Drivers of cyanobacterial diversity and community composition in mangrove soils in south‐east Brazil

Abstract

Summary Cyanobacteria act as primary producers of carbon and nitrogen in nutrient‐poor ecosystems such as mangroves. This important group of microorganisms plays a critical role in sustaining the productivity of mangrove ecosystems, but the structure and function of cyanobacteria assemblages can be perturbed by anthropogenic influences. The aim of this work was to assess the community structure and ecological drivers that influence the cyanobacterial community harboured in two Brazilian mangrove soils, and examine the long‐term effects of oil contamination on these keystone species. Community fingerprinting results showed that, although cyanobacterial communities are distinct between the two mangroves, the structure and diversity of the assemblages exhibit similar responses to environmental gradients. In each ecosystem, cyanobacteria occupying near‐shore areas were similar in composition, indicating importance of marine influences for structuring the community. Analysis of 16S rRNA sequences revealed the presence of diverse cyanobacterial communities in mangrove sediments, with clear differences among mangrove habitats along a transect from shore to forest. While near‐shore sites in both mangroves were mainly occupied by Prochlorococcus and Synechococcus genera, sequences retrieved from other mangrove niches were mainly affiliated with uncultured cyanobacterial 16S rRNA. The most intriguing finding was the large number of potentially novel cyanobacteria 16S rRNA sequences obtained from a previously oil‐contaminated site. The abundance of cyanobacterial 16S rRNA sequences observed in sites with a history of oil contamination was significantly lower than in the unimpacted areas. This study emphasized the role of environmental drivers in determining the structure of cyanobacterial communities in mangrove soils, and suggests that anthropogenic impacts may also act as ecological filters that select cyanobacterial taxa. These results are an important contribution to our understanding of the composition and relative abundance of previously poorly described cyanobacterial assemblages in mangrove ecosystems.

Cyanobacteria in lakes on Yungui Plateau, China are assembled via niche processes driven by water physicochemical property, lake morphology and watershed land-use

“…The diversity of cyanobacteria has been previously explored in many environmental settings such as eutrophic lake20, soil6, phyllosphere5, hot spring249 and marine habitat50. Here we presented the first study describing the biogeographic pattern of cyanobacteria in numerous plateau lakes, a rarely explored environment.…”

“…It indicated that the bacterial community could be strongly driven by electron acceptor availability, inducing probably different metabolic pathways52. Salinity was identified in many studies as a critical factor influencing cyanobacteria taxa256. The effects of salinity on microbial cells were related to osmoregulation and/or to metabolic changes triggered by salt, such as the ability to uptake different dissolved organic carbon compounds55.…”

“…Synechococcus , the most abundant cyanobacterial genus in these 21 plateau lakes, was also thought to have a potential of high cytotoxic activity66, in spite of its significant role in the nitrogen and carbon inputs in different ecosystems667. Toxic producer, not necessarily being the dominant species but just existing in smaller amounts, could produce large amounts of toxin in lakes1.…”

“…They play a critical role in sustaining the productivity of ecosystems through photosynthesis and nitrogen fixation, and accumulating phosphorus as cytoplasmic polyphosphate granules456. It is known that cyanobacteria can rapidly multiply and result in dense blooms in freshwater lakes under eutrophication378.…”

Strong in combination: Polyphasic approach enhances arguments for cold‐assigned cyanobacterial endemism

“…(Stal & Krumbein, ), or were placed within the genera Leptolyngbya (Nadeau et al., ), due to cryptic morphological features. Other studies have concentrated on molecular methods (Garcia‐Pichel & Belnap, ; Rigonato et al., ; Yeager et al., ), including extreme polar environments (Garcia‐Pichel, López‐Cortés, & Nübel, ), and have revealed that former culture‐based studies missed significant proportions of the microbial diversity (Torsvik & Øvreås, ; Ward, Weller, & Bateson, ). Modern approaches illustrate repeatedly the importance of combining different methodologies: Molecular data need to be correlated with ecological and morphological data, where comparisons are necessary to update or correct the present system, especially for cyanobacteria (Komárek, ).…”