coral reef status in 2009 maldives reefs

8/7/2019 Coral Reef Status in 2009 Maldives Reefs

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N.J. Quinn and H.N.J. Quinn and H. ZahirZahir

Marine Research Centre, MaleMarine Research Centre, Male

Republic of MaldivesRepublic of Maldives


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y The Maldives ~1192

islands with a 300 km2

land mass

y Exclusive economic zone

of 859,000 km2

y Within atoll lagoon and

reef areas ~21,300 km2

y

The 26 atolls lie along anorth-south axis between

7o N to 0.4oS and from

72o- 73o E. longitude in

the central part of the

Chagos Maldives Laccadive ridge in the

central Indian Ocean


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Reef Check survey techniques were used to monitor a suite of

biological indicators of coral reef health from a geographically

diverse set of lagoon, shallow reefs from northern Haa Dhaalu to

Addu atoll, south of the equator.


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The Marine Research Centres National Coral Reef Monitoring

Survey data provided an historical record, along with other outside

agency studies, for assessing the recovery of Maldivian coral reefs to

natural disasters in the past 12 years.


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The unprecedented coral bleaching in 1997 - 1998 around the world

including the Maldives, resulted in extensive mortality to scleractinian,

reef building corals.


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y Coral cover on Haa Dhaalu atoll was nearly 0% after the 1998

bleaching event.

y Subsequent reef recovery was slow with coral cover only

achieving 3-5% in 2005.

y However, since 2005, coral cover has been rapid.


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0

10

20

30

40

50

60

70

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

%C

oralCo

Hondaafushi

Finey

Hirimaradhoo

Coral cover on the northern reefs of Haa Dhaalu atoll was

nearly 0% after the 1998 bleaching event.

Subsequent reef recovery was slow with coral cover only

achieving 3 - 5% in 2005.

Since 2005, coral cover has been rapid.


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HaaHaa DhaaluDhaalu AtollAtoll

y In 2009, coral cover ranged from 14%-29%.

y

This was collectively the lowest coral cover for all the atolls surveyed.


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0

10

20

30

40

50

60

Hon'daafushi Finey Hirimaradhoo

%C

oralCover

3 m

10 m

Hondaafushi & Finey had higher coral cover at 10m than at 3m

Hondaafushi coral cover -50%, Finey coral cover 21%

At Hirimaradhoo because zooanthid was dominating the reef,

hard coral cover was the least of the Haa Dhaalu sites with only

14% cover at 3 m and 0.6% at 10 m

2009


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North and South Male Atoll

0

10

20

30

40

50

60

70

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

%C

oralCover

Boduban'dos

Udhafushi

aniyafushi

nboodhoofinolhu

Udhafushi was the outer reef slope of a faru in the center of North

Male atoll. From the post bleaching coral cover of 1.3% in 1998, the

site recovered slowly to 2.9% in 2002

Enboodhoofinolhu had the lowest live coral cover in NCRMS in

2009. The reef has been used for sand mining for several decades.

Coral cover at Bodubandos

after the 1998 bleaching was

2% . Coral cover increased

6.9% in 2002.Subsequent to the 2002

survey construction of a

harbour for the Bandos

Resort occurred adjacent to

the survey site. Despite the

nearby harbor the coral

cover increased to 41% in

2009. This is a remarkable

recovery!!


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0

10

20

30

40

50

60

70

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

%C

oral

Fesdhoo

Velidhoo

Maayafushi

Dega Giri

Kandholhudhoo

Ari Atoll

The shallow reefs of Fesdhoo, Maayafushi, Velidhooexhibited

exceptional resilience.

In 2005,most ofthese reefs hadcoralcover lessthan 11%.

Afterthebleaching event Fesdhooquickly recoveredto 10%coralcover in 2000.By 2005 it had over 30%coralcover.In 2009, itwas

amongthemost luxuriant reefs surveyedwith about 65%coral

cover.

Velidhooreef also demonstrated remarkable recovery from about

11% in 2005to 50% in 2009.


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After the sampling in 2005 the hotel atAfter the sampling in 2005 the hotel at MaayafushiMaayafushi reef hadreef had

expanded constructing water bungalows over the reef flat and withinexpanded constructing water bungalows over the reef flat and within

100 m of the reef edge.100 m of the reef edge.

It does not appear that the sedimentation associated with theIt does not appear that the sedimentation associated with theconstruction of the bungalows greatly thwarted the recruitment ofconstruction of the bungalows greatly thwarted the recruitment of

new corals by either smothering new recruits or covering suitablenew corals by either smothering new recruits or covering suitable

substrate with silt rendering then unsuitable for settlement.substrate with silt rendering then unsuitable for settlement.

Much of the recovery in these sites is due to successful recruitmentMuch of the recovery in these sites is due to successful recruitment

and growth of primarilyand growth of primarily acroporidacroporid colonies and to lesser extentcolonies and to lesser extent

pocilliporidpocilliporid colonies.colonies.

MaayafushiMaayafushi reef also had good recovery from 6% in 2005 to 31%reef also had good recovery from 6% in 2005 to 31%

coral cover in 2009.coral cover in 2009.


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Kandholhudhoo is a picnic island with beautiful beaches naturally

replenished by a diverse, healthy coral reef which surrounds the island

Kandholhudho reef

showing some

physical damage and

partial mortality to

tabulate Acropora

and intact tabulate

Acropora colonies,

March 2009.


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Addu Atoll

Addu atoll were subjected to the 1998 bleaching event, but had

the greatest recovery of live coral cover in sites distant from

anthropogenic influences. After the 1998 bleaching, the reefs at Addu atoll still had some

living coral.

1

199 1998 1999 1 8 9 1

%

CoralCove

GanVillingili

Hithadhoo


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The Vilingili reef had about 4% coral cover in 1998

increasing to 13% in 2002.

In 2009, the coral cover had increased to 55% in spite of its

proximity of the development of resort water bungalows and

beach restoration efforts.


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Recently killed coral was observed at Vilingili reef, but

only covered 0.3% of the substrate in the two transect

lines.


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Large colonies ofPorites lobata were common at Vilingili reef, May

2009.

Porities are slow growing corals

Indicate continuous coral community over the past several decades.


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A member of the MRC coral reef monitoring team conducting a survey

along four 20 m transects at Hithadhoo reef, Addu atoll in May 2009


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Assessing the recovery of the reefs in the Maldives is like the story

of three blind men each describing an elephant by touching the

trunk, leg or tail.

There is considerable variation among reefs and among habitats

within reefs.

This variation is a function of the wide latitudinal range of the atolls,

the structure of the atolls and chance.

These factors create considerable variation in the abiotic factors

that influence reef development and, therefore, considerable

variation among reefs.

The recovery of most of the reefs surveyed during the past decadeis remarkable and suggests the question:

Where were the new recruits coming from????


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Increasing sea water temperatures still threaten coral reefs.

Coral bleaching occurred in July2010.


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Reef restoration activities are an important way to enhanceReef restoration activities are an important way to enhancecoral recovery near areas used by human visitorscoral recovery near areas used by human visitors


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A detailed study of currents around the Maldives would help to

determine the larval dispersal for both invertebrate and reef fish

stocks.

This information is necessary to better understand and manage

these larval source communities.


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AcknowledgementsAcknowledgements

MRC Director ShihamA d a m i s g r a t e f u l l y

acknowledged for his

e nc ou ra ge me nt a n d

hospitality to N.J. Quinn

N. Thoufeeq, H. Amir, and

Y. Rilwan assisted in the

data collection and data

entry. B.L. Kojis assisted

with the reef surveytraining . Their assistance

and good cheer helpedexpedite the expeditions.


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Captain Shareef and crew of the M.V. Mohara, Captain Anwar ofM.V.

Gaaviya and Captain Adam of M.V. Noah provided the safe and

comfortable logistical platform for our field trips.

NJQ is grateful to the US State Department for the Senior Fulbright

Fellowship.

AcknowledgementsAcknowledgements

coral reef status in 2009 maldives reefs

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