. | . |
Two ocean studies look at microscopic diversity and activity across entire planet by Staff Writers Washington DC (SPX) Nov 18, 2019
In an effort to reverse the decline in the health of the world's oceans, the United Nations (UN) has declared 2021 to 2030 to be the Decade of Ocean Science for Sustainable Development. One key requirement for the scientific initiative is data on existing global ocean conditions. An important trove of data is already available thanks to the Tara Oceans expedition, an international, interdisciplinary enterprise that collected 35,000 samples from all the world's oceans between 2009 and 2013. The samples were collected by researchers aboard one schooner, the Tara, at depths ranging from the surface to 1,000 meters deep. Two papers being published November 14 in the journal Cell are the latest to use samples and data collected during the Tara Oceans expedition to analyze diversity across the entire planet of plankton, microscopic organisms that drift on oceanic currents that are key for the well-being of our oceans. One study focused on the diversity of plankton across Earth's oceans, whereas the other study assessed gene expression among microbial communities as a way to predict how these communities might adapt to changing environmental conditions.
Plankton Diversity across Different Latitudes "Our study focused on plankton because it's a major contributor to marine ecosystems in terms of biomass, abundance, and diversity," says co-senior author Lucie Zinger of IBENS. "All types of life have representatives in the plankton--bacteria, archaea, protists, animals and plants, as well as viruses. But the large majority of this diversity is invisible to the naked eye." The paper reports that the large majority of planktonic groups, from giant viruses to small animals, follow a gradient of diversity along latitudes, with the lowest level of diversity closest to the poles. "Ocean temperature is mainly responsible for this pattern," Zinger notes. "Ocean warming due to climate change is likely to lead to a 'tropicalization,' or increase, of plankton diversity in temperate and polar waters. The consequences of this are still unclear, but we know these geographic areas are currently very important for different ecosystem services, including fisheries and carbon sequestration." One innovative aspect of this study was that it combined both imaging and DNA-based techniques to assess plankton diversity. "We know a lot about how to process information from DNA sequences," Bowler says. "But images are much more complicated. We observed many different morphologies and different behaviors of these organisms. There are many new organisms and new kinds of interactions between them still to be discovered."
Understanding the Activity of Microbial Life at Different Ocean Depths and Geographies "Looking at transcriptomes is important for determining not just which microbes are present, but what those microbes are actually doing with regard to activities like photosynthesis and nutrient uptake," says senior author Shinichi Sunagawa of the Institute of Microbiology and Swiss Institute of Bioinformatics at ETH Zurich. "One of our goals was to learn whether microbial communities adjust to environmental and temperature variations with changes in their composition relative to each other or with changes in the gene expression patterns within these communities." The investigators found that in terms of taxonomic, genomic, and transcriptomic composition, there are distinct ecological boundaries separating both surface water from deep water and polar from nonpolar regions. They expected to see some of these changes--such as differences in the levels of photosynthetic organisms relative to water depth. But some other observations were rather unexpected. "We did not expect to find biogeographic patterns for the underlying mechanisms of metatranscriptomic composition variation. Specifically, we found differences in polar communities to be dominated by changes in organismal composition, while in nonpolar waters, the differences were dominated by changes in the expression of genes," Sunagawa says. He adds that his team was also surprised to find genomic and transcriptomic evidence for a nitrogen-fixing bacterium in deep Arctic waters. "Every drop of marine water is full of microbes, which play a central role in many processes relevant to life on Earth," he notes. "Understanding the ecological factors that determine the diversity, composition, and activity of these organisms is essential to better model and predict future deviations, especially in light of climate change." One limitation of the data to come from the Tara Oceans expedition is that the samples were collected over a relatively short period of time, less than four years. This makes it difficult to observe any measurable trends in today's oceans related to climate change. The researchers say that longer-term studies are needed to account for changes in factors like acidification, deoxygenation, and pollution.
A Call for Ocean Science in the Face of Climate Change "As revealed by the releases of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services global assessment and of the Special Report on the Ocean and Cryosphere of the IPCC, both in 2019, there is now an urgency to engage into sustainable pathways," says corresponding author Joachim Claudet of the CNRS. He adds that the main threats on the ocean's sustainability are overexploitation of fish, shellfish, and other organisms; land- and sea-based pollution; and land/sea-use change, including coastal development for infrastructure and aquaculture; and climate change. "We need science to develop evidence that can better inform policies to implement viable solutions, as well as operational and transformative actions that can better impact societies, from local to global scales," he says. "The Tara expeditions have multiple values. They allow us to collect local natural, chemical, and physical in situ data at the ocean scale. These data can feed into both basic and applied research. Tara's outreach programs can also be a driver of the most needed change in perception that the ocean is both highly valuable and vulnerable."
Research Reports "Global Trends in Marine Plankton Diversity across Kingdoms of Life" and "Gene Expression Changes and Community Turnover Differentially Shape the Global Ocean Metatranscriptome"
Strange disease threatens Caribbean coral reef Canc�n, Mexico (AFP) Nov 12, 2019 The breathtaking reds, yellows and purples of the Mesoamerican Reef have been turning sickly white, leading researchers on a desperate hunt to understand and fight the mysterious disease killing the Caribbean's corals. In a little over a year, the Mexican Caribbean has lost more than 30 percent of its corals to a little-understood illness called SCTLD, or stony coral tissue loss disease, which causes them to calcify and die. Experts warn the disease could kill a large part of the Mesoamerican Re ... read more
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |