Three surveys were conducted at low tide in the intertidal Tridacna gigas nursery at
Pioneer Bay, Orpheus Island, Great Barrier Reef (see Crawford et al., 19&S>, during
September-October 1989. More than 100 clams were carefully examined for the
presence and number of Turbonilla sp. during each survey. Clam shell lengths were also
measured during the first survey to determine if pyramidellid infestations were related to
clam size.
Throughout this paper all size measurements of clams are maximum shell length
unless otherwise indicated.