A groundbreaking study led by Bethany Kolody has unveiled how deep ocean currents shape microbial life across the South Pacific. The research team identified ten “functional zones” based on the presence of key metabolic genes, revealing the complex interplay between ocean dynamics and microbial diversity. This study’s journey started by Easter Island and ended in the vicinity of Antarctica. In the process, we collected over 300 water samples that spanned across the entire depth of the ocean.
Science has demonstrated that winds and storms greatly impact the upper 500 meters (1,640 feet) of the ocean. At the same time, deeper currents are largely controlled by shifts in water temperature and salinity. Microbial diversity increases dramatically to depths around 300 meters (1,000 feet) under the ocean surface. This metaphylic zone of intense environmental specialization is referred to as the “prokaryotic phylocline.” This unexpected result highlights the importance of studying marine ecosystems at multiple depths to fully appreciate their complexities.
Methodology of the Study
Bethany Kolody and her co-authors employed cutting-edge metagenomic and metabarcoding approaches. In turn, she and her colleagues were able to reconstruct the genomes of more than 300 microbes. This imaginative strategy let them focus in on tens of thousands of other microbial denizens using a swath of molecular fingerprinting sorcery. The comprehensive analysis led to the identification of six distinct microbial “cohorts,” three of which correspond to specific depths, while the other three align with major water masses: Antarctic Bottom Water, Upper Circumpolar Deep Water, and ancient Pacific Deep Water.
The old water group is really interesting. It contains microbes that are thriving in water circulating so slowly it may have not seen the surface in more than a thousand years. These microorganisms have very specific genes that allow them to exist in anoxic conditions and degrade very complex, low energy carbon compounds.
“Until now, it was unclear whether these water masses also served as distinct microbial ecosystems,” – Bethany Kolody
“We can now answer that question with a resounding, ‘yes.’” – Bethany Kolody
Implications for Climate Change
This study constitutes an important step toward understanding how microbial ecosystems will be organized under a new ocean regime. Andrew Allen, a collaborator on the project, emphasized its importance by stating, “The study provides a baseline for how microbial ecosystems are organized under current ocean conditions.” Climate change is already affecting global overturning circulation. In turn, alterations to the functional and taxonomic diversity of microbial communities can occur, potentially resulting in unforeseen impacts on global carbon cycling.
Allen further elaborated on the significance of understanding these ecosystems: “This study is a reminder that life in ocean ecosystems is, in part, governed by fundamental patterns and processes that are unknown to us.” He advocates for a more sensitive and thorough examination of marine life to gain a deeper understanding of its complexities.
“As climate change impacts global overturning circulation, the distribution and function of these microbial communities could shift, with unknown consequences for global carbon cycling.” – Andrew Allen
Future Directions for Research
Bethany Kolody and Andrew Allen are calling for the incorporation of molecular sampling techniques into global ocean monitoring programs such as GO-SHIP. To them, this innovative integration is key to a deeper understanding of microbial life and its importance in the provisioning of oceanic carbon cycling.
This study reveals some major advances. They were the fruits of the multidisciplinary teamwork of physical oceanographers, biological oceanographers and genome biologists. This unique, interdisciplinary approach allowed the research team to discover complex interactions between deep-surface currents and marine microbial diversity.
“The breakthroughs reported in this study are the result of a truly interdisciplinary effort involving physical oceanographers, biological oceanographers, and genome biologists all working very closely together.” – Not attributed to anyone