Using distribution models to estimate blooms of phytosanitary cyanobacteria in Brazil

Abstract: The multiple uses of aquatic ecosystems by humankind and the continuous interference of their activities have contributed to the emergence of potentially toxic cyanobacteria blooms. Here, we firstly created a database of occurrences of cyanobacteria blooms in Brazil through a systematic review of the scientific literature available in online platforms (e.g. Web of Science, Capes Thesis Catalogue). Secondly, we carried out ecological niche models with occurrence data obtained from these studies to predict climatically suitable areas for blooms. We select 21 bioclimatic variables input environmental data. We used five modeling methods for the current climate scenario: (1) Maxent; (2) Support Vector Machines; (3) Random Forest; (4) Maximum Likelihood e (5) Gaussian. We found that the number of publications about bloom events was higher in 2009 with a decline in the years 2012, 2013 and 2017. Furthermore, the years with the higher records of blooms in freshwater environments were 2005, 2011 e 2014. These events occurring mainly in public supply reservoirs and are mostly of the genera Microcystis Lemmermann, 1907, Dolichospermum (Ralfs ex Bornet & Flahault) P.Wacklin, L.Hoffmann & J.Komárek, 2009 and Raphidiopsis F.E.Fritsch & F.Rich, 1929. Modeling the potential distribution of blooms, we found sampling gaps that should be targeting for future researches, especially in the Amazon biome. Overall, the models did not predict highly suitable areas in the /north of Brazil, while other regions were relatively well distributed with a higher number of occurrence records in the Southeast region.摘要：人类对水生生态系统的多重利用及其活动的持续干扰，促成了潜在产毒蓝藻水华的暴发。本研究首先通过对在线平台（如"Web of Science"、Capes学位论文目录库）收录的科学文献开展系统综述，构建了巴西蓝藻水华发生数据库。其次，本研究利用上述文献获取的发生数据构建生态位模型，以预测蓝藻水华的气候适宜分布区。本研究选取21个生物气候变量作为环境输入数据，并针对当前气候情景采用5种建模方法：(1) Maxent；(2) 支持向量机（Support Vector Machines）；(3) 随机森林（Random Forest）；(4) 极大似然法（Maximum Likelihood）；(5) 高斯模型（Gaussian）。研究发现，有关水华事件的发文量在2009年达到峰值，随后在2012、2013及2017年出现下滑。此外，淡水环境中水华记录最多的年份为2005、2011及2014年。此类水华事件主要发生在公共供水水库中，优势类群主要为微囊藻属（Microcystis Lemmermann, 1907）、束丝藻属（Dolichospermum (Ralfs ex Bornet & Flahault) P.Wacklin, L.Hoffmann & J.Komárek, 2009）及拟柱胞藻属（Raphidiopsis F.E.Fritsch & F.Rich, 1929）。通过对水华潜在分布进行建模，本研究发现了未来研究应重点填补的采样空白，尤其是在亚马逊生物群落区。总体而言，模型未预测到巴西北部存在高度适宜的水华分布区，而其他区域则分布相对广泛，其中巴西东南部的发生记录数量最多。