Reproductive Cycle of Sulf clam, Coecella chinensis (Mesodesmatidae: Bivalvia)

Abstract

The reproductive cycle, gonad index, condition index, and the sex ratio in female and male Coecella chinensis, which were collected from the coastal waters of Namhae, the South Coast of Korea, were investigated by histological analysis and morphometric data. Monthly variations of the gonad index and condition index of this species showed similar patterns to that of the reproductive cycle. The reproductive cycle in female and male C. chinensis can be classified into six successive stages: early active stage (April), late active stage (May), ripe stage (June), partially spawned/spent stage (June to August), degeneration stage (August) and inactive stage (September to March). According to monthly changes in relative frequency distributions of ovarian egg diameters of this species, in particular, a number of ripe eggs ranging about 70 µm appear in June, however, in July and August, although the mode of egg diameters ranging about 50 µm appear about 80%, these ripe eggs ranging from 60 µm to 70 µm are gradually decreased during the period from June to August. Therefore, the spawning period of this species is continued from June to August with a peak between July and August when the seawater temperature exceeds about 24.5°C. The sex ratio of female and male individuals was not significantly different from 1:1 (χ 2 = 1.20, p > 0.05). No hermaphrodites were found.

Spatial variation in reproduction in southern populations of the New Zealand bivalvePaphies ventricosa(Veneroida: Mesodesmatidae)

“…Of interest in this study is the family Mesodesmatidae (Bivalvia: Veneroida), in which the reproduction has been described in a small number of species including the Australian Donacilla cuneata (Roberts 1984), Asian Coecella chinensis (Kim et al 2013), the South American Mesodesma donacium (Peredo et al 1987;Riascos et al 2009;Uribe et al 2012) and Mesodesma mactroides (Herrmann et al 2009), and the tropical species Atactodea striata (Baron 1992). Reproduction in New Zealand mesodematids, all in the genus Paphies, has been described for P. ventricosa (Redfearn 1974), P. australis (Hooker & Creese 1995), Paphies donacina (Marsden 1999) and Paphies subtriangulata (Grant & Creese 1995).…”

Oogenesis and Oocyte Degeneration in Coecella chinensis (Bivalvia: Mesodesmatidae)

“…In Korea, this species is found mainly in silty sand at the intertidal zone in the coastal waters of Namhae, Jollanam-do, Korea (Kwon et al, 1993;Min et al, 2004). Due to past reclamation project in the south coast of Korea, it has been identified as an environmental resource that should be gametogenesis and sexual maturation (Chung et al, 1987;Chung and Ryou, 2000;Kim et al, 2013), distribution (Kwon et al, 1993).…”

“…To date, regarding C. chinensis, several studies have been conducted on aspects of reproductive ecology, including artificial discharge of reproductive substance (Iwata, 1948), propagation (Kim et al, 2013), reproductive cycle (Kim et al, 2013).…”