Marine microalgae on the southern coast of Bahia, Brazil: composition and new records of phytoplankton species

Abstract The phytoplankton community is the first link in the aquatic trophic chain and knowledge of its composition is an important tool for ecological characterization; including as potential indicator of anthropic impacts. The southern coast of Bahia is one of the best preserved parts of the Brazilian coast, however, little is known about its biodiversity, especially on marine phycoflora. With the objective of characterizing the composition of microphytoplankton (> 20 µm) in this region, samples were collected by a horizontal dredger using a plankton net (20 µm mesh size) to study the community composition. Water samples were taken from the subsurface using a Van Dorn bottle in order to analyze phytoplanktonic cell concentration. A total of 149 taxa were identified, distributed in the following phyla: Bacillariophyta, Miozoa, Cyanobacteria, Euglenophyta, Haptophyta, and Ochrophyta. Diatoms (63%) and dinoflagellates (26%) were the most representative groups in the specific composition. 43 new taxonomic occurrences were recorded for the coasts of Bahia, Northeastern Brazilian coast, and Brazilian coast.

摘要 浮游植物群落（phytoplankton community）是水生营养链的首要环节，解析其组成是开展生态表征的重要手段，同时可作为人类活动影响的潜在指示因子。巴伊亚州南部海岸是巴西海岸中保存最为完好的区域之一，但目前对该区域的生物多样性认知较为匮乏，尤其是海洋藻类区系（marine phycoflora）。本研究以解析该区域微型浮游植物（microphytoplankton, >20 µm）的群落组成为目标，采用水平拖网搭配孔径为20 µm的浮游生物网（plankton net）采集样品，并利用范多恩采水器（Van Dorn bottle）采集表层下水体样本以测定浮游植物细胞浓度（phytoplanktonic cell concentration）。本次研究共鉴定出149个分类类群（taxa），隶属于以下6个门类：硅藻门（Bacillariophyta）、双鞭毛虫门（Miozoa）、蓝藻门（Cyanobacteria）、裸藻门（Euglenophyta）、定鞭藻门（Haptophyta）及不等鞭毛藻门（Ochrophyta）。物种组成中占比最高的两类为硅藻（63%）与甲藻（dinoflagellates，26%）。本研究为巴伊亚州海岸、巴西东北海岸及巴西海岸共计新增了43个分类类群的分布记录。