8 Measuring Vulnerability of Coastal Ecosystem and Identifying …
153
Climate Change Impact on Coral Reef
The impact of climate change on coral reef has occurred in these decades is the
increase in sea temperatures, causing coral reefs to experience bleaching and this
condition occurs in most of the world’s coral reefs such as Australia, Indonesia, Thailand, Sri Lanka, Malaysia, Singapore, Burma, India, Maldives, Caribbean, Jamaica,
Brazil, Colombia, Venezuela, and in various parts of East Africa. Coral bleaching is
an interesting phenomenon related to how zooxanthella as main organism of coral
reefs is affected by the temperature changes. Zooxanthella belongs to dinoflagellates
groups that can live and develop as a coral reef builder. Zooxanthella is very susceptible to changes in temperature, both temperature increases and decreases. Rapid
increase in seawater temperature causes zooxanthellae to leave coral reef tissue with
strong indications of reduced number of zooxanthellae in host reefs (Hoegh-Guldberg
dan Smith 1989a; Glynn dan DíCroz 1990; Lesser et al. 1990; Edward 1995; Gattuso
et al. 2014; CRITC COREMAP–LIPI 2016b).
Some experts report that decrease in the population of zooxanthella in coral reef
in particular Acropora sp. occurs when changes in temperature are at least 1 °C from
the initial temperature (Hasanan et al. 2018; IPCC 2018). Other studies confirm
that the bleaching process occurs for Acropora corals due to changes in temperature with very small variations either due to an increase or decrease in temperature
(Williams and Bunkley-Williams 1990). Marshall and Baird (2000) also noted the
same thing in observing sensitivity for coral bleaching for Acropora spp. on Great
Barrier Reef which is vulnerable and influences at temperatures of 30–31 °C. in
fact, some species such as Acropora palifera, A. hyacinthus, and A. cytherea have
the highest rates of death and only leave about <8% of the population that remains
alive. However, several other species of corals have a strong resistance to relatively
narrow temperature changes such as Montastrea annularis, M. cavernosa, Agaricia
lamarcki, A agaricites, and Siderastrea radians which tend to survive with temperatures < 30 °C (Fitt and Warner 1995; Warner et al. 1996). Longest stress period for
Isopora palifera and A. hyacinthus affects severe stress on the physiological functions
of zooxanthella (Hasanah et al. 2018). Weis (2008) and Higuchi et al. (2010) revealed
that long-term changes would damage the formation of photosynthetic membranes
and mitochondria of coral reefs and could cause oxidative stress.
Coral reefs in Indonesia are at constant risk of degradation. Long-term monitoring
from 1993 to 2012, covering more than 1000 stations in 78 areas, indicated that, by
the end of 2012, only 5.3% of Indonesia’s coral reefs were in very good condition,
27.2% were in good condition, 37.3% in reasonable condition, and 30.5% in bad
condition (Susanto et al. 2015). The results of research on 15 coral reefs in three
regions of Indonesia showed a relative decline in the diversity of habitat species
which resulted in the degradation of coral reef species. Reefs that experience landbased pollution (waste, sedimentation, and/or industrial pollution) show 30–50%
diversity decreases at 3 m, and 40–60% diversity decreases at a depth of 10 m.
Reefs that are bombed or damaged by anchors are approximately 50%. The reefs in
the Java Sea are around 20% less diverse than in Ambon, Maluku. The Spermonde
153
Climate Change Impact on Coral Reef
The impact of climate change on coral reef has occurred in these decades is the
increase in sea temperatures, causing coral reefs to experience bleaching and this
condition occurs in most of the world’s coral reefs such as Australia, Indonesia, Thailand, Sri Lanka, Malaysia, Singapore, Burma, India, Maldives, Caribbean, Jamaica,
Brazil, Colombia, Venezuela, and in various parts of East Africa. Coral bleaching is
an interesting phenomenon related to how zooxanthella as main organism of coral
reefs is affected by the temperature changes. Zooxanthella belongs to dinoflagellates
groups that can live and develop as a coral reef builder. Zooxanthella is very susceptible to changes in temperature, both temperature increases and decreases. Rapid
increase in seawater temperature causes zooxanthellae to leave coral reef tissue with
strong indications of reduced number of zooxanthellae in host reefs (Hoegh-Guldberg
dan Smith 1989a; Glynn dan DíCroz 1990; Lesser et al. 1990; Edward 1995; Gattuso
et al. 2014; CRITC COREMAP–LIPI 2016b).
Some experts report that decrease in the population of zooxanthella in coral reef
in particular Acropora sp. occurs when changes in temperature are at least 1 °C from
the initial temperature (Hasanan et al. 2018; IPCC 2018). Other studies confirm
that the bleaching process occurs for Acropora corals due to changes in temperature with very small variations either due to an increase or decrease in temperature
(Williams and Bunkley-Williams 1990). Marshall and Baird (2000) also noted the
same thing in observing sensitivity for coral bleaching for Acropora spp. on Great
Barrier Reef which is vulnerable and influences at temperatures of 30–31 °C. in
fact, some species such as Acropora palifera, A. hyacinthus, and A. cytherea have
the highest rates of death and only leave about <8% of the population that remains
alive. However, several other species of corals have a strong resistance to relatively
narrow temperature changes such as Montastrea annularis, M. cavernosa, Agaricia
lamarcki, A agaricites, and Siderastrea radians which tend to survive with temperatures < 30 °C (Fitt and Warner 1995; Warner et al. 1996). Longest stress period for
Isopora palifera and A. hyacinthus affects severe stress on the physiological functions
of zooxanthella (Hasanah et al. 2018). Weis (2008) and Higuchi et al. (2010) revealed
that long-term changes would damage the formation of photosynthetic membranes
and mitochondria of coral reefs and could cause oxidative stress.
Coral reefs in Indonesia are at constant risk of degradation. Long-term monitoring
from 1993 to 2012, covering more than 1000 stations in 78 areas, indicated that, by
the end of 2012, only 5.3% of Indonesia’s coral reefs were in very good condition,
27.2% were in good condition, 37.3% in reasonable condition, and 30.5% in bad
condition (Susanto et al. 2015). The results of research on 15 coral reefs in three
regions of Indonesia showed a relative decline in the diversity of habitat species
which resulted in the degradation of coral reef species. Reefs that experience landbased pollution (waste, sedimentation, and/or industrial pollution) show 30–50%
diversity decreases at 3 m, and 40–60% diversity decreases at a depth of 10 m.
Reefs that are bombed or damaged by anchors are approximately 50%. The reefs in
the Java Sea are around 20% less diverse than in Ambon, Maluku. The Spermonde