of the Verde Island Passage, Philippines - weADAPT

chapter 1 • vulnerability assessment of marine ecosystems and fisheries to climate change: sensitivity
curve was used since it is the only published account
available for the Philippines. However, the estimates
computed from these are considered conservative
because the Veron and Fenner’s curve is based
on beta/between-reef diversity while the current
application is seeks to estimate changes in alpha/
within-reef diversity. The latter is typically much higher
locally.
Coral diversity loss due to sea surface temperature
increase was estimated by obtaining the percentage of
coral genera that will be lost by removing the thermally
sensitive coral genera listed in Pratchett et al. (2008)
(Table 8). Lower range estimates were obtained by
removing the top 10 most vulnerable genera from the
total genera present per municipality. Whereas, higher
range estimates were calculated by removing all the
vulnerable coral genera based on the list to the total
genera present in each municipality. This decision is
arbitrary since, again, no dose-response curve for coral
communities and bleaching is available and thus we
based the cut-off on observations of vulnerable taxa
made in western Batangas during the 1998 bleaching
event, apparently the worst one for the VIP (Arceo et
al. 2001). The estimates based on projected cover
loss and the species-area curve served as the lower
range estimates of diversity loss, whereas the direct
vulnerabilities served as the higher range estimates.
Table 8. Coral genera thermally sensitive to bleaching events.
Acropora sp.
Stylophora sp.
Mycedium sp.
Isopora sp.
Montastrea sp.
Hydnophora sp.
Coeloseris sp.
Cyphastrea sp.
Pocillopora sp.
Montipora sp.
Source: Pratchett et al. 2008.
Leptoria sp.
Echinophyllia sp.
Lobophyllia sp.
Acanthastrea sp.
Goniopora sp.
Pectinia sp.
Galaxea sp.
Goniastrea sp.
Seriatopora sp.
Porites sp.
Favia sp.
Echinopora sp.
Favites sp.
Pavona sp.
Merulina sp.
Turbinaria sp.
Astreopora sp.
The assumptions of Pratchett et al. (2008) were based
on the numerous studies on the hierarchy of bleaching
susceptibilities of coral genera. Impacts of climateinduced
coral bleaching are less selective compared
to increased storminess and Acanthaster planci outbreaks.
Thermal sensitivities of coral genera have
been attributed to physiological and morphological
attributes such as colony integration, tissue thickness
and sensitivities of symbiotic zooxanthellae. Moreover,
differences in depth and habitats, history of thermal
stresses and hydrodynamics also play crucial roles in
coral bleaching susceptibility.
Seagrass and mangrove
The sensitivity assessment of mangrove and seagrass
areas surrounding the VIP was conducted using
available secondary information from municipal
and provincial agriculture offices, coastal resource
management plans and assessment reports from
various institutions. Using the most relevant information,
the status and sensitivity of mangroves and seagrasses
to climate change were assessed based on likely
response to the climate change component that will
have greatest impact on these ecosystems. In particular,
mangroves’ sensitivity to increasing sea level rise was
assessed based on the effects of flooding and the most
available areas for recruitment and settlement. The
vulnerability of these areas was assessed using McLeod
and Salm (2006) vulnerability conditions (Table 9).
Seagrass’ sensitivity and vulnerability to increasing sea
surface temperature and storm frequency and intensity
were assessed using information from Campbell et al.
(2006), Duarte et al. (1997), and Terrados et al. (1998).
In particular, seagrass response to thermal stress,
sediment perturbation, and eutrophication were given
emphasis to assess the vulnerability of this ecosystem
to climate change. However, since the available data
did not include information on the zonation of species
within a meadow, the sensitivity assessment was
species-specific.
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