摘要
莫桑比克南部的伊尼亚卡岛位于适合珊瑚礁生长纬度的南部边界线附近。珊瑚礁的生长只限于将伊尼亚卡岛上马普托湾一侧的潮间坪分割开的各个水道的边缘地区,生长深度也仅在水下约6m的范围内。与低纬度地区的珊瑚礁不同,这里的珊瑚礁生长在空间和深度方面都受到限制(主要是由水体的高浑浊度造成的)。在1999年末至2000年初严重的洪水期间,由于淡水和泥沙的排放量增加,使自然条件恶化。洪水造成的破坏程度不同,对伊尼亚卡岛内侧(即西侧)的珊瑚礁造成了非常严重的影响,这一地区的活珊瑚覆盖面积(LCC)由1999年的(占总面积的)60.5%下降到了2001年的24.0%。这种变化应归因于淡水所导致的珊瑚脱色。现场死亡的珊瑚覆盖面积由1999年的18.6%增加到2001年的51.3%。相比之下伊尼亚卡岛南端的珊瑚礁受的影响较小。有人认为这主要由于这一地区离印度洋的开阔水域较近,从而减轻了淡水稀释带来的影响。
Inhaca Island, southern Mozambique, is located towards the southerly latitudinal limits of coral reef growth. Reef development is restricted to the margins of channels which dissect intertidal flats on the Maputo Bay side of the island, and to depths of around 6 m. In contrast to lower latitude reefs, reef development is therefore both spatially and bathymetrically restricted (largely due to high turbidity levels). These natural stress levels were exacerbated, via increased freshwater and sediment discharge, during the severe floods of late 1999/early 2000. Flood impacts varied but were most significant on reefs on the inner (western) side of the island where live coral cover (LCC) decreased from 60.5% (1999) to 24.0% (2001). This is attributed to freshwater-induced bleaching. Dead in situ coral cover increased from 18.6% (1999) to 51.3% (2001). Reefs on the southern tip of the island, by contrast, were relatively unaffected. It is suggested that this largely reflects a closer proximity to the open Indian Ocean which mitigated the effects of freshwater dilution.
