Ocean and coastal Ecosystems
climate change, including rising temperatures, ocean
acidification and SLR, are known to affect the services and
livelihoods of the people depending on them.
The risk of irreversible loss of many marine and coastal
ecosystems increases with global warming, especially at 2C
or more high confidence (IPCC, 2018 )
In the South China Sea, coral growth and sea surface
temperature ( SST) have shown regional long-term trends
and inter-decadal variations, while coral growth is
predicted to decline by the end of this century( Yan etal
,2019)
Only 7.5% of the southern Persian Gulf basin's coral cover
was present on average in 2018. As the most vulnerable
taxa had already been eliminated by prior bleaching
events, this mass mortality did not result in significant
changes in the community composition.
An exception was the already rare Acropora spp. which
were locally extirpated in summer 2017( Burt et al. ,
2019.)During (2008-2011) also the coral communities of
Musandam and Oman showed changes depending on the
stress-tolerance levels of the species and the local
environmental disturbance level (Bento etal., 2016).
The health and resilience of corals have been found to be
associated with beneficial microorganisms of coral BMC
which alter during environmental stress. Increasing
seawater temperatures have been found to affect the
functioning of the symbiotic algae of corals (Lough etal. ,
2018 Gong etal 2019 ) and its bacterial consortia leading
to coral bleaching and mortality (Bourne etal. , 2016
Peixoto etal. , 2017 Bernasconi etal. , 2019( Motone etal. ,
2020).
Coral reefs were found to be affected differentially during
bleaching episodes, and those species which survived had
more stress-tolerant symbionts and higher tolerance to
thermal changes( Majumdar etal. , 2018 Thinesh etal.
,2019 van der Zande etal. , 2020).
Rare thermally tolerant algae and host species-specific
algae may play important roles in coral bleaching (van der
Zande etal. , 2020). Along the Indian coast, in the coral
reefs of Palk Bay( Bay of Bengal), varied bleaching and
recovery patterns among coral genera was observed
during the 2016 bleaching episode (Thinesh etal. , 2019).
Acropora species had the highest levels of bleaching
(86.36), followed by Porites (65.45), while Favites
Symphyllia, Favia, Platygyra, and Goniastrea showed only
mild to no bleaching.
cutting carbon emissions (bruno and valdivia,2016)limiting
warming to below 1. 5C is essential to preserving coral
reefs worldwide and protecting millions of people (Frieler
etal. , 2013 Hoegh-Guldberg etal. , 2017).
Many visitors to coral reefs have high environmental
awareness, and reef visitation can both help to fund and
encourage coral reef conservation (Spalding etal. , 2017).
About 42 percent of the mangroves on earth are found in
Asia, where the greatest mangrove forests are found. This
contains the Sundarbans, the biggest continuous
mangrove forest still existing in the world (Dashupta et al.,
2020).
The biodiversity of mangrove environments is extensive.
Flora and a wide variety of living organisms, including as
mammals, birds, fish, crabs, shrimp, insects, and bacteria,
support and maintain the ecosystems. Mangrove
deforestation rates today are lower than they were in the
late 20th century.
Jones and Gandhi,( 2019),( 2019 Friess) et al However, the
trend continues in several parts of Asia. Asia's main
mangrove-loss hotspot is Myanmar, which saw 35 losses
between 1975 and 2005 and 28 losses between( 2000 and
2014). From( 2000 to 2012), loss rates in Myanmar were
four times higher than the global average.
key drivers to vulnerability
Studies by Sajjad et al. (2018) that evaluated the
vulnerabilities of coastal communities along the Chinese
coast have shown that approximately 25 of the coastline
and more than 5 million residents are in highly vulnerable
coastal areas of mainland China, and these numbers are
expected to double by 2100. Husnayaen et al2018 .'s
assessment of the Indonesian city of Semarang's coast
revealed that 20 of its 48.7 km of coastline is extremely
vulnerable.
observed impacts
Primary production in the western Indian Ocean showed a
reduction by 20 during the past six decades, attributed to
rapid warming and ocean stratification which restricted
nutrient mixing( Roxy etal. , 2016).
Variation in secondary-production zooplankton densities
and biomass in the East Asian Marginal Seas affected the
recruitment of fishes due to mismatch in spawning period
and larval-feed availability during the last three climate
regime shifts (CRS) in the mid-1970s, late 1980s and late
1990s, which were characterised by the North Pacific index
and the Pacific Decadal Oscillation index (Kun Jung et al
2017).
imulation experiments have shown differential adaptation
capacity of common species Zheng, 2019 Yuan etal. , 2019.
The UNs 2019 report on climate action and support trends
highlights that the impacts of climate change on coastal
ecosystems are mainly increased risks due to flooding,
inundation due to extreme events, coastal erosions,
ecosystem processes and, in the case of fisheries,
variations in population or stock structures due to ocean
circulation pattern, habitat loss degradation and ocean
acidification.
projected impacts
It has been established that the combined effects of water
pollution and climate stressors would be more detrimental
to ecosystem sustainability than any stressor acting alone
(Buchanan et al., 2019).
Climate conditions were shown to raise the pollutant stress
on seagrass meadows by 2.6% (from 39.7 to 42.3%).
Different scenarios, including RCP2.6 and RCP8.5, were
developed for the Bohai Sea, with the results indicating an
amplified impact on the ecosystem under the assumption
that the pollution levels stay at the levels of 2014.
The main pollution stressors were pollutants such
petroleum hydrocarbons, dissolved inorganic nitrogen, and
soluble reactive phosphorus (Lu et al., 2018).
Projected changes in catch potential in percent by 2050
and 2100 relative to 2000 under RCP2. 6 and RCP8. 5,
based on outputs from the dynamic bioclimate envelop
model and the dynamic size-based food-web models,
indicate that the marine and coastal resources of most
Asian countries will be impacted with varying intensity
FAO, 2018.
Table
Apart from these threats, natural hazards have also been
found to affect coral reefs of Asia. The extensive and
diverse coral reefs of Muscat, Oman, in the northeast
Arabian Peninsula were found to have long-term effects
from Cyclone Gonu, which struck the Oman coast in June
2007, more than coastal development( Coles etal. , 2015).
Sandy beaches are subject to highly dynamic hydrological
and geomorphological processes, giving them more
natural adaptive capacity to climate hazards (Bindoff et al
2019).
