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 Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

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: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>