Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study highlights under-appreciated benefit of oyster restoration

10.05.2013
Oyster reefs shown to buffer acidic inputs to Chesapeake Bay
Scientists have identified many benefits for restoring oyster reefs to Chesapeake Bay and other coastal ecosystems. Oysters filter and clean the water, provide habitat for their own young and for other species, and sustain both watermen and seafood lovers.

A new study co-authored by Professor Roger Mann of the Virginia Institute of Marine Science adds another item to this list of benefits—the ability of oyster reefs to buffer the increasing acidity of ocean waters.
The study, “Ecosystem effects of shell aggregations and cycling in coastal waters: An example of Chesapeake Bay oyster reefs,” appears in Ecology, the flagship journal of the Ecological Society of America. It is co-authored by George Waldbusser of Oregon State University and Eric Powell of the Haskin Shellfish Research Laboratory at Rutgers University.

Concerns about increasing acidity in Chesapeake Bay and the global ocean stem from human inputs of carbon dioxide to seawater—either through the burning of fossil fuels or runoff of excess nutrients from land. The latter over-fertilizes marine plants and ultimately leads to increased respiration by plankton-filtering oysters and bacteria. In either case, adding carbon dioxide to water produces carbonic acid, a process that has increased ocean acidity by more than 30% since the start of the Industrial Revolution.

A more acidic ocean concerns marine-life experts, who cite its corrosive effects on the calcium carbonate shells of oysters, clams, and other mollusks, as well as its possible physiological effects on the larvae of fish and other marine creatures. At current rates of increase, ocean acidity is predicted to double by 2100.

The Ecology paper reports on the research team’s efforts to calculate past and present shell budgets for Chesapeake Bay, with a goal of estimating how effective healthy oyster reefs might be in moderating ocean acidity, and whether today’s depleted reefs can withstand future acidity increases.

“Oyster shells are like slow-dissolving TUMS in the belly of Chesapeake Bay,” explains Mann. “As ocean water becomes more acidic, oyster shells begin to dissolve into the water, slowly releasing their calcium carbonate—an alkaline salt that buffers against acidity. An oyster reef is a reservoir of alkalinity waiting to happen.”

The team’s calculations suggest that in 1870—before people began large-scale harvesting of oyster meat and shells from the Chesapeake—the amount of oyster shell exposed to Bay waters was more than 100 times greater than today, with an equally enhanced capacity to buffer acidity.

“Our data show that that oyster reefs likely played a key role in the pH budget of pre-harvest Chesapeake Bay,” says Mann. “The amount of carbonate in the shells of living oysters at that time was roughly equal to the total amount of carbonate dissolved in the modern Bay. If similar numbers of oysters were alive today, they could take up about half of the carbonate that rivers currently carry into Bay waters.”

Many people are familiar with the notion that the cloudy waters of the modern Bay would be clearer if over-harvesting and disease hadn’t drastically reduced the oyster population and its capacity to filter particles from the water. Mann says, “Our study suggests a similar loss of ecosystem function, but in terms of buffering acidity rather than improving water clarity. This has significant ecological ramifications, but hasn’t really been on anyone’s radar screen.”

Returning oyster shells to Bay waters—a practice that began in earnest in the 1960s to restore reefs for food and filtering—has helped buffer acidity in the Bay, but to nowhere near historical levels. Today, scientists estimate that the Bay loses 100 million bushels of oyster shell each year to harvesting and corrosion in Maryland waters alone, despite the return of 20-30 million bushels of shell through dredging and restaurant recycling.

The study by Mann and his colleagues estimates that oysters now contribute only 4% to buffering of acidity baywide, whereas they were responsible for 70% of all baywide buffering in 1870.

Looking towards the future, the team’s concern is that oyster reefs in the modern Bay—fewer and smaller than their pre-harvest counterparts and featuring smaller oysters—may be unable to keep pace with the increasing acidity of Bay waters.

“The shells of dead oysters degrade rapidly in estuarine environments,” says Mann, “with a half-life of only 3 to 10 years. For a reef to maintain the structure needed to support future generations, oysters must grow fast enough and large enough so that their rate of shell production exceeds that of shell degradation.”

The optimal rate of shell addition, says Mann, “occurs with larger, older animals that contribute more shell carbonate per mortality event.” But, he adds, “the onset of disease has unfortunately reduced the life span and maximum size of Bay oysters, thus compromising the shell budget.”

“What’s worrisome about this is that the shell reservoir is getting smaller and smaller,” says Mann. “Could we reach a tipping point where increasing acidity so overwhelms the decreased buffering capacity of dead shells that it then begins to significantly affect live oysters, further limiting their ability to add shell to the alkalinity buffer? If so, we could end up with a negative feedback loop and a worst-case scenario.”

David Malmquist | EurekAlert!
Further information:
http://www.vims.edu
http://www.vims.edu/newsandevents/topstories/oyster_buffer.php

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>