Influence of local and global environmental parameters on the composition of cyanobacterial mats in a tropical lagoon

Abstract

Cyanobacteria-dominated microbial mat communities thrive widely and year round in coral reefs and tropical lagoons, with periodic massive development of benthic blooms. We studied the diversity and spatiotemporal variation of the cyanobacterial dominance in mats of the shallow lagoon of La Réunion Island in the Indian Ocean by means of denaturing gradient gel electrophoresis and cloning-sequencing approaches targeting the 16S rRNA gene, combined with macromorphological and micromorphological characterization of corresponding phenotypes. The mat-forming cyanobacteria were highly diversified with at least 67 distinct operational taxonomic units identified in the lagoon, encompassing the entire morphological spectrum of the phylum Cyanobacteria, but with striking dominance of Oscillatoriales and Nostocales. It appeared also that selective pressures acting at different geographical scales have an influence on the structure and composition of these mats dominated by cyanobacteria. First, large changes were observed in their diversity and composition in relation to local changes occurring in their environment. Second, from the data obtained on the richness and composition of the mats and from the comparison with similar studies in the world, tropical mats seem to display wider cyanobacterial richness than in temperate and cold areas. Moreover, these tropical mats share more species with mats in other tropical regions than with those in temperate and cold climatic regions, suggesting that marine cyanobacteria in biofilms and mats display a biogeographic structure.

Caldora penicillata gen. nov., comb. nov. (Cyanobacteria), a pantropical marine species with biomedical relevance

“…Furthermore, two of the analyzed sequences are highly similar (99%–100% similarity on 16S rRNA gene sequences) to samples from the type locality of P. penicillatum (Saint‐Gilles, Réunion; Echenique‐Subiabre et al. ). We conclude that those specimens traditionally identified in the NPs literature as Symploca spp., in fact, refer to P. penicillatum Gomont () and, consequently, we propose Clade III as the new genus Caldora , accommodating Caldora penicillata comb.…”

“…Due to the troubled taxonomic history of this taxon and the inability to obtain representative DNA sequences from the type material of P. penicillatum , in addition to the absence of voucher specimens of recently sequenced samples from the type locality (Saint‐Gilles, Réunion; Echenique‐Subiabre et al. , see Discussion), we selected the recently collected strain FK13‐1 (N. Engene, 10 June 2013, Looe Key, Florida Keys) as epitype for future reference, designated under the provisions of Art. 9.8 and in accordance with Art.…”

Comparative Metagenomics of the Polymicrobial Black Band Disease of Corals

“…This conserved interdependence of Roseofilum and heterotrophic bacteria may be linked to metabolic requirements and may explain why this cyanobacterium is found within apparently healthy coral microbiomes (Meyer et al, 2016). In many ways, BBD consortia resemble microbial mats found in tropical lagoons (Echenique-Subiabre et al, 2015), mangroves (Guidi-Rotani et al, 2014), and modern marine stromatolites (Ruvindy et al, 2016) that are characterized by steep physicochemical gradients and the presence of Cyanobacteria, Bacteroidetes, and Proteobacteria (especially Alpha-, Delta-, and Gammaproteobacteria; Bolhuis et al, 2014). With the large size of filamentous cyanobacteria relative to other bacterial cells, their production of exopolysaccharides that consolidate the mat, and their critical roles in converting inorganic carbon, nitrogen, and sulfur to organic forms, Cyanobacteria are the pioneering microorganisms of microbial mats (Bolhuis et al, 2014).…”

Taxonomic and Functional Metagenomic Signature of Turfs in the Abrolhos Reef System (Brazil)

“…Previous researchers have suggested that cyanobacteria are the dominant microbial group in turf, representing more than half of the microbes in turf [25–27]. Turfs in the Mascarene Archipelago (Indian Ocean) are dominated by species of the genera Hydrocoleum , Anabaena , Symploca , Leptolyngbya , and Lyngbya [27].…”

“…Turfs in the Mascarene Archipelago (Indian Ocean) are dominated by species of the genera Hydrocoleum , Anabaena , Symploca , Leptolyngbya , and Lyngbya [27]. Furthermore, cyanobacteria can play a crucial role in the physical structuring of turf due to their filamentous (turf-like) nature.…”