The Impact of Selective-Logging and Forest Clearance for Oil Palm on Fungal Communities in Borneo

Tropical forests are being rapidly altered by logging, and cleared for agriculture. Understanding the effects of these land use changes on soil fungi, which play vital roles in the soil ecosystem functioning and services, is a major conservation frontier. Using 454-pyrosequencing of the ITS1 region of extracted soil DNA, we compared communities of soil fungi between unlogged, once-logged, and twice-logged rainforest, and areas cleared for oil palm, in Sabah, Malaysia. Overall fungal community composition differed significantly between forest and oil palm plantation. The OTU richness and Chao 1 were higher in forest, compared to oil palm plantation. As a proportion of total reads, Basidiomycota were more abundant in forest soil, compared to oil palm plantation soil. The turnover of fungal OTUs across space, true β-diversity, was also higher in forest than oil palm plantation. Ectomycorrhizal (EcM) fungal abundance was significantly different between land uses, with highest relative abundance (out of total fungal reads) observed in unlogged forest soil, lower abundance in logged forest, and lowest in oil palm. In their entirety, these results indicate a pervasive effect of conversion to oil palm on fungal community structure. Such wholesale changes in fungal communities might impact the long-term sustainability of oil palm agriculture. Logging also has more subtle long term effects, on relative abundance of EcM fungi, which might affect tree recruitment and nutrient cycling. However, in general the logged forest retains most of the diversity and community composition of unlogged forest

Responses of Intertidal Bacterial Biofilm Communities to Increasing pCO2

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Shallow water marine sediment bacterial community shifts along a natural CO2 gradient in the Mediterranean Sea off Vulcano, Italy.

The effects of increasing atmospheric CO(2) on ocean ecosystems are a major environmental concern, as rapid shoaling of the carbonate saturation horizon is exposing vast areas of marine sediments to corrosive waters worldwide. Natural CO(2) gradients off Vulcano, Italy, have revealed profound ecosystem changes along rocky shore habitats as carbonate saturation levels decrease, but no investigations have yet been made of the sedimentary habitat. Here, we sampled the upper 2 cm of volcanic sand in three zones, ambient (median pCO(2) 419 μatm, minimum Ω(arag) 3.77), moderately CO(2)-enriched (median pCO(2) 592 μatm, minimum Ω(arag) 2.96), and highly CO(2)-enriched (median pCO(2) 1611 μatm, minimum Ω(arag) 0.35). We tested the hypothesis that increasing levels of seawater pCO(2) would cause significant shifts in sediment bacterial community composition, as shown recently in epilithic biofilms at the study site. In this study, 454 pyrosequencing of the V1 to V3 region of the 16S rRNA gene revealed a shift in community composition with increasing pCO(2). The relative abundances of most of the dominant genera were unaffected by the pCO(2) gradient, although there were significant differences for some 5 % of the genera present (viz. Georgenia, Lutibacter, Photobacterium, Acinetobacter, and Paenibacillus), and Shannon Diversity was greatest in sediments subject to long-term acidification (>100 years). Overall, this supports the view that globally increased ocean pCO(2) will be associated with changes in sediment bacterial community composition but that most of these organisms are resilient. However, further work is required to assess whether these results apply to other types of coastal sediments and whether the changes in relative abundance of bacterial taxa that we observed can significantly alter the biogeochemical functions of marine sediments

Enduring legacy of coal mining on the fungal community in a High Arctic soil after five decades

Mineral extraction is known to affect soil fungi in polar environments, but it is unknown how long these effects persist. Here, by amplifying the internal transcribed spacer regions of rRNA genes in soil fungi, we compared soil fungal community in intact natural tundra with that in a nearby former coal mining area, abandoned 52 years previously, on Svalbard in the High Arctic. Compared with those in intact tundra, soils in the former mining area were more acidic and had lower plant coverage. Despite of similar diversity in the two areas, the fungal community was dominated by Basidiomycota in the intact tundra, but by Ascomycota in the former mining area. Ectomycorrhizal genera formed a major part of the tundra community, but were notably less abundant in the mining area. The principal variation among samples was soil pH. Surprisingly, network connectivity analysis indicated that the fungal community in the former mining area had greater network connectivity than that in the tundra area. Overall, the ecosystem in the former mining area has made only limited recovery towards the natural tundra state even after more than five decades. It is unclear whether the recovery of the fungal community is limited more by the low primary productivity, slow migration of fungi and plants, or slow changes in soil parameters. Our findings emphasize the susceptibility of polar ecosystems to disturbance, given their particularly slow recovery back towards the natural state. © 2022 Soil Science Society of China

Whole community and functional gene changes of biofilms on marine plastic debris in response to ocean acidification.

Plastics are accumulating in the world's oceans, while ocean waters are becoming acidified by increased CO2. We compared metagenome of biofilms on tethered plastic bottles in subtidal waters off Japan naturally enriched in CO2, compared to normal ambient CO2 levels. Extending from an earlier amplicon study of bacteria, we used metagenomics to provide direct insights into changes in the full range of functional genes and the entire taxonomic tree of life in the context of the changing plastisphere. We found changes in the taxonomic community composition of all branches of life. This included a large increase in diatom relative abundance across the treatments but a decrease in diatom diversity. Network complexity among families decreased with acidification, showing overall simplification of biofilm integration. With acidification, there was decreased prevalence of genes associated with cell-cell interactions and antibiotic resistance, decreased detoxification genes, and increased stress tolerance genes. There were few nutrient cycling gene changes, suggesting that the role of plastisphere biofilms in nutrient processes within an acidified ocean may not change greatly. Our results suggest that as ocean CO2 increases, the plastisphere will undergo broad-ranging changes in both functional and taxonomic composition, especially the ecologically important diatom group, with possible wider implications for ocean ecology

Shift from coral to macroalgae dominance on a volcanically acidified reef

Rising anthropogenic CO2 in the atmosphere is accompanied by an increase in oceanic CO2 and a concomitant decline in seawater pH (ref. 1). This phenomenon, known as ocean acidification (OA), has been experimentally shown to impact the biology and ecology of numerous animals and plants2, most notably those that precipitate calcium carbonate skeletons, such as reef-building corals3. Volcanically acidified water at Maug, Commonwealth of the Northern Mariana Islands (CNMI) is equivalent to near-future predictions for what coral reef ecosystems will experience worldwide due to OA. We provide the first chemical and ecological assessment of this unique site and show that acidification-related stress significantly influences the abundance and diversity of coral reef taxa, leading to the often-predicted shift from a coral to an algae-dominated state4, 5. This study provides field evidence that acidification can lead to macroalgae dominance on reefs