Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rise in mass die-offs seen among birds, fish and marine invertebrates

13.01.2015

Review of 727 studies points to disease, biotoxicity and other stressors

An analysis of 727 mass die-offs of nearly 2,500 animal species from the past 70 years has found that such events are increasing among birds, fish and marine invertebrates. At the same time, the number of individuals killed appears to be decreasing for reptiles and amphibians, and unchanged for mammals.


Shown are large numbers of dead sunfish and largemouth bass in April 2014 following a severe winter on Wintergreen Lake in Michigan. Fish are a taxon where mass mortality events have been increasing in frequency and magnitude through time.

Credit: Photo by Gary Mittelbach

Such mass mortality events occur when a large percentage of a population dies in a short time frame. While the die-offs are rare and fall short of extinction, they can pack a devastating punch, potentially killing more than 90 percent of a population in one shot. However, until this study, there had been no quantitative analysis of the patterns of mass mortality events among animals, the study authors noted.

"This is the first attempt to quantify patterns in the frequency, magnitude and cause of such mass kill events," said study senior author Stephanie Carlson, an associate professor at the University of California, Berkeley's Department of Environmental Science, Policy and Management.

The study, published today (Monday, Jan. 12) in the Proceedings of the National Academy of Sciences, was led by researchers at UC Berkeley, the University of San Diego and Yale University.

The researchers reviewed incidents of mass kills documented in scientific literature. Although they came across some sporadic studies dating back to the 1800s, the analysis focused on the period from 1940 to the present. The researchers acknowledged that some of their findings may be due to an increase in the reporting of mass die-offs in recent decades. But they noted that even after accounting for some of this reporting bias, there was still an increase in mass die-offs for certain animals.

Overall, disease was the primary culprit, accounting for 26 percent of the mass die-offs. Direct effects tied to humans, such as environmental contamination, caused 19 percent of the mass kills. Biotoxicity triggered by events such as algae blooms accounted for a significant proportion of deaths, and processes directly influenced by climate -- including weather extremes, thermal stress, oxygen stress or starvation -- collectively contributed to about 25 percent of mass mortality events.

The most severe events were those with multiple causes, the study found.

Carlson, a fish ecologist, and her UC Berkeley graduate students had observed such die-offs in their studies of fish in California streams and estuaries, originally piquing their interest in the topic.

"The catastrophic nature of sudden, mass die-offs of animal populations inherently captures human attention," said Carlson. "In our studies, we have come across mass kills of federal fish species during the summer drought season as small streams dry up. The majority of studies we reviewed were of fish. When oxygen levels are depressed in the water column, the impact can affect a variety of species."

The study found that the number of mass mortality events has been increasing by about one event per year over the 70 years the study covered.

"While this might not seem like much, one additional mass mortality event per year over 70 years translates into a considerable increase in the number of these events being reported each year," said study co-lead author Adam Siepielski, an assistant professor of biology at the University of San Diego. "Going from one event to 70 each year is a substantial increase, especially given the increased magnitudes of mass mortality events for some of these organisms.

This study suggests that in addition to monitoring physical changes such as changes in temperature and precipitation patterns, it is important to document the biological response to regional and global environmental change. The researchers highlighted ways to improve documentation of such events in the future, including the possible use of citizen science to record mass mortality events in real time.

"The initial patterns are a bit surprising, in terms of the documented changes to frequencies of occurrences, magnitudes of each event and the causes of mass mortality," said study co-lead author Samuel Fey, a postdoctoral fellow in ecology and evolutionary biology at Yale. "Yet these data show that we have a lot of room to improve how we document and study these types of rare events."

###

Funding from the Environmental Protection Agency and the National Science Foundation helped support this research.

Media Contact

Sarah Yang
scyang@berkeley.edu
510-643-7741

 @UCBerkeleyNews

http://www.berkeley.edu 

Sarah Yang | EurekAlert!

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

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...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

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...

Im Focus: Breaking the bond: To take part or not?

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...

Im Focus: New 2D Spectroscopy Methods

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....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Detecting damage in non-magnetic steel with the help of magnetism

23.07.2018 | Materials Sciences

Researchers move closer to completely optical artificial neural network

23.07.2018 | Information Technology

Enabling technology in cell-based therapies: Scale-up, scale-out or program in-place

23.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>