Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Impact of Perkinsus sp. on Manila clam Ruditapes philippinarum beds.

Abstract

The relationship between Perkinsus sp. and the growth and survival of Manila clams (Ruditapes philippinarum) was investigated over a 2-year period. In June 1993, 3 million Manila clams were sown in 3 sets: A, B and P at a mean weight of 0.65, 0.66 and 0.79 g/clam, respectively. The sets were planted in sand-gravel, intertidal beds of the Eo estuary (Asturias, northern Spain). Bi- or trimonthly clam samples were collected between June 1993 and August 1995. In January 1994, Perkinsus sp. was detected in set P. The growth rates of unparasitized clams in sets A and B were similar to the growth rates of infected clams in set P. This was probably due to the low prevalence of Perkinsus sp. (which ranged from 2 to 9%), which in turn, may have been due to the fact that water temperature remained below 20°C. It is suggested that, in most cases, clam mortality associated with Perkinsus sp. may be minimized with adequate management of clam beds. Additionally, 2 prophylactic measures are recommended: the removal of sets with parasitized clams and the introduction of unparasitized seed in clam culture areas.