Aulacoseira granulata

Aulacoseira granulata Scale bar indicates 25 µm. The specimen was gathered in the wetlands of national park Unteres Odertal (100 km north east of Berlin). The image was built up using several photomicrographic frames with manual stacking technique. Images were taken using Zeiss Universal with Olympus C7070 CCD camera. Image under Creative Commons License V 3.0 (CC BY-NC-SA). Place name: Creek in Oder valley 100 km north east of Berlin (Germany) Latitude: 53.135032 Longitude: 14.348738 Multiebenen-Abbildung, manuell gestapelt. Der Messbalken markiert eine Länge von 25 µm. Die Probe wurde in den Feuchtgebieten des Nationalpark Unteres Odertal (100 km nordöstlich von Berlin) gesammelt. Mikrotechnik: Zeiss Universal, Kamera: Olympus C7070. Creative Commons License V 3.0 (CC BY-NC-SA). For permission to use of (high-resolution) images please contact postmaster@protisten.de.

Aulacoseira granulata Scale bar indicates 25 µm. The specimen was gathered in the wetlands of national park Unteres Odertal (100 km north east of Berlin). The image was built up using several photomicrographic frames with manual stacking technique. Images were taken using Zeiss Universal with Olympus C7070 CCD camera. Image under Creative Commons License V 3.0 (CC BY-NC-SA). Place name: Creek in Oder valley 100 km north east of Berlin (Germany) Latitude: 53.135032 Longitude: 14.348738 Multiebenen-Abbildung, manuell gestapelt. Der Messbalken markiert eine Länge von 25 µm. Die Probe wurde in den Feuchtgebieten des Nationalpark Unteres Odertal (100 km nordöstlich von Berlin) gesammelt. Mikrotechnik: Zeiss Universal, Kamera: Olympus C7070. Creative Commons License V 3.0 (CC BY-NC-SA). For permission to use of (high-resolution) images please contact postmaster@protisten.de.

Ribadelago de Franco, Castilla y Len, Espaa

Miranda do Douro Municipality, Braganca, Portugal

Ribadelago, Castille and Leon, Spain

This is a typical filament of Aulacoseira (formerly Melosira) granulata (Bacillariophyta, Centrales)that was resuspended from the sediments not long before sampling. Its linking spines are of different lengths, possibly indicative of the filament having been broken at this place. In contrast, spines of equal length as in the other photo of this species are indicative of active growth. The chloroplasts here are partly compacted and do not fill the entire cell volume, indicative of the origin of this particular filament from the sediments. The other photo of this species shows actively growing, planktonic cells with chloroplasts filling the entire cell. This specimen was sampled from the shore of the lake in June 2006.

Aulacoseira (formerly Melosira) granulata (Bacillariophyta, Centrales) is one of the most common diatoms of Lake Kinneret, and certainly the major phytoplankton biomass contributor in winter (Dec – Feb), when the water column is homothermal. Typically, it occupies the entire 43 m water column. At the end of the winter bloom in early March the filaments sink and remain in the sediments in a dormant form with compressed chloroplasts till they are resuspended when the lake destratifies the following fall. It is a relatively large filamentous diatom, with cell diameter of 9 – 15 μm (median: 12.4 μm), cell height of 27-37 μm (median: 31 μm), and mean cell volume of 3700 μm3. The Kinneret Aulacoseira granulata filaments are straight, typically with 8 - 24 cells per filament. The picture shows the typical equal length marginal spines at the perimeter of the end-cell, these are “linking spines” which hold adjacent cells together. The chloroplasts fill the entire cells. This specimen was sampled from the shore of the lake in June 2006.   Aulacoseira granulata is a widespread centric diatom in the phytoplankton of lakes, reservoirs and rivers world-wide but particularly in African lakes and rivers, including the Nile River, L Naivasha, Kenya. It is typical of carbonate-rich, moderately eutrophic to eutrophic waters. It is used as indicator species of water with relatively low concentrations of salts, pH less than 9, and high silica concentrations. 

Filaments of different thickness typical of the winter (Jan-Feb) A. granulata bloom development season in Lake Kinneret