Purpose: The primary goal of leg 4 of the 2015 R/V Western Flyer expedition to the GOC is to examine the composition, abundance, condition, and physiological performance of benthic animals in the GOC, in relation to the changes in the development of the oxygen minimum zone and related carbonate chemistry of seawater. The oxygen minimum zone is very well developed in the GOC, particularly in the southern region (e.g. La Paz), moderates somewhat in the central GOC (e.g. Guaymas Basin), and is very weak in the northern basins (e.g. Salsipuedes Basin). Changes in oxygen are also correlated with patterns of carbonate chemistry due to the coupling of metabolic oxygen consumption and carbon dioxide release. Accumulation of respiratory carbon dioxide reduces seawater pH and carbonate saturation state in areas where oxygen is low (e.g. oxygen minimum zones). Benthic faunal communities vary in composition in relation to the tolerances of individual species to hypoxia, but may also be affected by carbonate chemistry. This cruise leg will sample benthic communities throughout the GOC to, 1) quantify the distribution of benthic fauna, 2) determine the condition of individuals (e.g. tissue and skeletal composition), and 3) measure metabolic rates of key benthic megafauna, in relation to variation in oxygen and carbonate chemistry. Results from this cruise will be published by the cruise participants in peer-review journals toward advancing our understanding of the influence of both oxygen and carbonate chemistry on the composition and function of benthic marine organisms inhabiting regions with strong gradients in oxygen (e.g. oxygen minimum zones). In addition, increased understanding of the influence of hypoxia and acidification within oxygen minimum zones is expected to provide inference concerning the potential response of benthic communities to future ocean conditions.
Chief scientist: Jim Barry
Scheduled start time: 3/20/2015 2:00:00 PM UTC
[3/20/2015 7:00:00 AM Pacific]
Scheduled end time: 3/30/2015 11:00:00 PM UTC
[3/30/2015 4:00:00 PM Pacific]
Equipment: ROV Doc Ricketts, Crane, Benthic Respiration System, Niskin Bottles, Suction Sampler, Sediment cores Haz mats: Formaldehyde, Ethanol, Glutaraldehyde, Mercuric Chloride, Magnesium chloride