Grimsditsch et al Pemba Resilience Survey 2009 low res
Grimsditsch et al Pemba Resilience Survey 2009 low res.pdf Grimsditsch et al Pemba Resilience Survey 2009 low res.pdf
Detailed Results Moderate Faviid Susceptible Misali Misali Misali Moderate non-Faviid Fundo Gap Shimba Transform: Square root Resemblance: S17 Bray Curtis similarity Njao Gap Msuka Bay Fundo Lagoon Kokota Fundo Outer The Hole Resistant Mandela Swiss Fundo Gap Paradise Manta 2D Stress: 0.1 Transform: Square root Resemblance: S17 Bray Curtis similarity Shimba Njao Gap Fundo Lagoon Msuka Bay Kokota Fundo Outer The Hole Mandela Fundo Gap Swiss Paradise Manta 2D Stress: 0.1 Transform: Square root Resemblance: S17 Bray Curtis similarity Njao Gap Msuka Bay Fundo Lagoon Kokota Fundo Outer The Hole Mandela Swiss Paradise Shimba Manta 2D Stress: 0.1 Similarity 75 Susceptible 7 Resistant 7 28 49 70 28 49 70 Genus susceptibility by site Genera were categorized into groups depending on their bleaching responses. Four groups were identified – Susceptible (Acropora, Pocillopora, Stylophora, Seriatopora and Montipora), Resistant (Porites massive and Pavona), Moderate tolerance Faviidae (Favia, Favites, Leptastrea, Echinopora, Platygyra) and moderate tolerance non-Faviidae (Galaxea, Porites branching, Lobophyllia, Fungia, Hydnophora, Coscinarea). The proportion of total coral cover occupied by each bleaching response group was calculated, and sites were compared using Multi- Dimensional Scaling analysis. Two outliers were identified- Simba Wall and Fundo Inner (Gap), both of which had a high cover of moderate tolerance non- Faviid genera due to the presence of very large Galaxea astreata colonies that distort the data. Most sites had a higher proportion of resistant corals by area, except for Misali, Kokota, Fundo Lagoon and Mandela that have a higher proportion of area covered by susceptible Acropora colonies. The general dominance of resistant corals in many sites shows that susceptible corals in many sites have been eliminated by previous bleaching stress, and a shift in coral community composition is occurring. Only certain sites such as Misali are still dominated by susceptible genera. The bubble plots show these trends, with the upper plot showing sites with higher cover of susceptible corals (larger bubbles at Misali, Kokota, Mandela and Fundo Lagoon), while the lower plot shows sites with higher cover of resistant genera (larger bubbles at Manta, Paradise, Msuka Bay, The Hole and Fundo Outer). 25
Detailed Results 700 Coral recruitment Density (per 100 m2) Density (per 100 m2) Site Density (per 100 m2) 600 500 400 300 200 100 0 2'000 1'500 1'000 500 0 2'200 2'000 1'800 1'600 1'400 1'200 1'000 800 600 400 200 0 Simba Kokota Fundo Outer Misali Pocillopora Portes massive Acropora Paradise Mandela Pavona Mandela Manta Fundo Inner Fundo Outer Seriatopora Porites branching Galaxea Swiss Kokota Simba The Hole Site Fundo Inner Swiss Njao Gap Njao Gap Paradise Manta The Hole Misali Fundo Lagoon 1-2 Fundo Lagoon '6-10 '3-5 '1-2 Msuka Bay Msuka Bay Echinopora Montipora Leptastrea Favia Favites Platygyra Fungia Coscinarea Hydnophora Lobophyllia Goniastrea Stylophora Site "1-2" The top graph shows that Simba, Fundo Outer, Paradise and Mandela had the highest coral recruitment (1-2 cm size corals) despite having lower coral cover than sites such as Misali, Mandela and Manta. This could be due to the fact that more available substrate is available because of the lower coral cover, and they are directly exposed to water currents flowing northwards and southwards along the island and thus plenty larvae are carried to these sites. Fundo Lagoon and Msuka Bay have significantly lower recruitment, probably due to their geographical positioning. Msuka Bay is to the north of the island, not connected to the dominant currents in the area, and in a high wave energy, Sargassum-dominated area where it is difficult for coral recruits to survive. Fundo Lagoon is in a very sheltered bay area, and although there is tidal exchange of water, it appears that coral larvae do not successfully reach or settle there. However, the graph in the middle shows recruit survivorship, that is the number of recruits that survive to become juvenile corals (3-10 cm), and the pattern changes. Sites such as Kokota, Misali, Mandela, Fundo Inner or Manta show higher than or equal recruit survivorship to outer fringing sites. Recruit survivorship is particularly low in Paradise, Simba and The Hole. Although recruitment is low in Fundo Lagoon and Msuka Bay, recruit survivorship is high. It thus appears that even though recruitment is high at degraded low-coral cover sites, corals are not surviving into more mature life stages due to some stress (perhaps predation by crown-ofthorns, regular bleaching or destructive fishing methods). The bottom graph shows that recruitment is largely dominated by Pocillopora, followed by Acropora, Porites massive, Pavona, Seriatopora and Porites branching. Other genera have low recruitment. 26
- Page 1 and 2: Coral Reef Resilience Assessment of
- Page 3 and 4: Coral Reef Resilience Assessment of
- Page 6 and 7: Executive Summary 1 Executive Summa
- Page 8 and 9: Executive Summary 2. Tackle the ove
- Page 10 and 11: The Study coral colony and coral co
- Page 12 and 13: The Study Table 2.1. Sites surveyed
- Page 14 and 15: The Study 7. Resilience indicators
- Page 16 and 17: Major Findings on the site that is
- Page 18 and 19: Major Findings rabbitfish, angelfis
- Page 20 and 21: Major Findings 2. Tackle the overfi
- Page 22 and 23: Detailed Results 4 Detailed Results
- Page 24 and 25: Detailed Results % coral colonies 1
- Page 26 and 27: Detailed Results 4.2 Coral communit
- Page 28 and 29: Detailed Results 4.3 Coral populati
- Page 32 and 33: Detailed Results 4.4 Crown-of-thorn
- Page 34 and 35: Detailed Results Density 250m2 200
- Page 36 and 37: Detailed Results 4.6 Resilience ind
- Page 38 and 39: Detailed Results Influence of resil
- Page 40 and 41: Detailed Results Fundo Lagoon Msuka
- Page 42: INTERNATIONAL UNION FOR CONSERVATIO
D<strong>et</strong>ailed Results<br />
700<br />
Cor<strong>al</strong> recruitment<br />
Density (per 100 m2)<br />
Density (per 100 m2)<br />
Site<br />
Density (per 100 m2)<br />
600<br />
500<br />
400<br />
300<br />
200<br />
100<br />
0<br />
2'000<br />
1'500<br />
1'000<br />
500<br />
0<br />
2'200<br />
2'000<br />
1'800<br />
1'600<br />
1'400<br />
1'200<br />
1'000<br />
800<br />
600<br />
400<br />
200<br />
0<br />
Simba<br />
Kokota<br />
Fundo Outer<br />
Mis<strong>al</strong>i<br />
Pocillopora<br />
Portes<br />
massive<br />
Acropora<br />
Paradise<br />
Mandela<br />
Pavona<br />
Mandela<br />
Manta<br />
Fundo Inner<br />
Fundo Outer<br />
Seriatopora<br />
Porites<br />
branching<br />
G<strong>al</strong>axea<br />
Swiss<br />
Kokota<br />
Simba<br />
The Hole<br />
Site<br />
Fundo Inner<br />
Swiss<br />
Njao Gap<br />
Njao Gap<br />
Paradise<br />
Manta<br />
The Hole<br />
Mis<strong>al</strong>i<br />
Fundo Lagoon<br />
1-2<br />
Fundo Lagoon<br />
'6-10<br />
'3-5<br />
'1-2<br />
Msuka Bay<br />
Msuka Bay<br />
Echinopora<br />
Montipora<br />
Leptastrea<br />
Favia<br />
Favites<br />
Platygyra<br />
Fungia<br />
Coscinarea<br />
Hydnophora<br />
Lobophyllia<br />
Goniastrea<br />
Stylophora<br />
Site<br />
"1-2"<br />
The top graph shows that Simba, Fundo<br />
Outer, Paradise and Mandela had the<br />
highest cor<strong>al</strong> recruitment (1-2 cm size<br />
cor<strong>al</strong>s) despite having <strong>low</strong>er cor<strong>al</strong> cover<br />
than sites such as Mis<strong>al</strong>i, Mandela and<br />
Manta. This could be due to the fact that<br />
more available substrate is available<br />
because of the <strong>low</strong>er cor<strong>al</strong> cover, and<br />
they are directly exposed to water<br />
currents f<strong>low</strong>ing northwards and<br />
southwards <strong>al</strong>ong the island and thus<br />
plenty larvae are carried to these sites.<br />
Fundo Lagoon and Msuka Bay have<br />
significantly <strong>low</strong>er recruitment, probably<br />
due to their geographic<strong>al</strong> positioning.<br />
Msuka Bay is to the north of the island,<br />
not connected to the dominant currents<br />
in the area, and in a high wave energy,<br />
Sargassum-dominated area where it is<br />
difficult for cor<strong>al</strong> recruits to survive.<br />
Fundo Lagoon is in a very sheltered bay<br />
area, and <strong>al</strong>though there is tid<strong>al</strong><br />
exchange of water, it appears that cor<strong>al</strong><br />
larvae do not successfully reach or s<strong>et</strong>tle<br />
there.<br />
However, the graph in the middle shows<br />
recruit survivorship, that is the number of<br />
recruits that survive to become juvenile<br />
cor<strong>al</strong>s (3-10 cm), and the pattern<br />
changes. Sites such as Kokota, Mis<strong>al</strong>i,<br />
Mandela, Fundo Inner or Manta show<br />
higher than or equ<strong>al</strong> recruit survivorship<br />
to outer fringing sites. Recruit<br />
survivorship is particularly <strong>low</strong> in<br />
Paradise, Simba and The Hole. Although<br />
recruitment is <strong>low</strong> in Fundo Lagoon and<br />
Msuka Bay, recruit survivorship is high.<br />
It thus appears that even though<br />
recruitment is high at degraded <strong>low</strong>-cor<strong>al</strong><br />
cover sites, cor<strong>al</strong>s are not surviving into<br />
more mature life stages due to some<br />
st<strong>res</strong>s (perhaps predation by crown-ofthorns,<br />
regular bleaching or destructive<br />
fishing m<strong>et</strong>hods).<br />
The bottom graph shows that recruitment<br />
is largely dominated by Pocillopora,<br />
fol<strong>low</strong>ed by Acropora, Porites massive,<br />
Pavona, Seriatopora and Porites<br />
branching. Other genera have <strong>low</strong><br />
recruitment.<br />
26
Change language