DOCSLIB.ORG

Deep-Ocean Life Where Oxygen Is Scarce

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Deep-Ocean Life Where Oxygen Is Scarce A reprint from American Scientist the magazine of Sigma Xi, The Scientific Research Society This reprint is provided for personal and noncommercial use. For any other use, please send a request to Permissions, American Scientist, P.O. Box 13975, Research Triangle Park, NC, 27709, U.S.A., or by electronic mail to [email protected]. ©Sigma Xi, The Scientific Research Society and other rightsholders Deep-Ocean Life Where Oxygen Is Scarce Oxygen-deprived zones are common and might become more so with climate change. Here life hangs on, with some unusual adaptations Lisa A. Levin n 1925, the Meteor expedition set out cano 7, a submerged mountain about region of the ocean containing less than Ifrom Germany to measure the ocean’s 200 miles west of Acapulco, Mexico. 0.5 milliliter of oxygen per liter of wa- depth, study marine chemistry and, on The seamount has its summit 730 me- ter. It is surprising that any life exists the side, extract gold from seawater. The ters below the surface and its base where the oxygen supply is so sparse. gold project didn’t pan out, but expedi- 3,400 meters deep. With a group of ge- In addition to the OMZs that lie off tion data revealed a curious feature in ologists, I first visited Volcano 7 in 1984 the western coasts of the Americas, the Atlantic, off southern Africa: a giant to photograph and study the moun- well-established OMZs have also been wedge of oxygen-deficient water 300 to tain’s slopes using Alvin, a submersible discovered in the Arabian Sea, the Bay 400 meters down. vehicle based at Woods Hole Oceano- of Bengal and off the western coast of The surface layers of the ocean gener- graphic Institution (WHOI), and AN- Africa. In the United States, the zones ally obtain oxygen from diffusion and GUS, a camera mounted on a sled. I lie off California and Oregon. Califor- brisk circulation. This water sinks to the noticed the fascinating sea life, but we nia’s Santa Barbara Basin, with its bot- seafloor, supplying oxygen to deep-sea did not measure oxygen on that trip. tom at 585 meters, is right within the life. But sluggish circulation and oxy- Four years later, I returned with a California OMZ and has very little gen-poor source waters can reduce oxy- group of women who were studying oxygen. My group at North Carolina gen concentrations at intermediate plankton and life on the ocean floor. State University and then at Scripps In- depths. In several oceans, this effect is Again, we employed Alvin to explore stitution of Oceanography, in collabo- unusually pronounced. Where primary the volcano’s surface. ration with U.S. and international in- production by photosynthetic life is Because Alvin had space for only a vestigators, has studied OMZs off very high, the decay of sinking organic pilot, two scientists and our gear, we California, Mexico, Peru, Chile and matter consumes so much oxygen that had to squeeze down on our knees and Oman. Using data on seafloor topog- the middle depths contain dramatically peer sideways to look through a port- raphy and oxygen measurements from less of the gas than water above or be- hole. The vehicle’s exterior lights, the National Oceanographic Data Cen- low. Such oxygen-minimum zones, or though powerful, illuminated only six ter, we recently teamed up with John OMZs, turn up in productive open to eight feet of water, focusing our Helly at the San Diego Supercomputer oceans and on continental margins. attention on the fauna at hand rather Center to estimate how much of the They can stretch for thousands of miles than the larger view. At about 800 me- continental margin seafloor is inter- and persist for thousands of years. ters below the surface, dense group- cepted by OMZs. Our global estimate I first encountered an OMZ while ings of crabs, shrimp, brittle stars and was about 2 percent. studying animal communities on Vol- sponges were zoned like invertebrates Seasonal oxygen-depleted zones are on a rocky shoreline. But as we moved also known. Water over the shallow Lisa A. Levin is a biological oceanographer in the up the mountain’s slope, the rocks sud- shelf off Chile becomes depleted dur- Integrative Oceanography Division at Scripps In- denly looked barren, covered with the ing the spring and summer, when it is stitution of Oceanography. She completed her Ph.D. merest fuzz of life fed by the poorly oxygenated Peru- at SIO in 1982 and then, after a year of postdoctoral Wondering what might account for Chile Undercurrent. In fall and winter, study at Woods Hole Oceanographic Institution, the dramatic change, we looked at the it becomes oxygenated again as cold, accepted a faculty position at North Carolina State oxygen data generated by a sensor sub-Antarctic currents prevail. Human University. In 1992, with their children, she and mounted on the submersible’s shell. A activities deplete other bodies of water. her oceanographer husband returned to SIO, where liter of seawater can hold 7 or more In some estuaries and coastal regions, both are now professors. She studies the ecology of milliliters of oxygen. (For comparison, fertilizer runoff or sewage outfall pro- animal communities in marine sediments, particu- a liter of air can hold 210 milliliters of motes periodic phytoplankton blooms, larly those of stressed environments, from the inter- tidal zone to the deep sea. Address: Integrative oxygen.) But the water that swathes which rob the water of oxygen as they Oceanography Division, Scripps Institution of the peak of Volcano 7 contains less decay. Such human-inspired hypoxic Oceanography, 9500 Gilman Drive, La Jolla, CA than one-seventieth of that amount— events have taken place in many parts 92093-0218. Internet: [email protected]; 0.1 milliliter per liter. The seamount of the world, including Chesapeake http://levin.ucsd.edu summit protrudes into a vast OMZ—a Bay, the New York Bight and the Gulf © 2002 Sigma Xi, The Scientific Research Society. Reproduction 436 American Scientist, Volume 90 with permission only. Contact [email protected]. phytodetritus seapens foraminifera sponges galatheid crabs serpulid worms upper summit shrimp brittle stars rattail lower summit pillow lava sponges flank xenophyophores bottom Figure 1. Oxygen-minimum zones, such as the one atop Volcano 7 in the eastern Pacific west of Acapulco, Mexico, are permanent features of sever- al oceans. They are found at intermediate depths and can stretch for thousands of miles. With an oxygen content one-fourteenth or less that at the sur- face, they provide habitats where certain marine organisms can enjoy abundant food and freedom from predators. Single-celled creatures in the or- der Foraminifera and minute worms called nematodes dominate the summit of Volcano 7. Farther down the seamount, near the lower boundary of the oxygen-minimum zone, the still-plentiful food supply and slightly higher oxygen concentrations support larger organisms such as seapens, sponges and shrimp. The density of animals at this lower boundary can be several times higher than the density farther down the volcano. © 2002 Sigma Xi, The Scientific Research Society. Reproduction 2002 September–October 437 with permission only. Contact [email protected]. of Mexico. A severe hypoxic event in the northern Adriatic in 1977 slaugh- tered masses of marine organisms. Understanding the formation and ecological impact of oxygen-depleted zones is critical because their number and intensity are likely to increase as global warming and nutrient enrich- ment rob the ocean of oxygen. Because such zones are inhospitable to animals we consider edible, their expansion could have a devastating effect on commercial fishing. OMZs: What, Where and Why OMZs generally form where winds cre- ate currents that move water along a continent’s western shoreline. Aided by the Earth’s rotation, such currents Figure 2. Extensive oxygen-minimum zones (gray) have arisen off the west coasts of North, sweep water offshore. Replacing the Central and South America, off southwest Africa, and in the Arabian Sea and Bay of Bengal. It lost mass, cold water rises up from the has been estimated that about 2 percent of the continental margin seafloor lies below such ocean’s depths. It brings nutrients, es- zones, which consist of midlevel waters depleted of oxygen by the decay of organic matter pecially nitrogen, to the sunlit surface, from highly productive surface waters. Incoming currents do not replenish them because they where a lack of nutrients would other- are also oxygen-poor. The map also includes hypoxic zones, such as those in the Black and wise limit plankton and nekton growth. Baltic seas, that have arisen by different processes. When the resulting glut of surface- 0 dwelling organisms dies, the bacterial garbage recyclers of the ocean deplete the water of oxygen as they degrade the detritus. If such conditions persist 50 for long periods, middle depths can be- come permanently short of oxygen, < 0.01–0.1 and an OMZ can appear. Areas that lack a constant supply of 1,00 oxygenated water are good candidates 0.1–0.5 for OMZ formation. For example, the eastern Pacific and Indian oceans re- ceive water from the North Atlantic, 0.5–1.0 1,50 where most new deep water forms. As this water travels south for hundreds of years, it loses oxygen. The Arabian 2.0 Sea, which contains a vast OMZ, also receives poorly oxygenated waters, depth (meters) 2,00 which come from the Red Sea, Persian Gulf and Banda Sea. Interested in the adaptations of sea- 2,500 floor communities to extreme environ- ments, I began to study OMZs in 1988, 3.0 when groups led by Karen Wishner (University of Rhode Island), Marcia Gowing (University of California, Santa 3,000 Cruz), Lauren Mullineaux (WHOI) and myself visited the slopes of Volcano 7 aboard WHOI’s research vessel Atlantis II.
Load more

Recommended publications
  • 8.4 the Significance of Ocean Deoxygenation for Continental Margin Mesopelagic Communities J
    8.4 The significance of ocean deoxygenation for continental margin mesopelagic communities J. Anthony Koslow 8.4 The significance of ocean deoxygenation for continental margin mesopelagic communities J. Anthony Koslow Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia and Scripps Institution of Oceanography, University of California, SD, La Jolla, CA 92093 USA. Email: [email protected] Summary • Global climate models predict global warming will lead to declines in midwater oxygen concentrations, with greatest impact in regions of oxygen minimum zones (OMZ) along continental margins. Time series from these regions indicate that there have been significant changes in oxygen concentration, with evidence of both decadal variability and a secular declining trend in recent decades. The areal extent and volume of hypoxic and suboxic waters have increased substantially in recent decades with significant shoaling of hypoxic boundary layers along continental margins. • The mesopelagic communities in OMZ regions are unique, with the fauna noted for their adaptations to hypoxic and suboxic environments. However, mesopelagic faunas differ considerably, such that deoxygenation and warming could lead to the increased dominance of subtropical and tropical faunas most highly adapted to OMZ conditions. • Denitrifying bacteria within the suboxic zones of the ocean’s OMZs account for about a third of the ocean’s loss of fixed nitrogen. Denitrification in the eastern tropical Pacific has varied by about a factor of 4 over the past 50 years, about half due to variation in the volume of suboxic waters in the Pacific. Continued long- term deoxygenation could lead to decreased nutrient content and hence decreased ocean productivity and decreased ocean uptake of carbon dioxide (CO2).
    [Show full text]
  • Metaproteomics Reveals Differential Modes of Metabolic Coupling Among Ubiquitous Oxygen Minimum Zone Microbes
    Metaproteomics reveals differential modes of metabolic coupling among ubiquitous oxygen minimum zone microbes Alyse K. Hawleya, Heather M. Brewerb, Angela D. Norbeckb, Ljiljana Paša-Tolicb, and Steven J. Hallama,c,d,1 aDepartment of Microbiology and Immunology, cGraduate Program in Bioinformatics, and dGenome Sciences and Technology Training Program, University of British Columbia, Vancouver, BC, Canada V6T 1Z3; and bBiological and Computational Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352 Edited by Edward F. DeLong, Massachusetts Institute of Technology, Cambridge, MA, and approved June 10, 2014 (received for review November 26, 2013) Marine oxygen minimum zones (OMZs) are intrinsic water column transformations in nonsulfidic OMZs, providing evidence for features arising from respiratory oxygen demand during organic a cryptic sulfur cycle with the potential to drive inorganic carbon matter degradation in stratified waters. Currently OMZs are expand- fixation processes (13). Indeed, many of the key microbial players ing due to global climate change with resulting feedback on marine implicated in nitrogen and sulfur transformations in OMZs, in- ecosystem function. Here we use metaproteomics to chart spatial cluding Thaumarchaeota, Nitrospina, Nitrospira, Planctomycetes, and temporal patterns of gene expression along defined redox and SUP05/ARCTIC96BD-19 Gammaproteobacteria have the gradients in a seasonally stratified fjord to better understand metabolic potential for inorganic carbon fixation (14–19), and
    [Show full text]
  • Climate-Driven Deoxygenation Elevates Fishing Vulnerability for The
    RESEARCH ARTICLE Climate-driven deoxygenation elevates fishing vulnerability for the ocean’s widest ranging shark Marisa Vedor1,2, Nuno Queiroz1,3†*, Gonzalo Mucientes1,4, Ana Couto1, Ivo da Costa1, Anto´ nio dos Santos1, Frederic Vandeperre5,6,7, Jorge Fontes5,7, Pedro Afonso5,7, Rui Rosa2, Nicolas E Humphries3, David W Sims3,8,9†* 1CIBIO/InBIO, Universidade do Porto, Campus Agra´rio de Vaira˜ o, Vaira˜ o, Portugal; 2MARE, Laborato´rio Marı´timo da Guia, Faculdade de Cieˆncias da Universidade de Lisboa, Av. Nossa Senhora do Cabo, Cascais, Portugal; 3Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, United Kingdom; 4Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Cientı´ficas (IIM-CSIC), Vigo, Spain; 5IMAR – Institute of Marine Research, Departamento de Oceanografia e Pescas, Universidade dos Ac¸ores, Horta, Portugal; 6MARE – Marine and Environmental Sciences Centre, Faculdade de Cieˆncias da Universidade de Lisboa, Lisbon, Portugal; 7Okeanos - Departamento de Oceanografia e Pescas, Universidade dos Ac¸ores, Horta, Portugal; 8Centre for Biological Sciences, Highfield Campus, University of Southampton, Southampton, United Kingdom; 9Ocean and Earth Science, National Oceanography Centre Southampton, Waterfront Campus, University of Southampton, Southampton, United Kingdom *For correspondence: [email protected] (NQ); Abstract Climate-driven expansions of ocean hypoxic zones are predicted to concentrate [email protected] (DWS) pelagic fish in oxygenated surface layers, but how expanding hypoxia and fisheries will interact to affect threatened pelagic sharks remains unknown. Here, analysis of satellite-tracked blue sharks †These authors contributed equally to this work and environmental modelling in the eastern tropical Atlantic oxygen minimum zone (OMZ) shows shark maximum dive depths decreased due to combined effects of decreasing dissolved oxygen Competing interests: The (DO) at depth, high sea surface temperatures, and increased surface-layer net primary production.
    [Show full text]
  • Ocean Deoxygenation and Copepods: Coping with Oxygen Minimum Zone Variability
    Biogeosciences, 17, 2315–2339, 2020 https://doi.org/10.5194/bg-17-2315-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Ocean deoxygenation and copepods: coping with oxygen minimum zone variability Karen F. Wishner1, Brad Seibel2, and Dawn Outram1 1Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA 2College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA Correspondence: Karen F. Wishner ([email protected]) Received: 27 September 2019 – Discussion started: 28 October 2019 Revised: 31 March 2020 – Accepted: 2 April 2020 – Published: 24 April 2020 Abstract. Increasing deoxygenation (loss of oxygen) of compression concept). These distribution depths changed by the ocean, including expansion of oxygen minimum zones tens to hundreds of meters depending on the species, oxygen (OMZs), is a potentially important consequence of global profile, and phenomenon. For example, at the lower oxycline, warming. We examined present-day variability of vertical the depth of maximum abundance for Lucicutia hulsemannae distributions of 23 calanoid copepod species in the East- shifted from ∼ 600 to ∼ 800 m, and the depth of diapause for ern Tropical North Pacific (ETNP) living in locations with Eucalanus inermis shifted from ∼ 500 to ∼ 775 m, in an ex- different water column oxygen profiles and OMZ inten- panded OMZ compared to a thinner OMZ, but remained at sity (lowest oxygen concentration and its vertical extent in similar low oxygen levels in
    [Show full text]
  • Eucalanoid Copepod Metabolic Rates in the Oxygen Minimum Zone of the Eastern Tropical North Pacific Effects of Oxygen and Tempe
    Deep-Sea Research I 94 (2014) 137–149 Contents lists available at ScienceDirect Deep-Sea Research I journal homepage: www.elsevier.com/locate/dsri Eucalanoid copepod metabolic rates in the oxygen minimum zone of the eastern tropical north Pacific: Effects of oxygen and temperature Christine J. Cass n,1, Kendra L. Daly College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA article info abstract Article history: The eastern tropical north Pacific Ocean (ETNP) contains one of the world’s most severe oxygen Received 5 June 2014 minimum zones (OMZs), where oxygen concentrations are less than 2 mmol kgÀ1. OMZs cause habitat Received in revised form compression, whereby species intolerant of low oxygen are restricted to near-surface oxygenated waters. 7 September 2014 Copepods belonging to the family Eucalanidae are dominant zooplankters in this region and inhabit a Accepted 18 September 2014 variety of vertical habitats within the OMZ. The purpose of this study was to compare the metabolic Available online 28 September 2014 responses of three species of eucalanoid copepods, Eucalanus inermis, Rhincalanus rostrifrons, and Keywords: Subeucalanus subtenuis, to changes in temperature and environmental oxygen concentrations. Oxygen Oxygen minimum zone consumption and urea, ammonium, and phosphate excretion rates were measured via end-point Copepod experiments at three temperatures (10, 17, and 23 1C) and two oxygen concentrations (100% and 15% Eucalanidae air saturation). S. subtenuis, which occurred primarily in the upper 50 m of the water column at our Metabolism Tropical Pacific Ocean study site, inhabiting well-oxygenated to upper oxycline conditions, had the highest metabolic rates per Nitrogen excretion unit weight, while E.
    [Show full text]
  • 8.1 the Significance of Ocean Deoxygenation for Mesopelagic Communities Brad A
    8.1 The significance of ocean deoxygenation for mesopelagic communities Brad A. Seibel and Karen F. Wishner 8.1 The significance of ocean deoxygenation for mesopelagic communities Brad A. Seibel1 and Karen F. Wishner2 1College of Marine Science, University of South Florida, Florida, USA. Email: [email protected] 2Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode island, USA. Email: [email protected] Summary • Mesopelagic community structure is directly dependent on the availability of oxygen for aerobic metabolism. Diversity, abundance, distribution and composition of mesopelagic species are all influenced by variations in oxygen at both large and small scales. • Ocean deoxygenation will decrease the minimum oxygen content in the mesopelagic zone and cause oxyclines to shift vertically (i.e. expansion of the oxygen minimum zone (OMZ) core) in the water column. • A species’ ability to extract oxygen from sea water has evolved to meet specific oxygen demand. As a result, species do not have excess capacity, nor do they live in environments with excess oxygen relative to their evolved capacity; thus, they are susceptible to reductions in oxygen partial pressure and increasing temperature (which elevates metabolic demand). • Changes in temperature and oxygen profiles within the water column may therefore decouple or enhance competition among different mesopelagic zooplankton species and the larger predators that forage on them at depth by changing zooplankton abundances, distributions, and the depth of layers, and altering species composition and diversity. The biogeochemical cycles (i.e. the biological pump and microbial assemblages) that rely on the mesopelagic zooplankton community will be substantially altered. SECTION 8.1 SECTION Ocean deoxygenation: Everyone’s problem 265 8.1 The significance of ocean deoxygenation for mesopelagic communities Ocean hypoxia effect Potential consequences Decreasing oxygen partial pressure (PO2) in any • Reduced capacity for prey capture and predator habitat will reduce aerobic metabolic performance evasion.
    [Show full text]
  • Multidisciplinary Observing in the World Ocean's Oxygen Minimum Zone Regions: from Climate to Fish - the VOICE Initiative
    W&M ScholarWorks VIMS Articles Virginia Institute of Marine Science 12-5-2019 Multidisciplinary Observing in the World Ocean's Oxygen Minimum Zone Regions: From Climate to Fish - The VOICE Initiative V Garcon J Karstensen A Palacz et al Kevin C. Weng Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/vimsarticles Part of the Environmental Sciences Commons, and the Marine Biology Commons Recommended Citation Garcon, V; Karstensen, J; Palacz, A; et al; and Weng, Kevin C., "Multidisciplinary Observing in the World Ocean's Oxygen Minimum Zone Regions: From Climate to Fish - The VOICE Initiative" (2019). VIMS Articles. 1815. https://scholarworks.wm.edu/vimsarticles/1815 This Article is brought to you for free and open access by the Virginia Institute of Marine Science at W&M ScholarWorks. It has been accepted for inclusion in VIMS Articles by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. fmars-06-00722 December 4, 2019 Time: 17:14 # 1 REVIEW published: 05 December 2019 doi: 10.3389/fmars.2019.00722 Multidisciplinary Observing in the World Ocean’s Oxygen Minimum Zone Regions: From Climate to Fish — The VOICE Initiative Véronique Garçon1*, Johannes Karstensen2*, Artur Palacz3, Maciej Telszewski3, Tony Aparco Lara4, Denise Breitburg5, Francisco Chavez6, Paulo Coelho7, Marcela Cornejo-D’Ottone8, Carmen Santos9, Björn Fiedler2, Natalya D. Gallo10,11, Marilaure Grégoire12, Dimitri Gutierrez13,14, Martin Hernandez-Ayon15, Kirsten Isensee16, Tony Koslow10, Lisa Levin10,11, Francis Marsac17, Helmut Maske18, Baye C. Mbaye19, Ivonne Montes20, Wajih Naqvi21, Jay Pearlman22, Edwin Pinto23, Grant Pitcher24,25, Oscar Pizarro26,27, Kenneth Rose28, Damodar Shenoy29, Anja Van der Plas30, Edited by: Melo R.
    [Show full text]
  • 3.4 Land-Sea-Atmosphere Interactions Exacerbating Ocean
    3.4 Land-sea-atmosphere interactions exacerbating ocean deoxygenation in Eastern Boundary Upwelling Systems (EBUS) Véronique Garçon, Boris Dewitte, Ivonne Montes and Katerina Goubanova 3.4 Land-sea-atmosphere interactions exacerbating ocean deoxygenation in Eastern Boundary Upwelling Systems (EBUS) Véronique Garçon1, Boris Dewitte1,2,3,4, Ivonne Montes5 and Katerina Goubanova2 1 Laboratoire d’Etudes en Géophysique et Océanographie Spatiales- LEGOS, UMR5566-CNRS /IRD/UT/CNES, Toulouse, France 2 Centro de Estudios Avanzados en Zonas Áridas, La Serena, Chile 3 Departamento de Biología Marina, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile SECTION 3.4 SECTION 4 Millennium Nucleus for Ecology and Sustainable Management of Oceanic Islands (ESMOI), Coquimbo, Chile 5 Instituto Geofísico del Perú, Lima, Perú Summary • While the biogeochemical and physical changes associated with ocean warming, deoxygenation and acidification occur all over the world’s ocean, the imprint of these global stressors have a strong regional and local nature such as in the Eastern Boundary Upwelling Systems (EBUS). EBUS are key regions for the climate system due to the complex of oceanic and atmospheric processes that connect the open ocean, troposphere and land, and to the fact that they host Oxygen Minimum Zones (OMZs), responsible for the world’s largest fraction of water column denitrification and for the largest estimated emission (0.2-4 Tg N yr-1) of the greenhouse gas nitrous oxide (N2O). • Taking into account mesoscale air-sea interactions in regional Earth System models is a key requirement to realistically simulate upwelling dynamics, the characteristics of turbulence and associated offshore transport of water mass properties.
    [Show full text]
  • The Ocean Is Losing Its Breath
    GSDR 2015 Brief The Ocean is Losing its Breath By Kirsten Isensee and Luis Valdes, IOC-UNESCO* Introduction In the coastal ocean, oxygen minimum zones (OMZs) have spread exponentially since the 1960s and have Decreased oxygen concentrations in the ocean, as a been reported for more than 400 systems (e.g. Baltic, result of climate change and other anthropogenic Black, Kattegat Sea, Gulf of Mexico, East China Sea) stressors, e.g. nutrient input due to inefficient fertilizer (Stramma et al. 2008a, Stramma et al. 2008b, use, was discussed in the latest IPCC report (2014). Stramma et al. 2010). OMZ are areas where However, so far this emerging threat for the ocean is subthermocline dissolved oxygen levels are<3.5 ml l -1 not fully acknowledged by policymakers and (< 150 mol kg-1; Prince & Goodyear 2006) In these stakeholders at the global level. Systematic shallow areas, where the bottom is occupied by deoxygenation of the ocean will have widespread ecologically and economically valuable benthic consequences. O2 plays a direct role in the communities, hypoxic/anoxic conditions cause biogeochemical cycling of carbon, nitrogen, and many catastrophic biological losses, acidification, secondary other biogeochemically important elements (P, Fe, pollution, nitrogen and phosphorus surplus Mn, etc.). O2 is also fundamental for all aerobic life, (eutrophication). In the open ocean, eastern boundary including organisms living in the dark ocean interior. upwelling systems (EBUSs) are characterized by high Deoxygenation (reduced oxygen concentration) primary and export production that, in combination mostly affects the marine environment at the local with weak ventilation, cause oxygen depletion and the level, nevertheless economic and socio-economic development of OMZs in sub-surface waters.
    [Show full text]
  • (Crustacea) and Its Distribution in the Eastern Pacific Ocean
    The Bathypelagic Mysid Gnathophausia (Crustacea) and Its Distribution in the Eastern Pacific Ocean LINDA HAITHCOCK PEQUEGNAT1 A NEED HAS LONG EXISTED for an improved are practically never encountered in shallow collecting device for capturing the larger and water. more actively swimming bathypelagic animals Specimens of Gnathophausia have been de­ of die sea. The Isaacs-Kidd Midwarer Trawl scribed from as early as the Challenger Expedi­ was developed at the University of California's tion in 1873-76 (Sars, 1885 and Willemoes­ Scripps Institution of Oceanography in 1950 Suhm, 1875), and have been reported from all and has largely satisfied this need (SIO Refer­ parts of the world from such other pre-twentieth ence 53-3, 1953). century expeditions as the Talisman, the Alba­ Bathypelagic specimens have frequently been tross, the Oceania, and the Investigator. The captured in the deeper hauls of the standard Dana Expedition in 1928-30 and the Discovery one-meter plankton nets. However, the self­ Expeditions in the 1920's and 1930's have re­ depressing midwater trawl, larger and capable vealed specimens of this genus in greater num­ , of greater depths ( up to 4000 m ) and speeds bers and from even more widespread locations (up to 5 knots) than the standard I-rnerer throughout the world. Prior to the Dana Ex­ net, has given us more productive samplings pedition relatively few specimens of Gnatho­ of the larger bathypelagic forms (Figs. 1 and phausia had ever been captured-probably 2). In addition, the midwarer trawl has cap­ fewer than 100 altogether. A total of 1,051 tured many species of deep-sea fishes not pre­ specimens of Gnathophausia were taken by the viously reported in the Pacific as well as spe­ Dana, adding considerably to -our knowledge of cies entirely new to scientific literature-forms this group of animals.
    [Show full text]
  • Oxygen Minimum Zones (Omzs) in the Modern Ocean
    Progress in Oceanography 80 (2009) 113–128 Contents lists available at ScienceDirect Progress in Oceanography journal homepage: www.elsevier.com/locate/pocean Oxygen minimum zones (OMZs) in the modern ocean A. Paulmier a,b,*, D. Ruiz-Pino b a LEGOS/CNRS 18, Av. Ed. Belin, 31401 Toulouse Cedex 9, France b LOCEAN, Université P&M Curie, Courrier 134, 4 pl. Jussieu, 75252 Paris Cedex 05, France article info abstract Article history: In the modern ocean, oxygen minimum zones (OMZs) are potential traces of a primitive ocean in Received 6 September 2007 which Archean bacteria lived and reduced chemical anomalies occurred. But OMZs are also keys to Received in revised form 1 August 2008 understanding the present unbalanced nitrogen cycle and the oceans’ role on atmospheric greenhouse Accepted 4 August 2008 control. OMZs are the main areas of nitrogen loss (as N ,NO) to the atmosphere through denitrifi- Available online 17 August 2008 2 2 cation and anammox, and could even indirectly mitigate the oceanic biological sequestration of CO2. It was recently hypothesized that OMZs are going to spread in the coming decades as a conse- Keywords: quence of global climate change. Despite an important OMZ role for the origin of marine life and for Oxygen minimum zones (OMZs) the biogeochemical cycles of carbon and nitrogen, there are some key questions on the structure of Oxygen Global ocean OMZs at a global scale. There is no agreement concerning the threshold in oxygen that defines an Denitrification OMZ, and the extent of an OMZ is often evaluated by denitrification criteria which, at the same time, Biogeochemistry are O2-dependent.
    [Show full text]
  • The Natural Resources of Monterey Bay National Marine Sanctuary
    Marine Sanctuaries Conservation Series ONMS-13-05 The Natural Resources of Monterey Bay National Marine Sanctuary: A Focus on Federal Waters Final Report June 2013 U.S. Department of Commerce National Oceanic and Atmospheric Administration National Ocean Service Office of National Marine Sanctuaries June 2013 About the Marine Sanctuaries Conservation Series The National Oceanic and Atmospheric Administration’s National Ocean Service (NOS) administers the Office of National Marine Sanctuaries (ONMS). Its mission is to identify, designate, protect and manage the ecological, recreational, research, educational, historical, and aesthetic resources and qualities of nationally significant coastal and marine areas. The existing marine sanctuaries differ widely in their natural and historical resources and include nearshore and open ocean areas ranging in size from less than one to over 5,000 square miles. Protected habitats include rocky coasts, kelp forests, coral reefs, sea grass beds, estuarine habitats, hard and soft bottom habitats, segments of whale migration routes, and shipwrecks. Because of considerable differences in settings, resources, and threats, each marine sanctuary has a tailored management plan. Conservation, education, research, monitoring and enforcement programs vary accordingly. The integration of these programs is fundamental to marine protected area management. The Marine Sanctuaries Conservation Series reflects and supports this integration by providing a forum for publication and discussion of the complex issues currently facing the sanctuary system. Topics of published reports vary substantially and may include descriptions of educational programs, discussions on resource management issues, and results of scientific research and monitoring projects. The series facilitates integration of natural sciences, socioeconomic and cultural sciences, education, and policy development to accomplish the diverse needs of NOAA’s resource protection mandate.
    [Show full text]