SYMBIOSES IN AMPHIPHOLIS-SQUAMATA (ECHINODERMATA, OPHIUROIDEA, AMPHIURIDAE) - GEOGRAPHICAL VARIATION OF INFESTATION AND EFFECT OF SYMBIONTSON THE HOSTS LIGHT PRODUCTION

Populations of the polychromatic and bioluminescent species Amphipholi s squamata from eight locations were examined for internal and externa l symbionts. Al three locations (two in the United Kingdom and one in Papua New Guinea), no symbionts were present, while four species were recovered from the remaining locations: Cancerilla tubulata and Parach ordeumium amphiurae (copepods), Rhopalura ophiocomae (orthonectid) and an undescribed species of rhabdocoel turbellarian. No ophiuroid indiv idual hosted more than one symbiont species, despite the presence of t wo or more within a population. Symbiont presence and prevalence varie d with location, and with colour variety, but with no apparent pattern or trends. Light-production characteristics of the host were affected by the presence of all symbionts except C. tubulata. These effects, h owever, did not vary between colour varieties or between geographical locations, but were specific to the symbiont species the presence of P . amphiurae resulted in enhanced intensity of light production, while that of R. ophiocomae and the turbellarian species resulted in reduced intensity. The kinetics of light production (time until maximum outpu t) were altered only by the presence of the turbellarian. Changes in t he light-production characteristics are discussed in relation to morph ological, energetical and physiological effects of the symbioses. (C) 1998 Australian Society for Parasitology. Published by Elsevier Scienc e Ltd. All rights reserved.