Epigrapsus notatus (Liu and Jeng, 2005)

Chang, Chung-Chieh, Hatch, Kent A., Hsu, Chia-Hsuan, Hwang, Wenbe, Liu, Hung-Chang & Chang, Yuan-Mou, 2023, Tripedalia maipoensis Sun & Tsui & Wong & Cheung & Ng & Or & Qiu 2023, sp. nov., Zoological Studies 62 (22), pp. 1-14 : 7

E. notatus

A total of 107 and 207 ovigerous female E. notatus were observed migrating to the sea in 2020 and 2021, respectively ( Fig. 3 ). The majority of the migration occurred at the onset of the dry season with a major movement of ovigerous females in late September and late October, but a minor movement in late November ( Fig. 3 ).

The migration exhibited a lunar rhythm. The peak migration occurred about 20 days after the new moon (20.5 ± 1.3 days in 2020; 20.0 ± 1.3 days in 2021) during the intermediate amplitude diurnal/nocturnal high tides ( Table 1; Fig. 3A, 3B ) and lasted for about one week. Based on the data collected in 2021, about one and a half times as many females migrated in late September (n = 124) than in October (n = 80) ( Fig. 3B ). The daily number of seaward migrating females varied with the lunar age. The highest number of daily migrating females was 27 and 39 crabs occurring on 7 October 2020 and 26 September 2021, respectively ( Fig. 3A, 3B ).

Timing of larval release

Figures

Fig. 3. Temporal pattern of migrating ovigerous female Epigrapsus notatus recorded on the embankment flood control road of Chengxi windbreaks between September and November in 2020 (A) and 2021 (B). Solid lines (─) and dash lines (---) represent nocturnal (1800-0559H) and diurnal (0600-1759H) high tides, respectively. The breaks in the lines indicate a lack of data on tidal height for the observation days. Closed and open circles represent new and full moons, respectively.