Featured Research

from universities, journals, and other organizations

Disease-resistant oysters call for shift in Chesapeake Bay restoration strategies, experts say

Date:
June 27, 2011
Source:
Virginia Institute of Marine Science
Summary:
The development of disease resistance among Chesapeake Bay oysters calls for a shift in oyster-restoration strategies within the Bay and its tributaries, say experts.

Professor Ryan Carnegie and marine scientist Nancy Stokes sort oysters at Aberdeen Rock on the York River in spring 2011.
Credit: Photo by Rita Crockett/VIMS.

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.

Related Articles


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."

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 naοve 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.


Story Source:

The above story is based on materials provided by Virginia Institute of Marine Science. The original article was written by David Malmquist. Note: Materials may be edited for content and length.


Journal Reference:

  1. RB Carnegie, EM Burreson. Declining impact of an introduced pathogen: Haplosporidium nelsoni in the oyster Crassostrea virginica in Chesapeake Bay. Marine Ecology Progress Series, 2011; DOI: 10.3354/meps09221

Cite This Page:

Virginia Institute of Marine Science. "Disease-resistant oysters call for shift in Chesapeake Bay restoration strategies, experts say." ScienceDaily. ScienceDaily, 27 June 2011. <www.sciencedaily.com/releases/2011/06/110627123027.htm>.
Virginia Institute of Marine Science. (2011, June 27). Disease-resistant oysters call for shift in Chesapeake Bay restoration strategies, experts say. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2011/06/110627123027.htm
Virginia Institute of Marine Science. "Disease-resistant oysters call for shift in Chesapeake Bay restoration strategies, experts say." ScienceDaily. www.sciencedaily.com/releases/2011/06/110627123027.htm (accessed October 25, 2014).

Share This



More Plants & Animals News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) — Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) — Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) — One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) — Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins