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
Major Findings 2. Tackle the overfishing and destructive fishing problems Overfishing is one of the major threats to Pemba’s coral reefs. Fish biomass is concentrated in small bodied (less than 10 cm long) fish and there is a lack of vital predators and herbivores. The no-take zone Misali has healthier fish populations than other sites due to larger populations of browsers (especially chubs) and small excavators, and the possibility of creating more no-take zones should be explored (for example at Mandela and Manta sites). Fishing activity in the reserve should also be supervised according to PeCCA regulations, and destructive fishing methods such as beach seining with small mesh sizes or dynamite fishing should be controlled or banned. However, we understand that fishing is a complex socio-economic issue as well as an ecological one, and alternative livelihoods to fishing should exits for fisherfolk. If sustainable fishing practices could be successfully implemented around the island, then coral reef resilience to climate change and other disturbances will improve and degraded reefs will have a better chance of recovering. 3. Understand the crown-of-thorns problem Crown-of-thorns starfish are a major cause of mortality of coral recruits in Pemba, and the cause for the recent increases in population should be studied and understood in order to provide solutions to the problem. Crown-of-thorns starfish population outbreaks have been linked to overfishing of predators, nutrient input or increasing sea surface temperature that increase larval survival. Possible direct management actions to counteract this threat are crown-of-thorns starfish monitoring and removal programmes involving environmental protection agencies and local dive operators. 4. Promote ecological resilience through protection of functional processes and alleviation of local stresses rather than technological fixes Technological fixes to environmental or climate problems are becoming increasingly popular due to the dire situation and the looming threat of collapse of ecosystems. An example is the deployment of reefballs in degraded coral reefs in order to promote coral recruitment. Although reefballs may provide good substrate for settlement, they do not alleviate the fundamental stresses that are causing recruit mortality and therefore are not likely to promote ecological resilience. Successful settlement of coral recruits is not the problem for Pemba’s degraded reefs (e.g. Paradise or Fundo Outer). Recruits are settling well, but are then not surviving and growing into larger colonies. This indicates that substrate quality is adequate for coral settlement, but that there are other stresses (e.g. crown-of-thorns starfish, destructive fishing or bleaching) that are causing coral mortality. Adding artificial reef substrate with reefballs does not remove these stresses, and recruits that settle on them will also be subjected to them and be at risk of mortality. If reefballs are to be deployed, we would recommend to do thisin areas dominated by unconsolidated rubble where Acropora-dominated patches have died leaving broken coral pieces that are easily dislodged by water movement and do not allow coral recruits to settle. Some areas or Misali or Paradise would be appropriate. However, we do not recommend deploying reefballs on degraded substrates that are consolidated. Rather than using this technological fix, it is more important to protect fundamental ecological processes through protection of resources and alleviation of local stresses. Reducing overfishing and destructive fishing practices, for example, would allow crucial planktivorous, herbivorous and carnivorous fish populations to recover and thus promote greater control of crown-of-thorns starfish and macro-algal populations that cause coral mortality. The IUCN Climate Change and Coral Reefs Working Group (www.iucn.org/cccr) is ready and willing to give technical advice and support on implementing these management strategies. Please contact David Obura (dobura@africaonline.co.ke) or Jerker Tamelander (jerker.tamelander@iucn.org) for further advice. 15
Major Findings Reefballs could be useful to facilitate coral recruitment in areas with unconsolidated rubble fields such as here in Misali. However, they are not a major driver for increasing reef resilience. Alleviation of local threats is a more effective management strategy. © Jerker Tamelander, IUCN. 16
- 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 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 30 and 31: Detailed Results Moderate Faviid Su
- 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
Major Findings<br />
Reefb<strong>al</strong>ls could be useful to facilitate cor<strong>al</strong> recruitment in areas with unconsolidated rubble fields such as here in Mis<strong>al</strong>i.<br />
However, they are not a major driver for increasing reef <strong>res</strong>ilience. Alleviation of loc<strong>al</strong> threats is a more effective<br />
management strategy. © Jerker Tamelander, IUCN.<br />
16
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