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首页> 外文期刊>Journal of Experimental Marine Biology and Ecology >Rapid proliferation and impacts of cyanobacterial mats on Galapagos rocky reefs during the 2014-2017 El Nino Southern Oscillation
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Rapid proliferation and impacts of cyanobacterial mats on Galapagos rocky reefs during the 2014-2017 El Nino Southern Oscillation

机译：2014-2017埃尔南诺南部振荡期间加拉帕戈斯岩礁对紫杉角岩礁的快速增殖和影响

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摘要

Cyanobacteria use limiting resources efficiently to take advantage of nutrient pulses, adapt to variable surroundings, and spread; this proliferation is often an indicator of ecosystem stress. We documented the sudden appearance of benthic cyanobacterial mats on a subtidal rocky reef (Roca Cousins, Galapagos Islands) during El Nino in January 2016. At this time, cyanobacteria covered 32.0% of horizontal rock surfaces and 2.6% of rock walls at 6-8 m depth. Monitored photo quadrats and observations indicated that these mats were previously absent from rock walls and horizontal-sloping substrata at this site for 16 years prior to their initial appearance. The cyanobacteria was also observed at 4 other sites in the central Galapagos Islands during 2016-2018. Laboratory experiments testing the effects of temperature (28-31 degrees C) on cyanobacterial growth and survival indicated that survival was higher at 28 than 31 degrees C, suggesting that 31 degrees C may be an upper thermal limit. Over two years in the field, cyanobacterial mats peaked during the warm El Nino (January 2016) and declined during two cold La Nina periods (June 2016, September 2017), ultimately declining to 6.0% cover in January 2018. Regression analysis of the temperature and cyanobacterial percent cover data indicated that temperature explained 56.9% of the variation in cyanobacteria cover in the field over the 2-year period. The cyanobacterial mats may be a consortium of several species as the closest genetic matches confirmed by Sanger sequencing (90-91.5%) were Oscillatoria spongeliae, Merismopedia glauca, and Synechococcus elongatus. Comparison of areas under the cyanobacterial mats to the adjacent uncovered rock substrata suggested that the cyanobacteria had a negative influence on underlying crustose coralline algae (CCA), as the cover of bleached CCA was 1.75 fold higher under the mats while the cover of "healthy" pink-pigmented CCA was 3 fold higher on the uncovered substrata. Short-term field experiments and feeding surveys performed to evaluate predation and to calculate electivity indices indicated that the cyanobacterial mats were avoided by dominant consumers (Eucidaris galapagensis, Pentaceraster cumingi, Nidorellia armata, and Prionurus laticlavius). Taken together, these results imply that the novel appearance of cyanobacterial mats in the Galapagos rocky subtidal zone was facilitated by unusually warm temperatures during the 2014-2017 El Nino (28-29 degrees C) and that the cyanobacteria were regulated by temperature, but not by consumers. Future outbreaks of mat-forming cyanobacteria during El Nino periods may negatively impact the abundance of CCA and have direct and indirect negative effects on other components of marine benthic communities that rely on CCA as either a settlement substratum or food source.
机译：Cyanobacteria利用限制资源有效利用营养脉冲，适应可变周围环境，并扩散;这种增殖通常是生态系统应力的指标。我们在2016年1月在El Nino在El Nino期间记录了底栖落基礁石（Roca Cousins，Galapagos群岛）的底栖岩石杆菌突然出现。此时，蓝藻覆盖32.0％的横向岩石表面，占岩壁的32.0％，距离6-8 m深度。监测的照片Quadrats和观察结果表明，在其初始外观之前，这些垫子以前在本网站上的岩壁和水平倾斜的副数据。在2016 - 2018年，在中央加拉帕戈斯群岛的4个地点也观察到蓝藻。测试温度（28-31摄氏度）对蓝细菌生长和存活影响的实验室实验表明，在28比3℃下存活率较高，表明31℃可以是上热限制。在该领域多年来，天瘤垫在温暖的埃尔尼诺（2016年1月）达到顶峰，在两年冷拉尼娜（2016年6月）在2017年9月的两年报（2016年6月）期间，最终在2018年1月下降至6.0％。对温度的回归分析和蓝藻百分比覆盖数据表明，在2年期间，温度解释了该领域的蓝藻覆盖的56.9％。蓝细菌垫可以是几种物种的联盟，因为Sanger测序确认的最接近的遗传匹配（90-91.5％）是振荡症Spongeliae，Merismopedia glauca和SyneChocccus Elongatus。在邻近的未染色岩层下的蓝细菌垫下的区域的比较表明，蓝细菌对底层的甲壳素藻类（CCA）对底层的负面影响，因为漂白CCA的盖子在垫子下较高1.75倍，而“健康”的盖子覆盖粉红色着色的CCA在未涂覆的Substra数据上较高3倍。进行的短期场实验和饲养调查来评估捕食和计算选择性指标表明，占主导地位的消费者（Eucidaris Galapagensis，Pentaceraster Cumingi，Nidorellia Armata和Prionurus Laticlavius）避免了蓝细菌垫。在一起携带这些结果意味着在2014-2017 El Nino（28-29℃）期间，通过异常温暖的温度促进了加拉帕戈斯岩石丘脑区中的蓝藻垫的新颖外观，并通过温度调节蓝色细菌，但不是消费者。 El Nino时期的未来爆发垫形成的蓝细菌可能会对CCA的丰度产生负面影响，并对依赖CCA的海洋底栖社区的其他组分具有直接和间接的负面影响，依赖于CCA作为沉降脱液或食物来源。

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