Oysters, like many bivalves, are important for marine ecosystems. The organisms filter water through their feathered gills, removing impurities as they inhale and exhale. In fact, native and invasive bivalves might filter the entire volume of the San Francisco Bay every 3-4 days!

However, oysters around the world are threatened by ocean acidification. The acidity breaks down the calcium carbonate shells of the oysters, as we reported in a video several months ago.

Recently, researchers discovered other effects of acidification on oysters and what the breakdown of the oysters’ calcium carbonate shells could mean for the acidic balance. Science Today sat down with the Academy’s own oyster expert, Dr. Peter Roopnarine, curator and chair of Invertebrate Zoology and Geology, to get some perspective on these recent studies.

In the first study, published earlier this month, scientists reported that acidification has negative effects for oysters in the larval stage. The acidity in the water makes the larvae expend much more energy than in neutral waters to make their shells.

“As the oyster larvae struggle early on and expend that embryonic energy,” Roopnarine says, “they have difficulty cranking up their own feeding.”

According to the paper’s lead author, George Waldbusser, “It becomes a death race of sorts. Can the oyster build its shell quickly enough to allow its feeding mechanisms to develop before it runs out of energy from the egg? They must build their first shell quickly on a limited amount of energy—and along with the shell comes the organ to capture external food more effectively.”

Last month, headlines reported that “Oyster Shells are an Antacid to the Oceans,” based on a study of oyster reefs in Chesapeake Bay. Roopnarine explains how oyster reefs are built over time, “Oysters do best on hard ground. The first oysters in a soft bottom environment eventually become the hard substrate that future oysters build upon. As the reef grows, the presence of the shells promotes a healthy, low acidic environment.” Or as the study’s introduction states, “Active and dense populations of filter-feeding bivalves couple production of organic-rich waste with precipitation of calcium carbonate minerals, creating conditions favorable for alkalinity regeneration.”

On a micro-scale, like the Chesapeake Bay, Roopnarine agrees that this could work. Restoration of oyster reefs could contribute to the reduction of ocean acidification problems. On a macro-scale, over geological time and large ocean mass, however, it seems that these oyster reefs could do little to undo the large amounts of CO₂ humans have been pumping into air (that’s absorbed by the oceans) for over a hundred years.

I asked Roopnarine about the San Francisco Bay’s oyster population. We had native oysters before overharvesting, pollution and sedimentation from gold mining in the Sierras buried the oyster reefs, Roopnarine says. A few are still found around the bay, but their numbers are small.

The oysters farmed locally are Japanese oysters, which, until a few years ago, were only found in hatcheries. Wild populations are now establishing themselves in the bay, Roopnarine says, which could be due to warmer temperatures. He and colleagues wrote a study a few years ago that looks at the Japanese oyster population locally.

With the important work these marine organisms do, it’s important we learn more about them to restore oyster reefs.

A former Academy staff-member, Jill Bible, is doing just this near Bodega Bay. To learn more watch this great video by the UC Communications team.

Image: Oysters showing the effects of ocean acidification, OSU

For scientists, policy-makers and organizers who frequently discuss climate change, the last few years have been rough! While they still may be discussing it amongst themselves, with the economic downturn, a larger audience has been absent. An episode of Frontline explores the massive shift in public opinion on climate change.

But the last two weeks might change all of that.

Hurricane Sandy affected so many people that climate change popped up in many new conversations. Click on these questions to find some of these headlines:

• Was the storm caused by climate change?
• Are humans to blame?
• Will global warming bring more “frankenstorms” like Sandy?
• How can cities protect themselves?
• What are some of the financial impacts?
• How can communities adapt to a new normal of storms like these?
• How do we find stormproof solutions?

Will Obama’s second term allow him to speak more freely (and more urgently) about climate change? Scientific American says that we’ll likely only see “more of the same.” But New Scientist has some suggestions about how he can create a “climate change legacy.” And Brandon Keim, in Wired, sees opportunity for the President:

A cap-and-trade system for carbon pollution is unlikely, but other approaches are possible, from adapting infrastructure and improving post-disaster resilience to revenue-neutral carbon taxes and reduced fossil fuel subsidies.

Let’s hope these conversations start quickly (the Academy’s Peter Roopnarine blogs about climate change, providing many conversation starters). According to recent news headlines (here and here), we’re quickly looking at worst-case scenarios for global warming.

What do you want to say about climate change? Share below.

Image: NOAA

This isn’t just a question heard on the playground; it’s asked by scientists as well. Though many agree that the mountain-sized asteroid (that left the now-buried Chicxulub impact crater on the coast of Mexico’s Yucatan Peninsula) ultimately caused the mass extinction, some scientists continue to argue about the health of dinosaurs before the event.

A new study this week, published in the Proceedings of the National Academy of Sciences looks at the health of ecosystems from 13 million to 2 million years prior to the impact. The Academy’s Peter Roopnarine and his colleagues constructed food webs to examine the communities that lived in North America at the time.

In fact, Peter has spent the past eight years constructing paleo food webs, looking comprehensively at who lived in a particular place at a particular time, what they ate and who ate them. It’s a great way to see into the past.

Constructing these food webs involves looking at the fossil record—bone damage, stomach contents, etc.—and creating computer models. Peter says this involves a lot of data. He finds ecologically similar species that occupied a similar space and time and likely shared the same predators and prey. He starts by creating links between them and then builds from there.

Peter also looks at the present to reconstruct the past. He looks at how predators and prey are distributed in a modern ecosystem—there will only be so many top predators, for example, yet there will be many organisms at the bottom of the food web. Peter says that modern food webs are dominated by specialists—those that just eat a few organisms. But as you follow along, you’ll find a few generalists that consume an assortment of items.

Like a baseball statistician looking to build a new team, Peter uses these numbers and statistics from current players to input into his model to map past scenarios.

But, of course, the food web he models represents just one possibility of how that ecosystem looked at that time. So Peter runs the model thousands of times to get the average picture of the dynamics of the food web.

Now back to the dinosaurs… Running the food webs for 13 million years before the impact, Peter and his colleagues found that the ecosystems had been changing in North America. There was less diversity of species with lots of smaller vertebrates and very, very large herbivores. These changes could have taken place when the interior western seaway dried up, which would have affected climate and vegetation.

This doesn’t mean that the ecosystems were fragile by any means. Peter says. They were fine, robust even. Perhaps just a little less robust closer to the impact.

But when the impact hit, these small differences played a significant role, Peter explains. The ecosystems were a bit more vulnerable. “It was a bad time to be alive.”

“Our study suggests that the severity of the mass extinction in North America was greater because of the ecological structure of communities at the time,” notes Peter’s colleague and lead author of the paper Jonathan Mitchell of the University of Chicago.

And these small changes in the past can help us learn what might happen in future major events, says Peter. “What do extreme occurrences look like, where is our vulnerability, what does a recovery look like? Besides shedding light on this ancient extinction, our findings imply that seemingly innocuous changes to ecosystems caused by humans might reduce the ecosystems’ abilities to withstand unexpected disturbances.”

“It looked too perfect to be a rock,” he told the Associated Press.

This is a great example of citizen science, says the Academy’s Peter Roopnarine, curator of Invertebrate Zoology and Geology.

Initial dating by the Transbay’s paleontology consultant put the fossil’s age at around 11,000 years old. The huge tooth—“about a foot in length and 8 inches tall,” according to The Bay Citizen—will be donated to the Academy.

The Academy has other mammoth teeth in its collection, including three specimens found in San Francisco. Other collections from that time period in California include a saber-tooth cat skeleton, bison and dire wolves.

Peter says if we’re able to put the recent find on display, it will be a great opportunity to tell the story of the recent fossil history of San Francisco.

The late Ice Age in California had a rich diversity of mammals—large saber-tooth cats, horses, wolves, bison and of course, mastadons and mammoths. Peter explains that the area was a series of lush valleys with open plains. The nearby ocean provided a very moderate climate—making this region a cooler version of today’s African savannah.

Peter says that it’s always difficult to reconstruct the past in modern, metropolitan areas, where fossils are moved or buried without a second thought. That’s what makes Brandon Valasik’s discovery such a treasure. And the fact that Valasik himself recognized it.

We’re not sure when we will receive the tooth here, but when it does arrive, our scientists will examine the specimen for more clues to the species and age. Stay tuned!

With the AGU meeting in town, it was a great week for science news! We covered several topics on Tuesday, Wednesday, and Thursday—and we’ll highlight a few more of them here for you.

Monday’s sessions included several discussions about the 2011 Tohoku tsunami in Japan—its effects on the local population and on far-reaching areas as well as how we can forecast future events.

One of the biggest surprises came during a presentation by Satoko Oki of the Earthquake Research Institute. She collected data from Japanese residents before and after the 2011 tsunami and found them less prepared for tsunamis after the Tohoku hit! When polled post 2011, they misidentified the minimum wave height from which to evacuate. They had correctly identified the minimum height less than a year before. The 80beats blog in Discover identifies the problem succinctly:

The Tohoku tsunami was so large–about 130 feet–that it may have dragged people’s expectations of what’s dangerous higher.

Another presentation revealed why the tsunami was so devastating—it was a “merging tsunami.” NASA researchers found that the tsunami doubled in intensity over rugged ocean ridges, amplifying its destructive power at landfall. This animation on NASA’s website illustrates the direction and power quite well.

The discovery helps explain how tsunamis can cross ocean basins to cause massive destruction at some locations while leaving others unscathed. The data raise hope that scientists may be able to improve tsunami forecasts.

Switching perspective from the oceans to outer space… NASA and NOAA held a joint workshop Tuesday on preparing for the solar max. As solar storms increase over the next 20 months or so, we can be prepared for what might and might not happen. This might remind you of a press briefing held earlier this year at the AAAS meeting that we covered here. It certainly reminded us how active the Sun can be, even during quiet times, as shown in this beautiful NASA video of SDO’s first year in space.

Finally, the Academy’s own Peter Roopnarine presented at the meeting on his research on oysters in the Gulf of Mexico. With colleagues, Peter has been testing for contaminants in the shells of oysters before and after the spill and hopes to model the spread of contaminants to other species through the food web. Check out this Science in Action video to learn more.

Image: Samuel Morse/US Air Force/Wikipedia

What we call Asian carp here in the US are actually four species of fish, according to the USDA: the Bighead carp, black carp, grass carp and silver carp. They were originally brought to the US to do good. According to NPR:

Originally imported to help control algae in fish farms and water treatment plants in the South, Asian carp made their way into Louisiana rivers, possibly during floods in the early 1990s, and spread quickly up the Mississippi River and its tributaries.

Lake Michigan is connected to the Mississippi by a series of artificial locks that bring commercial ships into and out of the Great Lakes and specifically the Chicago area. Barriers have been built to keep carp out, but recently, one of these invaders was found past the barrier, in Lake Cascade, six miles south of Lake Michigan. The New York Times quoted Henry Henderson of the Natural Resources Defense Council reacting to the news:

Asian carp are like cockroaches; when you see one, you know it’s accompanied by many more you don’t see.

Why the barriers? Are Asian carp so bad? Well, here’s what Time has to say:

They can weigh up to 100 pounds and measure up to 20 feet, and eat 40 percent of their weight daily in plankton, thus knocking out the bottom of food chains. Even crazier, they launch themselves out of the water when startled, often hitting — and injuring — boaters.

It’s hard to say if these fish will cause problems for the native species in the Great Lakes, according to the Academy’s Peter Roopnarine, PhD. He does a lot of work with food webs that include both native and non-native species, and says that, “it’s not clear why some exotic species become established and some don’t.” For example, the San Francisco Bay has many invasive species, but none have yet to cause native species to go extinct.

That doesn’t stop the controversy, though. The Asian carp have swum right into the middle of one, with several groups taking sides. 80beats from Discover described it this way, earlier this year:

On one side, many environmentalists, as well as people who rely on Great Lakes fishing for their livelihood, have called on the federal government to shut down locks that connect the river to Lake Michigan…

…Naturally there’s one group that would be mighty upset at closing the shipping locks: shipping companies.

Earlier this month, the governor of Illinois, hoping to find a solution that won’t close the locks, announced a plan to open a fish processing plant and export the carp to China.

Then, this week, five states filed a lawsuit against the Metropolitan Water Reclamation District of Greater Chicago and the Army Corps of Engineers. Per AOL,

The lawsuit seeks an order to close Chicago shipping locks that provide a century-old pathway to the Great Lakes via the Mississippi River basin. The lawsuit was filed by Michigan, Wisconsin, Ohio, Minnesota and Pennsylvania.

Who expected a fishy tale could get this large? Those of us in northern California know it only too well— the state involvement, debates, lawsuits—sounds like the Delta smelt. Except, ironically, the smelt are native to this area and have to compete with larger, invasive fish.

What will be the next big fish to fry?

Creative Commons image by kate.gardiner

“It’s important that scientists disagree. We’re trained to be skeptical, to be critical, “ according to the Academy’s own Peter Roopnarine, PhD, Curator of Invertebrate Zoology and Geology. “It’s actually when they agree that it’s significant. And there’s overwhelming agreement in the scientific community about global warming.”

In fact, according to this New York Times article, “nearly 90 percent of some 3,000 climatologists who responded agreed that there was evidence of human-driven climate change, 80 percent of all earth scientists and 64 percent of meteorologists agreed with the statement.” (What’s up with meteorologists? Find out here.)

Climate deniers may argue that scientists don’t agree on the science behind global warming, but overall, they do.  As seen in so-called “Climategate,” the arguments within the emails weren’t about the science, but about how to proceed with the findings and how to communicate the details. As published earlier this week, the science discussed in the emails was reviewed by other scientists and found to be sound, to be true.

Let the scientists disagree about the South African hominid skull. As Dr. Roopnarine points out, it wouldn’t be such a big deal if we were talking about an ancient clam.

But Earth? And humanity’s future on it? That is a big deal. And when it comes to climate change, scientists find plenty to agree on.

That was the headline James Fleming of Colby College wanted the press to use for a very heated press conference at the AAAS Meeting last Saturday.

The press conference brought together a diverse mix of scientists and researchers, including a science historian, a philosopher and an ethicist. And, as Dr. Fleming remarked, they certainly did not agree.

As the moderator of the conference said in his opening and indisputable statement, geoengineering is the altering of the Earth. At the meeting, three symposia addressed geoengineering as a response to another human activity—our altering the planet through global warming. The press conference combined aspects of the three different sessions.

Geoengineering can include carbon capture and sequestration, but the hot button issue at the conference and the one that many cannot agree on, including the experts Dr. Fleming referred to above, is the issue of solar radiation management. Much of the discussion centers on injecting sulfur into the stratosphere—also referred to as increasing stratospheric aerosols. This sounds pretty scary, but as Ken Caldeira mentioned, no climate intervention will be perfect, and it could be a bad thing compared to a worse situation, likening it to chemotherapy treatment for cancer. If you can save lives and reduce suffering, it may have to be a solution.

It has to be mentioned that this isn’t for the present climate crisis, but the future, as the climate is likely, under any IPCC scenario, to get worse. As Braden Allenby said, climate change is not a problem that can be fixed as long as we have seven billion people on the planet; it’s going to be a problem for a very long time. He went on to add that geoengineering, still very much in its infancy and currently only in the modeling and discussion levels, is a possible “response to the challenge ahead… a part of a portfolio of options.”

Philip Rasch of Pacific Northwest National Laboratory is researching how sea salts could be used to brighten clouds, another solar radiation management possibility. This solution would be more regionalized and less global than the sulfate aerosols.

On Monday morning, a Royal Society study was to address the pros and cons of each of these.

Our own paleo-ecologist, Peter Roopnarine has these comments about geoengineering:

Personally, I am very skeptical of geoengineering for two reasons. First, although the caveat is usually presented that this is an option for the future, it is nevertheless viewed as mitigation in many quarters. This is particularly true of carbon sequestration. Our efforts right now should be placed on reducing greenhouse gas emissions. Failure to do so will ultimately doom the current geoengineering proposals because they will be outstripped by the problem. Second, too many of the approaches are too simplistic. This is true of the other class of options, those of environmental manipulation. Here I include options such as solar shielding, cloud manipulation and ocean iron seeding. We have insufficient understanding of these processes on large spatial and temporal scales to predict all of the possible impacts. The systems are complicated and complex, and the models aren’t up to the job. Caldeira’s chemotherapy analogy is an interesting one; you literally kill a good deal of the body to solve one problem. But we’re talking about an entire planet here, and as complicated as the human body is, planet Earth is orders of magnitude more complicated.

Creative Commons image by Heikenwaelder Hugo