Effect of temperature on the duration of reproductive cycles of female Caprella mutica (Crustacea: Amphipoda) in the laboratory

Abstract

To quantitatively assess the fecundity of female Caprella mutica (Crustacea: Amphipoda), an invasive caprellid species in numerous regions of the world, I reared pairs of adult C. mutica under four different temperature regimes (5, 10, 15 and 208C) and measured the moulting interval, oviposition interval, oviposition-hatch period, and oviposition-juvenile emergence period. Concurrently, I examined changes in the number of eggs per oviposition and hatching success at the different temperatures, and clarified the timing of events from oviposition to juvenile emergence at all temperatures. The findings showed that this species reproduces at temperatures ranging from 5 to 208C. Moulting interval was closely correlated with oviposition interval, becoming longer at lower temperatures. Similarly, the mean oviposition-juvenile emergence period was also longer at lower temperatures. Eggs developed normally at 15 and 208C but showed decreased viability at 5 or 108C. The number of eggs produced per oviposition did not vary with rearing temperature. These findings indicated that reproduction in female C. mutica in the field was frequent with short intervals between oviposition events when temperatures exceeded 158C. Conversely, at temperatures below 108C, reproduction was less frequent, resulting in markedly reduced reproductive rate and an increased probability of unusual egg development.

Association of <i>Caprella</i> <i>fimbrillata</i> Vassilenko, 1993 (Crustacea: Malacostraca: Amphipoda) with the deep-sea holothurian <i>Scotoplanes globosa</i> (Théel, 1879) in the bathyal zone off Tohoku District, northern Japan

“…The mean fecundity of Caprella spp. during one spawning event has been reported as less than approximately 100 (Takeuchi & Hirano 1992b, Aoki 1997, Hosono 2009, Nuñez Valazques et al 2017. The number of embryos per female of C. mutica Shurin, 1935 in a 9.96 (maximumminimum: 7.02-12.56) mm BL has been reported as 35.6 (maximum-minimum: 3-140) (Hosono 2009).…”

“…during one spawning event has been reported as less than approximately 100 (Takeuchi & Hirano 1992b, Aoki 1997, Hosono 2009, Nuñez Valazques et al 2017. The number of embryos per female of C. mutica Shurin, 1935 in a 9.96 (maximumminimum: 7.02-12.56) mm BL has been reported as 35.6 (maximum-minimum: 3-140) (Hosono 2009). The number of juveniles attached to maternal females of C. monoceros Mayer, 1890 of 12.1 to 15.3 mm BL has been recorded as 53 to 103 (Aoki 1997).…”