Anaerobic Activity Is a Big Contributor in Marine “Dead Zones”
Climate models that do not account for anaerobic microbial activity may underestimate future expansion of oxygen-depleted waters.
"Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones. [...]"
Record-Setting Ocean Warmth Continued in 2019
"Human-emitted greenhouse gases (GHGs) have resulted in a long-term and unequivocal warming of the planet (IPCC, 2019). More than 90% of the excess heat is stored within the world’s oceans, where it accumulates and causes increases in ocean temperature (Rhein et al., 2013; Abram et al., 2019). Because the oceans are the main repository of the Earth’s energy imbalance, measuring ocean heat content (OHC) is one of the best way to quantify the rate of global warming (Trenberth et al., 2016; Von Schuckmann et al., 2016; Cheng et al., 2018). [...]"
Source: Advances in Atmospheric Sciences
Authors: Lijing Cheng et al.
Record-setting ocean warmth continued in 2019
"A new analysis shows the world's oceans were the warmest in 2019 than any other time in recorded human history, especially between the surface and a depth of 2,000 meters. The study, conducted by an international team of 14 scientists from 11 institutes across the world, also concludes that the past ten years have been the warmest on record for global ocean temperatures, with the past five years holding the highest record. [...]"
Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition
"The ocean is the main source of thermal inertia in the climate system. Ocean heat uptake during recent decades has been quantified using ocean temperature measurements. However, these estimates all use the same imperfect ocean dataset and share additional uncertainty due to sparse coverage, especially before 2007. Here, we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2) – levels of which increase as the ocean warms and releases gases – as a whole ocean thermometer. [...]"
Source: Scientific Reports
Authors: L. Resplandy et al.
Warming climate will impact dead zones in Chesapeake Bay
"In recent years, scientists have projected increasingly large summer dead zones in the Chesapeake Bay, areas where there is little or no oxygen for living things like crabs and fish to thrive, even as long-term efforts to reduce nutrient pollution continue. Researchers factored in local impacts of climate change to make projections of what the oxygen content of the Chesapeake Bay will look like in the future. [...]"
Source: Science Daily
Ocean acidification – a silently progressing crisis
"Ocean warming, acidification, deoxygenation, and marine heatwaves are all pressing marine issues that are quietly intensifying around the world. These challenges are diverse and occur on a massive scale, making it difficult for people to understand the full extent of the problem. To shed some light on this topic, the Sasakawa Peace Foundation (SPF) spoke with Mr. Tsunoda, Senior Research Fellow at the Ocean Policy Research Institute (OPRI). [...]"
Source: Sasakawa Peace Foundation
A crisis in the water is decimating this once-booming fishing town
"TOMBWA, Angola — His ancestors were Portuguese colonialists who settled on this otherworldly stretch of coast, wedged between a vast desert and the southern Atlantic. They came looking for the one thing this barren region had in abundance: fish.
By the time Mario Carceija Santos was getting into the fishing business half a century later, in the 1990s, Angola had won independence and the town of Tombwa was thriving. There were 20 fish factories strung along the bay, a constellation of churches and schools, a cinema hall built in art deco, and, in the central plaza, massive drying racks for the tons upon tons of fish hauled out of the sea. [...]"
Source: The Washington Post
Sensitivities to global change drivers may correlate positively or negatively in a foundational marine macroalga
"Ecological impact of global change is generated by multiple synchronous or asynchronous drivers which interact with each other and with intraspecific variability of sensitivities. In three near-natural experiments, we explored response correlations of full-sibling germling families of the seaweed Fucus vesiculosus towards four global change drivers: elevated CO2 (ocean acidification, OA), ocean warming (OW), combined OA and warming (OAW), nutrient enrichment and hypoxic upwelling. [...]"
Source: Scientific Reports
Authors: Balsam Al-Janabi et al.
Combined effects of ocean acidification and temperature on larval and juvenile growth, development and swimming performance of European sea bass
"Ocean acidification and ocean warming (OAW) are simultaneously occurring and could pose ecological challenges to marine life, particularly early life stages of fish that, although they are internal calcifiers, may have poorly developed acid-base regulation. This study assessed the effect of projected OAW on key fitness traits (growth, development and swimming ability) in European sea bass (Dicentrarchus labrax) larvae and juveniles. [...]"
Source: PLoS One
Authors: Louise Cominassi etal.
Oxygen supersaturation protects coastal marine fauna from ocean warming
"Ocean warming affects the life history and fitness of marine organisms by, among others, increasing animal metabolism and reducing oxygen availability. In coastal habitats, animals live in close association with photosynthetic organisms whose oxygen supply supports metabolic demands and may compensate for acute warming. [...]"
Source: Science Advances
Authors: Folco Giomi et al.