A multi-step nitrifying microbial enrichment to remove ammonia and nitrite in brackish aquaculture systems.

One of the most important advancements in harnessing the biological nitrification in the field is enrichment solution of nitrifying microbial consortia. In the current study, we developed an improved multi-step enrichment to amplify a targeted microbial consortium from a sediment sample collected in tropical mangrove, Vietnam. The results showed that it took 122 culturing days with five unique continuous enrichment steps, the microbial consortium consumed total 5665 mgN L-1. Relative substrate removal rate increased rapidly from 0.114 mgN L-1 h-1 at the end of the first-step enrichment up to 3.58 mgN L-1 h-1 at the end of the fifth-step enrichment. High-throughput sequencing revealed that Nitrospirae, Proteobacteria and Bacteroidetes were the dominant taxa at the phylum level while Nitrospira, Marinobacter, Denitromonas and Nitrosomonas were the dominant taxa at the genus level in the enriched consortia. A pilot-scale experiment for shrimp cultivation of L. vannamei in 84 day-period proved the efficiency of Total ammonium nitrogen and nitrite removal in the consortium-activated treatment was much higher than the control.

New Benthic Cyanobacteria from Guadeloupe Mangroves as Producers of Antimicrobials.

Benthic cyanobacteria strains from Guadeloupe have been investigated for the first time by combining phylogenetic, chemical and biological studies in order to better understand the taxonomic and chemical diversity as well as the biological activities of these cyanobacteria through the effect of their specialized metabolites. Therefore, in addition to the construction of the phylogenetic tree, indicating the presence of 12 potentially new species, an LC-MS/MS data analysis workflow was applied to provide an overview on chemical diversity of 20 cyanobacterial extracts, which was linked to antimicrobial activities evaluation against human pathogenic and ichtyopathogenic environmental strains.

Marivivens niveibacter sp. nov., isolated from the seawater of tropical mangrove.

A novel bacterial strain, designated HSLHS2T, was isolated from the seawater of a tropical mangrove forest. Cells of strain HSLHS2T were found to be aerobic, Gram-stain-negative, non-flagellated, non-motile, short rods. Oxidase- and catalase-positive. Growth was observed at 5-40 °C (optimum, 35 °C), at pH 6.0-10.0 (optimum pH 8.0) and in 0-10 % NaCl (optimum 2 %, w/v). Strain HSLHS2T shared highest 16S rRNA gene sequence similarity with Celeribacter halophilus ZXM137T (95.4 %), but formed a distinct phyletic lineage and coherent phylogenetic cluster associated with Marivivens donghaensis AM-4T (95.1 %). The dominant fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The respiratory quinone was determined to be Q-10. The polar lipids comprised phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, three unidentified aminolipids, four unidentified lipids, five unidentified phospholipids. The DNA G+C contents was 54.6 mol%. The combined genotypic and phenotypic data indicated that strain HSLHS2T represents a novel species of the genus Marivivens, for which the name Marivivensniveibacter sp. nov. is proposed. The type strain is HSLHS2T (=KCTC 52588T=MCCC 1A06712T).

Croceivirga radicis gen. nov., sp. nov., isolated from a rotten tropical mangrove root.

A novel bacterial strain, designated HSG9T, was isolated from aisolated from a rotten tropical mangrove root. Cells of strain HSG9T were aerobic, Gram-stain-negative, yellow, oxidase-negative and catalase-positive. Growth was observed in 0.5-9 % sea salt (optimum 3 %, w/v), at 10-42 °C (optimum 25-35 °C) and at pH 6.0-8.0 (optimum 7.0-8.0). Gelatin, esterase and Tweens 20, 40, 60 and 80 were hydrolysed, but starch, protein, cellulose and casein were not. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain HSG9T formed an independent lineage related to the family Flavobacteriaceae. The dominant fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G. The respiratory quinone was identified as MK-6 and the polar lipids were phosphatidylethanolamine, three unidentified phospholipids and an unidentified lipid. The DNA G+C content was 37.1 mol%. The combined genotypic and phenotypic data indicated that strain HSG9T represents a novel species of a new genus within the family Flavobacteriaceae, for which the name Croceivirgaradicis gen. nov., sp. nov. is proposed. The type strain is HSG9T (=MCCC 1A06690T=KCTC 52589T).

Influence of environmental patterns on the population structure and secondary production of the fiddler crab Uca maracoani (Latreille) in the Amazon mangroves.

Uca maracoani is a fiddler crab found in estuaries along the western Atlantic coast, with a notable preference for euhaline environments. This study aimed to analyze the population structure and dynamics of this species in an estuary on the North Coast of Brazil, specifically in an area of the upper estuary where seasonal rainfall fluctuations result in significant changes in salinity. Monthly crab samples were taken from December 2013 to November 2015, together with measurements of environmental variables, such as water and climate parameters. The population maintains a balanced sex ratio; however, males are generally larger, with lower mortality rates and longer lifespans than females. Reproduction is continuous but mainly takes place in the dry season when salinity levels are higher (above 12‰). Higher crab densities have been observed during the rainy season when, despite lower salinity levels (below 10‰), the conditions for survival (food availability and milder climate) seem to be more favorable. The estimated average annual biomass and production for the population were 2.62 g AFDM m-2 and 5.43 g AFDM m-2 year-1, respectively, characterized by a high turnover rate (P/B = 2.10 year-1). Our results suggest that U. maracoani has thriving populations in the Amazon coast's mangroves, benefiting from the vast muddy intertidal zone and the high organic content delivered by the estuaries.

Unveiling the Diversity of Periphytic Cyanobacteria (Cyanophyceae) from Tropical Mangroves in Penang, Malaysia.

Cyanobacteria are one of the most important groups of photoautotrophic organisms, contributing to carbon and nitrogen fixation in mangroves worldwide. They also play an important role in soil retention and stabilisation and contribute to high plant productivity through their secretion of plant growth-promoting substances. However, their diversity and distribution in Malaysian mangrove ecosystems have yet to be studied in detail, despite Malaysia hosting a significant element of remaining mangroves globally. In a floristic survey conducted in Penang, peninsular Malaysia, 33 morphospecies of periphytic cyanobacteria were identified and described for the first time from a mangrove ecosystem in Malaysia. Sixteen genera, comprising Aphanocapsa, Chroococcus, Chroococcidiopsis, Cyanobacterium, Desmonostoc, Geitlerinema, Leptolyngbya, Lyngbya, Microcystis, Myxosarcina, Oscillatoria, Phormidium, Pseudanabaena, Spirulina, Trichocoleus and Xenococcus, were obtained from field material growing on diverse natural and artificial substrata. Oscillatoriales was the dominant order with Phormidium the dominant genus at nine of the 15 sampling sites examined. Three of the morphospecies, Aphanocapsa cf. concharum, Xenococcus cf. pallidus and Oscillatoria pseudocurviceps, are rare and poorly known morphospecies worldwide. Chroococcus minutus, Phormidium uncinatum, P. amphigranulata, and some species of Oscillatoriales are considered as pollution indicator species. This study provides important baseline information for further investigation of the cyanobacterial microflora present in other mangrove areas around Malaysia. A complete checklist will enhance understanding of their ecological role and the potential for benefits arising from useful secondary metabolites or threats via toxin production to the ecosystem.

Levels, source appointment, and ecological risk of petroleum hydrocarbons in tropical coastal ecosystems (northeast Brazil): Baseline for future monitoring programmes of an oil spill area.

We reviewed 20 years of levels, sources, and environmental risks related to the main petroleum hydrocarbons in the northeast region of Brazil. The aim of this study was to conduct a systematic review to serve as a comprehensive baseline for future monitoring programmes related to the oil spill disaster in 2019/2020. Most contamination levels of both PAHs and AHs were classified as low, except those in specific areas influenced by human activities, such as ports, highly urbanised mangroves, or rivers of medium-sized cities with inadequate liquid and solid waste treatment. Most hydrocarbons were linked to natural sources and burning processes, except in regions of extraction activities and petrochemical facilities as well as highly urbanised areas, where degraded petroleum and oil hydrocarbons predominated. Only 2.5% of the samples exceeded threshold effect levels for ∑16-PAHs and no samples exceeded probable effect levels. When regional threshold levels were used, however, the probable effect for the ∑16-PAHs measured was high, ranging from 5.8 to 6.1%. The few studies reporting biological responses showed that hydrocarbons from anthropogenic sources can induce adverse effects on marine organisms even at low to moderate levels. As the region has recently received a considerable quantity of crude oil, studies should be prioritised for a more precise assessment of the impact of this oil spill.

Assessment of heavy metal distribution in seawater of Kakinada Bay, a tropical mangrove-rich coastal environment.

The main objective of the present study is to estimate the heavy metal concentrations and ecological risk index (ERI) in the seawater of Kakinada Bay. Turbidity, suspended particulate matter (SPM), pH, salinity, dissolved oxygen, along with heavy metals were recorded from twelve locations of the Bay to understand its hydrographical conditions. The distribution of environmental variables and heavy metal concentrations was noticed mostly from the south to north gradient. Significant positive correlations were detected in some pairs of metals such as Cu with Zn (R2 = 0.515; p < 0.05), Pb with both Cr (R2 = 0.810; p < 0.01) and Cd (R2 = 0.511; p < 0.05), and Cr with Ni (R2 = 0.573; p < 0.05) indicating their common origin. The ERI values (7.93-35.2) of seawater of Kakinada Bay in the present study were in the ecologically high-risk category. Industrial operations, domestic sewage, and natural processes are the major contaminant sources of Kakinada Bay leading its environment to a potential ecological concern.

Effects of oyster aquaculture on carbon capture and removal in a tropical mangrove lagoon in southwestern Taiwan.

Blue carbon ecosystems (BCEs) are a promising resource for the mitigation of global warming; however, climate spectrums and anthropogenic activities could influence the fragile balance of BCEs as carbon sinks or sources. We assess how oyster farming affects dissolved inorganic carbon (DIC) and total alkalinity (TA) on CO2 fluxes in a mangrove-dominated lagoon. Water physical, chemical and biological parameters were recorded by in-situ buoys within the lagoon and at its inflow. Structural equation modeling was adopted to clarify the factors/processes controlling the partial pressure of CO2 (pCO2). A three-dimensional environmental model followed by a conceptual DIC model was used to quantify the spatiotemporal patterns of capture and release of DIC and TA by oyster production. The results showed that 49% of TA and DIC released from mangroves was depleted by oyster shell formation. DIC was reduced by algal photosynthesis and algal was served as a food source supporting oyster production. Annual oyster production through phytoplankton photosynthesis accounted for 11% of the atmosphere carbon inflows, suggesting that oyster production served as a significant atmospheric/terrestrial carbon sink in the lagoon. The results indicate that mangroves benefit local oyster production by acting as an important source of DIC and TA, and that the oyster aquaculture contributed to carbon capture in a mangrove-dominated lagoon ecosystem.