CESAM
  • CESAM
    • ¿Quienes somos?
    • Directiva
  • BLOG
  • EVENTOS
    • Conferencias y Talleres >
      • ASLO 2019
      • Charlas Educativas 2018-2019
      • 2016
      • 2013
    • Actividades Recreativas >
      • Buceo
      • Snorkeling
      • Turismo Interno
    • Viajes Institucionales y Simposios >
      • 35th AMLC en Costa Rica
      • 36th AMLC en Jamaica
      • 64th GCFI en México
  • Información Educativa
    • Tortugas Marinas/ Marine Turtles >
      • Carey/ Hawksbill
      • Peje Blanco/ Green Turtle
      • Tinglar/ Leatherback
    • Peces/ Fish >
      • Ángel Francés/ French Angel
      • Ángel Gris/ Grey Angel
      • Chapín/ Trunkfish
      • Pez León/ Lionfish
      • Tiburón Gata/ Nurse Shark
    • Corales/ Corals >
      • Cuerno de Ciervo/ Staghorn
      • Cuerno de Alce/ Elkhorn
      • Tarrito de Venado
      • Coral de Fuego/ Fire Coral
  • Viajes de Campo
    • Costa Rica
    • Cuba
    • Culebra
    • Desecheo
    • Haití
    • Isla de Mona
    • Jamaica
    • México
    • Puerto Rico
    • St. Kitts
    • St. Cruz
  • Contactenos





CAPÍTULO ESTUDIANTIL DE LA SOCIEDAD AMbIENTE MARINO







Deep-sea corals record dramatic long-term shift in Pacific Ocean ecosystem

12/15/2013

0 Comments

 
PictureThis is Hawaiian gold coral in the deep ocean.
Long-lived deep-sea corals preserve evidence of a major shift in the open Pacific Ocean ecosystem since around 1850, according to a study by researchers at the University of California, Santa Cruz. The findings, published December 15 in Nature, indicate that changes at the base of the marine food web observed in recent decades in the North Pacific Subtropical Gyre may have begun more than 150 years ago at the end of the Little Ice Age.

Deep-sea corals are colonial organisms that can live for thousands of years, feeding on organic matter that rains down from the upper levels of the ocean. The corals' branching, tree-like skeletons are composed of a hard protein material that incorporates chemical signatures from their food sources. As a result, changes in the composition of the growth layers in deep-sea corals reflect changes in the organisms that lived in the surface waters at the time each layer formed.

"They're like living sediment traps, recording long-term changes in the open ocean that we can't see any other way," said coauthor Matthew McCarthy, professor of ocean sciences at UC Santa Cruz.

Scientists can study sediment cores taken from the ocean floor for clues to past conditions in the oceans, but that approach is not very useful for the most recent millennia. In the open ocean of the North Pacific, sediment accumulates so slowly that the entire Holocene epoch (the past 12,000 years or so) is represented by less than 10 centimeters (4 inches) of sediment that has been stirred up by organisms living on the seafloor. "Even if there were good sediment records, we would never get the level of detail we can get from the corals," McCarthy said.

To analyze the coral skeletons, the UCSC researchers combined carbon dating with a novel technique for analyzing nitrogen isotopes in proteins. They were able to reconstruct records over the past 1,000 years indicating that a shift occurred around 1850 in the source of nitrogen feeding the surface waters of the open ocean. As a result of decreasing nitrogen inputs from subsurface water, the phytoplankton community at the base of the food web became increasingly dominated by nitrogen-fixing cyanobacteria, which are able to use the nitrogen gas absorbed by surface waters from the atmosphere.
"In the marine environment, the two major sources of nitrogen are dissolved nitrate, which is more concentrated in the subsurface and deep water and is brought to the surface by upwelling, and nitrogen fixation by specialized microorganisms that are like the legumes of the sea," explained first author Owen Sherwood, who worked on the study as a postdoctoral researcher at UCSC and is now at the University of Colorado, Boulder.

The shift revealed in the coral record--from an ecosystem supported by nitrate coming up from deeper waters to one supported more by nitrogen-fixing organisms--may be a result of the North Pacific Subtropical Gyre expanding and becoming warmer, with more stable layering of warm surface water over cooler subsurface water. This increased "stratification" limits the amount of nutrients delivered to the surface in nutrient-rich subsurface water.

Scientists have observed warming and expansion of the major mid-ocean subtropical gyres in the past few decades and have attributed this trend to global warming. The new study puts these observations in the context of a longer-term trend. "It seems that the change in nitrogen sources, and therefore possibly large-scale shifts in ocean conditions, switched on at the end of the Little Ice Age and it is still continuing today," McCarthy said.

A key innovation in nitrogen isotope analysis was crucial to this study. Nitrogen-15 is a minor stable isotope of nitrogen, and the ratio of nitrogen-15 to nitrogen-14 is widely used to trace different sources of nitrogen. The nitrogen fixed by cyanobacteria in surface water, for example, has a different isotope ratio from the nitrates in deep ocean water. The isotope ratio also changes as organisms eat each other and nitrogen moves through the food web, with organisms at the base of the web having lower ratios than organisms at higher "trophic levels."

Thus, two independent factors--the trophic level and the original source of the nitrogen--determine the nitrogen isotope ratio in an organism. McCarthy's lab developed a technique that can separate these two factors by analyzing individual amino acids--the building blocks of proteins. It turns out that the isotope ratios of some amino acids remain unchanged as they move up the food web, while other amino acids become enriched in nitrogen-15 with each trophic transfer.


"Amino acid analysis decouples the two effects so we can see their relative magnitudes," McCarthy said. "What we're seeing in the central Pacific is a major shift at the base of the food web."

The extent of the change is dramatic: a 17 to 27 percent increase in nitrogen-fixation since about 1850, after almost a millennium of relatively minor fluctuations. "In comparison to other transitions in the paleoceanographic record, it's gigantic," Sherwood said. "It's comparable to the change observed at the transition between the Pleistocene and Holocene Epochs, except that it happens an order of magnitude faster."

These and other recent results are changing scientists' notions about the stability of open ocean gyres such as the North Pacific Subtropical Gyre, which is the largest contiguous ecosystem on the planet. These open ocean gyres were once considered relatively static, nutrient-deprived "deserts." In the 1980s, however, scientists began regularly monitoring oceanographic conditions at deep-water station ALOHA near Hawaii, revealing a surprising amount of variability.

"Instead of relatively constant ocean deserts, time-series data has shown dynamic decadal-scale changes," McCarthy said. "Our new records from deep-sea corals now show that the decadal-scale changes are really only small oscillations superimposed on a dramatic long-term shift at the base of the Pacific ecosystem. This long-term perspective may help us better predict the effects of global warming on open ocean regions."

The new findings also suggest a new interpretation of data from other researchers showing changes in nitrogen isotopes in the bones of seabirds. A recent study of Hawaiian petrel bones using bulk nitrogen isotope data attributed the change to shifts in the length of open ocean food chains, possibly induced by overfishing (forcing petrels to feed lower on the food chain). In fact, the compound-specific data strongly imply that isotopic changes on all trophic levels are more likely due to the long-term shift in nitrogen sources at the base of the food web, McCarthy said.

Coauthor Tom Guilderson, who is affiliated with UCSC and Lawrence Livermore National Laboratory, has been collecting deep-sea corals for more than a decade to study them for clues to past oceanographic and environmental conditions. He teamed up with McCarthy to initiate this project. In addition to McCarthy, Guilderson, and Sherwood, the coauthors of the paper include UCSC graduate students Fabian Batista and John Schiff.

Coral samples were collected by the Hawaiian Undersea Research Lab's Pisces V submersible, with funding from the National Oceanic and Atmospheric Administration (NOAA) and the National Geographic Society. The bulk of this research was funded by the National Science Foundation.


Source: http://www.eurekalert.org/pub_releases/2013-12/uoc--dcr121113.php


Picture
Layers of coral skeleton laid down over the past 1,000 years can be seen in this polished section of a deep sea coral.
0 Comments



Leave a Reply.

    Archivos

    August 2017
    July 2017
    April 2017
    March 2017
    February 2017
    January 2017
    September 2016
    July 2016
    April 2016
    March 2016
    July 2015
    May 2015
    March 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    December 2013
    November 2013
    October 2013
    September 2013
    August 2013
    July 2013
    June 2013
    May 2013
    April 2013
    March 2013
    February 2013
    January 2013
    December 2012
    November 2012
    October 2012
    September 2012
    August 2012
    July 2012
    June 2012
    May 2012
    April 2012
    March 2012
    February 2012
    January 2012
    December 2011
    November 2011
    October 2011
    September 2011

    Categorías

    All
    Actividades Culturales
    Actividades En UPR Rio Piedras
    Acuicultura
    Adaptación Del Cefalopodo
    AEE Pagará $205 Millones A Windmar
    Aquaculture
    Arrecife Isla Verde
    Arrestado Por Matar Tinglar
    Atipur En Ocean Park
    Australia Largest Amp
    Bahia Bioluminiscente
    Barnacles
    Blanket Octopus
    Bumphead Parrotfish Rivals
    Buque Isla De Mona
    Cambio Climático
    Caparazón De Una Tortuga Marina
    Caribbean Coral Reefs
    Caribe
    Carnivorous Sponge
    Catastrofe En Mona
    Cave Diving
    CESAM
    Charlas
    Cigarette Butts
    Climate Change
    Conversaciones De Ostras
    Coral Adaptation To Global Change
    Coral For Sunscreen
    Coral Reefs Vs Climate Change
    Corals
    Corals Benefit
    Costa Rica Tortugas
    Crustaceo Venenoso
    Cuba
    Cueva Ventana
    Culebra
    Daño Ambiental
    Deforestación En Culebra
    Delfinario Del Escambrón
    Delfines
    Deshielo En Ártico
    Designación Reserva Isla Verde
    Diseases Outbreak
    Dorado Conservación
    Dunas
    Eat Lionfish?
    Ecoturismo
    El Carey
    Electricity On Corals
    Emergencia Ambiental En Italia
    En Peligro Palominito
    Ensuciando El Orgullo Pr
    Erosión En Rincón
    Especies Invasivas
    Estrellas De Mar
    Estuario: Vertedero Ecologico
    Festival Del Tinglar
    Forosocial En Brazil
    Fósil Marino Antiguo
    [[\\\"Four Tracks\\\"]] En Bosque Seco De Guanica?
    Global Warming In 26 Sec
    Gran Barrera De Australia
    Hawaii Bans Plastic Bags
    Hawksbill Tracking
    Heat Effect On Sea-turtle Egg
    Huracán
    Huracán
    Impacto Del Desarrollo Costero En Pr
    Impacto Del Snorkeling Y Buceo
    Incineradora En Arecibo
    Invasive Starfish
    Jellyfish Scourge Threatens Israel
    Jireh En Mona
    Kayakeando Por El Caribe
    Kony 2012
    Leatherback
    Leatherbacks Crushed
    Ley Del Cen
    Limitaciones A La Pesca
    Limpieza De Costa
    Lionfish
    Lluvias Fuertes En Pr
    Manatee
    Manatíes En Peligro
    Mangroves As Filters
    Maricultura
    Mesa Informativa
    Mesophotic Reefs
    Mpa
    Muere Manati En Guayama
    Multa Por Basura
    Multa Por Tirar Basura
    Nieve En El Mar
    Nivel Del Mar
    Noche De San Juan
    Northeast Ecological Corridor
    Northeast Reserve Pr
    Observadores En El Embassy
    Overfishing
    Palau
    Parrotfish
    Penguins From Space
    Perspectiva Ambiental Del Candidato Santorum
    Pesca De Tiburones
    Pez Con Cancer563d9b013c
    Pitcairn
    Playa Isla Verde
    Playas Puerto Rico
    Pollution
    Praderas Submarinas
    Protección De Corales
    Puerto Rico
    Reserva Isla Verde
    Reserva Natura Culebra
    Samuel Suleiman
    Sea Turtle
    Sea Urchin
    Seaweed
    Seria Amenaza Al Cen
    Sharks
    Shark Trade Restrictions
    Tiburón Blanco
    Tiburones Del Pacifico
    Tinglar
    Tourism Marine
    Transgenicos
    Triunfo Del Arrecife Isla Verde
    Tuna
    Underwater Mystery Solved
    Varamientos
    Viajes De Campo
    Victoria Culebrense
    Vida Marina En Antartida
    Vieques
    White Marlin Pr

    Fuentes/
    Sources


    -Noticias Ambientales
    -Mi PR Verde
    -BBC Mundo
    -El Nuevo Día
    -Diálogo
    -Sea Grant Puerto Rico
    -
    NOAA Science Blog
    -TELESUR
    -NotiCel
    -Índice
    -The Atlantic
    - ScienceDaily
    -The Guardian
    -Compass Caiman
    -La Nación
    -ThinkProgress.Org
    - Greenerideal
    -Mi Nación
    -News.mongabay.com
    -CIELUPRM
    -
    Phys.org
    -
    Goedenshark.blogspot.com
    -Conservationmagazine.org/

    RSS Feed

Powered by Create your own unique website with customizable templates.
  • CESAM
    • ¿Quienes somos?
    • Directiva
  • BLOG
  • EVENTOS
    • Conferencias y Talleres >
      • ASLO 2019
      • Charlas Educativas 2018-2019
      • 2016
      • 2013
    • Actividades Recreativas >
      • Buceo
      • Snorkeling
      • Turismo Interno
    • Viajes Institucionales y Simposios >
      • 35th AMLC en Costa Rica
      • 36th AMLC en Jamaica
      • 64th GCFI en México
  • Información Educativa
    • Tortugas Marinas/ Marine Turtles >
      • Carey/ Hawksbill
      • Peje Blanco/ Green Turtle
      • Tinglar/ Leatherback
    • Peces/ Fish >
      • Ángel Francés/ French Angel
      • Ángel Gris/ Grey Angel
      • Chapín/ Trunkfish
      • Pez León/ Lionfish
      • Tiburón Gata/ Nurse Shark
    • Corales/ Corals >
      • Cuerno de Ciervo/ Staghorn
      • Cuerno de Alce/ Elkhorn
      • Tarrito de Venado
      • Coral de Fuego/ Fire Coral
  • Viajes de Campo
    • Costa Rica
    • Cuba
    • Culebra
    • Desecheo
    • Haití
    • Isla de Mona
    • Jamaica
    • México
    • Puerto Rico
    • St. Kitts
    • St. Cruz
  • Contactenos