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Ikan Alaska menyesuaikan
diri dengan perubahan iklim
dengan mengikuti makanannya
Tidak semua spesies menderita dari
perubahan iklim. analisis baru menunjukkan bahwaVarden Dolly, spesies umum di Tenggara Alaska,menyesuaikan migrasi mereka sehingga mereka dapat
berpesta di sumber makanan utamanya —telur ikan
salmon--bahkan pergeseran iklim
mengubah waktu ikan salmon bertelur......read more
Alaska fish
adjust to climate change by following the food
Date:
December 20, 2014
Source:
NOAA Fisheries West
Coast Region
Summary:
Not all species may
suffer from climate change. A new analysis shows that Dolly Varden, a species
of char common in southeast Alaska, adjust their migrations so they can keep
feasting on a key food source -- salmon eggs -- even as shifts in climate
altered the timing of salmon spawning.
........................
not all species may
suffer from climate change. A new analysis shows that Dolly Varden, a species
of char common in southeast Alaska, adjust their migrations so they can keep
feasting on a key food source -- salmon eggs -- even as shifts in climate
altered the timing of salmon spawning.
The resiliency of species to climate change may depend on how well they
adapt to climate-driven changes in their food and habitat, such as altered
growth of plants they feed on. A mismatch in timing between predators and the
availability of prey could cause some species to lose access to food. But
others such as Dolly Varden that successfully adjust to shifts in climate and
prey offer a climate change story with a happy ending, according to the study
published inFreshwater Biology.
Ignoring environmental cues may help this predator
The Dolly Varden's secret appears to be that instead of taking its
migration cues from environmental variables such as water temperature or
streamflow, the species cues directly off the presence of salmon the Dolly
Varden depend on for food, the study found.
"Despite warming temperatures and shifting salmon migrations, Dolly
Varden do a great job of following their food," said lead author Chris
Sergeant of the National Park Service's Inventory and Monitoring Program in
southeast Alaska. "Species that can handle a high degree of variability
are the ones that should be most resilient to further changes associated with
climate."
Dolly Varden get most of their energy over the course of each year by
gorging themselves on salmon eggs, which are abundant in summer and rich in
energy thanks to the same fatty acids that make fish healthy for humans. Eggs
from any single species of salmon may be available during a narrow spawning
window of two to six weeks. The Dolly Varden must follow salmon migrations
closely to take full advantage of this annual salmon egg bonanza.
Sticking with salmon to find food
But salmon migrations are shifting as the climate warms. Previous research
by the University of Alaska and NOAA Fisheries' Alaska Fisheries Science Center
in southeast Alaska's Auke Creek has shown that pink and coho salmon now
migrate to their spawning grounds 10 to 17 days earlier while sockeye salmon
migrate eight days earlier.
Instead of falling out of synch with salmon, though, seagoing Dolly Varden
in Auke Creek have accurately adjusted their annual migrations from the ocean
back to freshwater to stick with the salmon. The adjustment has maintained
their access to egg meals, according to the new research that includes
coauthors from the University of Wyoming and NOAA Fisheries' Northwest
Fisheries Science Center.
Researchers rely on long record of fish migration data
The research depended on a wealth of fish data from a weir on Auke Creek
maintained primarily since 1980 by NOAA Fisheries' Alaska Fisheries Science
Center Auke Bay Labs, supported by collaborations with the University of Alaska
Fairbanks and Alaska Department of Fish and Game. From 1997 to 2006 crews
counted and measured Dolly Varden migrating from the ocean, past the weir and
into Auke Creek, providing an unusual long-term picture of fish migration
times.
"We're really indebted to the people who kept that record going for so
long," said Eric Ward of the Northwest Fisheries Science Center. "It
turns out to be very valuable in understanding how species are responding to
the changing climate."
Researchers in the new study used the weir data to examine the relationship
between migrations of salmon and Dolly Varden from year to year. They found the
timing of Dolly Varden migration more closely related to the presence and
timing of the salmon than on environmental variables such as temperature and
precipitation that are often seen as driving animal migrations.
In short, the Dolly Varden are shifting their migration to follow their
food instead of following temperatures or other environmental cues that, as the
climate changes, might otherwise lead them to migrate at a different time than
the salmon that provide their most important food.
The researchers cautioned that it's unclear whether other salmon predators
could adjust their timing to follow salmon as effectively as Dolly Varden do,
apparently by watching salmon passing by or detecting salmon eggs through
smell. But the adaptability of Dolly Varden suggests that at least some species
may be more resilient to climate-induced changes in migration timing than
ecologists might assume.
Story Source:
The above story is based on materials provided by NOAA
Fisheries West Coast Region. Note: Materials may be edited for content and length.
Journal Reference:
1. Christopher J. Sergeant, Jonathan B.
Armstrong, Eric J. Ward. Predator-prey migration phenologies remain
synchronised in a warming catchment.Freshwater Biology, 2014;
DOI: 10.1111/fwb.12524