Year-round maturity of the chaetognath Aidanosagitta regularis in the Hauraki Gulf, New Zealand

Abstract

The reproductive biology of planktonic chaetognaths is poorly known, particularly with regard to the importance of seasonal factors such as daylength, temperature and lunar phase. We undertook semilunar plankton sampling (March 2013–March 2014) in the Hauraki Gulf, New Zealand, to survey sexual maturity of the abundant chaetognath Aidanosagitta regularis (the only chaetognath species present in sufficient numbers for reproductive study). Contrary to our expectations, breeding of A. regularis appeared unconstrained by seasonal factors, as reproductively mature individuals were available year-round. This finding has implications for embryological study of the chaetognaths.

The influence of environmental conditions onParasagitta friderici(Chaetognatha) abundance in a subtropical estuary (south Brazil)

“…The few other studied estuarine chaetognaths worldwide up to ~40° of latitude also have similar patterns of high juvenile dominance suggesting year-round reproduction with intermittent peaks, as is the case for tropical populations of Zonosagitta bedoti (Béraneck, 1895), F. enflata and P. tenuis (Srinivasan, 1980; Nair & Sankarankutty, 1988; Ramaiah & Nair, 1993), subtropical Ferosagitta hispida (Conant, 1895) (Reeve, 1964) and temperate Aidanosagitta regularis (Aida, 1897) (36°S; Webb & Sewell, 2015). Populations from colder regions such as Parasagitta setosa (J. Müller, 1847) from Black Sea (Besiktepe & Unsal, 2000), Parasagitta elegans (Verril, 1873) from Charente estuary, France (Modéran et al ., 2010) and P. tenuis and F. hispida from Chesapeake Bay, USA (Grant, 1977) tend to have marked seasonal cycles typically with abundance peaks and high dominance of juveniles mostly during summer, or occasionally winter such as P. elegans from Chesapeake Bay (Grant, 1977).…”