Agincourt Pontoon Quicksilver Connections, Port Douglas

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1 Quicksilver Connections, Port Douglas Written by Florent Cadé and Sam Birch and the Reef Check Australia Team. Edited by Jos Hill. Latitude: Longitude: 8 978S E Date: --4 and 3--4 SITE DESCRIPTION Photo by Florent Cadé 4 This Reef Check survey site is off Quicksilver Connection s Pontoon and is visited by some -4 people per day. The pontoon is situated at Agincourt Reef number 3 and is NM from Cape Tribulation. It lies on a back reef that comprises of a shallow reef flat, coral bommies and sandy patches. The maximum depth of the site is m. The survey site is within a Marine Park Green Zone and the only anthropogenic impact recorded was a small amount of broken coral, possibly caused by some of the numerous tourists who visit the site. There was a cyclone over years ago, which likely caused some of the rubble that was observed at this site. In 3, Reef Check surveys were conducted. In 4 three Reef Check surveys were conducted. All substrate data from each Reef Check survey within the Reef Check survey site have been combined for each year. Reef Check volunteer researchers conducting the invert/impact survey.

2 SUBSTRATE SURVEY Hard coral cover was high at 4%, 3% of which was branching coral (mainly Acropora sp.). There was % rock and.% of recently killed coral (figure ). The dominant algae were the golden noodle algae (Chrysosystis fragilis) (figure see the photograph below). The growth of golden noodle algae may be a consequence of recent reductions in live coral cover as a result of previous disturbances by crown-of-thorns starfish and/or bleaching. There is some evidence that hard corals overgrown by golden noodle sustain tissue damage. There is very limited information on the biology and distribution of golden noodle algae on the GBR and it may have been recently introduced or may indicate chronic disturbance of the reefs in the GBR region. Chronic blooms of this species have the potential to impede recovery of disturbed reefs. A CRC Reef project will explore conditions that trigger and promote the growth of this type of alga, its reproduction and dispersal mechanisms, and its potential impacts on the health and recruitment of hard corals (see During 4 Reef Check provided information to the CRC Reef on the location of golden noodle algae blooms on the Reef. Percent cover Percent Cover of Substrate for m depth 3--4 HC SC RKC NIA SP RC RB SD SI OT OT SI SD RB RCCA RCTA RC SPE SP NIA RKCTA RKCNIA RKC SCB SCZ SCL SC HCB HCP HCE HCM HCF HCBR HC Figure : Substrate and coral percent cover for the 3 Reef Check transect sites combined. The nutrient indicator algae Golden Noodle was observed on some rubble areas.

3 Substrate Monitoring 3-4: During 3, x Reef Check surveys ( Reef Check transect sites) were conducted at this dive site, with 3 being conducted during 4. All the data have been combined in the graph below (figure ). Hard and soft coral cover remained constant between 3-4. However, the abundance of nutrient indicator algae (NIA) decreased, while recently killed coral (RKC) and encrusting sponges (SP) increased. Mean Percent Cover of Benthic Communities at (m depth 3 to 4) /3/3 sites 3//4 3 sites 4 4 Percent cover +/- SE 3 3 HC SC RKC NIA SP RC RB SD SI OT Substrate type Figure : Percent cover of major substrate categories between 3-4. Limitations of this survey: Slight differences in the substrate categories from year to year are likely due to the variation on the reef as transects are not placed in exactly the same place, but are placed in the same area with the aim to encompass the same habitat. We anticipate that differences of less than a % change in percent cover of a substrate category cannot be determined from these data and those within a % range (or more if error bars overlap between years) should be interpreted with care. Higher precision would be achieved with use of additional transect replicates. INVERTEBRATES SURVEY There was a mean of 3.7 giant clams per m of the transect, the majority of which were less than cm in length but some greater than cm in size were also observed. Diadema sp., Trochus sp. and Drupella sp. were found in low abundance (see figures 3 and 4). Mean Abundance of Invertebrates at m depth 3--4 Mean Abundance +-SE Banded coral shrimp Diadema Pencil urchin T. ananas S. chloronotus H. nobilis H. fuscopunctata S. variegatus Crown of Thorns Giant clam Tripneustes Triton shell Lobster Trochus Drupella Figure 3: Invertebrate abundance. 3

4 Distribution of Giant Clams by Size ( 3--4). Mean abundance per m.. < cm - cm -3 cm 3-4 cm 4- cm > cm Giant clams size Figure 4: Giant clam size classes. One of the many friendly groupers at. Photo by Florent Cadé 4 4

5 IMPACTS SURVEY The majority of impacts fell into the other damage category, which included broken coral by divers and snorkellers and/or the effects of storm damage (figure ). There were few other impacts. We observed an incidence of coral black-band disease and a calcareous growth on the exterior of the polyps. Less than an estimated.% of corals were affected by bleaching, although a higher incidence of bleaching was observed by Reef Check volunteer researchers on the Great Barrier Reef and Coral Sea towards mid-march. Mean Abundance per m Boat/Anchor damage Mean Abundance of Impacts at m depth 3--4 Dynamite damage Other damage Trash: Fish nets Trash: General Drupella scars Crown of Thorns scars Other scars Figure : Abundance of impacts. Black band disease on staghorn Acropora sp. Disease only affected.% of the coral population. Photo Photo by by Sam Sam Birch Birch 4 4 An unidentified calcareous growth on the exterior of the polyps-this was the only colony found. Birch 4 Drupella sp. scars. Coral bleaching.