Powering Ocean Giants: The Energetics of Shark and Ray Megafauna
"Energetics studies have illuminated how animals partition energy among essential life processes and survive in extreme environments or with unusual lifestyles. There are few bioenergetics measurements for elasmobranch megafauna; the heaviest elasmobranch for which metabolic rate has been measured is only 47.7 kg, despite many weighing >1000 kg. Bioenergetics models of elasmobranch megafauna would answer fundamental ecological questions surrounding this important and vulnerable group, and enable an understanding of how they may respond to changing environmental conditions, such as ocean warming and deoxygenation. [...]"
Source: Trends in Ecology & Evolution
Authors: Christopher L. Lawson et al.
Processes affecting dissolved iron across the Subtropical North Atlantic: a model study
"Trace metal measurements in recent years have revealed a complex distribution of dissolved iron (dFe) in the ocean that models still struggle to reproduce. The GEOTRACES section GA03 across the subtropical North Atlantic was chosen to study the driving processes involved in the Fe cycle in the region. [...]"
Source: Ocean Dynamics
Authors: Anna Pagnone et al.
Uncovering mechanisms of global ocean change effects on the Dungeness crab (Cancer magister) through metabolomics analysis
"The Dungeness crab is an economically and ecologically important species distributed along the North American Pacific coast. To predict how Dungeness crab may physiologically respond to future global ocean change on a molecular level, we performed untargeted metabolomic approaches on individual Dungeness crab juveniles reared in treatments that mimicked current and projected future pH and dissolved oxygen conditions. [...]"
Source: Scientific Reports
Authors: Shelly A. Trigg et al.
Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica
"Bacteriohopanepolyols (BHPs) are pentacyclic triterpenoid lipids that contribute to the structural integrity and physiology of some bacteria. Because some BHPs originate from specific classes of bacteria, BHPs have potential as taxonomically and environmentally diagnostic biomarkers. For example, a stereoisomer of bacteriohopanetetrol (informally BHT II) has been associated with anaerobic ammonium oxidation (anammox) bacteria and suboxic to anoxic marine environments where anammox is active. [...]"
Authors: Emily D. Matys et al.
Organic Heterogeneities in Foraminiferal Calcite Traced Through the Distribution of N, S, and I Measured With NanoSIMS:
A New Challenge for Element-Ratio-Based Paleoproxies?
"Oceanic oxygen decline due to anthropogenic climate change is a matter of growing concern. A quantitative oxygen proxy is highly desirable in order to identify and monitor recent dynamics as well as to reconstruct pre-Anthropocene changes in amplitude and extension of oxygen depletion. Geochemical proxies like foraminiferal I/Ca ratios seem to be promising redox proxies. [...]"
Source: Frontiers in Earth Science
Authors: Nicolaas Glock et al.
Chromium isotope cycling in the water column and sediments of the Peruvian continental margin
"Chromium (Cr) isotope fractionation is sensitive to redox changes and the Cr isotopic composition (δ53Cr) of sedimentary rocks has been used to reconstruct marine redox conditions and atmospheric oxygenation in the past. However, little is known about the behaviour of chromium isotopes across modern marine redox boundaries. We investigated Cr concentrations and δ53Cr variations in seawater and sediment across the Peruvian oxygen minimum zone (OMZ) to provide a better understanding of Cr cycling in the ocean. [...]"
Source: Geochimica et Cosmochimica
Authors: S. Bruggmann et al.
Ventilation of the Northern Baltic Sea (Preprint)
"The Baltic Sea is a semi-enclosed, brackish water sea in northern Europe. The deep basins of the central Baltic Sea regularly show hypoxic conditions. In contrast, the northern parts of the Baltic Sea, the Bothnian Sea and Bay, are well oxygenated. Lateral inflows or a ventilation due to convection are possible mechanisms for high oxygen concentrations in the deep water of the northern Baltic Sea. [...]"
Source: Ocean Science
Authors: Thomas Neumann et al.
High-resolution records of Oceanic Anoxic Event 2:
Insights into the timing, duration and extent of environmental perturbations from the palaeo-South Pacific Ocean
"Oceanic Anoxic Event 2 (OAE 2), which took place around the Cenomanian–Turonian boundary (∼94 Ma), is associated with extreme perturbations to the global carbon cycle, affected ocean basins worldwide and was associated with significant biological turnover. Although this event has been well studied in the northern hemisphere, the evolution and character of OAE 2, particularly in terms of the vertical and lateral extent of anoxia, is poorly constrained in the palaeo-Pacific Ocean. [...]"
Source: Earth and Planetary Science Letters
Authors: S. K. Gangl et al.
Gulf Dead Zone Looms Large in 2019
"In 2019, predictions indicate that the Gulf of Mexico will retain the dubious distinction of having the second-largest low-oxygen dead zone on Earth (the Baltic Sea remains firmly in first place). By the end of the summer, the hypoxic region on the seafloor at the mouth of the Mississippi River is expected to occupy over 22,000 square kilometers—an area the size of the state of Massachusetts. [...]
Source: Earth & Space Science News
Author: Mary Caperton Morton
Anoxygenic photosynthesis and the delayed oxygenation of Earth’s atmosphere
"The emergence of oxygenic photosynthesis created a new niche with dramatic potential to transform energy flow through Earth’s biosphere. However, more primitive forms of photosynthesis that fix CO2 into biomass using electrons from reduced species like Fe(II) and H2 instead of water would have competed with Earth’s early oxygenic biosphere for essential nutrients. [...]"
Source: Nature Communications
Authors: Kazumi Ozaki et al.