Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Disease-Resistant Oysters Call for Shift in Bay Restoration Strategies

29.06.2011
Development of disease resistance among Chesapeake Bay oysters calls for a shift in oyster-restoration strategies within the Bay and its tributaries. That’s according to a new study by researchers at the Virginia Institute of Marine Science (VIMS).

The study, by professors Ryan Carnegie and Eugene Burreson, is the feature article in the most recent issue of Marine Ecology Progress Series. It is based on 50 years of research into the prevalence of MSX disease among the native eastern oyster Crassostrea virginica.

Carnegie, a Research Assistant Professor in the Shellfish Pathology Lab at VIMS, says “Our results point to substantial reproduction by disease-resistant oysters in the high-salinity areas where the parasite causing MSX thrives. We thus argue that reefs in areas of higher salinity should be the focus of conservation and restoration efforts, not just those in disease-free lower salinity areas.”

A histological image of Haplosporidium nelsoni (MSX). The pink refractory bodies are MSX spores in oyster tissues. Image by Dr. Gene Burreson.MSX is caused by the single-celled parasite Haplosporidium nelsoni. It first appeared in Chesapeake Bay in 1959, combining with overharvesting, declines in water quality, and a second parasitic oyster disease known as Dermo to push the Bay’s oyster population to one percent of historical levels. Both MSX and Dermo favor the saltier waters of the Bay’s main stem, decreasing in prevalence as one moves upriver into the fresher waters of Bay tributaries, which form a safe haven from the parasites and diseases.

Restoration strategies
To date, restoration strategies have rested on the idea of protecting these “low-salinity refugia” as sources of larvae for replenishment of disease-ravaged populations in saltier areas of the Bay. These strategies are based on the high levels of mortality traditionally seen among oyster populations in saltier waters (initially more than 90 per cent), and computer models showing that tidal currents can indeed carry oyster larvae downriver from fresher to saltier areas.

Carnegie says “there’s been a lot of attention given to these up-river, low salinity refugia. They’ve been viewed as the key source reefs that are exporting larvae into the higher salinity waters.” Disease-ravaged reefs in higher salinities have been valued primarily for their fishery, which has sought to harvest doomed oysters before they succumbed.

Carnegie and Burreson’s research, however, paints a different picture. They’ve found clear evidence that oysters in the Bay’s saltier waters are developing resistance to both MSX—the focus of their paper—and Dermo, despite the increasing prevalence in the Bay of the parasites responsible for the two diseases. This is only possible through reproduction by resistant oysters in high-disease areas, thus their call for a focusing of restoration efforts onto these disease-resistant areas and populations.

Carnegie says "We basically need to confront the diseases head-on where they are most active, rather than avoiding them by working in low salinities. It’s in the high-disease areas that resistance is developing most rapidly, so restoration efforts should be focused there."

Recent restoration initiatives in Virginia have included the designation of numerous sanctuary reefs in higher salinities and a rotational harvest scheme in the lower Rappahannock River, but these have been controversial. “Harvesters have viewed such efforts with skepticism,” says Carnegie, “because the protected oysters would likely be lost to diseases. Yet our results suggest that strategies like these that increase the number of resistant oysters are precisely the right approach.”

In fact, Carnegie and Burreson point out that restoration efforts focused on low-salinity refugia may actually be counter productive. Carnegie says “our study makes very clear what happens when oyster larvae from the low-salinity refugia settle in high salinity waters—they are removed quickly by the parasites because they are produced by genetically naïve parent oysters that haven’t been selected for disease resistance.” Genetic mingling of these susceptible oysters with their disease-resistant counterparts may be acting to slow the spread of disease resistance through the Chesapeake Bay oyster population.

"Spring Imports” project
Discovery of disease resistance among the Bay’s oysters is based on research that began at VIMS in 1960 with the “Spring Imports” project. Burreson says this long-term study “clearly shows increased resistance to MSX in response to increased disease pressure.” Carnegie adds “decreased disease in the wild despite favorable conditions for the parasites is a clear sign of increasing resistance among our native oysters due to long-term exposure.”

The pair’s research was supported in part by the A. Marshall Acuff, Sr. Memorial Endowment to the VIMS Foundation, which has supported oyster disease research at VIMS for almost 30 years. Carnegie says, “Our team really appreciates the flexibility Acuff support gives our program—the ability to rapidly respond to emerging questions, pursue new directions, and build the foundation for larger, extramurally funded projects.” Acuff support has played a key role in the renewed commitment to native oyster restoration, and has leveraged federal funds and created jobs for Virginia citizens.

David Malmquist | Newswise Science News
Further information:
http://www.vims.edu

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

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: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>