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Oyster Diseases In Chesapeake Bay
| Content Provider | Semantic Scholar |
|---|---|
| Author | Andrews, Jay D. |
| Copyright Year | 1979 |
| Abstract | Three major diseases of oysters have been monitored in Virginia estuaries for 2-3 decades. Dermocystidium marinum, causing a warm-season wasting disease, was discovered in Virginia in 1950 and continues actively to kill oysters where beds or populations are found in highsalinity waters (>15%0). This disease spreads by close proximity ofdying oysters to other oysters, hence each isolated bed must be sampled in early fall annually to document activity of the pathogen. Control involves avoiding infected seed oysters, cleaning beds of all oysters after harvest, and isolation of new beds. A new pathogen, Minchinia nelsoni (MSX), caused catastrophic oyster mortalities in 1959-60, and oyster planting ceased thereafter in a large area of highsalinity (>15%o) waters in lower Chesapeake Bay. A third pathogen, Minchinia costalis (Sea Side Organism or SSO), was found almost simultaneously on Seaside of Virginia in high-salinity waters ( >30 %o). January-February 1979 ported Jots of disease-free oysters in legged trays on natural oyster beds. Disease-free oysters were obtained from low-salinity waters « 15 %0) in the James River seed area of Virginia. Legged trays lined with I-inch mesh hardware netting prevented smothering and predation which were the major interfering problems on natural bottoms. In 1959, a disease caused by Minchinia costalis, a pathogen closely related to M. nelsoni, was discovered on Seaside of Eastern Shore, Virginia, in high-salinity waters (Andrews et aI., 1962). This disease has a well-defined seasonal pattern of activity, and the J. D. Andrews is with the Virginia Institute of Marine Science and School of Marine Science, The College of William and Mary, Gloucester Point, VA 23062. This paper is Contribution No. 898 of the Virginia Institute of Marine Science. Both these haplosporidan parasites kill native susceptible oysters at rates of 20-50 percent annually. Strains resistant to MSX were selected from survivors by laboratory breeding. SSO appears to be an endemic pathogen that causes confined periods ofinfection and mortality. Sporulation and infection occur regularly each May-June associated with oyster deaths. A long incubation period of8 months with hidden or subclinical infections characterizes the disease. SSO is confined to high-salinity waters along the seacoast from Cape Henry to Long Island Sound. MSX is a highly infectious pathogen that appears to be new by importation or advent ofa virulent strain. Infections occur during 5 warm months (June-October) and deaths occur throughout the year. Direct transmission has not been achieved in the laboratory for either haplosporidan. Transmission of the diseases and life cycles are still important objectives after 18 years of studies. pathogen achieves sporulation regularly in May-June each year (Andrews and Castagna, 1978). The life cycles of these two haplosporidans are obscure, and artificial infections have not been achieved. A comparison of epizootiological traits is made for clues to sources of infection which are a persistent mystery. Hypotheses on timing of activities and infective sources are derived from these comparisons. Studies of the two diseases in Chincoteague Bay were made by Couch and |
| Starting Page | 45 |
| Ending Page | 45 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| Volume Number | 41 |
| Alternate Webpage(s) | https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=2245&context=vimsarticles |
| Alternate Webpage(s) | https://spo.nmfs.noaa.gov/mfr411-2/mfr411-29.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
