Impact details: turbidity and sediment transport

impact chain for tropical coastal areas / increased rainfall and flooding (click nodes to view details):
selected case study results:
Case study reference
Spatial context
Impact description (case study)
Case study recommendations
Pereira, M. A., & Gonçalves, P. M. B. (2004). Effects of the 2000 southern Mozambique floods on a marginal coral community: the case at Xai-Xai. African Journal of Aquatic Science, 29(1), 113-116. Southeast Africa: Mozambique This study examines the impact of the 2000 flood on the coral communities in Xai-Xai lagoon. A decrease in hard coral cover of the order of 58.5% was observed. The soft coral community was significantly affected, with a decrease in percentage cover of 90.4%. Coralline algae also decreased by 85.1%. All other categories increased in percentage cover: turf algae (164.4%), other invertebrates (e.g. sponges, sea urchins - 111.1%), fleshy algae (80.4%), rubble (34.4%) and dead coral (379.0%). The main causes of this degradation were the reduced water salinity and the large amount of sediment discharged by the Limpopo River. Some massive (e.g. Porites, Favia, Favites and Goniopora) and encrusting (e.g. Echinopora) hard coral genera seemed less affected, suggesting an elevated capacity to cope with this kind of stress through mucus-sheet formation. -

Devlin, M., Schaffelke, B., 2009. Spatial extent of riverine flood plumes and exposure of marine ecosystems in the Tully coastal region, Great Barrier Reef. Marine and Freshwater Research 60, 1109-1122. Australia Adjacent marine ecosystems can be regularly exposed to land-derived material and riverine flood plumes during heavy precipitation events. Flood plumes can be grouped into three plume types: primary, secondary and tertiary plumes, based on water-quality characteristics (suspended solids, coloured dissolved organic matter and chlorophyll). The number of reefs and seagrasses exposed to plume waters varied from year to year in the Tully coastal region (Great Barrier Reef,) and was dependent on the characteristics of the event. Over the 11 years, out of the major 37 reefs and 13 seagrass meadows identified in the Tully marine area, between 11 (30%) and 37 coral reefs (100%) and most of the seagrass meadows were inundated by either a primary or secondary plume every year. This can be detrimental to reef health. -

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