Real-time PCR investigation of parasite ecology: in situ determination of oyster parasite Perkinsus marinus transmission dynamics in lower Chesapeake Bay

• Published in: Parasitology Vol. 132; no. 6; pp. 827 - 842
• Main Authors: AUDEMARD, C., RAGONE CALVO, L. M., PAYNTER, K. T., REECE, K. S., BURRESON, E. M.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.06.2006
• Subjects: abundance; Animals; Biological and medical sciences; Crassostrea - parasitology; Crassostrea virginica; disease transmission; ecology; environment; Eukaryota - physiology; Fundamental and applied biological sciences. Psychology; General aspects; General aspects and techniques. Study of several systematic groups. Models; Haplosporida - isolation & purification; host-parasite relationships; Incidence; Invertebrates; Investigations; Medical research; Microbiology; Mollusca; mortality; oysters; Parasites; Perkinsus marinus; Polymerase Chain Reaction - veterinary; population density; Prevalence; protozoal infections; real-time PCR; real-time polymerase chain reaction; Regression Analysis; Rivers - parasitology; salinity; Sodium Chloride; Specific Pathogen-Free Organisms; Studies; SYBR Green I; Temperature; Time Factors; transmission dynamics; Virginia; water temperature; waterborne; Chesapeake Bay; Virginia; environment; Crassostrea virginica; waterborne; host-parasite relationships; abundance; real-time PCR; Perkinsus marinus; transmission dynamics; SYBR Green I; Protozoa; Host parasite relation; Apicomplexa; In situ; Transmission; Parasite; Polymerase chain reaction; Bivalvia; Oyster; Environment; Invertebrata; Mollusca
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182006009851

Perkinsus marinus is a severe pathogen of the oyster Crassostrea virginica on the East Coast of the United States. Transmission dynamics of this parasite were investigated in situ for 2 consecutive years (May through October) at 2 lower Chesapeake Bay sites. Compared to previous studies where seasonal infection patterns in oysters were measured, this study also provided parasite water column abundance data measured using real-time PCR. As previously observed, salinity and temperature modulated parasite transmission dynamics. Using regression analysis, parasite prevalence, oyster mortalities and parasite water column abundance were significantly positively related to salinity. Perkinsus marinus weighted prevalence in wild oysters and parasite water column abundance both were significantly related to temperature, but the responses lagged 1 month behind temperature. Parasite water column abundance was the highest during August (up to 1200 cells/l) and was significantly related to P. marinus weighted prevalence in wild oysters, and to wild oyster mortality suggesting that parasites are released in the environment via both moribund and live hosts (i.e. through feces). Incidence was not significantly related to parasite water column abundance, which seems to indicate the absence of a linear relationship or that infection acquisition is controlled by a more complex set of parameters.