Certification of aquaculture: one of the strategies to sustainable seafood production

Sep. 5, 2013 — Certification of products from aquatic farming — aquaculture — is contributing to sustainable production, but it also has serious limits. Therefore it should be seen as one approach among many for steering aquaculture toward sustainability.This is argued by an international team of researchers in a paper published in Science on September 6th.Aquaculture is one of the fastest growing global food production systems, and now contributes around 13% of world animal-protein supply. It provides almost half of the world’s supply of seafood. The rapid expansion of the sector has come with a wide range of concerns about the environmental and social impact of aquaculture. In response, NGO-led certification schemes, such as the Dutch based Aquaculture Stewardship Council (ASC), have developed standards against which the environmental and social performance of aquaculture can be measured.Based on the work of an international network of researchers, the paper argues that aquaculture certification has limits as a means of governing sustainable production. Aquaculture certification is limited in the volume of global production it can certify, given market demand for certified seafood is currently limited to the US and EU while the majority of seafood consumption occurs in other markets. The impact of certification is also limited in reaching wider sustainability goals, it is focused on the farm-level instead of the cumulative impacts of multiple farms in one location on the surrounding environment or farming communities. Furthermore it is limited in its ability to include stakeholders, particularly smallholder producers, in the Global South where the vast majority of global production comes from.The implication of these limits is that certification needs to be seen as but one of a wider array of strategies for regulating sustainable production. Assumptions that countries in the Global South are unwilling or incapable to regulate aquaculture no longer holds true everywhere. …

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Newly discovered ocean plume could be major source of iron

Aug. 19, 2013 — Scientists have discovered a vast plume of iron and other micronutrients more than 1,000 km long billowing from hydrothermal vents in the South Atlantic Ocean. The finding, soon to be published in the journal Nature Geoscience, calls past estimates of iron abundances into question, and may challenge researchers’ assumptions about iron sources in the world’s seas.”This study and other studies like it are going to force the scientific community to reevaluate how much iron is really being contributed by hydrothermal vents and to increase those estimates, and that has implications for not only iron geochemistry but a number of other disciplines as well,” says Mak Saito, a WHOI associate scientist and lead author of the study.Saito and his team of collaborators — which includes WHOI researchers and a colleague affiliated with the University of Liverpool (U.K.) — didn’t set out to find iron plumes in the South Atlantic. They set sail aboard the R/V Knorr in 2007 as part of the Cobalt, Iron and Micro-organisms from the Upwelling zone to the Gyre (or CoFeMUG, pronounced “coffee mug”) expedition, which intended to map chemical composition and microbial life along the ship’s route between Brazil and Namibia. As the scientists traveled the route, they sampled the seawater at frequent intervals and multiple depths along the way, and then stored the samples for in-depth analysis back on land.Their route passed over the Mid-Atlantic Ridge, a band of mountains and valleys running along the Atlantic Ocean floor from the Arctic to the Antarctic where several of Earth’s major tectonic plates are slowly spreading apart. Hydrothermal vents, or fissures in Earth’s crust, are found along the ridge, but they haven’t been extensively studied because slow-spreading ridges are thought to be less active than fast-spreading ones. Past studies using helium, which is released from Earth’s mantle through hydrothermal vents and is routinely used as an indicator of vent activity, have found little coming from mid-Atlantic vents, and researchers have assumed that means the vents spew little iron as well.So Saito and his colleagues were surprised by what their samples revealed when later studied in the lab. Once filtered and analyzed, some of the seawater showed unexpectedly high levels of iron and manganese. When Abigail Noble, then a WHOI graduate student, and Saito plotted the sites where the iron-rich samples were taken, they realized the samples formed a distinct plume — a cloud of nutrients ranging in depth from 1,500 to 3,500 meters that spanned more than 1,000 km of the South Atlantic Ocean.”We had never seen anything like it,” Saito says. “We were sort of shocked — there’s this huge bull’s-eye right in the middle of the South Atlantic Ocean. …

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Evolution of diverse sex-determining mechanisms in mammals

July 29, 2013 — Scientists historically have argued that evolution proceeds through gradual development of traits. But how can incremental changes apply to the binary switch between two sexes, male or female? Researchers at Case Western Reserve University’s School of Medicine have found that a genetic process among the many species of rodents could have significant implications regarding our assumptions about sex determination and the pace of evolution.”What we addressed is a long-standing puzzle in natural history: why different types of rodents can exhibit profound differences in how male sex is determined in the embryo,” said Michael Weiss, MD, PhD, chairman of the Department of Biochemistry, the Cowan-Blum Professor of Cancer Research and a professor of biochemistry and medicine. “Some rodent populations have both XY males and XY females, and in other populations the Y chromosome has disappeared entirely.”In a study published in Proceedings of the National Academy of Sciences, Weiss and his research team analyzed the Sry gene, which is part of the Y chromosome. This mammalian gene, which steers differentiation in the embryonic gonad toward the development of testes, begins the process leading to the birth of males. For most mammals, including primates, Sry is a conserved feature of the Y chromosome, ultimately giving rise to male anatomy; females generally have two X chromosomes and no Y.But within anomalous families of rodents, common in South America, activation of the Sry gene may have uncertain consequences. Some of these groups have both XY males and XY females as normal components of the population. Other related species have even lost their Y chromosomes altogether. Without the emergence of compensating ways of specifying sex, the species could not produce males — and would become extinct. For such rodents, therefore, evolution meant inventing entirely different methods of sex determination. …

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