The reproductive cycle, condition index and biochemical composition of the horse-bearded mussel Modiolus barbatus

Abstract

The horse-bearded mussel Modiolus barbatus (Linneus, 1758) is an important edible bivalve in the Adriatic Sea; its population is especially large in the Mali Ston Bay area, where the species is present at depths up to 8 m. In order to assess the sustainable exploitation rate for this species, as well as to estimate its potential capacity for a sustainable aquaculture production, we determined the species' reproductive cycle along with its nutrient storage strategy, employing histological and biochemical methods. The population shows significantly more females than males, and no hermaphrodites. The smallest adult individual, an active male, was 16.0 mm in length, suggesting that sexual maturation starts around this length. While the period between January and February is characterized by sexual repose, early and late stages of gametogenesis were found between March and May, and spawning peaked from June till August. The increase of oocyte diameter followed the same trend. A significant positive correlation was observed between gonad index and temperature, and a negative correlation between gonad index and salinity. Oscillations of stored nutrients were tightly coupled with the gametogenic cycle.

Reproductive cycle of <i>Glycymeris nummaria</i> (Mollusca: Bivalvia) from Mali Ston Bay, Adriatic Sea, Croatia

“…In this study, an exception was a mean condition index value obtained for individuals collected in April, while the highest MGI values for males and females were obtained in June and July, respectively. A similar trend has been observed for Modiolus barbatus (Linnaeus, 1758), with the highest mean monthly condition index being recorded in May and the highest MGI occurring a few months later in August (Mladineo et al 2007). Villalejo-Fuerte et al (1995) noted that variations in G. gigantea condition index seemed to be influenced by gametogenic development, in accordance with our results.…”

Seasonal variation in reproductive activity and biochemical composition of flat oyster (<em>Ostrea edulis</em>) in the Homa Lagoon, Izmir Bay, Turkey

“…However, Mladineo et al (2007) reported that the use of stored protein as an energy source is widely dependant on the availability of the other sources such as carbohydrates and lipids, being lower when these other sources are used at higher levels, and vice versa. According to Whyte et al (1990), protein was more efficient than carbohydrate as the main contributor of energy in lean times and fed the oysters during the winter months, when food was scarce.…”

Field studies and projections of climate change effects on the bearded horse mussel Modiolus barbatus in the Gulf of Thermaikos, Greece

“…As reported above, early and late stages of gametogenesis were found between March and May, and spawning peaked from June until August (Mladineo et al 2007). Reproductive activity of Modiolus barbatus results in the depletion of carbohydrates and lipids such that gametogenesis may rely, for the most part, directly on the energy of ingested food (Mladineo et al 2007). Consequently, M. barbatus has to face both the reduction in food and the gradual elevation of ambient temperature from spring to summer.…”

“…The period between January and February is characterized by sexual repose in Modiolus barbatus. Early and late stages of gametogenesis were found between March and May, and spawning peaked from June until August (Mladineo et al 2007). …”