Considerations
for
the
measurement
of
spectrophotometric pH for
ocean acidification and other
studies
Posted on OA: 24 Dec 2014 — DeGrandpre M. D., Spaulding R. S.,
Newton J. O., Jaqueth E. J., Hamblock S. E., Umansky A. A. &
Harris K. E., 2014. Limnology and Oceanography Methods
12:830-839.
Indicator-based spectrophotometric pH is commonly used for the
analysis of seawater because of its high precision and longterm reproducibility. Users come from an increasingly diverse
range of disciplines, primarily motivated by studies focused
on the causes and effects of ocean acidification. While the
analysis is readily implemented and straightforward, there are
many variables that must be predetermined or measured, all of
which can contribute uncertainty to the measurement. The
indicator equilibrium constant and molar absorption
coefficient ratios are available in the literature, but for
various reasons, the conditions of analysis can be different,
creating errors. Most of the parameters are temperature,
salinity, and pressure dependent, posing potential additional
errors. Indicator impurities and indicator perturbation of the
sample pH also create uncertainties. We systematically
evaluate all of the sources of error and compute how the
errors propagate into CO2 equilibrium calculations of the
partial pressure of CO2 (pCO2) and calcium carbonate
saturation states (Ω). The primary sources of uncertainty
originate from wavelength and absorbance errors in low quality
or poorly functioning spectrophotometers (0.007 to 0.020 pH
units) and indicator impurities (0.000 to >0.040 pH units).
These errors generate pCO2 and Ω uncertainties of 11-200 μatm
and 0.08-0.38, respectively, depending upon the pH value and
its uncertainty.
DeGrandpre M. D., Spaulding R. S., Newton J. O., Jaqueth E.
J., Hamblock S. E., Umansky A. A. & Harris K. E., 2014.
Considerations for the measurement of spectrophotometric pH
for ocean acidification and other studies. Limnology and
Oceanography Methods 12:830-839. Article (subscription
required).
New
MBARI
project:
The
Emerging Science of a High
CO2 / Low pH Ocean
Posted on OA: 24 Dec 2014
This project developed by the Monterey Bay Aquarium Research
Institute (MBARI) proposes to tackle the problem of assessing
the future impacts of elevated oceanic CO2 levels (lower pH)
on marine ecosystems through a unique combination of field and
laboratory studies, and to address the associated policy,
economic, and permitting issues. This work will draw on
MBARI’s exceptional engineering skills, the institutional
investment in ships and vehicles, and the new presence of the
MARS cable as a unique experimental resource. The inevitable
association of higher CO2 levels with climate change and lower
oxygen levels, and the cascade of ocean policy issues arising
in the post-climate change world will bring additional
complexity that only a team effort can address.
The project aims at developing systems and methods for smallscale perturbation experiments in the laboratory and at sea to
expose marine animals to the conditions that will likely
represent the ocean of the late 21st century, to communicate
these findings to policy makers, and to make the systems and
knowledge we create available to users world-wide. CO2
perturbation experiments for land eco-systems have long been
carried out and have revealed important predictors and
insights that will influence policy. No equivalent experiments
have yet been carried out in the ocean.
For more information on the project, please visit MBARI
website.
NOAA offers $1.4 million to
help shellfish growers track
ocean acidification
by Diane Plescher-Steele — last modified Dec 18, 2014 11:08 AM
Posted on OregonLive: 17 Dec 2014 — By Kelly House
The National Oceanic and Atmospheric Administration is ponying
up $1.4 million to help West Coast shellfish growers and
scientists address ocean acidification.
The new three-year grant will help commercial shellfish
growers find ways to adapt their oyster and mussel-rearing
businesses to keep the animals from dying when waves of carbon
dioxide-saturated water come through.
High levels of carbon dioxide throw the water’s chemistry out
of balance, making it difficult for bivalves to form their
shells. The phenomenon has contributed to massive shellfish
die-offs throughout the Northwest.
Burke Hales, an Oregon State University professor who
developed a machine that detects chemical changes in the
water, will be the leading expert on the project.
Shellfish growers will learn how to monitor ocean
acidification levels, and will collaborate with Hales and
other scientists along the West Coast to develop more
affordable, accurate sensors that measure changes in ocean’s
chemistry.
The grant announcement is the latest development in NOAA’s
ongoing effort to combat carbon dioxide’s damaging effects on
ocean life. Earlier this fall, the agency announced the launch
of a new web-based tool that tracks ocean acidification along
the West Coast.
The announcement follows Oregon State University researchers’
discovery this fall that ocean acidification isn’t caused by
carbon dioxide alone, but the imbalance created when carbon
dioxide rises without a concurrent rise in seawater calcium
carbonate levels.
Benoit Eudeline looks through a screen covered with oyster
larvae at the Whiskey Creek Shellfish Hatchery near Netarts
Bay. (ynn Ketchum/Oregon State University )
NOAA offers $1.4 million to
help shellfish growers track
ocean acidification
Posted on OregonLive: 17 Dec 2014 — By Kelly House
Benoit Eudeline looks through a screen covered with oyster
larvae at the Whiskey Creek Shellfish Hatchery near Netarts
Bay. (ynn Ketchum/Oregon State University )
The National Oceanic and Atmospheric Administration is ponying
up $1.4 million to help West Coast shellfish growers and
scientists address ocean acidification.
The new three-year grant will help commercial shellfish
growers find ways to adapt their oyster and mussel-rearing
businesses to keep the animals from dying when waves of carbon
dioxide-saturated water come through.
High levels of carbon dioxide throw the water’s chemistry out
of balance, making it difficult for bivalves to form their
shells. The phenomenon has contributed to massive shellfish
die-offs throughout the Northwest.
Burke Hales, an Oregon State University professor who
developed a machine that detects chemical changes in the
water, will be the leading expert on the project.
Shellfish growers will learn how to monitor ocean
acidification levels, and will collaborate with Hales and
other scientists along the West Coast to develop more
affordable, accurate sensors that measure changes in ocean’s
chemistry.
The grant announcement is the latest development in NOAA’s
ongoing effort to combat carbon dioxide’s damaging effects on
ocean life. Earlier this fall, the agency announced the launch
of a new web-based tool that tracks ocean acidification along
the West Coast.
The announcement follows Oregon State University researchers’
discovery this fall that ocean acidification isn’t caused by
carbon dioxide alone, but the imbalance created when carbon
dioxide rises without a concurrent rise in seawater calcium
carbonate levels.
Ocean acidification a culprit
in
commercial
shellfish
hatcheries’ failures
Posted on PhysOrg: 16 Dec 2014 — By Cheryl Dybas
Mediterranean mussels at the Penn Cove Shellfish Farm in
Washington’s Puget Sound. Credit: Penn Cove Shellfish Farm
The mortality of larval Pacific oysters in Northwest
hatcheries has been linked to ocean acidification. Yet the
rate of increase in carbon dioxide in the atmosphere and the
decrease of pH in near-shore waters have been questioned as
being severe enough to cause the die-offs.
Now, a new study of Pacific oyster and Mediterranean mussel
larvae found that the earliest larval stages are sensitive to
saturation state, rather than carbon dioxide(CO2) or pH
(acidity) per se.
Saturation state is a measure of how corrosive seawater is to
the calcium carbonate shells made by bivalve larvae, and how
easy it is for larvae to produce their shells. A lower
saturation rate is associated with more corrosive seawater.
Increasing CO2 lowers saturation state, the researchers say,
and saturation state is very sensitive to CO2.
The scientists used unique chemical manipulations of seawater
to identify the sensitivity of saturation state for larval
bivalves such as mussels and oysters.
Results of the study, which was funded by the National Science
Foundation (NSF), are reported this week in the journal Nature
Climate Change.
“Biological oceanographers have speculated that early life
stages of marine organisms might be particularly sensitive
to ocean acidification, but the underlying mechanisms remain
unknown for most species,” says David Garrison, program
director in NSF’s Division of Ocean Sciences, which funded the
research through an ocean acidification competition.
NSF’s Directorates for Geosciences and for Biological Sciences
supported the ocean acidification awards.
“This research is an important step,” says Garrison, “in being
able to predict, and perhaps mitigate, the effects of ocean
acidification on coastal resources.”
Commercial hatchery failures
The findings help explain commercial hatchery failures, and
why improving water chemistry in those hatcheries has been
successful.
Shellfish hatcheries are now altering water chemistry to
create more favorable saturation state conditions for young
bivalves.
View of the Penn Cove Shellfish Farm, where mussel larvae are
sensitive to ocean acidification. Credit: Penn Cove Shellfish
Farm
“Bivalves have been around for a long time and have survived
different geologic periods of high carbon dioxide levels in
marine environments,” says George Waldbusser, an Oregon State
University (OSU) marine ecologist and biogeochemist and lead
author of the paper.
“The difference is that in the past, alkalinity (the opposite
of acidity) levels buffered increases in CO2, which kept the
saturation state higher relative to pH. In the present ocean,
the processes that contribute buffering to the ocean cannot
keep pace with the rate of CO2 increase.
“As long as the saturation state is high, the oysters and
mussels we tested could tolerate CO2 concentrations almost 10
times what they are today.”
The idea that bivalve development and growth is not as linked
to CO2 or pH levels as previously thought initially seems
positive.
However, the reverse is true, Waldbusser says.
Marine ecologists study ocean water chemistry back in the
lab. Credit: Oregon State University
Larvae sensitive to saturation state
Larval oysters and mussels are so sensitive to the saturation
state (which is lowered by increasing CO2) that the threshold
for danger will be crossed “decades to centuries,” says
Waldbusser, ahead of when CO2 increases (and pH decreases)
alone would pose a threat to bivalve larvae.
“At the current rate of change, there is not much more room
for the waters off the Oregon coast, for example, to absorb
more CO2 without crossing the threshold,” Waldbusser says.
The study builds on previous research by Waldbusser and
colleagues that outlined the mechanisms by which young
bivalves create their shells after fertilization.
The researchers found that young oysters and mussels build
their shells within 48 hours to successfully begin feeding at
a rate fast enough to survive, and that the rate of shellbuilding required significant energy expenditures.
Scientists have found that shellfish are affected by what’s
called saturation state. Credit: Wikimedia Commons
In the presence of acidic water, the oysters and mussels had
to divert too much energy to shell-building and lacked the
energy to swim and get food.
Sinking shellfish
“The hatcheries call it ‘lazy larvae syndrome’ because these
tiny oysters just sink in the water and stop swimming,”
Waldbusser says.
“These organisms have really sensitive windows to ocean
acidification—even more sensitive than we thought.”
In the current study, the researchers used high-resolution
images to analyze the development of oyster and mussel shells.
The effects of low saturation state waters were tested on
oyster larvae. Credit: Oregon State University
They found that the organisms—which are about 1/100th the
diameter of a human hair—build a complete calcium carbonate
shell within six hours, about 12 hours after fertilization.
Alter the ocean chemistry just a bit, however, and a greater
proportion of the shells do not develop normally.
Two-day-old Pacific oyster larvae showed abnormal growth with
changes in saturation state. Credit: Oregon State University
The ones that do are smaller, leading to potentially weaker
organisms that take longer to get to a size where they can
settle into adult life.
“When the water is more saturated and has greater alkalinity
it helps offset higher levels of carbon dioxide, ensuring that
shell formation can proceed—and also making the shells
bigger,” Waldbusser says. “This can have a significant effect
on their survivability.”
Explore further: New
acidification data
tool
displays
West
Coast
ocean
additional info
Journal reference: news infobox // Nature Climate Change
Provided by news infobox // National Science Foundation
Read
more
at: http://phys.org/news/2014-12-ocean-acidification-culprit-c
ommercial-shellfish.html#jCp