Reproductive biology of the invasive reef-forming serpulid, Ficopomatus enigmaticus, in the Mar Chiquita coastal lagoon, Argentina

Summary

The reef-forming serpulid polychaete, Ficopomatus enigmaticus, probably invaded Mar Chiquita coastal lagoon (Argentina) during the 1950s, dramatically modifying this estuarine environment. Its reproductive biology was studied through periodical sampling, and optical and electron microscopy. Specific aspects investigated include the morphology and distribution of gametes, gametogenesis, sexual maturation and mode of spawning. Both males and females lack true gonads; ovaries and testes are masses of germ cells and gametes develop from proliferative zones associated with the septa of abdominal segments. Oogenesis seems to be extraovarian. Mature gametes are liberated through paired gonoducts present in abdominal segments, opposite to proliferative zones. The proportion of individuals engaged in gametogenesis and with mature gametes, respectively, was always higher for males than for females. No hermaphrodite individuals were observed. Although this population appears to be gonochoristic, a male-biased sex ratio and the comparatively large mean size of mature females suggest the possibility of sequential protandric hermaphroditism. Females reach sexual maturity in four months, producing three generations of oocytes per year. Spermatogenesis seems to be continuous and faster than oogenesis, as observed in other polychaetes.

Key words:

• Reef-forming polychaetes
• reproduction
• coastal lagoon