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

Dates: 11th March to 24th March 2014

Vessel: RV Cape Ferguson

Survey leader: Kate Osborne

Manta tow surveys for the 2014 survey year were completed on four reefs in the Cairns sector, three reefs in the Innisfail sector and two reefs in the Townsville sector of the Great Barrier Reef (GBR). Surveys of reefs in the Cairns sector were completed for 2014*.

Detailed surveys for benthic organisms, visual census of fishes and surveys for agents of coral mortality (scuba search) were made on the five reefs in the Cairns sector plus five other reefs in the Innisfail and Townsville sectors. Preliminary results of the manta tow and scuba search surveys are presented in this report.

Median reef-wide live coral cover in the Cairns sector had increased or remained at levels similar to those recorded in the last survey. Three of the four reefs surveyed had moderate cover (10-30%) in 2014. An incipient outbreak of crown-of-thorns starfish (COTS) was recorded from manta tows of one outer shelf reef. The other three reefs were classified as non-outbreaking or recovering. No COTS were observed during scuba surveys.

Three reefs in the Innisfail sector were surveyed along with two reefs in the Townsville sector. Indications are that reefs in both sectors are recovering from Cyclone Yasi (2011). No COTS were seen in manta tow surveys of the five reefs, though one small COTS was recorded in scuba surveys at Rib Reef and scars believed to be caused by COTS feeding were observed at two reefs in the Innisfail sector and at Rib Reef in the Townsville sector.

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 white syndrome accompanying increased coral cover. Outbreak levels of coralline algal disease were recorded at Agincourt Reef.

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.

*Survey year reflects financial year of survey, for instance the 2012 survey year represents reefs surveyed between July 2011 and June 2012. Surveys for this current financial year are presented as 2014 despite some surveys actually taking place in the 2013 calendar year.

Perimeters of four reefs were surveyed using manta tow (Table 1). Three sites on each of five reefs were also surveyed in detail using scuba (Table 2). Manta tow surveys recorded single COTS at Hastings Reef and St Crispin Reef. An Incipient Outbreak of COTS (IO) was found at Arlington Reef. No COTS were recorded in scuba search surveys at any reef. Coral cover at the majority of reefs in the Cairns sector declined slightly following Cyclone Yasi (2011) but coral cover in 2014 was moderate (10-30%) and similar to the levels observed prior to Cyclone Yasi. The exception was Agincourt Reef, where coral cover was low (5-10%).

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 at Hastings Reef was low, but was slightly higher at the other reefs, as has been the case in previous surveys. Counts of both Coralline White-Band Disease and Coralline Algae Orange Disease at Agincourt Reef were higher than 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.

I=inner, M=mid, O=outer, 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 three reefs were surveyed using manta tow (Table 3). Sites at each of these reefs were also surveyed in detail using scuba (Table 4). No COTS were recorded during manta tow or scuba search surveys. Scars believed to be caused by COTS feeding were seen at Peart and Feather Reef. Coral cover has increased at Peart and Feather Reefs since the last survey in 2012 with both reefs having moderate cover in 2014 (10-30%). Coral cover on Peart Reef was at the highest level since manta tow surveys began in 1986. Along with increasing coral cover incidence of coral disease had also increased, reaching moderate levels at Feather Reef. White Syndrome was the most common disease. Several reefs in the Innisfail sector remain to be surveyed for 2014.