Metagenomic Analysis of Cyanobacteria in an Oligotrophic Tropical Estuary, South Atlantic

Abstract

This study assessed the species composition, distribution, and functional profiles of cyanobacteria in Camamu Bay, a tropical oligotrophic estuarine system on the northeast coast of Brazil, using shotgun metagenomic sequencing. Surface-water samples were evaluated in two different rainfall periods (rainy and dry seasons), at nine stations in the three hydrodynamic regions of the bay. At a fixed sampling station, on each season, samples were taken over a tidal cycle at 3-h intervals over 12 h. A total of 219 cyanobacterial taxa were identified, demonstrating a diverse community of freshwater, euryhaline, and marine cyanobacteria. The genera of greater relative abundance, Synechococcus and Prochlorococcus, corresponded to the picoplankton fraction. Although Camamu Bay has conspicuous marine characteristics, the contribution of freshwater during the rainy season caused variation in cyanobacteria community, with an increase in species richness. Due the high prevalence of Synechococcus (90% of the sequences), the functional analysis revealed only minor differences in gene content between the dry and rainy seasons. In both rainy and dry seasons, an increase in Prochlorococcus relative abundance occurred during high tide, demonstrating the tidal influence in the bay. The environmental characteristics of the bay provide niche conditions for a wide variety of cyanobacteria, including freshwater, euryhaline, and marine strains.

Phytoplankton functional groups: Short‐term variation in a tropical tidal‐forced estuarine system

“…The data of the present study revealed a phytoplankton community that is characteristic of a preserved tropical oligotrophic estuarine system, corroborating the oligotrophic condition of the bay (Affe, Menezes, et al, ; Affe, Rigonato, Nunes, & Menezes, ). The low variation in abiotic conditions between the dry and rainy seasons supports a stable community with ecological strategies that allow it to persist in a turbulent, non‐stratified water column (Amorim, Cirano, Soares, & Lentini, ; Amorim et al, ).…”

“…The data of the present study revealed a phytoplankton community that is characteristic of a preserved tropical oligotrophic estuarine system, corroborating the oligotrophic condition of the bay Affe, Rigonato, Nunes, & Menezes, 2018).…”

“…The microphytoplankton fraction of Camamu Bay consists of predominantly chain‐forming diatoms (Affe, Menezes, et al, ). Considering the taxonomic identification of the phytoplankton in the bay through metagenomic analysis (see Affe, Rigonato, et al, ), it is possible to affirm that the highly abundant smallest fractions detected in the present study are represented by picocyanobacteria of the genera Synechococcus and Prochlorococcus . Variation in phytoplankton abundance evidenced the influence of tidal forcing, which transports cells from the adjacent oceanic region to the interior of the bay.…”

Advances in the Biotechnological Potential of Brazilian Marine Microalgae and Cyanobacteria

“…The Spirulina genus is hardly studied in Brazil, with most patents worked with it due to the fact that its species are well known and widely studied worldwide. Other species like Nostoc and Synechococcus are often chosen for studies because they are almost always found when collections are carried out and also because their genomes have already been identified worldwide, which improves understanding in the research carried out by groups in Brazil [ 9 , 54 ].…”

“…In the search for inputs, it is well known that the marine environment is abundant in organisms that produce substances with high biotechnological value; enable a wide variety of products and which can be used as possible solutions to diseases due to the discovery of new substances with biological activity. Therefore, there is a great demand for different species of marine cyanobacteria and microalgae which may have unknown substances or untapped actions with pharmacological potential [ 6 , 7 , 8 , 9 ].…”