The Health and Growth Potential of the

Reefs of Tern Cay

Yannique EwersRyan Nembhard

Judith Mendes

Tern Cay

Tern Cay

Backreef transects

Forereef transects

Location of Study sites

Biorock Artificial Reef

Studies conducted

• Coral Species Richness visual survey

• Substrate (Coral & Algae) Abundance survey

• Diadema (Long-spined black urchin) survey

• Coral Recruit survey

Coral Species Richness

• 32 species in Jamaica above 25 feet

• 13 species at Tern Cay above 25 feet

• 40% of maximum species richness

First Conclusion

• Relative species richness is high (40%)

• Good for reef rehabilitation

Coral and Algal Abundance

Coral and Algal AbundanceTern Cay Feb 2013

0.7

75.3

21.7

4.3

45.5

35.6

0

20

40

60

80

100

coral algae sand & rubble

Pe

rce

nt

cove

r (%

+/-

1sd

)

Backreef Forereef

Character of reef depends on interaction between slow growing corals and fast growing algae.

This interaction is mediated by herbivorous fish and urchins

Herbiverous fish (parrot, doctor)population reduced by fishing

Before 1983 Caribbean reefs still had high densities of Diadema antillarum and

algae was not a problem

After Diadema mass mortality

Before Diadema mass mortality

Phase-shift from coral to algal dominated reefs Discovery bay, Jamaica (Hughes, 1994)

Impact of Diadema die-offExample from Discovery Bay

Diadema Survey

13.9

0.2 0

4.8

1.32.35

0.1 0.20

2

4

6

8

10

12

14

16

1982 1983 1984 2007 2008 2009 2011 2013

Dia

de

ma

pe

r m

2

Mass mortality of Diadema

Discovery Bay

Mexico Puerto Rico

Bahamas This Study

Impact of storms on algal abundancein the Backreef of Tern Cay

0

20

40

60

80

100

sept oct nov dec jan feb mar

Pe

rce

nt

co

ver

(%+/

-SD

)Hurricane Sandy strikes Jamaica

24th Oct 2012

Bio

rock

reef

inst

alle

d

2012 2013

Impact of Hurricane Sandy on algal abundancein the Backreef of Tern Cay

12th October 2012 2nd November 2012

Path of Hurricane Sandy across Jamaica

24th October 2012

November 2012 February 2013

Same pattern of algal abundance on Biorock Reef

Second Conclusion

• No biological control (by herbivores) of macroalgae at Tern Cay

• Abundance of macroalgae dependant only on intensity wave action and time elapsed since last storm

Why it is so difficult to return to coral dominated reefs

Coral Recruitment Survey Method

Data Labels on ruler –

Fluorescent on frame b

Skirt- blocks

excess light

Black cloth to mimic

dark conditions

Position of camera a

b

Coral Recruitment Survey Method

Coral Recruitment Results(Jamaica)

Year No of Recruits per m2 Location Study

1980 60 Discovery Bay Sammarco (1980)

1983 378 Discovery Bay Ryslardam (1983)

2002 1- 6.4 Rackhams Cay Wilkinson et al (2002)

2005 0.3 - 8 Discovery Bay Quinn & Kojis (2005)

2013 0.2 Tern Cay Present Study

Diadema mass mortality

Third Conclusion

• Natural recruitment very low

• Regeneration of reef unlikely/very slow without intervention

Summary of Conclusions

1. Relative species richness is high (40%).– Good for reef rehabilitation

2. No biological control of macroalgae at Tern Cay.– Abundance of macroalgae dependant only on

intensity wave action and time elapsed since last storm

3. Natural recruitment very low.– Regeneration of reef unlikely/very slow without

intervention

Recommendations

1. Use biorock reef as reproductive hub

– Attach large reproductively mature corals

• Increase chance of fertilization

• Ideal location for transport of gametes/larvae to other reefs in PBPA

Biorock Reef in Thailand

Recommendations

2. Increase herbivory– Already in fishing sanctuary (no-fishing zone)– Actively restore Diadema in sanctuary

• Move adult Diadema into sanctuary• Grow Diadema in laboratory

3. Monitor condition of reefs to determine if actions are working

4. Extend study to other sites in PBPA

Acnowledgements

• C-CAM

– Brandon Hay

• UWI Department of Life Sciences

– Ryan Nembhard

– Judith Mendes

• Port Royal

– Hugh Small

– Terrence Hall