Effects of tidal influence on the structure and function of prokaryotic communities in the sediments of a pristine Brazilian mangrove

Abstract

Abstract. Mangrove forests are ecosystems that constitute a large portion of the world's coastline and span tidal zones below, between, and above the waterline, and the ecosystem as a whole is defined by the health of these tidal microhabitats. However, we are only beginning to understand tidal-zone microbial biodiversity and the role of these microbiomes in nutrient cycling. While extensive research has characterized microbiomes in pristine vs. anthropogenically impacted mangroves, these have, largely, overlooked differences in tidal microhabitats (sublittoral, intertidal, and supralittoral). Unfortunately, the small number of studies that have sought to characterize mangrove tidal zones have occurred in impacted biomes, making interpretation of the results difficult. Here, we characterized prokaryotic populations and their involvement in nutrient cycling across the tidal zones of a pristine mangrove within a Brazilian Environmental Protection Area of the Atlantic Forest. We hypothesized that the tidal zones in pristine mangroves are distinct microhabitats, which we defined as distinct regions that present spatial variations in the water regime and other environmental factors, and as such, these are composed of different prokaryotic communities with distinct functional profiles. Samples were collected in triplicate from zones below, between, and above the tidal waterline. Using 16S ribosomal RNA (rRNA) gene amplicon sequencing, we found distinct prokaryotic communities with significantly diverse nutrient-cycling functions, as well as specific taxa with varying contributions to functional abundances between zones. Where previous research from anthropogenically impacted mangroves found the intertidal zone to have high prokaryotic diversity and be functionally enriched in nitrogen cycling, we find that the intertidal zone from pristine mangroves has the lowest diversity and no functional enrichment, relative to the other tidal zones. The main bacterial phyla in all samples were Firmicutes, Proteobacteria, and Chloroflexi while the main archaeal phyla were Crenarchaeota and Thaumarchaeota. Our results differ slightly from other studies where Proteobacteria is the main phyla in mangrove sediments and Firmicutes makes up only a small percentage of the communities. Salinity and organic matter were the most relevant environmental factors influencing these communities. Bacillaceae was the most abundant family at each tidal zone and showed potential to drive a large proportion of the cycling of carbon, nitrogen, phosphorus, and sulfur. Our findings suggest that some aspects of mangrove tidal zonation may be compromised by human activity, especially in the intertidal zone.

Bacterial and molecular contamination of a small freshwater effluent used for drinking water

“…All samples were placed on ice and transported to the laboratory for analysis within 2 hours of sampling. A list of all samples along with their physical characterization (i.e., GPS coordinates, date, temperature, salinity, conductance, particulate) is available in de Santana et al . (2022).…”

“…To evaluate this potential, we conducted a three month field-based study of sewage-associated bacteria and genetic material in water and sediment in a freshwater tributary of the Hudson River (NY, USA), (de Santana et al . 2022).…”

Bacteria communities and water quality parameters in riverine water and sediments near wastewater discharges

“…The discharge of effluents from wastewater treatment plants (WWTPs) into surrounding waterways can have detrimental effects on the health of aquatic ecosystems. For one, WWTPs discharge important pollutants, including pharmaceuticals 1 , 2 and household products 3 , which can impact on the local fauna 4 as well as microbial communities 5 , 6 . WWTP can also be a source of allochthonous microorganisms distinct from the receiving waterway, including pathogens 7 and antibiotic-resistant bacteria 8 .…”

Large-scale differences in diversity and functional adaptations of prokaryotic communities from conserved and anthropogenically impacted mangrove sediments in a tropical estuary

“…At the conserved mangrove site (13 • 44 34.6 S, 39 • 03 30.6 W), collection points withing each tidal zone (supralittoral, intertidal and sublittoral) were 15 m distant from each other. Within each tidal zone we collected three sediment samples, each sample consisting of three combined sediment cores taken within an immediate vicinity (50-60 cm), resulting in nine samples at this site (De Santana et al, 2021). Collections were made in July 2018.…”

“…Paired reads from the conserved site were combined as described previously (De Santana et al, 2021), briefly, paired reads were combined using QIIME2 for reads with an overlap greater than 9 while paired reads with an overlap greater than 6 were combined using a custom script (Article S1) before denoising using DADA2 (denoise-single, -p-trim-left 3, -p-trunc-len 0, -p-max-ee 2.0, -p-trunc-q 2). The reads from the impacted site were also denoised using DADA2 (denoise-paired, -p-trim-left-f 13, -p-trim-left-r 13, -p-trunc-len-f 150, -p-trunc-len-r 150).…”