Deep Sea

Overview

The deep sea is a dark, cold environment that includes a variety of habitats from the mid-water region to the abyss; these are populated by a wide array of animals that are specially adapted to live under the tremendous water pressure and low oxygen level of this harsh environment. In recent years, improved sampling techniques and technologies have shown that the diversity of deep-sea fauna is greater than once thought.

Based on the topography of the seafloor, the deep sea begins at the continental shelf break, at a depth of approximately 200 meters (650 feet). Beyond the shelf break, the continental slope descends through the deep sea to the ocean floor.

Of the total seafloor area in the sanctuary, approximately two-thirds (9,164 square kilometers, or 3,538 square miles) are located in the deep sea. This region also encompasses two distinct pelagic zones: the mesopelagic zone, which starts 200 meters below the surface and extends to about 1,000 meters; and the bathypelagic zone, from 1,000 meters down to the seafloor.

Although the deep sea encompasses 98 percent of all living space on the planet by volume, it is among the least understood ecosystems because of the challenges inherent in accessing it. Marine scientists claim that we know more about space than we do about this remote environment.

To reach the ocean’s depths, scientists require a platform from which to deploy sampling or observational gear. Today, in addition to net sampling, manned and unmanned research submersibles are deployed from research ships to collect data and make observations in this remote environment.

The deep sea comes very close to shore in the sanctuary through the heads of several canyons (Monterey Canyon is the largest), making deep water relatively easy to access here.

Conservation and management issues affecting sanctuary resources in the deep sea include seabed disturbance, nonsustainable fishing and carbon dioxide (CO2) sequestration.

  • Bottom trawling: This practice is widely believed to have negative impacts on benthic habitats, such as modification of the substrate, disturbance of soft-bottom communities and removal of non-target fish species. The structure of entire seafloor communities is at risk from this fishery practice. Currently, there is an incomplete picture about the extent of these impacts in the sanctuary, but the use of trawl gear is an ongoing source of concern.
  • Nonsustainable fishing: In June 2006, the Pacific Fishery Management Council and NOAA Fisheries closed large portions of the continental slope to trawling in order to protect essential fish habitat (EFH) for groundfishes. In addition, closures called Trawl Rockfish Conservation Areas (RCAs; from 183 to 274 meters’ depth in the Monterey Bay National Marine Sanctuary) have been established to minimize the bycatch of overfished rockfishes. RCA boundaries, however, may change during the year. Trawling is not allowed in state waters.
  • CO2 sequestration: International agencies are investigating deep-sea carbon sequestration as one possible mitigation technique for emissions of CO2, one of the primary greenhouse gases involved in global warming. Scientists at the Monterey Bay Aquarium Research Institute (MBARI) have conducted some of the first experiments aimed at understanding the chemistry and physics of CO2 in the deep sea and the ecological effects of CO2 sequestration. The release of CO2 on the seafloor caused a change in seawater chemistry and high mortality of organisms living in the sediments. Results indicate that large changes in seawater chemistry will cause high mortality rates for nearby deep-sea communities.

Monitoring

Archiving of Mid-Water and Benthic Survey Data at Moss Landing Marine Laboratories
Since the early 1970s, faculty and students in Marine Ecology, Invertebrate Zoology and Ichthyology at Moss Landing Marine Laboratories (MLML) have participated in class cruises to survey the fishes and invertebrates in shallow-benthic (50 and 150 meters), deep-benthic (650 meters) and mid-water (400 and 800 meters) habitats in Monterey Bay. Sampling is conducted using various types of trawling equipment.

Available biological information includes identification of the organisms to the lowest possible taxa, their numbers, and sometimes sizes or size ranges. Survey data are entered into a database, and maps and charts are scanned.

As of March 2005, 158 invertebrates species (and 358 others identified to genus or higher) and 231 fish species (and 55 other fish taxa) have been observed. Definite, predictable changes in fish assemblages were observed with depth. During some warm-water events, such as El NiÒo events, fishes more commonly observed in southern California were collected from sanctuary waters.

Patterns and Dynamics of Benthic Soft-Sediment Faunal Communities
Since 1994, scientists at MBARI have been monitoring megafaunal populations on the deep seafloor (200 to 1,000 meters) at Smooth Ridge in Monterey Bay to determine patterns of abundance and measure changes over time. These data will provide a measure of the interannual variation in community structure in the region.

One interesting finding of this monitoring program is the horizontal patchiness in the abundance of some species. For example, four shelf-dwelling rockfish species are much more abundant at one end of the 200-meter transect than at the other end. In addition, the structure of the seafloor community is variable from year to year, particularly along the shallower (200 meters) transect.

Abyssal Fauna Associated With a Whale Fall in Monterey Canyon
In 2002, MBARI scientists discovered an unusual deep-sea community associated with the remarkably well-preserved carcass of a gray whale, Eschrichtius robustus, at 2,891 meters’ depth in the axis of Monterey Canyon.

As a result of the whale fall, an intense burst of approximately 20,000 kilograms (44,092 pounds) of organic material was exported to the typically food-poor seafloor. Particularly noteworthy was the absence of large scavengers, the presence of a number of opportunistic deep-sea species and the abundance of unusual polychaetes – two of which actually digest bone and are new to science.

Since its discovery, the whale fall has been revisited, which has allowed scientists to document faunal community changes in one of the deepest large food falls known to date. MBARI continues to monitor this and other whale fall communities. Whale falls provide opportunities to study localized effects of organic enrichment at depths as well as the unusual animals that rely exclusively on these very transient habitats.

Davidson Seamount Exploration
In 2002 and 2006, a diverse group of scientists explored and began characterizing Davidson Seamount; one of the largest seamounts on the West Coast located beyond the sanctuary boundary. For more information, see the Seamounts Overview.

Photos

Below is a sampling of related images found in the SIMoN Photo Library. Click or tap on an image for more details.

Maps

Winter Shipping Container/Benthic Ecology Cruise (Dec 11-16, 2013) Study Sites

Winter Shipping Container/Benthic Ecology Cruise (Dec 11-16, 2013) Study Sites

This map shows study areas during from the Winter Shipping Container/Benthic Ecology Cruise (Dec 11-16, 2013), which operated from the R/V Western Flyer. The purple polygons are Sanctuary Ecologically Significant Areas.
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Deep Sea (Depth Zone Area by Sanctuary)

Deep Sea (Depth Zone Area by Sanctuary)

This map shows depth zones by sanctuary, focusing on the deep sea (>200 meters). Published in 2007.
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ROV Dives on Sur Ridge Through August 2016

ROV Dives on Sur Ridge Through August 2016

This map represents all 24 ROV dives conducted at Sur Ridge by MBARI and MBNMS through August 2016.
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California Seamounts

California Seamounts

This map shows all known seamounts that occur in federal waters off the California coast.
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National Marine Sanctuaries of Central California

National Marine Sanctuaries of Central California

This map depicts the three National Marine Sanctuaries that exist off the central California coast: Monterey Bay, Greater Farallones, and Cordell Bank.
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Projects

Ongoing

Abyssal Fauna Associated With a Whale Fall in Monterey Canyon

On Feb 6, 2002 using the ROV Tiburon, we discovered an unusual deep-sea community associated with the remarkably well-preserved carcass of a gray whale (Eschrichtius robustus) at 2,891 m depth in the axis of Monterey Canyon.

Historic

Archival of Midwater and Benthic Survey Data at Moss Landing Marine Laboratories

Since the early 1970s, faculty and students in Marine Ecology, Invertebrate Zoology, and Ichthyology courses at Moss Landing Marine Laboratories (MLML) have participated in class cruises aboard several research vessels to survey the fishes and invertebrates in shallow-benthic, deep-benthic and midwater habitats in Monterey Bay.

Historic

Davidson Seamount: 2002 Expedition

The Davidson Seamount is an impressive geologic feature located 120 km southwest of Monterey, California. This inactive volcano is roughly 2,300 m tall and 40 km long, yet its summit is far below the ocean surface (1,250 m). In May 2002, a diverse group of scientists led by the Monterey Bay National Marine Sanctuary embarked on an exploration to more fully characterize the Davidson Seamount.

Historic

Davidson Seamount: 2006 Expedition to Ancient Coral Gardens

Building off the successes of an Office of Ocean Exploration (OE) expedition to Davidson Seamount in 2002, this project focused on deep-water corals. The week-long expedition in 2002 was the initial effort to characterize the biology and geology of the Davidson Seamount, 1,250 – 3,700 meters deep off Central California.

Ongoing

Deepwater Characterization and Baseline Monitoring in the Monterey Bay National Marine Sanctuary

This project characterizes seafloor communities in the deeper waters of the MBNMS, including fish, macrofaunal invertebrates, and seafloor habitats. Baseline data are collected that can serve as the foundation for future monitoring efforts.

Ongoing

Ecological Assessment of a Lost Shipping Container in the MBNMS

In February 2004, the cargo ship M/V Med Taipei encountered a storm and lost fifteen 40-ft shipping containers in MBNMS, and another nine south of the sanctuary. The Monterey Bay Aquarium Research Institute (MBARI) discovered one of these containers in June 2004 at a depth of 1,281 meters on Smooth Ridge, 17.5 nm NW of Point Pinos. This monitoring project describes the March 2011 and December 2013 research cruises to study the impacts, natural habitat recovery rate, and decomposition rate/characteristics of this submerged container.

Ongoing

Exploration of Sur Ridge

Exploration of Sur Ridge began December 15, 2013 during a larger research cruise to revisit a lost shipping container. The surprising discoveries of that cruise led to subsequent exploration.

Historic

Long-term Monitoring of Groundfishes in the Monterey Bay National Marine Sanctuary

Because many populations of fish and invertebrates are declining, we are developing a long-term monitoring plan to assess changes of benthic fishes and macroinvertebrates in the in the Monterey Bay National Marine Sanctuary. Initially we conducted submersible to survey groundfishes in selected deep rocky continental shelf and slope habitats of the sanctuary.

Historic

Marine Protected Area Monitoring and Shelf Characterization in Monterey Bay National Marine Sanctuary

This project will assess the functionality of the Sanctuary’s towed camera sled for collecting data on seafloor habitats and associated communities in the Monterey Bay National Marine Sanctuary.

Ongoing

MARS: Passive Acoustic Monitoring (Hydrophone)

The marine 'soundscape' is a continuously changing mosaic of sounds that originate from living organisms (communication and foraging), non-living natural processes (breaking waves, rain) and human activities (shipping, construction, and resource extraction). Listening to sound in the sea is a rich exploration of the marine environment, which includes some of the ways in which human activities may intersect with marine life.

Ongoing

Pattern and Dynamics of Benthic Soft Sediment Faunal Communities

The objectives of this project are to determine the patterns of abundance of marine megafaunal populations on the continental shelf and slope to 1000 m depth in Monterey Bay, and measure changes in abundance over time.

Ongoing

Population Dynamics of Sessile Deep-sea Invertebrates in Monterey Bay

The objectives of this study are to determine the rates of survival and reproduction of common benthic invertebrate megafauna that inhabit the continental slope in Monterey Bay.

Ongoing

Potential Impacts of the Monterey Accelerated Research System (MARS) Cable on the Seabed and Benthic Faunal Assemblages

To assess the condition of the MARS cable and its potential effects on seabed geology and biology, several assessments were performed (2004, 2007-2008 and 2010). The most recent study was concluded 37 months after the cable was installed.

Historic

Survey of deep-water coral and sponge habitats
along the West Coast of the US using a remotely
operated vehicle

Remotely operated vehicle surveys were conducted from a NOAA ship (the FSV Bell M. Shimada) during a six‐day transit November 1‐5, 2010 between San Diego, CA and Seattle, WA. The objective was to locate and characterize deep‐sea coral and sponge ecosystems at several recommended sites in and adjacent to NOAA sanctuaries.

Links

Discovering Hidden Habitats: MBARI & NOAA

Join NOAA and the Monterey Bay Aquarium Research Institute’s (MBARI) 2002 expedition to the deep trenches of the Monterey canyon where they discovered previously unknown species.
http://www.youtube.com/watch?feature=player_embedded&v=jVrugjn79XY#!

MBARI – Cold Seeps

Learn about the benthic communities that are linked to the seepage of methane and sulfide rich fluids from the ocean floor
http://www.mbari.org/benthic/coldseeps.htm

MBARI – Current Research Projects

Learn about current research projects conducted by the Monterey Bay Aquarium Research Institute (MBARI).
http://www.mbari.org/rd/projects/current_projects.html

MBARI – Deep Sea Benthic Invertebrate Guide

Find digital images of small organisms (macrofauna) collected in sediment core samples taken between 200 – 3600 m near Monterey Bay, California by the Monterey Bay Aquarium Research Institute (MBARI).
http://www.mbari.org/benthic/fauna.html

MBARI – Deep-Sea Guide

A web-based system that allows for the correlation of visual, descriptive, and observational data with environmental data from multiple sources by providing tools for searching, identifying, and examining occurrence data (e.g., depth, time, abundance) for biological, geological, and experimental observations.

http://dsg.mbari.org/

MBARI video of trash in the deep sea

Monterey Bay Aquarium Research Institute shares video of trash observed during deep sea missions with their ROV.
http://www.youtube.com/watch?v=mOZngsJU2k0

Monterey Bay National Marine Sanctuary – Cold Seep Communities

A comprehensive and educational scientific characterization of an important habitat in the Monterey Bay Sanctuary.
http://montereybay.noaa.gov/sitechar/cold.html

Monterey Bay National Marine Sanctuary – Deeper Bottom Habitats

A comprehensive and educational scientific characterization of an important habitat in the Monterey Bay Sanctuary.
http://montereybay.noaa.gov/sitechar/deep.html

NOAA – Ocean Explorer Program

Explore the ocean realm with NOAA. This Web site chronicles the adventures and discoveries of NOAA’s at-sea science and education teams.
http://oceanexplorer.noaa.gov/welcome.html

University of Delaware – Voyage to the Deep

Learn about an expedition to the deep sea and what scientists found there.
http://www.ocean.udel.edu/deepsea