Particle Tracking Analysis of Larvae of Land Hermit Crab Coenobita brevimanus in Amitori Bay, Iriomote Island, Japan

Abstract

This study aims at investigating of dynamic states of larvae of land hermit crab Coenobita brevimanus in Amitori Bay, Iriomote Island, Japan from the perspective of numerical analysis. An ecological investigation of Coenobita brevimanus was conducted to provide input data for a numerical model. Reproduction of coastal currents in Amitori Bay was done using a coastal ocean current model CCM. The dynamic states of larvae of Coenobita brevimanus were examined using particle tracking analysis based on the ecological investigation and the current field reproduced by the CCM. Coenobita brevimanus is speculated to employ a strategy to maintain the group of individuals by making most of the larvae stay around the release place.

Seaward migration and larval release of the land hermit crab <i>Coenobita</i> <i>brevimanus</i> Dana, 1852 (Anomura: Coenobitidae) on Iriomote Island, Japan

“…The larvae of C. brevimanus and C. cavipes show smaller growth increments, but size of hatching larvae and pelagic duration of larvae are larger and shorter, respectively, for C. brevimanus, and smaller and longer, respectively, for C. cavipes (Hamasaki et al, 2015b). At the present study site, the numerical simulation using a biophysical model showed that about 10% of the larvae of C. brevimanus were retained near the spawning site after completion of the larval stage (Murakami et al, 2014). C. brevimanus with its shorter pelagic larval period may promote larval retention near the source population and strict constraint of the timing of spawning compared to the export strategy of C. cavipes.…”

“…This species shows a phenology and rhythm of spawning that is common in coenobitids of the Ryukyu Islands (Imafuku, 2001;Nakasone, 2001;Sato & Yoseda, 2008, 2009Doi et al, 2016Doi et al, , 2018a. The results of this study are valuable for understanding the population dynamics and structure as well as promoting conservation and management of the near-threatened C. brevimanus in this area along with previous findings from studies using numerical simulation of larval dispersal (Murakami et al, 2014;Doi et al, 2018b), spatiotemporal patterns of recruitment (Hamasaki et al, 2018) and genetic population network analysis with a sensitive genetic marker (Hamasaki et al, 2015a).…”

“…In the areas around this village, many large-sized C. brevimanus greater than 20 mm in palm width that that were utilize the shells of edible gastropods such as the silvermouthed turban Turbo argyrostomus that were discarded by former residents (Doi et al, 2019). Some individuals of C. brevimanus have been documented to migrate to the beach in front of the village and release larvae, but descriptions of the larval release are brief and cover limited periods of observation Murakami et al, 2014;.…”