Study
finds climate change is causing modifications to marine life behavior
Warming
oceans are causing marine species to change breeding, feeding, and
migration timing.
26
January, 2013
Oceans cover 71 percent of the Earth's surface, yet our knowledge of the impact of climate change on marine habitats is a mere drop in the proverbial ocean compared to terrestrial systems. An international team of scientists set out to change that by conducting a global meta-analysis of climate change impacts on marine systems
Counter
to previous thinking, marine species are shifting their geographic
distribution toward the poles and doing so much faster than their
land-based counterparts. The findings were published in Nature
Climate Change.
The
three-year study, conducted by a working group of UC Santa Barbara's
National Center for Ecological Analysis and Synthesis (NCEAS) and
funded by the National Science Foundation, shows that warming oceans
are causing marine species to change breeding, feeding, and migration
timing as well as shift where they live. Widespread systemic shifts
in measures such as distribution of species and phenology—the
timing of nature's calendar—are on a scale comparable to or greater
than those observed on land.
"The
leading edge or front-line of marine species distributions is moving
toward the poles at an average of 72 kilometers (about 45 miles) per
decade—considerably faster than terrestrial species, which are
moving poleward at an average of 6 kilometers (about 4 miles) per
decade," said lead author Elvira Poloczanska, a research
scientist with Australia's national science agency, the Commonwealth
Scientific and Industrial Research Organisation (CSIRO), Marine and
Atmospheric Research in Brisbane. "And this is occurring even
though sea surface temperatures are warming three times slower than
land temperatures."
The
report, which involved scientists from 17 institutions, including
NCEAS associates Carrie Kappel and Ben Halpern and former NCEAS
postdoctoral associates Mary O'Connor, Lauren Buckley, and Camille
Parmesan, forms part of the Fifth Assessment Report of the United
Nations Intergovernmental Panel for Climate Change (IPCC). The
Geneva-based IPCC assesses scientific, technical, and socioeconomic
information concerning climate change, its potential effects, and
options for adaptation and mitigation.
"The
effects of climate change on marine species have not been a major
focus of past IPCC reports because no one had done the work to pull
together all the disparate observations from around the world,"
said Kappel. "This study provides a solid basis for including
marine impacts in the latest global accounting of how climate change
is affecting our world."
Unlike
previous climate change assessments, which relied heavily on
terrestrial data to estimate marine impacts, the NCEAS working group
scientists gathered from seven countries to assemble a large
marine-only database of 1,735 changes in marine life from the global
peer-reviewed literature. The biological changes were documented from
time series, with an average length of 40 years of observation.
"Here's
a totally different system with its own unique set of complexities
and subtleties," said Camille Parmesan, professor in the
Department of Integrative Biology at University of Texas at Austin.
"Yet the overall impacts of recent climate change remain the
same: an overwhelming response of species shifting where and when
they live in an attempt to track a shifting climate.
"This
is the first comprehensive documentation of what is happening in our
marine systems in relation to climate change," added Parmesan.
"What it reveals is that the changes occurring on land are being
matched by the oceans. And far from being a buffer and displaying
more minor changes, what we're seeing is a far stronger response from
the oceans." Parmesan has been active in IPCC since 1997, and in
her capacity as a lead author, she shared in the award of the 2007
Nobel Peace Prize to IPCC.
The
research revealed telltale traces that collectively build the case
for climate change causing modifications in the ocean. These
fingerprints of climate change include movements of species toward
the poles as ocean temperatures rise, with an average displacement up
to ten times that for terrestrial species.
Phytoplankton,
zooplankton, and bony fish showed the largest shifts.
Researchers
also found that the timing of spring events in the oceans had
advanced by more than four days, nearly twice the figure for land.
The strength of response varied among species, but again, the
research showed the greatest response—up to 11 days in
advancement—occurred in invertebrate zooplankton and larval bony
fish.
Multiple
lines of evidence supported the hypothesis that climate change is the
primary driver behind the observed changes: for example, opposing
responses in warm-water and cold-water species within a community and
similar responses from discrete populations at the same range edge.
In total, 81 percent of all observations, whether for distribution,
phenology, community composition, abundance, or demography, across
different populations and ocean basins were consistent with the
expected impacts of climate change.
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