Diversity of solitary forms of centric diatoms in Bilbao estuary: morphological and molecular analyses

Supervisors: Aitor Laza, Emma Orive (UPV/EHU)
The assessment of the Phytoplankton community of the Bilbao estuary has been done taking into account the general taxonomic groups and the abundance and size of the cells. The classification was made using light microscopy. Despite centric diatoms are bloom forming in this area, there is a lack of information about the species that form the community. In this work, a species level study have been done based on morphological analyses of Scanning Electron Microscopy (SEM) micrographs from field samples. This information has been completed with molecular analyses based on the 28S ribosomal sequences. Results from the ultrastructural plus the molecular analyses were compared with the counting size method with the aim to demonstrate that the deep taxonomical study uncover a high diversity in this group of centric diatoms. Seven species of solitary forms of centric diatoms from four genera were described in this study: Cyclotella atomus var. atomus, Cyclotella marina, Cyclotella meneghiniana, Cyclotella cryptica, Conticribra weissflogii, Discostella pseudostelligera and Thalassiosira pseudonana. A description of blooms, in terms of species and sites, was done using an integration of both methods.