John Brewer Reef Sunferries-Townsville

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Paul Ryan
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John Brewer Reef Sunferries-Townsville Latitude: 18 57.364S Longitude: 146 57.375E Date: 31-1-4, 1-2-4 and 24.3.4 Florent Cade 24 SITE DESCRIPTION John Brewer Reef is a mid shelf reef situated approximately 72km from Townsville.

1 John Brewer Reef Sunferries-Townsville Latitude: S Longitude: E Date: , and Florent Cade 24 SITE DESCRIPTION John Brewer Reef is a mid shelf reef situated approximately 72km from Townsville. It is a lagoonal back reef habitat comprising a number of shallow bommies surrounded by sand. It is a protected yellow zone in the Great Barrier Reef Marine Park. Few boats visit the site but Sunferries takes up to 1 people to the reef 4 days a week. The main anthropogenic impact could therefore be considered to be due to regular scuba diving and snorkelling and the occasional fishing for commercial and recreational purposes. A Crown of Thorns eradication program is in place. There is a large diversity of fish life. Three sites have been surveyed in 24 on three different days. The results of these have been combined to attain a smaller standard error. A comparison has been made to see whether the Crown of Thorns program is making a difference.

2 SUBSTRATE SURVEY Hard coral accounts for approximately 5% of the substrate, all of which was branching Acropora sp. There is approximately 9% of Nutrient Indicator Algae, which is commonly found on rock surfaces and 53% of Rock, 48% of which was dead staghorn Acropora sp. covered in turf algae (see figures 1 and 2) Percent cover Percent Cover of Substrate for John Brewer Reef 5m depth, sites 1-3, , and HC SC RKC NIA SP RC RB SD SI OT Figure. 1: Substrate cover percentages for John Brewer Reef, Rock being the dominant substrate OT SI SD RB RCCA RCTA RC SPE SP NIA RKCTA RKCNIA RKC SCB SCZ SCL SC HCB HCP HCE HCM HCF HCBR HC Percent Cover of Substrate at John Brewer Reef 5m depth, sites 1-3,31-1-4,1-2-4 and Percent cover +/- SE HC SC RKC NIA SP RC RB SD SI OT Figure. 2: Substrate cover at John Brewer Reef

3 INVERTEBRATES SURVEY A large number of Giant Clams were found on the survey site (Figure 1), the majority of which were 1-2cm in length. There were also a few different species of sea cucumbers in the sandy area surrounding the reef patches and a small number of Drupella snails. Mean Abundance +-SE Mean Abundance of Invertebrates at John Brewer Reef 5m depth,sites 1-3, , and Banded coral shrimp Diadema Pencil urchin T. ananas S. chloronotus H. nobilis H. fuscopunctata S. variegatus Crown of Thorns Giant clam Tripneustes Triton shell Figure. 3: Mean Abundance of Invertebrate Target Species Observed at John Brewer Reef. Lobster Trochus Drupella Mean abundance per 1 m Distribution of Giant Clams by Size John Brewer Reef 5m <1 cm 1-2 cm 2-3 cm 3-4 cm 4-5 cm >5 cm Giant clams size Figure.4: The dominant giant clam size at John Brewer was 1-2cm in length

4 IMPACTS SURVEY A number of incidents of other damage was seen (a mean of 4 per 1m 2 ) which was mainly broken coral due to snorkel and diver damage. There was an average of 3 Crown of Thorns scars per 1m 2 (figure 5). Mean Abundance per 1 m Boat/Anchor damage Mean Abundance of Impacts at John Brewer Reef 5m depth,sites 1-3, , and Dynamite damage Other damage Trash: Fish nets Trash: General Drupella scars Crown of Thorns scars Other scars Figure. 5: Other damage and Crown of Thorns scars are the dominant impacts at John Brewer Reef. BLEACHING Approximately 6% of corals had some bleaching. This was commonly the upper surfaces of branching staghorn Acropora sp.and only affected approximately 13% of the corals that were bleached (figure 6). Percentage of Coral Population Affected by Bleaching at John Brewer Reef 5m depth to Figure.6: Corals affected by bleaching at John Brewer Reef 6% Bleached Corals (%) Non-bleached Corals (%) 94%

5 CROWN OF THORNS ERADICATION STUDY RESULTS The surveys were placed in order to attempt to compare hard coral cover in areas where the Crown of Thorns eradication program is in place and where it is not. Although the control area only spanned 5m of our survey the results clearly show that in the control area there is a much higher proportion of hard coral to rock (Figure 7) than in the non-control area where no eradication program is in place (Figure 8). Percentage of Living Hard Coral in the COTs Control Area (John Brewer to ) Hard Coral 21% Rock 79% Figure.7: There is 21% of hard coral cover in the COTs control area at John Brewer Reef Percentage of Living Hard Coral in the Non-COTS Control Area (John Brewer to ) Hard Coral 4% Rock 96% Figure. 8: There is 4% of hard coral cover where the COTs control program is not in place at John Brewer Reef

2: Some bleaching was observed on the upper surfaces of

6 PICTURES Pic.1: There are a number of Crown-of Thorns at John Brewer Reef that prefer to eat the branching Acropora sp. Florent Cade 24 Pic.2: Some bleaching was observed on the upper surfaces of branching Acropora sp.(john Brewer) Florent Cade 24 Pic.3: The nutrient indicator algae Golden Noodle was fairly common in places (John Brewer) Florent Cade 24

STATUS OF REEFS AROUND MAGNETIC ISLAND: REEF CHECK AUSTRALIA

STATUS OF REEFS AROUND MAGNETIC ISLAND: 2003-2006 REEF CHECK AUSTRALIA Zoë Andrews Loren Hartley Jos Hill April 2006 1 INTRODUCTION The purpose of this project was to engage Townsville community members