coral bleaching inspections 2006 · less than 20% of the hard coral community. of these,...

CORAL BLEACHING INSPECTIONS

2006

Climate Change Response Programme

CORAL BLEACHING INSPECTIONS

KEPPEL ISLANDS – January 2006

CAPRICORN BUNKER GROUP - February 2006

General Summary ........................................................................................3 Sea Surface Temperatures ..........................................................................4 Survey Results: Keppel Island Group, January 2006 ...................................5

Halfway Island ..........................................................................................5 Barren Island ............................................................................................6 Egg Rock ..................................................................................................6 Pelican Island ...........................................................................................7 Middle Island.............................................................................................8 Corroboree Island .....................................................................................8 North Keppel Island ..................................................................................9

Survey Results: Capricorn Bunker Group, February 2006 .........................10 Lady Elliot Island.....................................................................................10 Fitzroy Island ..........................................................................................11 One Tree Island ......................................................................................12 Heron Island ...........................................................................................13 Wistari Reef ............................................................................................14 Erskine Island .........................................................................................15 Masthead Island .....................................................................................16

GBRMPA Climate Change Response Programme 2006 2

General Summary The first signs of coral bleaching were reported by BleachWatch participants and coral reef scientists in January 2006. Seven BleachWatch reports were received of moderate to severe coral bleaching at Heron Island, the Keppel Islands and Lady Elliot Island. The Climate Change Response Programme implemented investigative surveys at a number of sites to verify these reports of moderate to severe bleaching. In late January 2006, inspections were conducted in the Keppel Islands with the assistance of Queensland Parks and Wildlife Service (QPWS) at seven sites, most of which were core GBRMPA bleaching sites (also AIMS Long Term Monitoring sites and QPWS long-term monitoring sites). In early February 2006, inspections were conducted at the Capricorn Bunker Group with the assistance of QPWS and Lady Elliot Island Resort. Nine sites were inspected, with One Tree Island being a core GBRMPA bleaching site. Hard coral cover and diversity in the Keppel Islands was generally high but variable between transects and sites (20%-95%). Moderate to severe bleaching was observed at five of the seven sites surveyed, with greater than 65% of corals showing signs of bleaching i.e. paling, fluorescing or upper surfaces bleached. Hard coral cover and diversity was generally high at Lady Elliot Island and the Capricorn Bunker Group (36%-92%), although diversity was lowest on the reef flats at Lady Elliot Island (18%) and Heron Island (13%). Moderate to severe bleaching was observed at most sites, with only the two exposed sites at Lady Elliot Island and Fitzroy Reef showing no signs of bleaching. Overall, the observations are consistent with the early signs of spatially extensive mass bleaching in the southern region. The amount of bleaching observed is representative of the impacts to be expected from severe thermal stress this summer, and the region has been experiencing sea surface temperatures 1 – 2.5 degrees C above long-term monthly averages since December 2005 (ReefTemp data).


Sea Surface Temperatures

igure 1. Anomalous sea surface temperature: Figure 2. NOAA HotSpot chart in degrees C:

ea surface temperatures (SST) in the southern GBR exceeded the expected erage

ded

F23 Jan 2006 4 Feb 2006 Smonthly average in December 2005 and remained significantly warmer than av(0.5 - 2.5 degrees C) through all of January 2006 (Figure 1). SST conditions in early February exceeded the long-term summer maxima by up to 2 degrees C (Figure 2). In contrast, heavy cloud cover and rain over northern parts of the GBR kept SST close to average for most of January but began to increase in early February (Figures 3 & 4). Central GBR waters warmed during February, and SST exceethe monthly long-term average by 0.5 - 1.5 degrees C (Figure 3). Consistent with these temperature patterns, reports of severe coral bleaching were confirmed for reefs in the southern region during coral bleaching inspections conducted by the Climate Change Response team and reported in this document.

Figure 3. Anomalous SST: 6 February 2006

Figure 4. Degree heating days: 6 February 2006


Survey Results: Keppel Island Group, January 2006 The Keppel Island Group lie approximately 15 km offshore from Yeppoon in the southern region of the Great Barrier Reef. There are nine main islands and a number of rocky outcrops in the island group. Sites that were inspected include Halfway Island, North Keppel Island, Pelican Island, Egg Rock, Barren Island, Middle Island and Corroboree Island. Rapid assessment surveys of coral communities and bleaching level were conducted at all sites on mid-slope (6-9 m depth) and upper reef slope (3-4 m depth). Video transects were recorded at the worst affected sites, on the mid-slope and upper reef slope. The aim of these inspections was to document the amount and severity of coral bleaching at these sites, and to provide a general assessment of the condition of these sites. Halfway Island HC Cover

SC Cover

Bleaching level

90% 0% Category 5 – 95% of colonies bleached; Affected colonies generally upper surfaces or fluorescent

The reef at this site had high hard coral cover, dominated by very dense branching Acropora thickets. No soft corals were present. Branching Acropora were the dominant coral type on both the shallow (3 m) and deep (5 m) transects, making up 95% of the hard coral community. Small numbers of faviids were present on the lower reef slope, making up less than 5% of the hard coral cover.

Large stands of branching Acropora were severely bleached, with 90% of corals in the shallow transects and 100% of corals in the deep transects with upper surfaces bleached or colonies fully white. Many of the tabular Acropora were fluorescing green, yellow and blue. The extensive vista of bleached Acropora was a spectacular feature of this site. The Keppel Island region has experienced elevated sea surface temperatures since December 2005, and the severe bleaching observed is the likely result of this extended heat stress.


Barren Island HC Cover SC

Cover Bleaching level

57-92% 0-7% Category 4 – 67% of colonies bleached; Affected colonies generally upper surfaces or fluorescent

This site had a steep drop-off from the shore down to 5 m depth, and the lower slope was extensively terraced. The reef at this site had abundant hard corals, with no soft corals in the shallow transects and only very few in the deep transects. Branching and tabular Acropora were the dominant coral types on both the shallow (2 m) and deep (5 m) transects, making up 60-95% of the hard coral cover. Faviids, pocilloporidsMontipora and Porites made up on average less than 20% of the hard coral community. Of these, pocilloporids and faviids were more abundant on the upper reef slope, and Porites was the only family other than Acropora on the lower reef slope, making up approximately 5% of the hard coral cover.

,

All coral families except Porites were showing signs of severe bleaching, with 47% of corals in the deep transect and 87% of corals in the shallow transect showing signs of bleaching. Corals in the shallow transects were primarily bleaching on upper surfaces while the most dominant bleaching in the deep transect was paling and fluorescing. Egg Rock HC Cover

SC Cover

Bleaching level

20-23% 18-30% Category 3 – 40% of colonies bleached; Affected colonies generally paling or fluorescent

This site had a steep rock wall down to 20 m depth, with the upper slope including terraces and ledges. The reef at this site had moderate hard and soft coral cover, with soft corals dominating in the deep transects. Branching Acropora, faviids and pocilloporids were the dominant coral types on the deep transects (9 m), with Montipora, Porites and Goniopora making up 15-20% of the hard coral community. Acropora (branching and tabular), pocilloporids and faviids were the dominant hard corals on the upper reef slope (6 m), with acroporids accounting for approximately 60% of the hard coral cover.


Large stands of encrusting Montipora and Acropora, were prominent throughout the area. A diversity of less common taxa made up the remainder of the community in both upper and lower parts of the reef slope, including Turbinaria, Tubastrea and Platygyra. Common soft corals included Sinularia, Sarcophyton, Lobophyton and Xenia.

All coral families except Porites were showing signs of bleaching, with 43% of corals in the deep transects and 37% of corals in the shallow transects showing signs of bleaching. Corals in both the shallow and deep transects were primarily bleaching on upper surfaces, paling or fluorescing. The bleaching observed at this site is less than any other site surveyed in the Keppel Island Group. This is a deeper site, located on the windward side of the Keppel Islands, and as a result of this likely to have experienced ocean cooling.

Pelican Island HC Cover SC


50-57% 8% Category 3 – 47% of colonies bleached; Affected colonies generally paling or fluorescent

This site is an inshore site, with lower visibility. The reef at this site had moderately abundant hard corals, with soft corals only present in low numbers in both deep (6 m) and shallow (2 m) transects. Branching and tabular Acropora were the dominant coral types on the deep transects (approx. 66%), with Montipora, faviids, pocilloporids and Porites making up 30% of the hard coral community. Acropora (branching and tabular) were also the dominant hard coralon the upper reef slope, accounting for approximately 66% of the hard coral coveMontipora, faviids, pocilloporids and Porites made up 30% of the hard coral community.

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A diversity of less common taxa made up the remainder of the community in both upper and lower parts of the reef slope, including Turbinaria and Platygyra. Large stands of sargassum and padina were present throughout the area. All coral families showed some signs of bleaching, with 50% of corals in the deep transects and 43% of corals in the shallow transects affected. Corals in both the shallow and deep transects were mainly bleaching on the upper surfaces, paling or fluorescing.


Middle Island HC Cover

SC Cover

Bleaching level

83% 4% Category 5 – 92% of colonies bleached; Affected colonies generally bleached on upper surfaces

This site had a gently sloping fringing reef with little depth stratification. The reef at this site had abundant hard corals, with soft corals only present in low numbers in the one depth that was sampled (6 m). Acropora were the dominant coral type on the lower reef slope representing 80-90% of the hard coral community, with Montipora, faviids, pocilloporids and Porites making up the remaining 10-20%. Soft corals were low in abundance and included Sinularia and Sarcophyton. The Acroporids and faviids were the most seriously bleached corals, with 92% of corals in affected. Affected corals were bleaching on upper surfaces, paling or fluorescing. Corroboree Island HC Cover SC


67% 0% Category 5 – 100% of colonies bleached; Affected colonies generally paling or totally white

This site had the highest levels of coral bleaching, with extensive thickets of Acropora affected. The reef at this site had abundant hard corals, with no soft corals present in the one depth that was sampled (3 m). Branching and tabular Acropora were the dominant coral types (90-95%), with Montipora, faviids and pocilloporids making up only 5-10% of the hard coral community.

This site was the most affected site in the Keppel Islands in terms of extent of coral bleaching. Extensive thickets of Acropora were paling or fully white, as were the faviids and pocilloporids. Montipora were the only corals unaffected, however, were present in such low abundance, that the site was recorded as having 100% of corals bleached.


North Keppel Island HC Cover SC


43-77% 0% Category 5 – 94% of colonies bleached; Affected colonies generally paling or totally white

This site had a gently sloping fringing reef, with extensive stands of Acropora. The reef at this site had abundant hard corals, particularly on the upper reef slope, and no soft corals.

Branching and tabular Acropora were the dominant coral types on the deep transects (90-100%), with Montipora, pocilloporids and fungids making up 5-10% of the hard coral community. Acropora (branching and tabular) were also the dominant hard corals on the upper reef slope (3 m), accounting for approximately 90% of the hard coral cover. Montipora, pocilloporids and Porites made up the remaining 10% of the hard coral community. The lower reef slope (6 m) had extensive areas of old dead standing coral with small colonies growing amongst the rubble. Large stands of padina and filamentous turf were present on the rubble.

Large stands of branching Acropora were severely bleached, with 95-100% of acroporids in the shallow transects and 90% of acroporids in the deep transects paling or fully white. Many of the Acropora in the shallow transects were fluorescing with many pastel colours observed. Some Monitpora, Porites and fungid colonies were unaffected by bleaching, however, 93% of corals on the lower reef slope and 95% of corals on the upper reef slope showed some signs of bleaching.


Survey Results: Capricorn Bunker Group, February 2006 The Capricorn Bunker Group of reefs is offshore from Gladstone and includes islands and cays that are inhabited, as well as reefs that are representative of offshore reef types. Sites that were inspected included Lady Elliot Island, Fitzroy Reef, One Tree Island, Heron Island, Wistari Reef, Erskine Island and Mast Head Island. Rapid assessment surveys of coral communities and bleaching level were conducted at all sites on mid-slope (6-9 m depth) and upper reef slope (3-4 m depth), except Mast Head Island where time only permitted an inspection of the upper reef slope. Video transects were recorded at Lady Elliot Island, Fitzroy Reef and One Tree Island, on the mid-slope and upper reef slope. Two of the nine sites had moderate bleaching levels with greater than 50% of corals showing signs of bleaching, primarily upper surfaces and fluorescing, and four sites had between 30-50% of corals showing signs of bleaching. Lady Elliot Island HC Cover SC


S1. 60-92% S2. 45-52% S3. 18-23%

0-2% 0% 0%

Category 0 – 0% bleaching Category 0 – 0% bleaching Category 3 – 37% of colonies bleached

Site 1. Flank of Island. No bleaching was observed at either depth at this site. The deep site (9 m) had a moderate slope of outcrops, gullies and shallow spurs leading to a sand base at 12 m. The hard coral community (60%) was dominated by fields of branching Acropora and tabulate Acropora. None of the tabulate colonies were larger than 1 m in diameter, which is likely to be the result of extensive physical damage caused by a cyclone in 1992. Other coral groups present included Montipora, and faviids. The shallow site (3-5 m) had large spurs supporting high coral cover (92%), dominated by tabulate and branching Acropora. Other coral groups present were pocilloporids and Montipora. There was no sign of bleaching at either depth but patches of disease were noted. Some anchor damage was observed. Site 2. The Arches. No bleaching was observed at either depth. The reef slope is convoluted, allowing for varied coral habitat. Both the deep slope (9 m) and shallow slope (3-5 m) have moderate hard coral cover (45-50%) dominated by Acropora and Montipora corals. Other corals present include Porites and pocilloporids (deep slope), and Pavona and Echinopora (shallow slope). Some patches of disease were noted on Montipora, Acropora and faviids (possible ‘White Syndrome’). A notable feature of this coral community was the abundance of fleshy macroalgae among the bases and branches of Acropora (principally A. formosa and A. tenuis) and digitate Montipora. The algae appears to be a combination of macroalgae, turf algae and cyanobacteria.


Site 3. Reef Flat. Minor bleaching of a few isolated colonies, particularly S.hystrix and Acropora, was evident on the reef flat. The reef flat is a consolidated matrix of hard substrate covered in turf algae with large pockets and fissures supporting patchily distributed coral communities. The exposed and shallow habitat reduces the opportunity for extensive colony growth. The hard coral community was sparse (18%) and dominated by branching, digitate and sub-massive Acropora. Other common corals included Montipora, faviids, Pavona and pocilloporids. Bleaching was patchily distributed within and between coral species, and restricted to the paling of upper surfaces. Most Acropora millepora and A. palifera showed paling. Paling was also observed in Platygyra daedalea, Pocillopora damicornis, and Goniastrea retiformis. Bleaching was variable within the Montipora sp, with some colonies fully white. Other coral groups appeared unaffected including Pavona decussata and massive Porites sp. Bleaching was observed among anemones but not among tridacniid clams.

Fitzroy Island HC Cover SC


43-53% 10-12% Category 0 – 0% bleaching

North-west back-reef slope site. No bleaching was observed among coral communities at either the deep (7 m) or shallow (3 m) transects. The reef structure had gullies and spurs in the shallows and a continuous, moderate, slope to a base at 12-15 m. The hard coral community (47%) was composed principally of Acropora branching corals (mainly, but not limited to A. formosa, A.nobilis, A. micropthalma) and a few other coral groups (mainly, but not limited to faviids: Platygyra, Leptoria; and Merulinidae: Hydnophora).


One Tree Island HC Cover SC


62% 5-18% Category 2 – 28% of colonies bleached; Affected colonies bleached on upper surfaces

Western back-reef slope site. Bleaching was observed on upper surfaces of corals at both depths. The deep slope site (7-8 m) was a broad flat area with a very shallow slope to depth. Hard coral cover was extensive (62%), principally of branching Acropora (a combination of A. formosa and A. nobilis). Paling on the upper surfaces was observed for most A. formosa colonies but not for A. nobilis colonies. Thus bleaching at depth appeared patchy. Other corals at the deep site included Platygyra, foliose Montipora, and Pocillopora. Some Pocillopora colonies showed paling while other Pocillopora colonies appeared to have full colour. The presence of soft coral (principally Sinularia sp.), and algae (a combination of Halimeda sp., extensive turf algae and cyanobacteria) was noted among the lower branches of Acropora sp. In the shallows (2-3 m) more bleaching was evident among the dominant branching Acropora. Paling on upper branches was observed for both A. formosa (more abundant in the shallows) and for A. nobiOther corals present showing signs of bleaching include foliose Montipora (somecolonies white, some colonies fluorescent), Platygyra and Leptoria (some paling), Stylophora (a few colonies were fluorescent),and Pocillopora (some colonies pale, otcolonies f

lis.

her

ull colour). The presence of disease among several branching Acropora colonies and some Pocillopora colonies at both depths was noted. Typically, the disease seems to have spread upward from the lower stem to the tip of the branch.


Heron Island HC Cover SC


13-43% 1% Category 4 – 55% of colonies bleached; Affected colonies bleached on upper surfaces and paling

South-west back-reef slope site. Bleaching was observed at both depths, with bleaching more severe on the lower slope (6 m). The hard coral cover on the deep slope was 43% and dominated by branching Acropora (principally A. formosa and A. nobilis). There were extensive formations of dead standing coral (not recent) covered with turf algae. Other coral groups present but not abundant include Montipora, Pocillopora, Porites and faviids. Acropora, Montipora and Pocillopora corals showed a range of bleaching with both Acropora and Montipora exhibiting white bleaching, and a few Acropora colonies were dead. The reef flat (1-2 m) was a consolidated matrix of hard substrate broken by shallow channels and sand pockets. Hard coral cover was sparse (13%), widely scattered and composed principally of digitate Acropora (A.millepora, A. digitifera, and compact A. formosa) and sub-massive Acropora (A. palifera). Among the Acropora few colonies were completely bleached (cf the deep slope); most were ¾ pale, with colour remaining on the undersides of branches. Of the other corals present, Goniastrea had full colour, branching Montipora had some colonies paling, foliose Montipora had colonies with fluorescing edges, and the occasional Goniopora was observed to be fluorescing yellow. The impact of bleaching among other benthic fauna was variably distributed: the zoanthid Palythoa (very pale), the soft corals Sarcophyton (fluorescing yellow) and Klyxum (full colour) and tridacniid clams (full colour).


Wistari Reef HC Cover SC



North-east back-reef slope site – opposite Heron Island site across the channel separating both reefs. A moderate amount of bleaching was observed, mainly at the deep site (6-7 m). The deep reef slope has a sheltered aspect and was comprised of a series of spurs and channels that dropped quickly to a sand base at 6 m. Hard coral cover was moderate (58%) and composed mainly of branching, tabulate and sub-massive Acropora (A. formosa, A. nobilis, A. hyacinthu and A. palifera). Other common coral groups include Montipora, Pocillopora, Porites, faviids, Astreopora and Pavona. Bleaching of Acropora was confined to the branching forms and manifest as paling and fluorescing. The majority of Montipora were pale or fluorescing while some Platygyra and Leptoria were pale on upper surfaces only. No signs of bleaching were observed in Porites colonies. It was noted that some stands of branching Acropora with pale tips had dense turf algae on lower branches suggesting some disease event in the recent past.

By contrast the upper reef slope / reef flat (2 m) had much less hard coral cover (25%) and extensive consolidated hard substrate. Acropora dominated the coral community in branching and tabulate forms, with Montipora, pocilloporids and faviids much less common. Bleaching was minor and variably distributed in the shallows, with only a few Acropora and faviids showing paling on upper surfaces. A few colonMontipora colonies were fluorescing, while most Pocillopora sp. were pale or

fluorescing. It was noted that where zoanthid colonies were observed they were all pale.

ies of


Erskine Island HC Cover SC



West back-reef site. Bleaching was patchily distributed throughout the coral community at both depths. The deep slope has a slight gradient to a sand base at 6m. The slope was broken and patchy with hard coral cover a relatively modest 22%. Acropora tabulate and branching forms dominated the coral community, with other less common corals present Montipora, pocilloporids, Porites and faviids. The impact of bleaching is variable within and between species; while some colonies showed no colour change others were pale, fluorescing and, for some Montipora and Porites colonies, completely white. The shallow reef flat (2 m) was formed from outcrops of solid substrate on sand. Coral cover (36%was only slightly greater than the deep site and was dominated by Acropora corals, mainly tabulate forms (principally A. hyacinthus), withdigitate, branching and sub-massive Acropora forms less common. Ocorals include Montipora, faviids, pocilloporids and Porites. Bleaching impact was mixed with most coral groups showing a range of responfrom none to fluorescing / pale. Some A hyacinthus (60-100 cm diameter) were observed to fluoresce green or cream colour. Paling was noted among A. palifera and fluorescing was observed in some small Porites massives and Goniopora sp. Among the soft corals most retained full colour while some were fluorescent yellow. Colonies of the zoanthid Palythoa were b

)

ther

ses

leached pale.


Masthead Island HC Cover SC


62% 0% Category 5 – 87% of colonies bleached; Affected colonies bleached on upper surfaces or fluorescing

West back-reef site. Signs of bleaching were observed among most corals. The shallow reef slope (3-4 m) formed from spurs of hard substrate on sand. Hard coral cover was high (62%) and dominated by large stands of branching Acropora (mainly A. formosa and A. nobilis). Tabulate Acropora (mainly A. hyacinthus and many colonies > 1 mdiameter) was common in shallower water (2-3 m). Other corals included Montipora, pocilloporids, Porites, afaviids. Bleaching impact was widespreaand varied, with most corals exhibiting paling, bleaching on upper surfaces or

fluorescing. Among the branching Acropora somestands exhibited blue fluorescing A. formosa among colonies of white A. formosa. Tabulate Acropora in the shallows were only slightMost Montipora were bleached white or fluorescing green, blue and yellow, especially the foliose form. Leptoria and Echinopora were pale. The encrusting so

nd d

ly pale.

ft coral Briareum appeared to be uorescing pink.

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coral bleaching inspections 2006 · less than 20% of the hard coral community. of these,...

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