The scientists merged data collected underwater by UCSB divers with satellite images of giant kelp canopies taken by the Landsat 5 Thematic Mapper. The findings are published in the feature article of the May 16 issue of Marine Ecology Progress Series.
In this marriage of marine ecology and satellite mapping, the team of UCSB scientists tracked the dynamics of giant kelp –– the world's largest alga –– throughout the entire Santa Barbara Channel at approximately six-week intervals over a period of 25 years, from 1984 through 2009.David Siegel, co-author, professor of geography and co-director of UCSB's Earth Research Institute, noted that having 25 years of imagery from the same satellite is unprecedented. "I've been heavily involved in the satellite game, and a satellite mission that goes on for more than 10 years is rare. One that continues for more than 25 years is a miracle," said Siegel. Landsat 5 was originally planned to be in use for only three years.
Giant kelp is particularly sensitive to changes in climate that alter wave and nutrient conditions. The scientists found that the dynamics of giant kelp growing in exposed areas of the Santa Barbara Channel were largely controlled by the occurrence of large wave events. Meanwhile, kelp growing in protected areas was most limited by periods of low nutrient levels.
Images from the Landsat 5 satellite provided the research team with a new "window" into how giant kelp changes through time. The satellite was built in Santa Barbara County at what was then called the Santa Barbara Research Center and launched from Vandenberg Air Force Base. It was designed to cover the globe every 16 days and has collected millions of images. Until recently these images were relatively expensive and their high cost limited their use in scientific research.
However, in 2009, the entire Landsat imagery library was made available to the public for the first time at no charge. "In the past, it was not feasible to make these longtime series, because each scene cost over $500," said Kyle C. Cavanaugh, first author and UCSB graduate student in marine science. "In the past, you were lucky to get a handful of images. Once these data were released for free, all of a sudden we could get hundreds and hundreds of pictures through time."
Giant kelp grows to lengths of over 100 feet and can grow up to 18 inches per day. Plants consist of bundles of ropelike fronds that extend from the bottom to the sea surface. Fronds live for four to six months, while individual plants live on average for two to three years. According to the article,
"Giant kelp forms a dense floating canopy at the sea surface that is distinctive when viewed from above. …Water absorbs almost all incoming near-infrared energy, so kelp canopy is easily differentiated using its near-infrared reflectance signal."
Cavanaugh explained that, thanks to the satellite images, his team was able to see how the biomass of giant kelp fluctuates within and among years at a regional level for the first time. "It varies an enormous amount," said Cavanaugh. "We know from scuba diver observations that individual kelp plants are fast-growing and short-lived, but these new data show the patterns of variability that are also present within and among years at much larger spatial scales. Entire forests can be wiped out in days, but then recover in a matter of months."
Satellite data were augmented by information collected by the Santa Barbara Coastal Long Term Ecological Research Project (SBC LTER), which is based at UCSB and is part of the National Science Foundation's Long Term Ecological Research (LTER) Network. In 1980, the NSF established the LTER Program to support research on long-term ecological phenomena. SBC LTER became the 24th site in the LTER network in April of 2000. The SBC LTER contributed 10 years of data from giant kelp research dives to the current study.
The scientists said that interdisciplinary collaboration between geographers and marine scientists is common at UCSB and is a strength of its marine science program.
Daniel C. Reed, co-author and research biologist with UCSB's Marine Science Institute, is the principal investigator of SBC LTER. Reed has spent many hours as a research diver. He explained: "Kelp occurs in discrete patches. The patches are connected genetically and ecologically. Species that live in them can move from one patch to another. Having the satellite capability allows us to look at the dynamics of how these different patches are growing and expanding, and to get a better sense as to how they are connected. We can't get at that through diver plots alone. The diver plots, however, help us calibrate the satellite data, so it's really important to have both sources of information."
The fourth author of the paper is Philip E. Dennison. He received his Ph.D. in geography at UCSB and is now an associate professor in the Department of Geography at the University of Utah.
The research team received funding from NASA and the National Science Foundation.
Gail Gallessich | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences