Reproductive biology of the ascidians Styela rustica and Halocynthia pyriformis from Kongsfjorden, Svalbard, Arctic

LUCIANA FERRERO; NATALIA SERVETTO; JURGEN LAUDIEN; RICARDO SAHADE

POLAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2019

0722-4060

Ascidians are abundant and well represented members of worldwide benthic communities including Antarctica and the Arctic. These organisms exhibit different reproductive patterns usually related to a latitudinal gradient, as do many marine invertebrate species. Reproductive seasonality varies between one and two annual peaks in species of cold and temperate water, to a continuously reproduction throughout the year in warm water species. Styela rustica (Linnaeus, 1767) and Halocynthia pyriformis (Rathke, 1806) are solitary species with external fertilization and a wide distribution range, from the North Atlantic to the Arctic. Reproductive patterns of these two species were assessed for Arctic populations by a year-round sampling and structural analysis of the gonads. Both species are hermaphrodites and showed a marked seasonality in oocytes maturity and spawning;, S. rustica peaked during the boreal summer and H. pyriformis in late spring. These two species also showed marked differences in mature oocytes sizes: H. pyriformis almost doubled those of S. rustica and while spermatocytes of H pyriformis were mature year-round, maturity of male and female gametes were synchronized in S. rustica. Therefore, these two species showed an annual reproductive cycle coupled with a higher production period in the ecosystem but also exhibited different strategies developed under the same environmental pressures.