Carl L. Kaiser

Footprint of Deepwater Horizon blowout impact to deep-water coral communities.

Significance The Deepwater Horizon blowout released more oil and gas into the deep sea than any previous spill. Soon after the well was capped, a deep-sea community 13 km southwest of the wellhead was discovered with corals that had been damaged by the spill. Here we show this was not an isolated incident; at least two other coral communities were also impacted by the spill. One was almost twice as far from the wellhead and in 50% deeper water, considerably expanding the known area of impact. In addition, two of four other newly discovered coral communities in the region were fouled with commercial fishing line, indicating a large cumulative effect of anthropogenic activities on the corals of the deep Gulf of Mexico. On April 20, 2010, the Deepwater Horizon (DWH) blowout occurred, releasing more oil than any accidental spill in history. Oil release continued for 87 d and much of the oil and gas remained in, or returned to, the deep sea. A coral community significantly impacted by the spill was discovered in late 2010 at 1,370 m depth. Here we describe the discovery of five previously unknown coral communities near the Macondo wellhead and show that at least two additional coral communities were impacted by the spill. Although the oil-containing flocullent material that was present on corals when the first impacted community was discovered was largely gone, a characteristic patchy covering of hydrozoans on dead portions of the skeleton allowed recognition of impacted colonies at the more recently discovered sites. One of these communities was 6 km south of the Macondo wellhead and over 90% of the corals present showed the characteristic signs of recent impact. The other community, 22 km southeast of the wellhead between 1,850 and 1,950 m depth, was more lightly impacted. However, the discovery of this site considerably extends the distance from Macondo and depth range of significant impact to benthic macrofaunal communities. We also show that most known deep-water coral communities in the Gulf of Mexico do not appear to have been acutely impacted by the spill, although two of the newly discovered communities near the wellhead apparently not impacted by the spill have been impacted by deep-sea fishing operations.

Evidence for extensive methane venting on the southeastern U.S. Atlantic margin

We present the first evidence for widespread seabed methane venting along the southeastern United States Atlantic margin beyond the well-known Blake Ridge diapir seep. Recent ship- and autonomous underwater vehicle (AUV)–collected data resolve multiple water-column anomalies (>1000 m height) and extensive new chemosynthetic seep communities at the Blake Ridge and Cape Fear diapirs. These results indicate that multiple, highly localized fluid conduits punctuate the areally extensive Blake Ridge gas hydrate province, and enable the delivery of significant amounts of methane to the water column. Thus, there appears to be an abundance of seabed fluid flux not previously ascribed to the Atlantic margin of the United States.

Design of Nereid-UI: A remotely operated underwater vehicle for oceanographic access under ice

This paper reports the development of a new underwater robotic vehicle, Nereid-UI, with the goal of being capable of deployments in polar ocean regions traditionally considered difficult or impossible to access such the ice-ocean interface in marginal ice zones, in the water column of ice-covered seas, and the seas underlying ice shelves. The vehicle employs a novel lightweight fiber-optic tether that will enable it to be deployed from a ship to attain standoff distances of up to 20 km from an ice-edge boundary under the real-time remote-control of its human operators, providing real-time high-resolution optical and acoustic imaging, environmental sensing and sampling, and, in the future, robotic intervention.

Autonomous Marine Robotic Technology Reveals an Expansive Benthic Bacterial Community Relevant to Regional Nitrogen Biogeochemistry.

Benthic accumulations of filamentous, mat-forming bacteria occur throughout the oceans where bisulfide mingles with oxygen or nitrate, providing key but poorly quantified linkages between elemental cycles of carbon, nitrogen and sulfur. Here we used the autonomous underwater vehicle Sentry to conduct a contiguous, 12.5 km photoimaging survey of sea-floor colonies of filamentous bacteria between 80 and 579 m water depth, spanning the continental shelf to the deep suboxic waters of the Santa Barbara Basin (SBB). The survey provided >31 000 images and revealed contiguous, white-colored bacterial colonization coating > ∼80% of the ocean floor and spanning over 1.6 km, between 487 and 523 m water depth. Based on their localization within the stratified waters of the SBB we hypothesize a dynamic and annular biogeochemical zonation by which the bacteria capitalize on periodic flushing events to accumulate and utilize nitrate. Oceanographic time series data bracket the imaging survey and indicate rapid and contemporaneous nitrate loss, while autonomous capture of microbial communities from the benthic boundary layer concurrent with imaging provides possible identities for the responsible bacteria. Based on these observations we explore the ecological context of such mats and their possible importance in the nitrogen cycle of the SBB.

Integration and algorithm development for forward looking imaging sonars on hybrid and autonomous underwater robots

We present the integration of Blueviews P900 2D forward looking imaging sonars on two vehicles developed at WHOIs Deep Submergence Laboratory and the software to support them. For the Sentry AUV, a 6000m AUV, we developed a software system designed to run on low-power embedded Linux platforms that applies real-time computer vision techniques on acoustic returns intensity images to detect threats to vehicle safety. The system operates in the horizontal plane to simultaneously allow the collection of forward looking data that would be relevant to science. It can autonomously inform the vehicle control system to avoid threats that would otherwise result in a collision. Simultaneously, the system logs forward looking acoustic returns data for subsequent use in post processed science products. We developed a data pipeline that injects the post-processed vehicle navigation, with fused USBL and DVL navigation, in the sonar logs that the system generates and creates maps. We present results from the June 2014 R/V Atlantis expedition in the Gulf of Mexico. During this expedition we used Sentrys forward looking sonar to generate very high resolution maps of steep slope subsea escarpments sections. We also present results from our new HROV Nereid Under Ice (nUI) a 2000m depth rated fiber tethered ocean robot. First, deployed from the R/V Polarstern in a July 2014 expedition in the Arctic Ocean, nUI provided observations at the ice-sea interface. We developed software for the vehicles Blueview P900 forward looking imaging sonar to improve under-ice precision localization and science under drifting and fragmented sea ice. Navigation under through-ice GPS-referenced poles was improved by developing software that could track the vehicle-relative position of the poles. This enabled the generation of a high-accuracy, highfrequency floe-relative vehicle position estimate. Ice floe-relative vehicle velocity, when in open water surrounded by ice floes without DVL ice lock, could be estimated by applying optical flow computer vision techniques to forward looking sonar images.

Autonomous acoustic-aided optical localization for data transfer

The emergence of high speed optical communication systems has introduced a method for transferring data relatively quickly underwater. This technology coupled with autonomous underwater vehicles (AUVs) has the potential to enable efficient wireless data transfers underwater. Data muling, a data transport mechanism in which AUVs visit remote sensor nodes to transfer data, enables remote data to be recovered cheaply from underwater sensors. This paper details efforts to develop a system to reduce operational complexities of autonomous data-muling. We report a set of algorithms, systems, and experimental results of a technique to localize a sub-sea sensor node equipped with acoustic and optical communication devices with an AUV. Our homing system was designed to utilize the long-range, lowpower acoustic signal to determine the sensor location from great distances. When within optical communication range, it exploits the optical power pattern to center the vehicle over the sensor node for optimum data transfer. These implementations were tested over three dives at varying levels of automation. Data collected from the real-time system has been tested in full-automation mode within our simulation environment.

The design and 200 day per year operation of the Autonomous Underwater Vehicle Sentry

The Autonomous Underwater Vehicle (AUV) Sentry has been in routine operation since 2009. It is a 6000m depth rated autonomous survey and sampling platform and is a “fly-away” system meaning it transports easily anywhere in the world to utilize vessels of opportunity. Sentry, initially a radical concept and experiment in AUV design, is now the AUV component of the National Deep Submergence Facility (NDSF) operated by Woods Hole Oceanographic Institution and as such spends up to 200 days per year in the field conducting operations for ocean scientists. Accordingly, Sentry must be reliable enough for a customer focused mission, but flexible enough to undertake previously unconceived missions on very short notice and with a high success rate. Field operations on a “Global Class” research vessel can easily exceed

Satellite based remote management and operation of a 6000m AUV

100,000 per day placing a premium on efficiency. Here we describe not only the vehicle Sentry, but also, the systems and infrastructure which supports Sentry and the unique nature of operations within the NDSF.

Cold-seep habitat mapping: high-resolution spatial characterization of the Blake Ridge Diapir seep field

During a July, 2012 expedition to the Hatteras Transverse Canyon, Blake Ridge, and Cape Fear Diapir, the AUV Sentry, aboard the NOAA Ship Okeanos, conducted experiments into remote operation of an AUV via satellite link. Remote launch, remote engineering, remote data processing and remote watch standing were all explored with varying degrees of success. Remote engineering and troubleshooting was found to be exceptionally promising and worthy of further effort. Remote data processing was a valuable addition for a telepresence enabled cruise where a substantial component of the science team was on shore. Remore watch standing and remote launch were both found to be viable though requiring improvement. Technology infrastructure is discussed along with successes, difficulties, and recommendations for future improvement.