Thu 30 May 2013
Archive for May, 2013
Tue 28 May 2013
Some people prefer strong vertical lines in their clothing over horizontal ones, as they can appear slimming. As for cuttlefish? According to a new MBL study, when these marine creatures adaptively change their skin patterns for camouflage purposes, they respond to vertical visual cues in their environment more strongly than to horizontal cues.
Many prior experiments have shown the influence of two-dimensional (2D) substrates, such as sand and gravel habitats, on camouflage, yet many marine habitats have three-dimensional (3D) structures, such as rocks and coral, among which cuttlefish camouflage from predators. In this study, Ulmer and Hanlon tested the relative influence of horizontal versus vertical visual cues on cuttlefish camouflage. They found that visual stimuli in the vertical dimension (2D or 3D) have a stronger influence on changeable camouflage than do 2D stimuli presented horizontally. This effect is noteworthy because in many of the experiments, the vertical stimuli represented only a small proportion of the total visual surrounds, indicating that cuttlefish are selectively responding to vertical cues.
Such choices highlight the selective decision-making that occurs in cuttlefish as they determine their camouflage body patterns.
Ulmer KM, KC Buresch, MM Kossodo, LM Mathger, LA Siemann and RT Hanlon (2013) Vertical visual features have a strong influence on cuttlefish camouflage. Biological Bulletin 224: 110-118.
Fri 17 May 2013
In 1989, MBL Senior Scientist Gaius Shaver and his colleagues set up a series of small experimental greenhouses on a hillside above the Toolik Field Station at the National Science Foundation Arctic Long Term Ecological Research site in northern Alaska. The clear plastic-covered greenhouses increase ambient soil temperatures by up to 2°C and are used by Shaver and other scientists to observe the effects of sustained warming on the Arctic environment. Today, the test plots are the longest-running climate warming study in the tundra.
New research from Seeta Sistla, a doctoral student at the University of California, Santa Barbara and a graduate of the Brown-MBL Partnership and Graduate Program in Biological and Environmental Sciences, her adviser, Josh Schimel, Shaver, and their colleagues reports the results the long-term warming experiment at the site.
The study reveals that decades of slow and steady warming have not changed the amounts of carbon in the soil, despite changes in vegetation and even the soil food web. Whether or not this phenomenon—no net loss of soil carbon despite long-term warming—is a transient phase that will eventually give way to increased decomposition activity and more carbon release, remains to be seen.
“This work demonstrates why long-term ecological research, and especially long-term whole-ecosystem experiments, are a good thing,” says Shaver. “The experiment on which this paper is based was set up in 1989, when Seeta Sistla was about 6 years old. There is no way she could have produced such a nice thesis if we had not set up these experiments so many years ago, not always knowing exactly how they would be used.”
The paper appeared in the May 15, 2013 Advance Online Publication of the journal Nature.
Other researchers participating in this study include John C. Moore and Rodney T. Simpson from Colorado State University, Fort Collins and Laura Gough from the University of Texas at Arlington.
Funding came from the National Science Foundation Long Term Ecological Research (LTER) Program, DOE Global Change Education Program Graduate Fellowship, a Leal Anne Kerry Mertes scholarship, and Explorer’s Club.