Approaches to use coastal marine ecosystems for
climate change mitigation
Daniel Murdiyarso1, Richard MacKenzie2, and Boone J. Kauffman3
1
Center for International Forestry Research, Jl. CIFOR, Situgede, Bogor 16115
2
Institute of Pacific Islands Forestry, Pacific Southwest Research Station, USDA Forest Service, 60 Nowelo St. Hilo,
HI 96720
3
Department of Fisheries and Wildlife, Oregon State University, Corvallis Oregon USA 97331
Abstract
Large carbon stocks in coastal marine ecosystems (CMEs), including mangroves, salt marshes,
and seagrass are well documented. Mangrove ecosystems are among the largest carbon store
in the tropics. Globally, they store more than 20 Pg C, and 70-80% is kept belowground as
organic soil. Their net primary production (NPP) which is higher than most tropical terrestrial
ecosystems is also allocated belowground. The near-term benefits of these carbon stocks may
be captured by engaging coastal community through well-design mitigation measures while
sustaining their local livelihoods.
Coastal zone communities are facing multiple stressors generated by the changing climate.
These stressors include increased rates of sea level rise that threaten coastal human
populations through flooding, erosion of coastline and loss of habitat that support culturally
and economically important nearshore finfish species. Conserving and restoring coastal zones
would, therefore, enhance their resilience by increasing their ability to adapt to gradual impacts
as well as abrupt change due to catastrophic extreme events.
Key messages
 High-carbon reservoirs found Coastal Marine Ecosystems (CMEs), including mangroves offer
huge potentials for climate change mitigation. Hence, these should be included in the new
climate agreement.
 Nearshore fisheries that benefit small scale fishing communities are positively influenced by
the geomorphology, nutrient availability and net primary production of the high level plants
from coastal ecosystems.
 Climate change and sea level rise (SLR) are among multiple stressors experienced by the
coastal zones and the communities whose lives depend on them.
 Gradual impacts of SLR combined with extreme events such as storm surges are real threats.
However, mangroves can increase the resilience of intact coastal zones by maintaining
coastal elevations relative to sea level rise through surface accretion.
 The mitigation potentials of CMEs in developing countries, which are hit-hard by the adverse
impacts of climate change, may be bundled with benefits from ecosystem services.
Introduction
Carbon loss in coastal wetland ecosystem due to land-use change is well documented. The
importance of carbon-rich ecosystem, such as that of Coastal Marine Ecosystems (CMEs) has
been recently recognized by the UNFCCC secretariat. A SBSTA expert meeting was organized on
24-25 October 2013, following the request of the SB37. The Ad hoc Working Group on Durban
Platform (ADP) that met at SB40 on 4-15 June 2014 was informed about the results of the
workshop1.
The recent release of the 2013 Supplement of the 2006 IPCC Guidelines for National
Greenhouse Gas Inventories or Wetlands Supplement signifies the development of scientific
understanding for accounting anthropogenic GHG emissions from wetlands. Inventories of GHG
emissions due to land-use change and wetland management are now possible to include CMEs.
This paper attempts to explore the possibility of using CMEs as mitigation options for climate
change and sea level rise. Vegetated CMEs (mangroves, salt marsh, seagrass) are high-carbon
reservoirs and mangrove is among the most carbon-rich forests in the tropics (Donato et al.
2011). This could be promoted to mitigate climate change and enhance the resilience of coastal
community to sea level rise and livelihood options, as there is a wide range of goods and
services provided by intact mangrove ecosystems.
Decarbonizing coastal development
Carbon metrics. Carbon stocks per unit area in CMEs especially in mangroves are well above
1,000 Mg ha-1 or 3-5 times larger than those found in any terrestrial ecosystem and most of
them are stored belowground. This storage is maintained by high NPP, which exceed most of
terrestrial ecosystems. Even in small island states like Federation States of Micronesia, with
mangrove forests of less than 10,000 hectares, the ecosystem carbon stocks is around 1,100 Mg
C ha-1 and slightly lower (800 Mg ha-1) found in the Republic of Palau (Kauffman et al. 2011).
Based on the area of mangroves that covers more than 13 Mha, it was estimated that globally
mangroves store more than 20 Pg C (Murdiyarso et al. 2013).
In the near-term mitigation horizon, managing carbon assets in high-C reservoirs should receive
more attention and meaningful incentives. In order to improve the accountability of the
managers, the development of reference emission level (REL), by which carbon accounting will
be based, is necessary. Historically data is usually adopted while understanding the underlying
drivers causing the gain and loss of carbon stocks in the system.
In addition, countries would be encouraged to determine their own country-specific emission
factors (EFs), the measure of greenhouse gas emissions per unit area per unit time of a certain
activity in the vegetated CMEs. However, if they are not prepared, default values may be
obtained from the IPCC emission factors database2. At the same time the activity data (AD)
should be prepared based on the area of CME involved.
1
FCCC/SBSTA/2014/INF.1. Report on the workshop on technical and scientific aspects of ecosystems with highcarbon reservoirs not covered by other agenda items under the Convention. UNFCCC Secretariat. 1 April 2014.
2
http://www.ipcc-nggip.iges.or.jp/home/wetlands.html
Ecosystem services. Incentive mechanisms may be combined with various aquaculture
practices despites high pressures of land-use change. Intact vegetated coastal zones are an
integral component of near-shore fish communities. Catch, densities, and biomass of many
commercial and artisanal important fish and shrimp species have been positively correlated to
intact and extent of mangrove forests (Manson et al. 2005, Meynecke et al. 2007, Meynecke et
al. 2008) and are often significantly greater in areas adjacent to mangroves than areas without
(Primavera 1998, Mumby et al. 2004).
The positive association between nearshore fish and mangrove forests is due in part to the
provision of refuge from predation as well as abundant food resources. As the incoming tides
flood the mangrove forest floor, smaller fish (e.g., juveniles, small adults) can avoid predation
by hiding within the small, shaded spaces provided by mangrove roots and trunks (Laegdsgaard
and Johnson 2001, Verweij et al. 2006, MacKenzie and Cormier 2012). However, this value can
vary with species of mangrove tree and condition of forest (MacKenzie and Cormier 2012). The
inundation of mangrove forests also allows species of nearshore fish to access areas where they
can feed on smaller fish, invertebrates, algae, and to a degree leaf litter (Demopoulos et al.
2007, Layman 2007, Lin et al. 2007).
Mangrove forests may also indirectly influence nearshore fisheries through the provision of
particulate and dissolved nutrients. As tidewaters drain mangrove forests, high loads of
particulate and dissolved nutrients enter adjacent water (Hemminga et al. 1994 ), where they
have been hypothesized to support high levels of nearshore primary and secondary production
(Odum and Heald 1975, Lee 1995).
The value of mangroves as fisheries habitat has been greatly exploited over the last 30 years
and has resulted in the conversion and loss of a substantial amount of mangrove forests (de
Graaf and Xuan 1998, FAO 2007). While increased aquaculture has replaced dwindling ocean
fish stocks, providing 30% of the total global fisheries production (Primavera 2006), it also
continues to threaten the structure and function of intact mangrove forests. More ecologically
friendly aquaculture techniques have been recently been suggested that may result in lower
ecological impacts to coastal ecosystems (Naylor et al. 2000, Primavera 2006). This includes
sylvofisheries that are currently being utilized in Vietnam. Here, shrimp ponds are restored by
planting mangrove trees around their borders, providing shade to ponds, lower water
temperatures, and producing healthier shrimp stocks with less fertilizer or antibiotics
(Broadhead, pers. comm). This is anticipated to have less of an impact to the quality of adjacent
bodies of water or mangrove forests.
Ecosystem-based approach
Mitigation or avoiding emission activities in the CMEs may be bundled with other activities such
as coping with sea level rise. Sea level rise is the greatest climate change impact that threatens
coastal ecosystems and the many ecosystem services that they provide (Gilman et al. 2008).
Fortunately, mangroves have been able to keep up with rising and falling seas for the last
millions of years by maintaining their forest floor elevation relative to sea level through
accretion. Accretion involves the growth of many fine belowground roots coupled with the
accumulation of leaf litter and healthy loads of sediment trapped on the mangrove surface by
aboveground roots and trunks (Krauss et al. 2003, Krauss et al. 2014). Mangroves have also
been able to migrate inland in the past with rising seas (Semeniuk 1994). Unfortunately,
increased rates of deforestation of mangroves inhibits their ability to accrete and thus their
ability to keep up with sea level rise. Even the cutting of a few trees can result in the death of
belowground roots and collapse of the mangrove forest floor (Krauss et al. 2010). Increased
sediment loads to mangroves from upland activities (e.g., poorly built roads, deforestation) can
smother mangrove roots, while upstream dams can minimize healthy sediment loads needed
by mangroves to keep up with sea level rise. Finally, development and the construction of roads
on the inland side of mangrove forests inhibit their ability to migrate inland.
Identifying mangroves that are currently keeping up with sea level rise using rod surface
elevation tables (Webb et al. 2013) or naturally occurring tracers (MacKenzie unpublished data)
and then prioritizing those mangroves for conservation action is one mechanism that has been
identified to help mangroves adapt to climate change (McLeod and Salm 2006). Conserving
mangroves that are capable of migrating inland is another (McLeod and Salm 2006).
Hydroperiod of intertidal zones, defined as seasonal pattern of water level, during which the
inundation of the area causing saturation, either permanently or temporarily. The period may
be assessed (Nuttle 1997) and will affect species distribution and success in colonizing the area.
In many cases coastal wetland restoration fails to consider this situation causing unsuccessful
results. While mangrove conservation and restoration are taking place, it is possible to quantify
surface accretion by sedimentation and burial of organic materials from biomass (litterfall, dead
woods etc.). – keeping up with gradual sea level rise (Alongi 2008, Breithaupt et al. 2011, Smoak
et al. 2013).
References
Alongi DM. 2008. Mangrove forests: Resilience, protection from tsunamis, and responses to
global climate change. Estuarine, Coastal and Shelf Science, 76,1-13.
Breithaupt JL, Smoak JM, Smith III TJ, Sanders CJ, and Hoare A. 2012. Organic carbon burial
rates in mangrove sediments: Strengthening the global budget, Global Biogeochem.
Cycles, 26, GB3011, doi:10.1029/2012G B004375.
de Graaf, G. J. and T. T. Xuan. 1998. Extensive shrimp farming, mangrove clearance and marine fisheries
in the southern provinces of Vietnam. Mangroves and Salt Marshes 2:159-166.
Demopoulos, A. W. J., B. Fry, and C. R. Smith. 2007. Food web structure in exotic and native mangroves:
A Hawaii-Puerto Rico comparison. Oecologia 153:675-686.
FAO. 2007. The World's Mangroves: 1980-2005. FAO Forestry Paper 153, Rome.
Gilman, E. L., J. Ellison, N. C. Duke, and C. B. Field. 2008. Threats to mangroves from climate change and
adaptation options: A review. Aquatic Botany 89:237-250.
Hemminga, M. A., F. J. Slim, J. Kazungu, G. M. Ganssen, J. Nieuwenhuizel, and N. M. Kruyt. 1994 Carbon
outwelling from a mangrove forest with adjacent seagrass beds and coral reefs (Gazi Bay,
Kenya). Marine Ecological Progress Series 106.
Krauss, K. W., J. A. Allen, and D. R. Cahoon. 2003. Differential rates of vertical accretion and elevaton
change among aerial root types in Micronesian mangrove forests. Estuarine, Coastal and Shelf
Science 56:251-259.
Krauss, K. W., D. R. Cahoon, J. A. Allen, K. C. Ewel, J. C. Lynch, and N. Cormier. 2010. Surface elevation
change and susceptilibity of different mangrove zones to sea-level rise on Pacific high islands of
Micronesia. Ecosystems 13:129-143.
Krauss, K. W., K. L. McKee, C. E. Lovelock, D. R. Cahoon, N. Saintilan, R. Reef, and L. Chen. 2014. How
mangrove forests adjust to rising sea level. New Phytologist 202:19-34.
Laegdsgaard, P. and C. Johnson. 2001. Why do juvenile fish utilise mangrove habitats? Journal of
Experimental Marine Biology and Ecology 257:229-253.
Layman, C. A. 2007. What can stable isotope ratios reveal about mangroves as fish habitat? Bulletin of
Marine Science 80:513-527.
Lee, S. Y. 1995. Mangrove outwelling: a review. Hydrobiologia 295:203-212.
Lin, H.-J., W.-Y. Kao, and Y.-T. Wang. 2007. Analyses of stomach contents and stable isotopes reveal food
sources of estuarine detritivorous fish in tropical/subtropical Taiwan. Estuarine, Coastal and
Shelf Science 73:527-537.
MacKenzie, R. A. and N. Cormier. 2012. Stand structure influences nekton community composition and
provides protection from natural disturbance in Micronesian mangroves. Hydrobiologia
685:155-171.
Manson, F. J., N. R. Loneragan, G. A. Skilleter, and S. R. Phinn. 2005. An evaluation of the evidence for
linkages between mangroves and fisheries: a synthesis of the literature and identification of
research directions. Oceanography and Marine Biology: an annual review 43:483-513.
McLeod, E. and R. V. Salm. 2006. Managing Mangroves for Resilience to Climate Change. Gland,
Switzerland.
Meynecke, J.-O., Y. L. Shing, N. C. Duke, and J. Warnken. 2007. Relationships between estuarine habitats
and coastal fisheries in Queensland, Australia. Bulletin of Marine Science 80:773-793.
Meynecke, J. O., S. Y. Lee, and N. C. Duke. 2008. Linking spatial metrics and fish catch reveals the
importance of coastal wetland connectivity to inshore fisheries in Queensland, Australia.
Biological Conservation 141:981-996.
Mumby, P. J., A. J. Edwards, J. E. Arias-Gonzalez, K. C. Lindeman, P. G. Blackwell, A. Gall, M. I.
Gorczynska, A. R. Harborne, C. L. Pescod, H. Renken, C. C. C. Wabnitz, and G. Llewellyn. 2004.
Mangroves enhance the biomass of coral reef fish communities in the Caribbean. Nature
427:533-536.
Naylor, R. L., R. J. Goldburg, J. H. Primavera, N. Kautsky, M. C. M. Beveridge, J. Clay, C. Folke, J.
Lubchenco, H. Mooney, and M. Troell. 2000. Effect of aquaculture on world fish supplies. Nature
405:1017-1024.
Odum, W. E. and E. J. Heald. 1975. The detritus-based food web of an estuarine mangrove community.
Pages 265-286 in L. E. Cronin, editor. Estuarine Research, Volume I Academic Press, New York.
Primavera, J. H. 1998. Mangroves as nurseries: Shrimp populations in mangrove and non-mangrove
habitats. Estuarine, Coastal and Shelf Science 46:457-464.
Primavera, J. H. 2006. Overcoming the impacts of aquaculture on the coastal zone. Ocean and Coastal
Management 49:531-545.
Semeniuk, V. 1994. Predicting the Effect of Sea-Level Rise on Mangroves in Northwestern Australia.
Journal of Coastal Research 10:1050-1076.
Verweij, M. C., I. Nagelkerken, D. de Graaff, M. Peeters, E. J. Bakker, and G. van der Velde. 2006.
Structure, food and shade attract juvenile coral reef fish to mangrove and seagrass habitats: a
field experiment. Marine Ecology Progress Series 306:257-268.
Webb, E. L., D. A. Friess, K. W. Krauss, D. R. Cahoon, G. R. Guntenspergen, and J. Phelps. 2013. A global
standard for monitoring coastal wetland vulnerability to accelerated sea-level rise. Nature
Climate Change 3:458-465.