This content will become publicly available on April 27, 2023
- Campbell, Barbara J.
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- Sponsoring Org:
- National Science Foundation
More Like this
Abstract The deepest part of the global ocean, hadal trenches, are considered to act as depocenters for organic material. Relatively high microbial activity has been demonstrated in the deepest sections of some hadal trenches, but the deposition dynamics are thought to be spatially and temporally variable. Here, we explore sediment characteristics and in-situ benthic oxygen uptake along two trenches with contrasting surface primary productivity: the Kermadec and Atacama trenches. We find that benthic oxygen consumption varies by a factor of about 10 between hadal sites but is in all cases intensified relative to adjacent abyssal plains. The benthic oxygen uptake of the two trench regions reflects the difference in surface production, whereas variations within each trench are modulated by local deposition dynamics. Respiratory activity correlates with the sedimentary inventories of organic carbon and phytodetrital material. We argue that hadal trenches represent deep sea hotspots for early diagenesis and are more diverse and dynamic environments than previously recognized.
Taxonomic, Genomic, and Functional Variation in the Gut Microbiomes of Wild Spotted Hyenas Across 2 Decades of StudyHird, Sarah M. (Ed.)The gut microbiome provides vital functions for mammalian hosts, yet research on its variability and function across adult life spans and multiple generations is limited in large mammalian carnivores. Here, we used 16S rRNA gene and metagenomic high-throughput sequencing to profile the bacterial taxonomic composition, genomic diversity, and metabolic function of fecal samples collected from 12 wild spotted hyenas ( Crocuta crocuta ) residing in the Masai Mara National Reserve, Kenya, over a 23-year period spanning three generations. The metagenomic data came from four of these hyenas and spanned two 2-year periods. With these data, we determined the extent to which host factors predicted variation in the gut microbiome and identified the core microbes present in the guts of hyenas. We also investigated novel genomic diversity in the mammalian gut by reporting the first metagenome-assembled genomes (MAGs) for hyenas. We found that gut microbiome taxonomic composition varied temporally, but despite this, a core set of 14 bacterial genera were identified. The strongest predictors of the microbiome were host identity and age, suggesting that hyenas possess individualized microbiomes and that these may change with age during adulthood. The gut microbiome functional profiles of the four adult hyenas were also individual specificmore »
Thermal Stress Interacts With Surgeonfish Feces to Increase Coral Susceptibility to Dysbiosis and Reduce Tissue RegenerationDysbiosis of coral microbiomes results from various biotic and environmental stressors, including interactions with important reef fishes which may act as vectors of opportunistic microbes via deposition of fecal material. Additionally, elevated sea surface temperatures have direct effects on coral microbiomes by promoting growth and virulence of opportunists and putative pathogens, thereby altering host immunity and health. However, interactions between these biotic and abiotic factors have yet to be evaluated. Here, we used a factorial experiment to investigate the combined effects of fecal pellet deposition by the widely distributed surgeonfish Ctenochaetus striatus and elevated sea surface temperatures on microbiomes associated with the reef-building coral Porites lobata . Our results showed that regardless of temperature, exposure of P. lobata to C. striatus feces increased alpha diversity, dispersion, and lead to a shift in microbial community composition – all indicative of microbial dysbiosis. Although elevated temperature did not result in significant changes in alpha and beta diversity, we noted an increasing number of differentially abundant taxa in corals exposed to both feces and thermal stress within the first 48h of the experiment. These included opportunistic microbial lineages and taxa closely related to potential coral pathogens (i.e., Vibrio vulnificus , Photobacterium rosenbergii ).more »
Bacterial and eukaryotic intact polar lipids point to in situ production as a key source of labile organic matter in hadal surface sediment of the Atacama TrenchAbstract. Elevated organic matter (OM) concentrations are found in hadalsurface sediments relative to the surrounding abyssal seabed. However, theorigin of this biological material remains elusive. Here, we report on thecomposition and distribution of cellular membrane intact polar lipids (IPLs)extracted from surface sediments around the deepest points of the AtacamaTrench and adjacent bathyal margin to assess and constrain the sources oflabile OM in the hadal seabed. Multiscale bootstrap resampling of IPLs'structural diversity and abundance indicates distinct lipid signatures inthe sediments of the Atacama Trench that are more closely related to thosefound in bathyal sediments than to those previously reported for the upperocean water column in the region. Whereas the overall number of unique IPLstructures in hadal sediments contributes a small fraction of the total IPLpool, we also report a high contribution of phospholipids with mono- anddi-unsaturated fatty acids that are not associated with photoautotrophicsources and that resemble traits of physiological adaptation to highpressure and low temperature. Our results indicate that IPLs in hadalsediments of the Atacama Trench predominantly derive from in situ microbialproduction and biomass, whereas the export of the most labile lipidcomponent of the OM pool from the euphotic zone and the overlying oxygenminimum zone is neglectable. While other OMmore »
Mercury isotopic compositions of amphipods and snailfish from deep-sea trenches reveal information on the sources and transformations of mercury in the deep oceans. Evidence for methyl-mercury subjected to photochemical degradation in the photic zone is provided by odd-mass independent isotope values (Δ199Hg) in amphipods from the Kermadec Trench, which average 1.57‰ (±0.14,
n= 12, SD), and amphipods from the Mariana Trench, which average 1.49‰ (±0.28, n= 13). These values are close to the average value of 1.48‰ (±0.34, n= 10) for methyl-mercury in fish that feed at ∼500-m depth in the central Pacific Ocean. Evidence for variable contributions of mercury from rainfall is provided by even-mass independent isotope values (Δ200Hg) in amphipods that average 0.03‰ (±0.02, n= 12) for the Kermadec and 0.07‰ (±0.01, n= 13) for the Mariana Trench compared to the rainfall average of 0.13 (±0.05, n= 8) in the central Pacific. Mass-dependent isotope values (δ202Hg) are elevated in amphipods from the Kermadec Trench (0.91 ±0.22‰, n= 12) compared to the Mariana Trench (0.26 ±0.23‰, n= 13), suggesting a higher level of microbial demethylation of the methyl-mercury pool before incorporation into the base of the foodweb. Our study suggests that mercury in the marine foodweb at ∼500 m, which is predominantly anthropogenic, is transported to deep-seamore »