on surveys of the Cairns and Innisfail sectors of the Great Barrier Reef

Dates: 30^th November to 19^th December 2015

Vessel: RV Cape Ferguson

Survey leader: Mike Emslie

Manta tow surveys for the 2016* survey year were completed on six reefs in the Cairns sector and ten reefs in the Innisfail sector of the Great Barrier Reef (GBR). Detailed surveys for benthic organisms, visual census of fishes and surveys for agents of coral mortality (scuba search) were made on the six reefs in the Cairns sector and another seven reefs in the Innisfail sector. Preliminary results of the manta tow and scuba search surveys are presented in this report.

Median reef-wide live coral cover (coral cover) in the Cairns sector had increased or remained at levels similar to those recorded in the last survey. All six reefs surveyed had moderate cover (10-30%) in 2016. Although low numbers of crown-of-thorns starfish (COTS) were recorded in manta tows of two mid-shelf reefs, no reefs were classified as having incipient or active outbreaks; all reefs were classified as non-outbreaking or recovering. Only 2 COTS were observed during detailed scuba surveys on one outer-shelf reef.

Ten reefs were surveyed in the Innisfail sector. The majority of these reefs have largely recovered from Severe Tropical Cyclone (STC) Yasi (2011). Two reefs had low coral cover (0-10%), six reefs had moderate coral cover (10-30%) and the remaining two had high coral cover (30-50%). Outbreak levels of COTS were seen in manta tow surveys of two mid-shelf reefs, and localised outbreaks were recorded from a further two reefs, while the rest of the reefs had no COTS or very low numbers present.

Signs of coral disease and counts of Drupella spp. on the reefs that were surveyed using scuba were generally at levels similar to previous surveys, with some increases in coral disease likely accompanying increased coral cover.

Details of the manta tow method can be found in the Standard Operational Procedure No. 9 [AIMS Research - Crown-of-thorns Starfish and Coral Surveys - Standard Operational Procedure 9]. For a full explanation of COTS outbreak terminology refer to the following web-page: Crown-of-thorns on the Great Barrier Reef.

Perimeters of six reefs were surveyed using manta tow (Table 1). Three sites were also surveyed in detail using scuba on five reefs (Table 2). Manta tow surveys recorded single COTS at Thetford Reef and eight individuals at Arlington Reef, although these numbers were below Incipient (IO) or Active Outbreak (AO) levels and all reefs were classified as No Outbreak or Recovering. Only two COTS were recorded in scuba search surveys at St Crispin Reef on the outer-shelf. Coral cover at the majority of reefs in the Cairns sector declined slightly following Cyclone Yasi (2011). Coral cover in 2016 increased on four reefs (Mackay, Thetford, Hastings and Agincourt NO.1) and remained unchanged on two (Arlington and St Crispin). Overall coral cover was moderate (10-30%) and similar to the levels observed prior to Cyclone Yasi.

Table 1: Summary of manta tow surveys for reefs in the Cairns sector.

Reef	Shelf Position	Tows	COTS	COTS per tow	Median % Live Coral Cover	Median % Dead Coral Cover	Median % Soft Coral Cover	Reef Status
MACKAY	Mid	21	0	0	10 to 20	0 to 0	5 to 10	RE
THETFORD	Mid	44	1	0.02	20 to 30	0 to 5	40 to 50	RE
HASTINGS	Mid	67	0	0	20 to 30	0 to 0	10 to 20	NO
ARLINGTON	Mid	60	8	0.13	10 to 20	0 to 0	20 to 30	NO
AGINCOURT NO.1	Outer	31	0	0	10 to 20	0 to 0	20 to 30	NO
ST. CRISPIN	Outer	95	0	0	10 to 20	0 to 0	20 to 30	NO
Overall GBR average for last survey - 2012	All			0.13	10 to 20	0 to 5	0 to 5	-
Long-term average value	Mid			0.06	10 to 20	0 to 5	5 to 10	-
Long-term average value	Outer			0.02	10 to 20	0 to 5	5 to 10	-
Average last survey – 2014	Mid			0.13	10 to 20	0 to 5	10 to 20	-
Average last survey – 2014	Outer			0.01	10 to 20	0 to 5	0 to 5	-

Scuba searches on the intensive survey sites (Table 2) found that incidence of coral diseases and counts of Drupella spp. were unexceptional. The number of diseased colonies was similar among all reefs and similar to levels reported in previous years. For more information on coral disease refer to the AIMS web site here: Coral disease.

 

Table 2: Summary of SCUBA search surveys for reefs in the Cairns sector.

Reef	Shelf	COTS (<5cm)	COTS (>5cm)	COTS (>15cm)	COTS (>25cm)	WS	BBD	BrB	SEB	Drupella
HASTINGS	Mid	0	0	0	0	10	0	1	17	6
ARLINGTON	Mid	0	0	0	0	7	0	2	17	20
THETFORD	Mid	0	0	0	0	15	0	2	5	9
AGINCOURT NO.1	Outer	0	0	0	0	4	0	2	3	1
ST. CRISPIN	Outer	2	0	0	0	1	0	1	9	1
Overall GBR Average for last survey - 2012	All	0	0.04	0.16	0.48	9.7	0.04	5	5.4	11
Long term average	Mid	0.061	0.53	1.6	0.079	9.5	0.38	1.2	7.2	15
Long term average	Outer	0.034	0.32	0.1	0	5.5	0.083	0.85	2.3	5
Average for last survey – 2014	Mid	0	0	0	0	12	0	1	5.3	18
Average for last survey - 2014	Outer	0	0	0	0	1.5	0	0.5	0	1

WS = White Syndrome, BBD = Black Band Disease, BrB = Brown Band Disease, SEB = Skeletal Eroding Band Disease

Reefs in the Innisfail sector have suffered a number of large disturbances (COTS outbreaks, STC Larry, STC Yasi) since 2000 causing substantial losses of coral cover. Perimeters of ten reefs were surveyed using manta tow (Table 3). Sites at seven of these reefs were also surveyed in detail using scuba (Table 4). Outbreak levels of COTS were recorded during manta tow surveys on McCulloch and Peart Reefs, but few or no COTS were recorded on the rest of the reefs surveyed by manta tow. Coral cover has increased at Taylor and Potter Reefs since they were last surveyed in 2012 and 2014 respectively, with both reefs having high cover in 2016 (30-50%). Coral cover on both reefs was at the highest level since manta tow surveys began in 1986. All other reefs had small increases in coral cover, but levels remained similar to those recorded during the last surveys.

Table 3: Summary of manta tow surveys for reefs in the Innisfail sector.

Reef	Shelf Position	Tows	COTS	COTS per tow	Median % Live Coral Cover	Median % Dead Coral Cover	Median % Soft Coral Cover	Reef Status
MOORE	Mid	87	1	0.01	10 to 20	0 to 5	5 to 10	NO
MCCULLOCH	Mid	113	75	0.66	5 to 10	0 to 5	0 to 5	IO
PEART	Mid	55	53	0.96	10 to 20	0 to 5	5 to 10	AO
FEATHER	Mid	53	0	0	20 to 30	0 to 5	0 to 5	NO
BEAVER	Mid	50	0	0	10 to 20	0 to 5	0 to 5	RE
FARQUHARSON	Mid	67	0	0	10 to 20	0 to 0	0 to 5	NO
TAYLOR	Mid	57	0	0	30 to 40	0 to 5	0 to 5	NO
HEDLEY	Outer	63	4	0.06	5 to 10	0 to 0	20 to 30	RE
WARDLE	Outer	61	0	0	10 to 20	0 to 5	5 to 10	RE
POTTER (A)	Outer	82	7	0.09	30 to 40	0 to 0	0 to 5	NO
Overall GBR average for last survey - 2012	All			0.13	10 to 20	0 to 5	0 to 5	-
Long-term average value	Mid			0.22	5 to 10	0 to 5	0 to 5	-
Long-term average value	Outer			0.09	10 to 20	0 to 5	5 to 10	-
Average last survey - 2014	Mid			0	10 to 20	0 to 5	0 to 5	-

 

 

Scuba searches on the intensive survey sites revealed exceptionally high numbers of COTS on Peart Reef, and moderate numbers on McCulloch, Farquharson and Taylor Reefs (Table 4). In all the latter three cases these numbers would be enough to qualify as localised outbreaks. The remaining reefs in this sector had low numbers or no COTS recorded during scuba searches. White Syndrome was the most common disease, although it remained at levels similar to previous surveys. In general the incidence of Skeletal Eroding Band Disease remained largely similar to levels in previous surveys, although there were increases in the incidence of SEB at five reefs and particularly evident on Feather Reef. Similarly there were increased counts of Drupella spp. on Hedley Reef when compared to previous surveys however neither case would be considered an immediate threat to coral cover.

Table 4: Summary of SCUBA search surveys for reefs in the Innisfail sector.

Reef	Shelf	COTS (<5cm)	COTS (>5cm)	COTS (>15cm)	COTS (>25cm)	WS	BBD	BrB	SEB	Drupella
MOORE	Mid	0	0	0	0	4	0	0	1	5
MCCULLOCH	Mid	0	0	1	7	11	0	1	6	9
PEART	Mid	0	2	8	120	14	0	5	9	5
FEATHER	Mid	0	0	0	0	23	0	6	29	10
FARQUHARSON	Mid	0	6	3	0	4	0	5	8	14
TAYLOR	Mid	0	4	23	6	17	0	8	3	9
HEDLEY	Outer	0	1	0	0	8	0	3	6	23
Overall GBR Average for last survey - 2014	All	0	0.04	0.16	0.48	9.7	0.04	5	5.4	11
Long term average	Mid	0	0.36	1.1	4	10	0.15	1.9	5.1	8.5
Long term average	Outer	0	0.19	0	0	7.5	0.56	4.1	8.1	9.2
Average for last survey - 2014	Mid	0	0	0	0	24	0.33	3.7	4.7	10

WS = White Syndrome, BBD = Black Band Disease, BrB = Brown Band Disease, SEB = Skeletal Eroding Band Disease.