ALBERT

Description: Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (〈 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (〈 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.

Description: The cryosphere, which comprises a large portion of Earth’s surface, is rapidly changing as a consequence of global climate change. Ice, snow, and frozen ground in the polar and alpine regions of the planet are known to directly impact atmospheric composition, which for example is observed in the large influence of ice and snow on polar boundary layer chemistry. Atmospheric inputs to the cryosphere, including aerosols, nutrients, and contaminants, are also changing in the anthropocene thus driving cryosphere-atmosphere feedbacks whose understanding is crucial for understanding future climate. Here, we present the Cryosphere and ATmospheric Chemistry initiative (CATCH) which is focused on developing new multidisciplinary research approaches studying interactions of chemistry, biology, and physics within the coupled cryosphere – atmosphere system and their sensitivity to environmental change. We identify four key science areas: (1) micro-scale processes in snow and ice, (2) the coupled cryosphere-atmosphere system, (3) cryospheric change and feedbacks, and (4) improved decisions and stakeholder engagement. To pursue these goals CATCH will foster an international, multidisciplinary research community, shed light on new research needs, support the acquisition of new knowledge, train the next generation of leading scientists, and establish interactions between the science community and society.

Description: The distribution and magnitude of benthic N2 fixation in OMZs, and its relevance for the community inhabiting these sediments was investigated. A possible coupling to sulfate reducers was determined by rate measurements of N2 fixation and sulfate reduction, as well as by molecular analysis in the respective environment. In sediments of the Peruvian OMZ, N2 fixation and sulfate reduction occurred throughout the sediment and depth profiles largely overlapped, suggesting a coupling of both processes. This coupling was further supported by the molecular analysis. In the Mauritanian OMZ N2 fixation activity often overlapped with sulfate reduction, as well as with ferrous iron concentrations. The molecular analysis confirmed the presence of sulfate- and iron-reducing bacteria. Burrowing organisms potentially create a biogeochemical zonation pattern in sediments that enhanced N2 fixation in deeper sediment layers. To examine the marine benthic diazotrophic diversity, samples from OMZs, methane seeps and brackish water sediments were used for high-throughput sequencing. Results showed a small diversity of diazotrophs among sites and a dominance of sulfate reducers. The redundancy analysis showed a positive correlation between diazotrophs and sulfate reduction. To conclude, the detection of benthic N2 fixation in OMZs, as well as the diversity study of benthic diazotrophs from different environments, shows that it is a ubiquitous process in the benthic environment. The global distribution of benthic diazotrophs, as revealed by the diversity study, highlights its previously underestimated role in the benthic N cycle, as well as in the marine N budgets. The controlling factors of diazotrophs in marine sediments are: abundance of sulfate reducers; organic matter content in the sediments; and sulfide concentration in the porewater, as a potential inhibitor.

Description: Science Board Meeting 2022 — Note from the Science Board Chair. FUTURE SSC’s 8th Annual Meeting ~ Highlights. PICES-2022 and the first hybrid annual meeting. Featuring PICES-2022 Award recipients: (Chair Award, Wooster Award, Zhu-Peterson Award, PICES Ocean Monitoring Service Award, ECS Best Presentation Awards). PICES-2022 Workshop Reports: (W1: Distributions of pelagic, demersal, and benthic species associated with seamounts in the North Pacific Ocean and factors influencing their distributions, W2: Integrated Ecosystem Assessment (IEA) to understand the present and future of the Central Arctic Ocean (CAO) and Northern Bering and Chukchi Seas (NBS-CS), W3: SmartNet: Promoting PICES and ICES Leadership in the UN Decade of Ocean Science for Sustainable Development, W4: Exploring Engagement Opportunities for Early Career Ocean Professionals (ECOPs) within PICES and Internationally, W5: Integrating biological research, fisheries science and management of broadly distributed flatfish species across the North Pacific Ocean in the face of climate and environmental variability, W7: Anthropogenic stressors, mechanisms and potential impacts on Marine Birds, Mammals, and Sea Turtles, W8: Science Communication Training: How to Create Memorable PICES Science Stories, W10: A TCODE Workshop on “Openly Discoverable, Accessible, and Reusable Data and Information in the U.N. Decade”). PICES AP-NPCOOS "Ocean Big Data" Summer School. PICES AP-CREAMS Virtual Summer School on Ocean Turbulence: From Observing to Research. Science and Innovation to Scale Up Ocean Action: UN Ocean Conference 2022. ECOP Perspective on the 4th Early Career Scientist Conference (ECSC4). Symposium in Lisbon Re-unites the Global Community Investigating Small Pelagic Fish. SPF2022 Symposium Workshop Reports: (1: Application of Genetics to Small Pelagic Fish, 2: The Devil’s in the Details of Using Species Distribution Models to Inform Multispecies and Ecosystem Models, 3: Small Pelagics for Whom? Challenges and Opportunities for the Equitable Distribution of Nutritional Benefits, 4: Evaluating Inter-Sectoral Tradeoffs and Community-Level Response to Spatio-Temporal Changes in Forage Distribution and Abundance, 5: Recent Advances in the Daily Egg Production Method (DEPM): Challenges and Opportunities, 6: Small Pelagic Fish Reproductive Resilience). SOLAS Open Science Conference, 2022. Early Career Scientist Participation in SOLAS Open Science Conference, 2022. PICES SeaTurtle researchers find clues linking derelict fishing lines of “Urban Fishermen” to sea turtle stranding. NPAFC's IYS Synthesis Symposium - Key Takeaways. The Bering Sea: Current Status and Recent Trends. Western North Pacific: Current status and recent topic: Sea Surface Temperature during the 2022 warm season, The Northeast Pacific: Update on marine heatwave status and trends. PICES Events Calendar. PICES by the Numbers, and an Invitation to join SG-GREEN. Open call for PICES Press submissions | About PICES Press

Description: Published

Description: Non Refereed