Benefits of mangroves - Australian Coral Reef Society

Australian Coral Reef Society Inc. A society promoting scientific study of Australian Coral Reefs ACRS Correspondence c/- Biological Sciences The University of Queensland St Lucia QLD 4072 (07) 3365 1686 [email protected]

Science-Based Policy Plan for Australia’s Coral Reefs Benefits of Mangroves Science Brief for Hon. Mark Butler MP 27 May 2016

One of the greatest threats facing Australia’s Economic Benefit coral reefs is water quality1. Agriculture, coastal development and land clearing are “An Australia-wide investment of dramatically increasing the levels of nutrients, $350 million into [mangrove] repair sediments and pollutants being deposited to will be returned in less than 5 watersheds that feed directly into the Great years”5 Barrier Reef2 (see map bottom-right). Declining water quality has already led to decreased coral diversity and coverage on coastal reefs of the GBR3,4. Importantly, mangroves have the ability to reduce impacts of water quality. Australia has the 2nd largest area of mangroves in the world. Below, we have highlighted the benefits of mangroves, and recommend immediate action to protect and restore mangrove forests along the Queensland coast.

Suspended Sediment Capture •

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Coastal areas with mangroves have been shown to accumulate 4-14 mm of sediment annually, versus losses of up to 38 mm of sediment per year in adjacent areas without mangroves, a net benefit of 50mm 6,7 Suspended capture increases the resilience of coastlines to sea level rise8



President: Vice-President: Hon Secretary: Hon Treasurer:

Dr Andrew Hoey; Tel: 0458 174 583; Email: [email protected] Dr Anna Scott; Tel: 02 6648 3923; [email protected] Dr O. Selma Klanten; Tel: 0417 341 941; Email: [email protected] Dr Jennifer Donelson; Tel: 0402 062 046; Email: [email protected]

Fisheries •

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75% of commercially caught fish and prawns depend on mangroves for part of their life cycle9 Biomass more than doubles in numerous commercial fish species when adult reef habitat is connected to mangroves10



Mangrove Restoration •

“Mangrove conservation and restoration efforts in areas close to human populations will likely give the greatest return on investment for enhancing fisheries.”11,12

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Mark Spalding



Nutrient Sequestration •

Carbon Sequestration •

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Carbon sequestration from mangrove forests rival some of the most productive terrestrial forests per unit area, playing a vital role in mitigating effects of carbon emissions Mangroves store 10-15% of coastal carbon, despite occupying only 0.5% of coastal area13



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Restoration of mangroves was used to adapt to coastal erosion along Thailand’s coast. A return of biodiversity was also observed14 (see photo above) Mangrove forests have been used to restore abandoned and unviable shrimp ponds, and restore the natural hydrology in the area15

Mangroves are coastal kidneys, improving water quality of areas used for agriculture, mining and effluent discharge by absorbing high rates of nutrients and heavy metals16,17 An estimated 2-22 : 1 ratio of mangroves to prawn ponds are needed to capture nutrient runoff by prawn aquaculture activity 18

Kind Regards,

For Further Advice, Please Contact: Dr. Norman Duke: [email protected] Dr. Ruth Reef: [email protected] Dr. Kerrylee Rogers: [email protected] Prof. Colin Woodroffe: [email protected] Australian Mangrove and Saltmarsh Network www.amsn.net.au

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Dr. Andrew Hoey President, Australian Coral Reef Society ACRS thanks the writing team of Ms. Carrie Sims, Mr. Michael McWilliam, Ms. Paloma Matis, Mr. Steve Doo, and Ms. Stephanie Duce for their contribution as well as advice from Drs. Ruth Reef, Kerrylee Rogers.

References: 1. ACRS Policy plan for Australia’s Coral Reefs (2016) http://goo.gl/dghdze 2. Great Barrier Reef Marine Park Authority (2014) Great Barrier Reef Outlook Report 2014. GBRMPA, Townsville. 3. De'Ath G & Fabricius K (2010) Water quality as a regional driver of coral biodiversity and macroalgae on the Great Barrier Reef. Ecological Applications 20:840-850. 4. Fabricius K et al. (2005) Changes in algal, coral and fish assemblages along water quality gradients on the inshore Great Barrier Reef. Marine Pollution Bulletin 51:384398. 5. Creighton, C et al. (2015) Repairing Australia’s estuaries for improved fisheries production – what benefits, at what cost? Marine and Freshwater Research 66:493507. 6. Hayden, HL & Granek, EF (2015) Coastal sediment elevation change following anthropogenic mangrove clearing. Estuarine, Coastal and Shelf Science 165:70-74. 7. Stokes, DJ et al. (2009) Surface elevation changes and sediment characteristis of intertidal surfaces undergoing mangrove expansion and mangrove removal, Waikaraka Estuary, Tauranga Harbour, New Zealand. International Journal of Ecology and Development 12:88-106. 8. Lovelock, C et al. (2015) The vulnerability of Indo-Pacific mangrove forests to sealevel rise. Nature 526:559-563. 9. Horst, W (1998) Mangroves, http://www.athiel.com/lib10/horstman.htm 10. Mumby, PJ et al. (2004) Mangroves enhance the biomass of coral reef fish communities in the Caribbean. Nature 427:533-536. 11. https://www.weadapt.org/knowledge-base/vulnerability/the-role-of-mangroves-infisheries-enhancement 12. Aburto-Oropeza O et al. (2008) Mangroves in the Gulf of California increase fishery yields. PNAS 105:10456-10459. 13. Alongi DM (2014) Carbon cycling and storage in mangrove forests. Annual Review of Marine Science 6:195-219. 14. Nguyen, TP et al. (2016) Community perspectives on an internationally funded mangrove restoration project: Kien Giang province, Vietnam. Ocean Coast Management 119:146-154. 15. Corredor, JE & Morell JM (1994) Nitrate depuration of secondary sewage effluents in mangrove sediments. Estuaries 17:294-300. 16. McKinnon, AD et al. (2002) Water column production and nutrient characteristics in mangrove creeks receiving shrimp farm effluent." Aquaculture research 33:55-73. 17. Reef, R et al. (2010) Nutrition of mangroves. Tree Physiology 30:1148-1160. 18. Roberson, AI & Phillips, MJ (1995) Mangroves as filters of shrimp pond effluent: predictions and biogeochemical research needs. Hydrobiologia 295:331-321.

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