Biodiversity of diatoms in the Karaj River in the Central Alborz, Iran

Iran is a large country with a great diversity of aquatic ecosystems including rivers, springs, shallow seas, lakes, waterfalls, lagoons, and wetlands. Despite the many types of aquatic habitats, there has been a limited study of the diatom flora. The purpose of this study is to present the diatom species and characterize their distribution in the Karaj River, which flows in Iran's Central Alborz region. The Alborz is one of the Irano-Anatolian ecoregions that serve as biodiversity hotspots. The Central Alborz, located in the middle part of this mountainous area, is an outstanding ecological and geological resource. This study uses the diatom flora to determine the biodiversity in one of the major rivers of the Central Alborz. Periphytic diatom samples were collected monthly from six stations along the length of the Karaj River between May 2011 and April 2012. A total of 128 diatom taxa was found from 48 genera expanding our understanding of regional aquatic diversity as 42 species are recorded as new for the diatom flora of Iran. Furthermore, the biogeography of the diatom flora of the Karaj River is considered in relation to the rest of Iran, the Middle East, and Asian and European diatom communities.