Creatures behaving strangely
Posted on OA: 23 Dec 2013 — Reporting by Craig Welch.
Illustrations by Mark Nowlin. Sea Change, The Seattle Times,
22 December 2013
Our understanding of how souring seas will transform the
oceans is growing more sophisticated every day. Here is a
glimpse of what scientists are finding in laboratory studies
about how ocean acidification could affect marine life.
Brittlestar
This starfish relative is known for its ability to regenerate
broken limbs, a feat employed to escape predators. Even small
changes in ocean chemistry can cause some baby brittlestars to
die in less than a week. Adults of other brittlestar species
show loss of muscle mass when regrowing arms in high-carbon
dioxide water. And warming water temperatures can make things
worse by slowing regrowth. Adults of some brittlestar species
appear resistant to ocean-chemistry changes.
Clams
Like other shellfish, acidification eventually affects hard
and soft shelled clams, sometimes weakening their shells.
Fertilization is hampered in at least one species. In another,
when mud is too high in carbon dioxide, baby clams simply die.
In baby clams, the smallest sizes struggle the most to
overcome acidification. Giant clams can be hit quite hard by
the combination of souring seas and warming temperatures.
Clownfish
Researchers a few years ago stumbled upon a surprise.
Scientists had expected fish would easily handle changing sea
chemistry, but work with reef fish, primarily clownfish,
showed high carbon-dioxide levels altered fish behavior,
changing how young fish see, hear and smell. They lost
inhibition, traveling farther from home than normal. They also
lost fear of predators and raced toward them rather than away.
These fish survived far less oftenthan fish in normal water.
Yet when they reproduced, their offspring weathered the highCO2 water. It’s not clear how that apparent resilience might
translate to other species or real-world conditions, when
water chemistry is expected to change year after year.
Corals
These undersea cities provide shelter and food for thousands
of animals, but are directly assaulted by changes in marine
chemistry. Warming can bleach and kill reefs, while waters
slightly more sour than normal slow or halt reef growth.
Acidification also increases bleaching. And it lets matforming algae thrive, which is bad for corals. There is
evidence that some corals appear to handle acidification well,
but the combination of rising temperatures and sea-chemistry
changes makes things worse for many others. Even the special
algae needed for baby corals to take root struggle. In Papua
New Guinea, where natural carbon-dioxide vents offer a glimpse
of life in more corrosive seas, intricate corals favored by
marine life were virtually nonexistent while rounded boulder
corals remained. Algae replaced corals at a similar vent
site in the Mediterranean Sea near Italy. If CO 2 emissions
aren’t curtailed, reef erosion could outpace reef building by
midcentury.
Crab, red king
Perhaps no creature better represents the perilous thrill of
fishing the icy Bering Sea than this crimson crustacean. But
unlike hardier relatives, so manyjuvenile red king crab
died when exposed to higher-carbon dioxide waters that
scientists fear acidification could drastically reduce their
populations before century’s end. Scientists are exploring
whether this species might adapt.
Jellyfish
Few studies have examined how jellyfish respond directly to
souring seas. One showed moon jellies were quite tolerant of
several combinations of rising temperature and shifting sea
chemistry. Some scientists have said they suspect
acidification eventually could help make oceans more
hospitable to jellyfish, but such a change has not
been definitively documented. Still, jellyfish may influence
the carbon system. When they die, jellyfish sink lightningfast, taking carbon straight to the bottom of the ocean.
Krill
These shrimplike crustaceans travel in swarms and serve as
food for everything from fish to seabirds to whales. At carbon
dioxide levels expected by the end of the century, eggs of the
Antarctic variety fail to develop properly, which researchers
fear eventually may lead to a population collapse. Impacts are
greater when acidification is combined with rising
temperatures, which severely limits where and how many
Antarctic krill survive. It’s not clear if acidification will
affect krill in the eastern Pacific Ocean the same way.
Mussels
These shellfish cluster in rocky tidal areas with harsh waves,
where they help host other creatures. But acidification can
hurt their immune systemsand can dramatically weaken the
threads mussels use to attach to rocks. Pathogens can
infect mussels more easily in acidified waters. And the
problems worsen without enough food. When researchers tracked
sea chemistry changes on Tatoosh Island over eight years, they
saw mussels quickly replaced by barnacles and algae. When the
environment is healthy and mussels get enough to eat,
some handle high carbon dioxide well. Some mussels also may
adapt, though they may not keep pace with acidification as
well as some other species (see sea urchin).
Oysters
The Pacific oysters grown in Oregon and Washington were among
the first species harmed by acidification. Their calcium
carbonate shells are particularly susceptible, especially
during the first few days of life, to changes in sea
chemistry. Fossil fuel emissions mixed with water naturally
high in carbon dioxide welled up from the deep on windy days
and came to shore, killing billions of Northwest oyster
larvae in recent years — decades earlier than expected. The
nonnative Pacific oysters were brought from Japan a century
ago. Native oysters may cope better, at first, because they
carry eggs for weeks rather than releasing them into the water
immediately. But native oysters, too, eventually show
sensitivity.
Pteropod
Elevated carbon dioxide can harm these translucent sea
butterflies by altering shell growth, sometimes leaving their
shells pockmarked with pits, which can limit survival.
Increasing temperatures worsen the problem. Like krill, these
tiny animals are a staple of the marine food chain, key
nutrition sources for auklets, puffins, whales and fish, and a
major food for pink salmon. In Antarctica, scientists expected
acidification would start harming pteropods by the year 2038,
but discovered last year it was happening already.
Sea grass
While harmful to many creatures, acidification can be a boon
to
marine
plants.
Eelgrass
populations
increase
dramatically in higher carbon-dioxide environments. In fact,
sea grasses, through photosynthesis, can actually reduce
acidification’s impact on other species. But souring seas can
also help invasive species take over sensitive environments.
Warming temperatures also can reduce gains.
Sea urchin
Acidification
is
hard
on
many
of
these
spiky
delicacies, deforming some larvae and perhaps shrinking
others. High CO 2 can complicate reproduction in several
species, in several ways, and alter development in others. It
can even impair digestion. Urchins graze on seaweed and kelp
forests. Otters and sea stars, in turn, keep urchins in check.
At a natural volcanic CO 2 vent off Italy’s coast, urchins
exposed to high CO 2 began to disappear. The good news: When
urchins from the Pacific Northwest — where water chemistry
swings wildly — were mated with urchins from more stable
Southern California waters, their offspring were more
resistant to acidification. In a similar mating study, gene
sequences actually shifted, suggesting some urchins might
adapt — at least in some places, and at least for a while.
Spiny damselfish
When waters become more acidic, this common reef species
transforms into an aerobic superfish. One measure of a spiny
damselfish’s aerobic fitness increased dramatically in
response to high carbon-dioxide conditions. The fish somehow
transported more oxygen to its tissues. But this is far from a
universal phenomenon. Related fish in the same
environment showed no increase in the same measure. Meanwhile,
the aerobic performance of cardinalfish in the same
region went down in high CO2 water and the fish died more often
— especially when water temperatures rose.
Walleye pollock
With billions of pounds of this Alaskan fish sold each year
for fish sticks, fast-food fish sandwiches or imitation crab,
marine scientists were relieved to find acidification did not
directly affect reproduction or growth. But much
like clownfish, pollock may experience behavioral problems
when exposed to high levels of carbon dioxide. In early
experiments, pollock, key to a Seattle-based fishing fleet
that nets half the nation’s catch, struggled to recognizethe
scent of their prey. Scientists are performing more tests.
Walrus
Little is known about how souring sea chemistry might affect
marine mammals. Researchers expect food-web changes from
acidification might alter how mammals interact with marine
life and each other. For instance, Pacific walrus were
recently seen attacking spectacled eiders on floating ice in
the Bering Sea. Researchers don’t know why, but
suggest existing declines in Arctic clams, expected to worsen
with shifting sea chemistry, might drive hungry walrus to
chase sea ducks.
Reporting by Craig Welch. Illustrations by Mark Nowlin. Sea
Change, The Seattle Times, 22 December 2013. Article.
Can variable pH and low
oxygen
moderate
ocean
acidification outcomes for
mussel larvae?
Posted on OA: 23 Dec 2013 — Frieder C. A., Gonzalez J. P.,
Bockmon E. E., Navarro M. O., Levin L. A., in press. Global
Change Biology.
Natural variation and changing climate in coastal oceans
subject meroplanktonic organisms to broad ranges of pH and
oxygen ([O2]) levels. In controlled laboratory experiments we
explored the interactive effects of pH, [O2], and semidiurnal
pH fluctuations on the survivorship, development and size of
early life stages of two mytilid mussels, Mytilus
californianus and M. galloprovincialis. Survivorship of larvae
was unaffected by low pH, low [O2] or semidiurnal fluctuations
for both mytilid species. Low pH (< 7.6) resulted in delayed
transition from the trochophore to veliger stage, but this
effect of low pH was absent when incorporating semidiurnal
fluctuations in both species. Also at low pH, larval shells
were smaller and had greater variance; this effect was absent
when semidiurnal fluctuations of 0.3 units were incorporated
at low pH for M. galloprovincialis but not for M.
californianus. Low [O2] in combination with low pH had no
effect on larval development and size indicating that early
life stages of mytilid mussels are largely tolerant to a broad
range of [O2] reflective of their environment (80 – 260 μmol
kg−1). The role of pH variability should be recognized as an
important feature in coastal oceans that has the capacity to
modulate the effects of ocean acidification on biological
responses.
Frieder C. A., Gonzalez J. P., Bockmon E. E., Navarro M. O.,
Levin L. A., in press. Can variable pH and low oxygen moderate
ocean acidification outcomes for mussel larvae? Global Change
Biology. Article (subscription required).
Decadal water-property trends
in
the
California
Undercurrent,
implications
acidification
for
with
ocean
Posted on OA: 19 Dec 2013
This study uses data along the West Coast of North America to
analyze the spatial and temporal evolution of water properties
to around 500 m depth. The analysis uses potential density as
the vertical coordinate and bottom depth and latitude as the
horizontal coordinates. The study uses historical data from
the World Ocean Database 2009 from 25°N to 50°N and 1950–2012
for a large-scale analysis of water-property spatial structure
and temporal trends in the California Current System (CCS),
finding significant trends from 1980 to 2012 along density
surfaces near the core of the California Undercurrent (CUC),
including decreasing dissolved oxygen (DO) concentration,
increasing warmth and salinity, and decreasing potential
vorticity. All these changes are consistent with an increasing
influence of Pacific equatorial waters with time. Mixing
characteristics along the core of the CUC reveal that the
1980–2012 trends in the water-mass properties in the CUC are
mostly consistent with a northward shift of these properties,
with additional decreases in DO concentration. These
modifications are associated with the shoaling and
strengthening of the CUC. The changes also imply increased
ocean total (natural and anthropogenic) acidification, as the
trend in the DO concentration is consistent with a natural
decrease in pH all along the CUC, suggesting that
significantly more acidic waters are feeding upwelling onto
the shelf around 2012 than around 1980.
Meinvielle M. & Johnson G. C., in press. Decadal water-
property trends in the California Undercurrent, with
implications for ocean acidification. Journal of Geophysical
Research: Oceans. Article (subscription required).
Insights from stable isotope
dynamics into the sensitivity
of larval Pacific oysters to
ocean acidification
Posted on OA: 19 Dec 2013
Larvae of the Pacific Oyster, Crassostrea gigas, at Whiskey
Creek Shellfish Hatchery (WCH) in Netarts Bay, Oregon, are
negatively impacted by high-CO₂ water and exposure during the
initial shell formation period appears to be particularly
damaging. To investigate the mechanism of this early
susceptibility, several cohorts of larvae at WCH were
monitored for stable isotope incorporation and biochemical
composition: one in May 2011 and two in August 2011. The
observations presented here focus on the isotopic shifts
associated with initiation and rate of feeding, and the
catabolism of C-rich (lipid) and N-rich (protein) pools.
Persistent ontological patterns in bulk composition among the
cohorts suggest that the creation of the initial shell is
energetically expensive, and that the major energetic source
during this period is maternally-derived egg lipids. The May
cohort did not isotopically reflect their food source as
rapidly as the August cohorts, indicating slower feeding,
higher metabolic demand or lower maternal energy investments.
All cohorts turned over organic carbon faster than organic
nitrogen. Shell carbon isotopes of all cohorts show a
decreasing dependence on ambient dissolved inorganic carbon
(DIC) carbon with time and subtle differences in this trend
between the May and August cohorts are explored. Patterns in
shell δ¹³C suggest greater exposure to ambient conditions
during initial shell development, which could be an important
process linking ambient carbonate chemistry and larval
susceptibility. Scanning electron microscopy (SEM) images are
used to document the initial shell formation. Kinetic isotope
fractionation, dissolved organic matter (DOM) utilization, and
the dissolvability of shell microstructures are also briefly
considered in the context of larval susceptibility.
Brunner E. L., 2013. Insights from stable isotope dynamics
into the sensitivity of larval Pacific oysters to ocean
acidification.
MSc
thesis,
Oregon
University. Thesis (restricted access).
State
NE-CAN: The Northeast Coastal
Acidification Network
New folder under Resources tab provides link to Regional OA
Associations
http://www.neracoos.org/necan
The Northeast Coastal Acidification Network (NE-CAN)
represents a nexus of scientists, federal and state agency
representatives, resource managers, and affected industry
partners dedicated towards coordinating and guiding regional
observing, research, and modeling endeavors.
The purpose is to better identify critical vulnerabilities,
particularly with respect to regionally important and
economically significant marine resources. NE-CAN is part of
the larger Integrated Sentinel Monitoring Network coordinated
by the joint Ocean and Coastal Ecosystem Health Committee
of NERACOOS and the Northeast Regional Ocean Council (NROC).
NE-CAN serves as a necessary interface between research and
industry interests whereby state-of-the-science information
can be readily exchanged. Regional interest groups and key
data and information synthesis products can as a result be
specifically tailored and informed by user group needs. NECAN’s area of focus is on the waters from Long Island Sound to
the Scotian Shelf.