Luminous capabilities and life-history traits of the polychromatic ophiuroid Amphipholis squamata in two isolated populations from Oliveri-Tindari lagoon system, Sicily

Amphipholis squamata is a small ophiuroid with a worldwide distribution except for Polar regions. Global populations of A. squamata! are morphologically uniform but inter- and intrapopulational variability occurs at levels from the population to the genotype. The species is polychromatic and two colour varieties (dark-brown and spotted) from two adjacent populations (separated from each other for only 20 years) in a lagoonal system (Sicily) were compared using bioluminescence and life-history traits as indicators of variability. The dark-brown variety was dominant in Lago Nuovo and the spotted one was dominant in Porto Vecchio. Important variations were observed within populations, however, there were significant differences in life-history traits and luminous capabilities between the dark-brown and spotted varieties. The dark-brown variety invested more energy in somatic growth than reproduction (1 cohort each year and growth rate of 0.279 mm each month). whereas energy was devoted mainly to reproduction in the spotted variety (4 cohorts each year and growth rate of 0.171 mm each month). The chronology of the life cycles was completely different between the two varieties. Fertilization occurred mainly in spring for the spotted but only in autumn for the dark-brown. Recruitment occurred mainly in autumn for spotted and in spring for dark-brown individuals. Finally, significant differences were observed for maximal intensity of emitted light and kinetic parameters between the two varieties.