摘要
1999年大西洋飓风造成了整个加勒比海和美国大西洋中部沿海地区大面积的环境灾难,但也同时为某些微生物提供了栖息场所,尤其是以蓝藻细菌为主要种群的藻垫。现代的藻垫代表着地球上为人们所知的最古老的生物群落——叠层群落(stromatolites)。当代的藻垫是大西洋飓风所到之处高盐分的巴哈马湖泊的优势生物群落。在巴哈马群岛圣·萨尔瓦多岛的盐湖,我们分析了不同盐度水平如何通过影响光合作用和氮的固定这两个过程来控制藻垫生长的。研究表明,5倍于盐水浓度的高盐度大大抑制了这两个过程,佛罗伊德飕风以及其它风暴所带来的淡水,则缓解了这种抑制作用。在可以遇见的10～40年内,随着大西洋飓风活动的增强,所导致的稀释效应将促进藻垫的繁殖、CO_2的吸收以及养分循环。蓝藻为主要种群的藻垫,将成为气候和生态长期或短期变化的敏感的指示因子。
The Atlantic hurricanes of 1999 caused widespread environmental damage throughout the Caribbean and US mid-Atlantic coastal regions. However, these storms also proved beneficial to certain microbial habitats; specifically, cyanobacteria-dominated mats. Modern mats represent the oldest known biological communities on earth, stromatolites. Contemporary mats are dominant biological communities in the hypersaline Bahamian lakes along the Atlantic hurricane track. We examined the impacts of varying levels of hypersalinity on 2 processes controlling mat growth, photosynthesis and nitrogen fixation, in Salt Pond, San Salvador Island, Bahamas. Hypersalinity (> 5 times sea-water salinity) proved highly inhibitory to these processes. Freshwater input from Hurricane Floyd and other large storms alleviated this salt-inhibition. A predicted 10 to 40 year increase in Atlantic hurricane activity accompanied by more frequent “freshening” events will enhance mat productivity, CO2 sequestration and nutrient cycling. Cyanobacterial mats are sensitive short- and long-term indicators of climatic and ecological changes impacting these and other waterstressed environments.
