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Comprehensive knowledge of the distribution of active hydrothermal vent fields along midocean ridges is essential to understanding global chemical and heat fluxes and endemic faunal distributions. However, current knowledge is biased by a historical preference for on-axis surveys. A scarcity of high-resolution bathymetric surveys in off-axis regions limits vent identification, which implies that the number of vents may be underestimated. Here, we present the discovery of an active, high-temperature, off-axis hydrothermal field on a fast-spreading ridge. The vent field is located 750 m east of the East Pacific Rise axis and ∼7 km north of on-axis vents at 9° 50'N, which are situated in a 50- to 100-m-wide trough. This site is currently the largest vent field known on the East Pacific Rise between 9 and 10° N. Its proximity to a normal fault suggests that hydrothermal fluid pathways are tectonically controlled. Geochemical evidence reveals deep fluid circulation to depths only 160 m above the axial magma lens. Relative to on-axis vents at 9° 50'N, these off-axis fluids attain higher temperatures and pressures. This tectonically controlled vent field may therefore exhibit greater stability in fluid composition, in contrast to more dynamic, dike-controlled, on-axis vents. The location of this site indicates that high-temperature convective circulation cells extend to greater distances off axis than previously realized. Thorough high-resolution mapping is necessary to understand the distribution, frequency, and physical controls on active off-axis vent fields so that their contribution to global heat and chemical fluxes and role in metacommunity dynamics can be determined.

The conversion of dissolved nutrients and carbon to organic matter by phytoplankton in the surface ocean, and its downward transport by sinking particles, produces a “biological pump” that reduces the concentration of atmospheric CO2. Global rates of organic matter export are a poor indicator of biological carbon storage however, because organic matter gets distributed across water masses with diverse pathways and timescales of return to the surface. Here we show that organic matter export and carbon storage can be related through a sequestration efficiency, which measures how long regenerated nutrients and carbon will be stored in the interior ocean before being returned to the surface. For the first time, we derive global maps of the sequestration efficiency of the biological pump at different residence time horizons. These maps reveal how regional patterns of organic matter export contribute to the biological pump, and how the biological pump responds to changes in biological productivity driven by climate change.

There are significant questions about how the physiology and behavior of marine fishes will respond to elevated carbon dioxide concentrations in future ocean conditions, an issue referred to as ocean acidification. Marine fish are the most vulnerable to changes in ocean chemistry at the egg and larval stage because of their thinner skin and heightened exposure to environmental conditions. This study investigates the impacts of elevated carbon dioxide for the swimming behavior of larval white seabass, Atractoscion nobilis. White seabass larvae were reared to 7 days post fertilization under variable carbon dioxide concentrations with the control infused with 380ppm CO2 (close to current atmospheric conditions) and the treatment with 2500ppm CO2. The larvae were filmed in shooting session on days 4-7, and these films were analyzed using imagej particle tracker, an image analysis tool to attain information form the trajectories of each larval movement. Three categories were used to determine swimming conditions; distance traveled along each trajectory, mean swim speeds, and maximum swim speeds. Overall, the results from t-tests showed that there was not a signification difference between the control and treatment for all three categories. The elevated swimming activity of the treatment larvae compared to the control throughout the experiment was a surprising result. There was no observational evidence that the larvae were disoriented under the elevated carbon dioxide as compared to the control and there was no impact for the survival rate to day 7. These results indicate that marine fish larvae may express resilience to changes in swimming behavior from ocean acidification.