Identification of Cyanobacteria in a Eutrophic Coastal Lagoon on the Southern Baltic Coast

Abstract

Cyanobacteria are found worldwide in various habitats. Members of the picocyanobacteria genera Synechococcus and Prochlorococcus dominate in oligotrophic ocean waters. Other picocyanobacteria dominate in eutrophic fresh or brackish waters. Usually, these are morphologically determined as species of the order Chroococcales/clade B2. The phytoplankton of a shallow, eutrophic brackish lagoon was investigated. Phytoplankton was dominated by Aphanothece-like morphospecies year-round for more than 20 years, along a trophy and salinity gradient. A biphasic approach using a culture-independent and a culture-dependent analysis was applied to identify the dominant species genetically. The 16S rRNA gene phylogeny of clone sequences and isolates indicated the dominance of Cyanobium species (order Synechococcales sensu Komárek/clade C1 sensu Shih). This difference between morphologically and genetically based species identifications has consequences for applying the Reynolds functional-groups system, and for validity long-term monitoring data. The literature shows the same pattern as our results: morphologically, Aphanothece-like species are abundant in eutrophic shallow lagoons, and genetically, Cyanobium is found in similar habitats. This discrepancy is found worldwide in the literature on fresh- and brackish-water habitats. Thus, most Aphanothece-like morphospecies may be, genetically, members of Cyanobium.

Prokaryotic Diversity and Distribution in Different Habitats of an Alpine Rock Glacier-Pond System

“…On the one hand, the shallow sediment samples were clearly separated from the deepest ones in terms of overall community structure (as shown by NMDS analysis based on both phylogenetic and not phylogenetic distances) and showed the highest number of indicator OTUs shared with G and RG samples, potentially indicating stronger relationships with the terrestrial habitats. On the other hand, the deepest samples harboured higher proportions of cyanobacterial sequences than the shallow ones, mainly corresponding to a single OTU showing 100% sequence similarity with Cyanobium species and uncultured Cyanobacteria detected and isolated from the Baltic Sea [60] and lacustrine sediments [61]. Interestingly, the relative abundance of such OTU decreases in shallower sediments, where other phylotypes occupy higher proportions of the cyanobacterial sequences pool.…”

Phytoplankton community structure and diversity in the indoor industrial aquaculture system for Litopenaeus vannamei revealed by high‐throughput sequencing and morphological identification

“…The microscopic method mainly relies on identification of the cell morphology, which makes it difficult to recognize and distinguish similar taxa and small cells (Manoylov, 2014). In addition, morphological features are not always stable as they can change in response to environmental factors (Albrecht, Pröschold, & Schumann, 2017), which increases the difficulty of microscopic identification. Therefore, microscopy is potentially vulnerable to subjective judgments and requires advanced taxonomic skills and expertise.…”

Chaos theory discloses triggers and drivers of plankton dynamics in stable environment

“…These assemblages were representing four trophic levels: primary producers, primary and secondary consumers, and decomposers 42 . As shown recently by molecular data, most Microcystis -like and Aphanothece -like morphospecies that originated from the Darss-Zingst Bodden are currently attributed to alpha-picocyanobacteria, being genetically most close to Cyanobium which taxonomy is largely unresolved 43 .…”

“…Plankton composition, abundance, and their dynamics varied in time and strength demonstrating comparable trends. Dynamics of micro-biotic components (nutrients concentration, the bacteria and cyanobacteria 43 ) was relatively uniform (Supplementary Fig. S2a–g).…”