Infection dynamics of Marteilia refringens in flat oyster Ostrea edulis and copepod Paracartia grani in a claire pond of Marennes-Oléron Bay.
The protozoan parasite Marteilia refringens has been partly responsible for the severe decrease in the production of the European flat oyster Ostrea edulis Linnaeus in France since the 1970s. The calanoid copepod Paracartia grani Sars was recently found to be a host for M. refringens in French shallow-water oyster ponds ('claires'). This study reconsidered M. refringens transmission dynamics in the light of this finding, taking into account not only oyster infection dynamics and environmental factors but also data concerning the copepod host. P. grani population dynamics in the claire under study revealed that this species is the dominant planktonic copepod in this confined ecosystem. During winter, M. refringens overwintered in O. edulis, with P. grani existing only as resting eggs in the sediment. The increase in temperature in spring controlled and synchronized both the release of M. refringens sporangia in the oyster feces, and the hatching of the benthic resting eggs of the copepod. Infection of oysters by M. refringens was limited to June, July and August, coinciding with (1) the highest temperature recorded in the claire, and (2) the highest abundance of P. grani. PCR detection of M. refringens in P. grani during the summer period was linked to the release of parasite sporangia by the oyster. Our results are supported by previous results on the effective transmission of this parasite from the oyster to the copepod.
Audemard
Corinne
C
Laboratoire Génétique et Pathologie, IFREMER, BP 133, 17390 La Tremblade, France. audemard@vims.edu
Sajus
Marie-Céline
MC
Barnaud
Antoine
A
Sautour
Benoit
B
Sauriau
Pierre-Guy
PG
Berthe
Frank J C
FJ
D000818:Animals; D017756:Aquaculture; D033342:Copepoda / Q000469:parasitology*; D017753:Ecosystem; D056890:Eukaryota / Q000235:genetics / Q000502:physiology*; D005602:France; D006790:Host-Parasite Interactions; D010125:Ostreidae / Q000469:parasitology*; D011157:Population Dynamics; D012621:Seasons; D012623:Seawater; D013696:Temperature