How ocean eddies influence blue shark foraging
Blue shark. Image courtesy of Tom Burns (photographer).
Anticyclonic eddies, masses of water swirling clockwise in oceans’ pelagic zones, make up oceans’ internal weather systems and are generally considered nutrient deserts due to their low productivity. Powerful anticyclonic eddies draw warm water from the Sargasso Sea to north of the Gulf Stream off the northeastern US coast, creating anomalous conditions, and previous studies have suggested that such eddies may shape the migration of marine life. Camrin Braun et al. (pp. 17187–17192) used Earth-observing satellites to track the 3D movements of 15 electronically tagged blue sharks (Prionace glauca), a highly exploited predator, in the Gulf Stream region of the Atlantic Ocean over 2,000 days. Blue sharks tended to favor anticyclonic (clockwise-rotating) rather than cyclonic (counterclockwise-rotating) eddies, particularly while foraging. The sharks foraged on vertically migrating prey—likely cephalopods and fishes that inhabit the ocean twilight zone—during daytime dives through anticyclonic eddies, which provided a warm passageway to depths otherwise beyond the sharks’ reach due to thermal limits on physiology. Commercial fishing operations increasingly harvest biomass from twilight zones, and current fisheries management approaches fail to account for dynamic ocean processes such as eddies. According to the authors, the findings suggest that large-scale removal of twilight-zone biomass may adversely affect stocks of commercially important species such as blue sharks, swordfish, and tuna. — P.N.
Financial investors and racial bias
Globally, people of color manage less than 2% of assets for hedge funds, mutual funds, private equity, and real estate, which amount to more than $69.1 trillion. To examine the basis of the racial homogeneity, Sarah Lyons-Padilla, Jennifer Eberhardt, et al. (pp. 17225–17230) designed an experiment in which 180 primarily white asset allocators from North America were asked to evaluate 1-page descriptions of fund manager teams. The 1-pagers, which included headshots, summaries of the teams’ track records, and investment strategies, were systematically varied so that the managing partner was a white or black male and that the team’s credentials were strong or weak. Asset allocators rated strong white-male-led teams more favorably than strong black-male-led teams. Asset allocators rated weak black-male-led teams more favorably than weak white-male-led teams. However, asset allocators were not likely to invest in weak teams, regardless of race. Asset allocators took team competence into account when predicting future performance for white-male-led teams more so than for black-male-led teams. The findings suggest that the more qualified black-led teams are, the more bias they are likely to face. Such bias may contribute to the lack of diversity in the investment industry, according to the authors. — M.S.
Origin of domestic pigs
Feral male juvenile pig from inner Sardinia.
Archaeological and genetic evidence indicates that humans began domesticating pigs in the Near East around 10,500 years ago and that the pigs arrived in Europe around 8,500 years ago. However, whether humans independently domesticated European wild boar without genetic contribution from Near Eastern pigs is unclear. Laurent Frantz, James Haile, Audrey Lin, et al. (pp. 17231–17238) analyzed the mitochondrial DNA sequences of 2,099 ancient and modern pig samples and 63 ancient nuclear genomes from European and Near Eastern pigs. The authors found that European domestic pigs that lived between 7,100 and 6,000 years ago had both European and Near Eastern ancestry, whereas pigs that lived after 6,000 years ago possessed up to approximately 4% of Near Eastern ancestry. The findings suggest that besides a locus that encodes coat color differences between wild and domestic pigs, modern European pigs almost completely lost their Near Eastern ancestry less than 3,000 years after being introduced, as a result of gene flow from European wild boars. Further, interbreeding with local wild boars was sufficient to almost completely erase the original genomic ancestry of pigs domesticated in the Near East, according to the authors. — M.S.
Forest biomass loss from pest invasion
A red bay stand killed by laurel wilt disease in Evans County, Georgia. Image courtesy of Kevin M. Potter (North Carolina State University, Raleigh, NC).
Nonnative pests—insects and diseases—can adversely affect vital ecosystem services, such as carbon sequestration, provided by forests worldwide. The large-scale impacts of individual pests have been assessed, but estimates of the aggregate impacts of all nonnative pests on tree mortality and forest carbon budgets are limited. Songlin Fei et al. (pp. 17371–17376) used data from more than 92,000 field plots throughout the continental United States to quantify the biomass loss associated with the 15 most damaging nonnative forest pests. The authors estimated that these 15 species combined contributed to the death of approximately 5.5 TgC per year above background mortality rates. Compensatory growth of nonhost trees was observed 2–5 decades following initial pest invasion of a region. Given that most of these pests have not yet invaded their hosts’ full ranges, the authors estimate that approximately 40% of the total live forest biomass in the continental United States is at risk of future damage from these pests. The results provide insight into the impact of nonnative pests on forest carbon budgets and could inform future policy measures aimed at protecting US forests against nonnative pests, according to the authors. — B.D.
Climate change, air quality, and health in China
Smog over Beijing, China. Image courtesy of Flickr/NOAA/NASA.
Every year, more than 1 million people die prematurely in China because of air pollution. Climate change may exacerbate the health impacts by increasing the frequency and intensity of extreme weather events, but the relationship between extreme events and air quality is not well understood. Chaopeng Hong et al. (pp. 17193–17200) estimated climate contributions to future air quality and associated mortality in China using climate, air quality, and epidemiological models. The models predicted that climate change would worsen air pollution over more than half of China’s land area, encompassing more than 85% of the current population, by the mid-21st century, compared with the years 2006–2010. Population-weighted average fine particulate matter (PM2.5) and ozone concentrations increased by 3% and 4%, respectively, leading to approximately 12,000 additional deaths per year due to PM2.5 and 9,000 additional deaths per year due to ozone. Nearly 40% of the increased mortality could be attributed to an increase in atmospheric stagnation events, with an additional 6% attributed to increased heat waves. The results suggest that climate change may exert a significant impact on air quality by increasing extreme weather events, according to the authors. — B.D.
Stimulating natural killer cells to treat lung adenocarcinoma
Stimulated NK cells can enhance antitumor immunity and recruit T cells to tumors.
Immunotherapy research has shown that innate immune lymphocytes known as natural killer (NK) cells can recognize and destroy certain cancers, but NK cells often poorly infiltrate solid tumors, and many tumor-infiltrating NK cells exhibit signs of dysfunction. Leah Schmidt et al. (pp. 17460–17469) report a genetically engineered mouse model of lung adenocarcinoma, in which the activity of endogenous NK cells within the tumor microenvironment (TME) was stimulated to fight established disease. The model revealed that inducing the expression of activating ligands enhanced the ability of NK cells to proliferate, produce cytokines, and penetrate tumor tissue. Notably, the heightened activity did not appear to destroy tumor cells directly, but rather enhanced the ability of NK cells within the TME to recruit T cells, which can directly target tumor cells. Though the findings are promising, the authors caution that the response was short-lived and additional studies are required to determine the underlying mechanisms. According to the authors, the findings suggest that NK cells can be activated even in established disease to help boost antitumor immunity. — T.J.