Some benthic dinoflagellates produce toxins that can affect other organisms including humans, and their proliferation seems to be related to the environmental variability. For this reason, the present study aims to compare the structural variation of potentially toxic dinoflagellates associated with the seagrass Thalassia testudinum from two nearby systems, with different environmental characteristics in Colombian Caribbean, corresponding to a brackish water coastal lagoon and an adjacent bay. Between January 2014 and December 2015, leaves of T. testudinum were collected monthly to obtain the dinoflagellates. Salinity, temperature, dissolved oxygen, pH, nutrients and total suspended solids (TSS) were measured, and precipitation data and the Oceanic Niño Index (ONI) were obtained. Dinoflagellates were detached from the leaves, morphologically identified by analyzing their thecal plates arrangements, and quantified using a Sedgewick-Rafter chamber. The information was analyzed using standard statistics and regression models. Fourteen species of potentially toxic epiphytic dinoflagellate belonging to four genera were recorded, being Prorocentrum the most representative in number of species. The maximum density, dominated by P. lima, were found in Bahía Chengue during the rainy season of 2014 (18452 and 20109 cells g⁻¹ w.w.), with salinity of 35.50, high temperatures (>29.60 °C), dissolved oxygen >6 mg L⁻¹, pH close to 8 and TSS >85 mg L⁻¹. Densities at the Lagoon were lower than 80 cells g⁻¹ w.w. with the highest values of Prorocentrum sp.1 under different environmental conditions. With the statistical relationships between the most abundant species and the main environmental variables, fundamental niche models were proposed in which cells could proliferate. The degree of risk to human health due to the presence of these potentially toxic epiphytic dinoflagellates will not be resolved until their toxicity discarded.

一些底栖的鞭毛藻产生可影响包括人类在内的其他生物的毒素，其增殖似乎与环境多变性有关。由于这个原因，本研究旨在比较哥伦比亚加勒比海两个邻近系统，环境特征不同的潜在毒性与鞭毛海藻地中海藻相关的潜在鞭毛藻的结构变异，这对应于咸水沿海泻湖和相邻海湾。在2014年1月至2015年12月之间，T。testudinum的叶子每月收集一次以获得鞭毛。测量盐度，温度，溶解氧，pH，养分和总悬浮固体（TSS），并获得降水数据和海洋Niño指数（ONI）。从叶上分离出鞭毛藻，通过分析它们的标板排列对其进行形态学鉴定，并使用Sedgewick-Rafter室进行定量。使用标准统计和回归模型对信息进行了分析。记录了属于四个属的十四种潜在毒性附生的鞭毛鞭毛藻，在原种中最有代表性。在2014年的雨季期间，在巴伊亚成格犬（BahíaChengue）中发现了由利马假单胞菌（P. lima）所控制的最大密度（18452和20109细胞g ^-1ww），盐度为35.50，高温（> 29.60°C），溶解氧> 6 mg L ^-1，pH值接近8，TSS> 85 mg L ^-1。在不同的环境条件下，泻湖的密度低于80个细胞g ^-1 ww，其中Prorocentrum sp.1的值最高。利用最丰富的物种和主要环境变量之间的统计关系，提出了细胞可以增殖的基本生态位模型。这些潜在的毒性附生的鞭毛鞭毛藻的存在，对人类健康的威胁程度只有在消除其毒性后才能解决。