Increased nitrogen input enhances Kandelia obovata seedling growth in the presence of invasive Spartina alterniflora in subtropical regions of China

Mangrove interaction with saltmarsh varies at different life stages

Mangroves and saltmarshes are two of the most relevant coastal habitats for humans. These ecosystems offer several services like coastal protection, climate mitigation, and nursery habitats for many artisanal and commercially exploited fish, crabs, and shellfish. They mostly dominate different latitudinal ranges but in several places around the world they co-occur and interact. Here, we summarize the current scientific knowledge on mangrove-saltmarsh ecological interactions and propose a conceptual model. We screened 1410 articles from 1945 to 2022 and selected 29 experiments that assessed mangrove-saltmarsh ecological interactions. Both positive and negative interactions are observed but there is variation along different mangrove life stages. Higher retention and establishment of mangrove propagules are found inside saltmarshes than on bare flats, i.e. facilitation, and these effects are higher at grass than at succulent saltmarsh species. Mangrove seedlings, saplings, or trees mostly compete with saltmarshes, negatively affecting mangrove growth. We propose a model with different outcomes considering the interaction between different mangrove's life stages and saltmarsh forms and discussed these interactions in the light of anthropogenic threats and climate change.

Invasion of Spartina alterniflora on Zostera japonica enhances the abundances of bacteria by absolute quantification sequencing analysis

Plant invasion can alter soil organic matter composition and indirectly impact estuary ecology; therefore, it is paramount to understand how plant invasion influences the bacterial community. Here, we present an absolute quantification 16S rRNA gene sequencing to investigate the bacterial communities that were collected from Zostera japonica and Spartina alterniflora covered areas and Z. japonica degradation areas in the Yellow River Estuary. Our data revealed that the absolute quantity of bacteria in the surface layer was significantly (p < .05) higher than that in the bottom and degradation areas. Following the invasion of S. alterniflora, the abundances of Bacteroidia, Acidimicrobiaceae, and Dehalococcoidaceaewere enriched in the S. alterniflora sediment. In addition, variations in the composition of sediment bacterial communities at the phylum level were the most intimately related to total organic carbon (TOC), and the content of heavy metals could reduce the abundance of bacteria. This study provided some information to understand the effects of S. alterniflora invasion on Z. japonica from the perspective of microbiome level.

Effects of Spartina alterniflora Invasion on Soil Microbial Community Structure and Ecological Functions

It has been reported that the invasion of Spartina alterniflora changed the soil microbial community in the mangrove ecosystem in China, especially the bacterial community, although the response of soil fungal communities and soil microbial ecological functions to the invasion of Spartina alterniflora remains unclear. In this study, we selected three different communities (i.e., Spartina alterniflora community (SC), Spartina alterniflora-mangrove mixed community (TC), and mangrove community (MC)) in the Zhangjiangkou Mangrove Nature Reserve in China. High-throughput sequencing technology was used to analyze the impact of Spartina alterniflora invasion on mangrove soil microbial communities. Our results indicate that the invasion of Spartina alterniflora does not cause significant changes in microbial diversity, but it can alter the community structure of soil bacteria. The results of the LEfSe (LDA Effect Size) analysis show that the relative abundance of some bacterial taxa is not significantly different between the MC and SC communities, but different changes have occurred during the invasion process (i.e., TC community). Different from the results of the bacterial community, the invasion of Spartina alterniflora only cause a significant increase in few fungal taxa during the invasion process, and these taxa are at some lower levels (such as family, genus, and species) and classified into the phylum Ascomycota. Although the invasion of Spartina alterniflora changes the taxa with certain ecological functions, it may not change the potential ecological functions of soil microorganisms (i.e., the potential metabolic pathways of bacteria, nutritional patterns, and fungal associations). In general, the invasion of Spartina alterniflora changes the community structure of soil microorganisms, but it may not affect the potential ecological functions of soil microorganisms.

Microbial Communities Associated with Acetaminophen Biodegradation from Mangrove Sediment

Acetaminophen (ACE) is a widely used medicine. Currently, concerns regarding its potential adverse effects on the environments are raised. The aim of this study was to evaluate ACE biodegradation in mangrove sediments under aerobic and anaerobic conditions. Three ACE biodegradation strategies in mangrove sediments were tested. The degradation half-lives (t1/2) of ACE in the sediments with spent mushroom compost under aerobic conditions ranged from 3.24 ± 0.16 to 6.25 ± 0.31 d. The degradation half-lives (t1/2) of ACE in sediments with isolated bacterial strains ranged from 2.54 ± 0.13 to 3.30 ± 0.17 d and from 2.62 ± 0.13 to 3.52 ± 0.17 d under aerobic and anaerobic conditions, respectively. The degradation half-lives (t1/2) of ACE in sediments amended with NaNO3, Na2SO4 and NaHCO3 under anaerobic conditions ranged from 1.16 ± 0.06 to 3.05 ± 0.15 d, 2.39 ± 0.12 to 3.84 ± 0.19 d and 2.79 ± 0.14 to 10.75 ± 0.53 d, respectively. The addition of the three electron acceptors enhanced ACE degradation in mangrove sediments, where NaNO3 yielded the best effects. Sixteen microbial genera were identified as the major members of microbial communities associated in anaerobic ACE degradation in mangrove sediments with addition of NaNO3 and Na2SO4. Three (Arthrobacter, Enterobacter and Bacillus) of the sixteen microbial genera were identified in the isolated ACE-degrading bacterial strains.