Provisioning and supporting services of mangroves

Provisioning services of mangroves

There are a number of tangible products that can be directly utilised and marketed from mangrove forests. In 2013 a study by Uddin et al., showed that the main revenue generating provisioning services at the Bangladeshi Sundarbans Reserve forest (largest mangrove forested site in the world) included timber, fish, thatching materials, fuel-wood, crabs, honey and wax.[1] The timber and fish accrued the greatest proportion of annual income of the aforementioned products in the Sundarbans from 2009-2010. Primarily, the source of timber came from timber seized from encroachers and trees that fell due to extreme weather scenarios such as hurricanes.[1]  In the global perspective fibres and other material from plants and trees are processed for wood, timber, and fodder.[2] Mangroves have also proved to be very important for the worldwide fisheries industry. Humans have caught and processed approximately 78.9 million tonnes of fisheries produce in 2011 and this figure is expected to rise by 2030.[3]

Fisheries are an important source of economic revenue from mangrove forests. Fisheries products can be used for subsistence, livelihood and commercial practices and acquired through either the natural fish stock or from aquaculture.[2] Mangrove forests are considered a home to a large variety of fish, crab, shrimp and mollusc species.[4] According to the 2014 study by Hutchinson et al., fish productivity increases when the total area of mangrove increases. Fisheries production is enhanced by mangroves through two main reasons; these are the availability of food such as leaves, woody matter and phytoplankton and shelter such as tree root structure and the flow and ebb of water channels.[3]  The availability of food and shelter not only increases the likelihood of net gains in current fisheries but it leads to the supporting service of mangroves functioning as breeding and nursery grounds for various fish species.[5][6][7]

Supporting services of mangroves

Mangrove forests functions as a vital breeding and nursery ground for marine and freshwater fish species thus creating a mangrove-fisheries linkage.[8][9][3][10] Juvenile fish depend on the shelter provided by mangrove trunks and roots to reduce their risk of predation. Juvenile fish, prawns and crabs benefit from the calm physical environment with low current speeds and reduced wave action.[3] They also access the supply of food at mangroves and are able to grow to a size where they can go back into coral reefs, offshore sites and upstream into rivers.[8][3] Mangroves are sometimes interconnected with sea grass beds and coral reefs that result in functional linkages. Despite ecosystem services (ES) being provided by each seascape (land-sea interface) habitat the inherent interdependence of corals, mangroves and seagrass beds are essential to provide support for marine fisheries.[8]

For instance, in a 2014 meta-analysis study conducted by Igulu et al., it was found that mangroves are the preferred nursery habitat of juvenile fish species in the Caribbean region.[11] This compliments the previous assertion that the mangrove-fisheries linkage is present as a supporting service to replenish fish stocks in coral reefs and other sites. According to Mumby et al., in 2004 the mangrove-fisheries linkage is so significant that it influences the biomass of important commercial species and in particular the coral reefs in the Caribbean.[12] Due to the linkages formed across the seascape and the tropical niche of the mangrove habitat a web of biological diversity is present in mangrove forests. Inshore and offshore fisheries inclusive of mollusc and crabs are one aspect but there is also the terrestrial domain of flora and fauna that inhabit mangrove forests.[13]

There is biodiversity in the flora and fauna in mangrove forested sites. This includes a variety of mammals, reptiles, amphibians, insects, birds, meiofauna (tiny organisms in the sediment) plants and fungi.[13][14][15][16] In 2006, according to Gopaul and Chauhan, the Sundarbans was recorded as having approximately 350, 250 and 300 species of vascular plants, fish and birds respectively.[14] This is combined with the additional species diversity of vertebrates and invertebrates of which some are rare and endangered animals.[14] It is also important to note that though supporting services is a classification of ES in itself, it contributes in the establishment of the other ES (provisioning, regulating and cultural).[17][18]

Featured Image courtesy: Elizabeth J Z Robinson taken in Vietnam

[1] Uddin, M., de Ruyter van Steveninck, E., Stuip, M. and Shah, M. (2013). Economic valuation of provisioning and cultural services of a protected mangrove ecosystem: A case study on Sundarbans Reserve Forest, Bangladesh. Ecosystem Services, 5, pp.88-93.

[2] Mukherjee, N., Sutherland, W., Dicks, L., Hugé, J., Koedam, N. and Dahdouh-Guebas, F. (2014). Ecosystem Service Valuations of Mangrove Ecosystems to Inform Decision Making and Future Valuation Exercises. PLoS ONE, 9(9), p.e107706.

[3] Hutchison, J; Spalding, M, and zu Ermgassen, P (2014) The Role of Mangroves in Fisheries Enhancement. The Nature Conservancy and Wetlands International. 54 pages

[4] WWF. (n.d.). Mangrove importance. [online] Available at: http://wwf.panda.org/our_work/oceans/coasts/mangroves/mangrove_importance/.

[5] Alongi, D. (2002). Present state and future of the world’s mangrove forests. Environmental Conservation, 29(3), pp.331-349.

[6] Barbier, E. (2017). Valuation of Mangrove Restoration. Oxford Research Encyclopedia of Environmental Science.

[7] Anneboina, L. and Kavi Kumar, K. (2017). Economic analysis of mangrove and marine fishery linkages in India. Ecosystem Services, 24, pp.114-123.

[8] Barbier, E. (2017). Marine ecosystem services. Current Biology, [online] 27(11), pp.R507-R510.

[9] Brander, L.M., Wagtendonk, A.J., Hussain, S.S., McVittie, A., Verburg, P., de Groot, R. and van der Ploeg, S. (2012). Ecosystem service values for mangroves in Southeast Asia: A meta-analysis and value transfer application. Ecosystem Services, 1(1), pp.62-69.

[10] Manson, F.J., Lonergan, N. R., Skilleter, G.A. and Phinn, S.R. (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.

[11] Igulu, M., Nagelkerken, I., Dorenbosch, M., Grol, M., Harborne, A., Kimirei, I., Mumby, P., Olds, A. and Mgaya, Y. (2014). Mangrove Habitat Use by Juvenile Reef Fish: Meta-Analysis Reveals that Tidal Regime Matters More than Biogeographic Region. PLoS ONE, 9(12), p.e114715.

[12] Mumby, P., Edwards, A., Ernesto Arias-González, J., Lindeman, K., Blackwell, P., Gall, A., Gorczynska, M., Harborne, A., Pescod, C., Renken, H., C. C. Wabnitz, C. and Llewellyn, G. (2004). Mangroves enhance the biomass of coral reef fish communities in the Caribbean. Nature, 427(6974), pp.533-536.

[13] Ellison, A. (2008). Managing mangroves with benthic biodiversity in mind: Moving beyond roving banditry. Journal of Sea Research, 59(1-2), pp.2-15.

[14] Gopal, B. and Chauhan, M. (2006). Biodiversity and its conservation in the Sundarban Mangrove Ecosystem. Aquatic Sciences, 68(3), pp.338-354

[15]  Hogarth, P. (2013). Mangrove Ecosystems. Encyclopedia of Biodiversity, 5.

[16] Luther, D. and Greenberg, R. (2009). Mangroves: A Global Perspective on the Evolution and Conservation of Their Terrestrial Vertebrates. BioScience, 59(7), pp.602-612.

[17] Mitsch, W., Bernal, B. and Hernandez, M. (2015). Ecosystem services of wetlands. International Journal of Biodiversity Science, Ecosystem Services & Management, 11(1), pp.1-4.

[18] Dencer-Brown, A., Alfaro, A., Milne, S. and Perrott, J. (2018). A Review on Biodiversity, Ecosystem Services, and Perceptions of New Zealand’s Mangroves: Can We Make Informed Decisions about Their Removal?. Resources, 7(1), p.23.