Reproductive capacity of the eastern oyster Crassostrea virginica infected with the parasite Perkinsus marinus

Abstract

ABSTRACT. We studied the influence of the protozoan parasite P e r h s u s marinus (Mackin. Owen & Collier) on reproduction in the eastern oyster Crassostrea virginica (Gmelin) from 2 sub-estuaries of central Chesapeake Bay, Maryland, in 1990 and 1991 One hypothesis was that increased levels of infection by P marinus cvould result in smaller egg size and diminished lipid reserves within individual eggs. Our results did not reveal any consistent deleterious effects of l? marinus on these gametogenic characteristics, although some of our sample sizes were small and the average disease intensities were low. Our second hypothesis, that there would be a decllne in reproductive output as a result of high levels of P marinus infection, was supported for one estuary when those oysters were near their peak of reproductive condition (July). We found no evidence to support our third hypothesis that there would be a negative influence of infections during the 1990 reproductive season on subsequent reproductive output (summer 1991). Based on published evidence that P marinus can inhibit oyster growth, we speculate that oysters infected at low intensities by P marinus can divert energy from growth to reproduction. This differential energy partitioning allows infected oysters to produce fewer eggs than uninfected oysters but with no change in the amount of lipid reserves stored in each egg.

Non‐indigenous species as stressors in estuarine and marine communities: Assessing invasion impacts and interactions

“…The impacts of introduced pathogens seem to have resulted in significant, widespread, and complex changes throughout the bay. The two protistan pathogens Haplosporidium nelsoni and Perkinsus marinus, classified respectively as a probable and a possible introduction, have been a significant factor in the decline in abundance of the oyster Crassostrea virginica (e.g., Andrews 1979;Kennedy 1996;see Lauckner 1983;Sindermann 1990). In Chesapeake Bay, oyster abundance has declined Ͼ90% in the past century.…”

Impact of Brown Ring Disease on the energy budget of the Manila clam Ruditapes philippinarum

“…The protozoan parasite Perkinsus marinus significantly reduces growth rate, condition index and gametogenesis of its host, Crassostrea virginica (Kennedy et al, 1995;Paytner, 1996;Dittman et al, 2001). A similar pattern has also been shown for Perkinsus olseni in the clam Tapes decussatus (see review in Villalba et al, 2004).…”

Physiological performance of juvenile Haliotis rufescens and Haliotis discus hannai abalone exposed to the withering syndrome agent

“…The rate of food intake (entry of energy into the organism) is one of the most important components of the energy balance, and in this case, its reduction led to a reduction in the proportion of energy available for growth in juveniles by 49% in the most infected individuals, even though the energy losses via metabolism were lower in the latter group. Several studies in marine mollusks have found that infectious diseases can alter the energy balance of the host (Newell, 1985;Barber et al, 1988;Kismohandaka et al, 1993;Kennedy et al, 1995;Villalba et al, 2004;Rosenblum et al, 2005;Flye-Sainte-Marie et al, 2007). The magnitude of these changes and their effects depend on the virulence of the parasite, the extent of disease development, and the resistance of the host.…”

“…These indicators are highly sensitive and allow anticipation of effects on growth, reproduction, and survival. Several studies have reported that the presence of parasites and/or pathogens in marine mollusks alters their energy balance, leading to a diminution or loss of the animal's capacity for growth or reproduction (Barber et al, 1988;Newell, 1985;Kennedy et al, 1995;Flye-Sainte-Marie et al, 2007). While the marked changes provoked by WS may indicate that associated physiological alterations occur in infected organisms, the dynamics of this response during the evolution of infection are not currently understood, especially during its initial phases in which clinical signs are not evident.…”