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Effects of the 2000 southern Mozambique floods on a marginal coral community: the case at Xai-Xai
Abstract
In early 2000 the
southern part of Mozambique suffered the worst flooding in 50 years, causing
fatalities and considerable material loss. This study aimed to investigate
the impact of this flood on the coral communities in Xai-Xai lagoon. Benthic
cover was
assessed in January 2000 (before the floods) and September 2000 (after the
floods) using the line intercept transect technique. 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. The extent of the flood
effect on other reefs on the southern Mozambique coast is discussed and a
monitoring programme is proposed.
African Journal of Aquatic Science
2004, 29(1): 113–116
southern part of Mozambique suffered the worst flooding in 50 years, causing
fatalities and considerable material loss. This study aimed to investigate
the impact of this flood on the coral communities in Xai-Xai lagoon. Benthic
cover was
assessed in January 2000 (before the floods) and September 2000 (after the
floods) using the line intercept transect technique. 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. The extent of the flood
effect on other reefs on the southern Mozambique coast is discussed and a
monitoring programme is proposed.
African Journal of Aquatic Science
2004, 29(1): 113–116
