of the Verde Island Passage, Philippines - weADAPT
of the Verde Island Passage, Philippines - weADAPT
of the Verde Island Passage, Philippines - weADAPT
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climate change vulnerability assessment <strong>of</strong> <strong>the</strong> verde island passage, philippines<br />
Table 9. An assessment <strong>of</strong> mangrove vulnerability to sea-level rise based on environmental conditions.<br />
Vulnerability Local conditions Explanation<br />
Most<br />
vulnerable<br />
Least<br />
vulnerable<br />
low relief islands<br />
lack <strong>of</strong> rivers<br />
carbonate settings<br />
areas subsiding due to tectonic<br />
movements, groundwater extraction, or<br />
underground mining<br />
micro-tidal sediment-starved environments<br />
(small Caribbean islands) (Ellison 1993)<br />
mangroves blocked by coastal development<br />
or steep topography<br />
mangroves in deep sediment on high<br />
islands<br />
riverine mangroves<br />
macro-tidal sediment rich environments<br />
(mangroves in nor<strong>the</strong>rn Australia)<br />
mangroves with room to move landward<br />
(backed by low-lying areas, salt flats,<br />
undeveloped areas)<br />
mangroves in remote areas<br />
mangroves surrounded by flourishing dense<br />
mangrove forests<br />
• low rates <strong>of</strong> sediment and peat accretion, particularly vulnerable to sea-level rise because <strong>the</strong>y are subject to drought<br />
and wave erosion<br />
• expected to experience increased flooding, inundation and salinization <strong>of</strong> soils and freshwater (Shea et al. 2001)<br />
• lack <strong>of</strong> sediment and freshwater<br />
• <strong>of</strong>ten associated with atolls and islands, where landward migration to escape sea-level rise may not be possible<br />
• sediments are mostly locally derived<br />
• will experience higher sea-level rise and inundation<br />
• lack <strong>of</strong> sediment will lead to decreased geographic distribution and species diversity <strong>of</strong> mangroves (Houghton et al.<br />
2001)<br />
• unable to move inland when sea level rises<br />
• structurally stronger than mangroves in shallow sediment on low islands (Gillison 1980) and less vulnerable to storm<br />
surges than low islands (UNEP 1994)<br />
• high islands will be better adapted to survive predicted climate changes due to <strong>the</strong>ir larger surface areas, freshwater<br />
availability, better soils, and more diverse resources (Shea et al. 2001)<br />
• receive large amounts <strong>of</strong> sediment from o<strong>the</strong>r areas (Woodr<strong>of</strong>fe and Grindrod 1991)<br />
• most productive mangrove habitats due to high nutrient concentrations associated with sediment trapping (Ewel et al.<br />
1998)<br />
• access to sediment and strong tidal currents to redistribute sediment (Woodr<strong>of</strong>fe and Grindrod 1991)<br />
• have <strong>the</strong> opportunity to expand inland when sea level rises<br />
• have limited anthropogenic stresses and not blocked by coastal communities from moving landward<br />
• have steady supply <strong>of</strong> propagules and seeds<br />
Source: McLeod and Salm 2006.<br />
Sea surface temperature impact<br />
Coral<br />
Increasing sea surface temperatures have been<br />
documented as a cause <strong>of</strong> coral bleaching. Seasurface<br />
temperature (SST) vulnerability estimates <strong>of</strong><br />
coral communities were computed by subtracting <strong>the</strong><br />
percentage covers <strong>of</strong> <strong>the</strong> taxa that are susceptible<br />
to temperature increases. Lower range estimates<br />
were calculated by removing <strong>the</strong> percentage cover<br />
<strong>of</strong> Acropora sp., whereas <strong>the</strong> higher range estimates<br />
were calculated by removing <strong>the</strong> percentage cover<br />
<strong>of</strong> Acropora sp. and pocilloporids (Pocillopora sp.,<br />
Seriatopora sp,. and Stylophora sp.). Acroporids and<br />
pocilloporids are deemed to be <strong>the</strong> most <strong>the</strong>rmally<br />
sensitive due to <strong>the</strong> low <strong>the</strong>rmal thresholds <strong>of</strong> <strong>the</strong>se<br />
families, <strong>the</strong>ir symbionts, and o<strong>the</strong>r factors. There have<br />
also been observations <strong>of</strong> high mortalities in Lian,<br />
Batangas where <strong>the</strong> first coral bleaching cases in <strong>the</strong><br />
1998 bleaching (<strong>the</strong> worse one on record) where first<br />
observed (Arceo et al. 2001) and is <strong>the</strong> only place<br />
where it has been studied in <strong>the</strong> entire VIP region.<br />
Although analyses <strong>of</strong> past <strong>the</strong>rmal events suggest<br />
this part <strong>of</strong> <strong>the</strong> VIP is more prone to temperature<br />
fluctuations, <strong>the</strong> response <strong>of</strong> acroporids and<br />
pocilloporids were similar in o<strong>the</strong>r parts <strong>of</strong> <strong>the</strong> country<br />
(Arceo et al. 2001).<br />
Analysis showed that <strong>the</strong> percentage loss <strong>of</strong> live<br />
hard coral cover ranged from 3% to 22% across <strong>the</strong><br />
<strong>Verde</strong> <strong>Island</strong> <strong>Passage</strong>. The sites deemed to be highly<br />
vulnerable are those with high cover <strong>of</strong> <strong>the</strong> taxa listed<br />
above. Sites with minimal losses are mostly dominated<br />
by <strong>the</strong> coral Porites sp. As such, <strong>the</strong> municipalities<br />
<strong>of</strong> Mabini and Tingloy have <strong>the</strong> highest vulnerability<br />
with percentage loss <strong>of</strong> 11% to 22% and 14% to<br />
21% respectively. The municipality <strong>of</strong> Lubang had an<br />
estimated loss 8% to 15% (Table 10).<br />
Table 10. Percentage (%) cover and percentage loss <strong>of</strong> coral cover during<br />
elevated sea surface temperatures (SST) in <strong>the</strong> eight municipalities<br />
surveyed in <strong>the</strong> <strong>Verde</strong> <strong>Island</strong> <strong>Passage</strong>.<br />
% living hard coral<br />
before<br />
Cover<br />
Municipality Sites bleaching low high loss (%)<br />
Batangas City<br />
Calatagan<br />
Looc<br />
Lubang<br />
Mabini<br />
Nasugbu<br />
San Juan<br />
Tingloy<br />
4<br />
8<br />
6<br />
6<br />
3<br />
2<br />
8<br />
3<br />
12.9<br />
24.2<br />
29.4<br />
24.8<br />
33.8<br />
29.3<br />
19.6<br />
19.2<br />
12.2<br />
23.5<br />
28.0<br />
22.8<br />
29.9<br />
27.6<br />
19.0<br />
16.5<br />
11.6<br />
22.3<br />
26.8<br />
21.2<br />
26.4<br />
26.8<br />
18.5<br />
15.1<br />
6-10<br />
3-8<br />
5-9<br />
8-15<br />
11-22<br />
6-9<br />
3-6<br />
14-21<br />
Seagrass<br />
Campbell et al. in 2006 studied <strong>the</strong> acute<br />
photosyn<strong>the</strong>tic response <strong>of</strong> 7 tropical species <strong>of</strong><br />
seagrasses to <strong>the</strong>rmal stress and <strong>the</strong>ir ability to<br />
recover from this stress. As mentioned in this article,<br />
temperatures rising above <strong>the</strong> tolerable limit <strong>of</strong> 35°C<br />
inhibit plants' ability to produce carbon and bring about<br />
increased respiration and breakdown <strong>of</strong> photosyn<strong>the</strong>tic<br />
enzymes. Although tropical species <strong>of</strong> seagrasses<br />
may have adopted to high temperature as some <strong>of</strong> <strong>the</strong><br />
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