Mangrove

Mangrove – Outputs

 

The conceptual models were compiled by researchers in collaboration with a wide range of stakeholders from Natural Resource Management groups, universities and government agencies and based on available scientific information[5].

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Air

Denitrification rates in mangroves of the Great Barrier Reef (GBR) catchments are associated with nitrate (NO₃) concentrations in the floodwater[3].

Greenhouse gas emissions from mangroves vary depending on nitrogen (N) load, denitrification rates, and temperature. The emissions of N₂O are higher where N loads are high, soil carbon and nitrogen are high, salinity is low and temperature is high[7][5]. Mangroves in the Hinchinbrook Channel in Queensland are sinks of 0.5 g/ha/day of N₂O[8]. This may be due to low N concentrations in these mangroves.

Water

Tidal inundation

Tidal water in mangroves is usually lower in nitrate in the ebb (outgoing) tide compared to the flood (incoming) tide, suggesting removal by the mangroves[1]. However, ammonium (NH₄) can be either exported during dry periods (4,512 g/ha/day^*) or imported (1,624 g/ha/day^*) during wet periods[1][10].

Dissolved inorganic nitrogen (as NH₄) is typically output from mangrove systems at 1,444 (0-4,512) g/ha/day^*.

Vegetated litter

Exports of particulate N as litter could be substantial with mean values of 393 (299-485) g/ha/day^* measured in the Great Barrier Reef region[6][2]. Exports of DON can also occur in mangroves, especially after rainfall events[11].

Groundwater

N transported through groundwater could account for almost half of the N exported from mangroves[10]. Groundwater exports are higher in the wet compared to the dry season.  

Biota

Nitrogen movement from one ecosystem to another can serve a critical link among ecosystems. The transfer of materials across the terrestrial-to-marine boundary is considered to be driven by hydrological connectivity, but animal movement can provide another pathway for nitrogen transfers. This transfer is often highly variable (e.g. seasonal) or localised[9][4]. For example smaller organisms may be consumed by top predators in nearby environments.

^*_{Nitrogen quantities are displayed as an average followed by a minimum and maximum (range), e.g. “average (min. of range - max. of range) units”.}

References

1. ^ a b Adame, MF, Virdis, B & Lovelock, CE (2010), 'Effect of geomorphological setting and rainfall on nutrient exchange in mangroves during tidal inundation', Marine and Freshwater Research, vol. 61, no. 1197-1206.
2. ^ Adame, MF & Lovelock, CE (2011), 'Carbon and nutrient exchange of mangrove forests with the coastal ocean', Hydrobiologia, vol. 663, pp. 23-50.
3. ^ Adame, MF, Roberts, ME, Hamilton, DP, Ndehedehe, CE, Lu, J, Griffiths, M, Curwen, G & Ronan, M (2019), 'Tropical coastal wetlands ameliorate nitrogen exports during floods', Frontiers in Marine Science, vol. 6, 1-14.
4. ^ Allaway, WG & Ashford, AE (1984), 'Nutrient input by seabirds to the forest on a coral island of the Great Barrier Reef', Marine Ecology Progress Series, vol. 19, pp. 297-298.
5. ^ Allen, D, Dalal, RC, Rennenberg, H & Schmidt, S (January 2011), 'Seasonal variation in nitrous oxide and methane emissions from subtropical estuary and coastal mangrove sediments, Australia: Seasonal N2O and CH4 mangrove sediment fluxes in Australia', Plant Biology. [online], vol. 13, no. 1, pp. 126-133. Available at: http://doi.wiley.com/10.1111/j.1438-8677.2010.00331.x [Accessed 2 November 2020].
6. ^ Boto, KG & Bunt, JS (1981), 'Tidal export of particulate organic matter from a Northern Australian mangrove system', Estuarine, Coastal and Shelf Science, vol. 13, pp. 247-255.
7. ^ Kreuzwieser, J, Buchholz, J & Rennenberg, H (2003), 'Emission of methane and nitrous oxide by Australian mangrove ecosystems', Plant Biology, vol. 5, pp. 423-431.
8. ^ Maher, DT, Sippo, JZ, Tait, DR, Holloway, C & Santos, IR (2016), 'Pristine mangrove creek waters are a sink of nitrous oxide', Scientific Reports. [online], vol. 6, no. May, pp. 1-8. Available at: http://dx.doi.org/10.1038/srep25701.
9. ^ Reef, R, Feller, IC & Lovelock, CE (2010), 'Nutrition of mangroves', Tree Physiology, vol. 30, no. 9, pp. 1148-1160.
10. ^ a b Sadat-Noori, M, Santos, IR, Tait, DR & Maher, DT (2016), 'Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary', Science of the Total Environment. [online], vol. 566-567, pp. 1440-1453. Available at: http://dx.doi.org/10.1016/j.scitotenv.2016.06.008.
11. ^ Waterhouse, J, Schaffelke, B, Bartley, R, Eberhard, R, Brodie, J, Star, M, Thorburn, P, Rolfe, J, Ronan, M, Taylor, B & Kroon, F (2017), 2017 Scientific Consensus Statement. Land use impacts on Great Barrier Reef water quality and ecosystem condition, Australia.

Last updated: 31 July 2021