Leg 3 Begins

Wednesday, August 13, 2014
Deck load for Leg 3

After the last two Legs of the VISIONS '14 cruise, which took place at Slope Base and Axial Seamount, thousands of meters deep in the ocean, Leg 3 takes place in relatively shallow water. The Endurance Oregon Offshore site is 600 meters (about 2000 feet) deep, only about 40 miles from land, and is designed to be the deepest part of the coastal Endurance Oregon portion of the Ocean Observatories Initiative. The science questions that the Endurance infrastructure is designed to answer have less to do with hydrothermal vents and seismic activity and more to do with upwelling, hypoxia, ocean acidification, riverine inputs, and topics relevant to fisheries in the area. The Array is being implemented by Oregon State University in a partnership with the University of Washington. The UW Applied Physics lab has built two state-of-the-art moorings for installation at this site to address the myriad processes that operate here. One mooring is a Deep Profiler Mooring that includes an instrumented deep wire crawler. The second mooring is a Shallow Profiler system that includes a 13-ft-across instrumented platform at a water depth of 200 meters (about 600 feet), and a winched instrument pod that will travel several times a day up through the water column to just beneath the surface and back down to the platform. 

There are six Endurance sites that are in shallow-inshore, mid-shelf, and continental-slope environments off the coasts of Oregon and Washington. Only the Oregon Offshore (600 m) and Oregon Shelf (80 m) sites are connected to the seafloor cable that connects the cabled array to shore. They are complemented by the cabled moorings and seafloor instruments at the Slope Base site at nearly 3000-meter (about 9000 feet) water depth to the west. The other Endurance sites, which host "uncabled," battery-powered moorings, began to be deployed in April 2014 and will be finished in February 2015.

During Leg 3 we will deploy a Benthic Experiment Package (BEP) containing a set of oceanographic sensors (pH, pCO2, CTD, oxygen, optical attenuation, current meters, and a hydrophone), a digital-still camera, a deep profiler mooring, and a shallow profiler 2-legged mooring. The Endurance Offshore site deployments will be completed during Leg 4, when the shallow profiler and platform instruments will be deployed on the 2-legged mooring.

One downside of the proximity of this site to shore is that the steam to get here was short, meaning that we were on site before people had a chance to get over seasickness, and that prepping of the first set of deployments has to be done on site rather than during an extended steam. However, the relatively shallow depth means that ROV deployments will be that much quicker, and we should be able to get quite a bit of work done in a short period of time. Stay tuned for the upcoming Endurance Array deployments!