Purpose: This research is focused on the Gulf's oxygen minimum zone (OMZ) and its influence on the ecology and physiology of midwater animals. We will employ the ROV Doc Ricketts, supplemented by MBARI's mini-ROV and by midwater trawling and nighttime jigging for squid. Operations will be located in the Gulf's central and southern basins. Our hypothesis is that the unusual composition, vertical distribution and migration patterns typical of the Gulf's midwater fauna, are driven chiefly by the characteristics of the OMZ, which vary from basin to basin within the Gulf. The effects of hypoxic water include: physiological and behavioral adaptations that allow some species to inhabit the OMZ during the daylight hours; vertical distribution patterns for some species that are compressed above the OMZ; and diel vertical migration cycles that regularly separate then re-combine species which in other regions stay together throughout the day/night cycle. To investigate these issues we will determine the vertical distribution, migration and abundance patterns of the principal midwater species, measure their oxygen consumption rates in shipboard respirometers, observe their behavior and activity levels in situ, and study their trophic linkages. The Gulf's unique environment has favored the development of midwater communities dominated by very few taxa. Unlike the relatively even distribution of species that we find off Alta California, samples in these semi-enclosed basins are frequently dominated by particular species. This distinctive community structure may reflect the future state of the ocean in other regions. Quantification of the relative abundance and distribution of Gulf species and their adaptations to their extreme environment will provide important data which can be used to anticipate how other seas will be affected by ongoing changes that lead to similar conditions (warming, acidification, eutrophication, fishing pressure). Our results will be shared with our Mexican counterparts, disseminated through a real-time outreach program, presented at scientific meetings, and published in the scientific literature.
Chief scientist: Bruce Robison
Scheduled start time: 2/22/2015 3:00:00 PM UTC
[2/22/2015 7:00:00 AM Pacific]
Scheduled end time: 3/4/2015 UTC
[3/3/2015 4:00:00 PM Pacific]
Equipment: ROV Doc Ricketts, Mini-ROV and support equipment, Winch trawling wire, EK-500 Ecosounder, cold room, Equipment provided by MW Group: 2-meter midwater trawl, lab respirometer equipment, dissecting scopes, sample processing supplies, lab equipment and aquaria