Diatoms from distinct habitats of a highly heterogeneous reservoir, Billings Complex, southeastern Brazil

ABSTRACT A diatom survey was carried out in the largest reservoir of the city of São Paulo. Twenty-four phytoplankton, 15 periphyton, and 12 surface sediment samples covering a gradient of trophic states were collected in 2009 and 2010. Overall, 67 taxa were sampled (60 species and varieties and seven identified at the genus level). Four species are new records to Brazil (Stephanodiscus minutulus, Fragilaria aquaplus, F. perminuta and Ulnaria ferefusiformis), and beyond those, six others are new records to the State of São Paulo. Periphyton accounted for the highest number of species (68.6%) and exclusive taxa (21). The eutrophic and natural mesotrophic regions presented the highest number of species (46 and 41 taxa, respectively), contrasting with the hypereutrophic and artificial mesotrophic regions (22 taxa each). Present findings highlight that the local biodiversity can be directly influenced by the type of habitat analyzed, and different habitats should be included for improving the knowledge of local biodiversity.

摘要 本研究针对圣保罗市最大的水库开展了硅藻（diatom）调查。2009年至2010年间，采集了覆盖不同营养状态梯度的24份浮游植物（phytoplankton）样本、15份周丛藻类（periphyton）样本以及12份表层沉积物（surface sediment）样本。本研究共记录到67个分类单元（taxa），其中60个鉴定至种及变种水平，7个仅鉴定至属级水平。其中4个物种为巴西新记录种（Stephanodiscus minutulus、Fragilaria aquaplus、F. perminuta及Ulnaria ferefusiformis），另有6个物种为圣保罗州新记录种。周丛藻类的物种占比达68.6%，且拥有最多的独有分类单元（21个）。富营养化区域与自然中营养化区域的物种数量最多，分别包含46个和41个分类单元；与之形成鲜明对比的是超富营养化区域与人工中营养化区域，二者均仅包含22个分类单元。本研究结果表明，本地生物多样性可直接受所分析生境类型的影响，因此为提升对本地生物多样性的认知水平，应纳入多种不同生境类型开展相关研究。