Historically, many people, including marine scientists, have considered the abyssal plains, more than 2,000 meters below the sea surface, to be relatively isolated and stable ecosystems.
However, according to Ken Smith, a marine ecologist at the Monterey Bay Aquarium Research Institute (MBARI) and lead author of the recent PNAS article, changes in the Earth's climate can cause unexpectedly large changes in deep-sea ecosystems. Based on 18 years of studies, Smith and his coauthors show that such ecosystem changes occur over short time scales of weeks to months, as well as over longer periods of years to decades.
The recent paper covers two time-series studies-one at "Station M," about 220 kilometers off Central California coast, and a second on the Porcupine Abyssal Plain, several hundred kilometers southwest of Ireland. The flat, muddy seafloor at these sites lies between 4,000 and 5,00 meters beneath the ocean surface.
In this cold, dark environment, very little food is available. What food there is takes the form of bits of organic debris drifting down from the sunlit surface waters, thousands of meters above. During it's long descent, this organic matter may be eaten, excreted, and decomposed, drastically reducing it's nutritive value. It is estimated that less than five percent of the organic matter produced at the surface reaches the abyssal plains.
Research by Smith and his co-authors has shown that the amount of food reaching the deep sea varies dramatically over time. For example, at the Porcupine Abyssal Plain, the amount of organic material sinking from above can vary by almost an order of magnitude from one year to another.
Such variations in food supply have several causes. On a seasonal basis, algal blooms near the sea surface send pulses of organic material to the deep seafloor. Other factors may also come into play, including how much of the algae is eaten by marine animals, and how the material is moved by ocean currents.
The authors point out that global climate change could affect the food supply to the deep sea in many ways. Some relevant ocean processes that may be affected by climate change include wind-driven upwelling, the depth of mixing of the surface waters, and the delivery of nutrients to surface waters via dust storms. Climate-driven changes in these processes are likely to lead to altered year-to-year variation in the amount of organic material reaching the seafloor.
As one example of ongoing changes in deep-sea ecosystems, the authors point to the fact that one of the most important groups of fish on the deep seafloor, the grenadiers, doubled in abundance between 1989 and 2004 at Station M. They speculate that change may be linked to a combination of climate change and commercial fishing.
In another example, some previously common species of sea cucumbers at Station M virtually disappeared after 1998, while others became much more abundant. These changes were tied to a significant El Niño event in 1997-98. Similar dramatic year-to-year changes were observed at Porcupine Abyssal Plain, where they were linked to changes in both the quantity and type of food reaching the seafloor.
Based on their observations, the authors conclude that long-term climate change is likely to influence both deep-sea communities and the chemistry of their environment. According to Smith, "Essentially, deep-sea communities are coupled to surface production. Global change could alter the functioning of these ecosystems and the way carbon is cycled in the ocean."
Changes in deep-sea carbon cycling are not considered in most climate models, an oversight that the authors believe should be corrected. In order to obtain the information needed to include seafloor-community changes in global climate models, the authors suggest that long-term, automated systems must be developed for monitoring the deep sea.
Smith and his colleagues point out that deep-sea ecosystems are prime targets for monitoring using cabled ocean observatories, new seafloor moorings, and robots, which can provide continuous data to capture both long-term and short-term changes in seafloor conditions. As co-author Henry Ruhl put it, "What we need is to move beyond fragmented research programs and transition to a comprehensive global effort to monitor deep-sea ecosystems."
The research at Station M was sponsored by grants from the National Science Foundation and the David and Lucile Packard Foundation. Research at the Porcupine Abyssal Plain Sustained Observatory site was supported by the European Union and the Natural Environment Research Council of the United Kingdom.
Kim Fulton-Bennett | MBARI
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences