Comparison of Alteration in growth, Maturity and Spawning Ecology of Patella-gastropod, Cellana karachiensis (Winkworth, 1930) Deduced from Macro and Microscopic Techniques
Fatima Hayat Shaheen Zafar
Zarrien Ayub
Sher Khan Panhwar
In the present study sex-ratio, gonadal maturation and temporal variation in the reproductive pattern of the limpet Cellana karachiensis was determined by the histological examination of the gonads. The specimens of Cellana karachiensis were collected from two rocky shores of Buleji and Paradise Point, located at the distance of 50km in the northwest of Karachi, Pakistan. Some 721 handpicked specimens were sampled from November 2007 to April 2009. The maximum total length of C. karachiensis was measured 50 mm and 40 mm at Buleji and Paradise Point respectively. This size variation might be due to adequate food-availability or space. Sex ratios at both sampling locations were male biased. The size-class distribution analysis showed that males and females in this species were equally represented in all the size-classes, which indicated that this species probably does not change sex. It was further validated by the histological study of gonad that no hermaphrodites were observed. The seawater temperature at both sites was low (average 23° C) in winter (northeast monsoon) with sudden rise of 5° C in spring inter-monsoon (average 28 °C) which remained high throughout the summer (south west monsoon). The highest gonado sometic index GSI = 18.1, 18.6 mean values calculated for males and 15.8, 16.3 for females at Buleji and Paradise Point during summer (south west monsoon) respectively. Three developmental stages of developing, ripe and spawning with no spent condition were deduced from microscopic gonad characteristics. The study showed an extended pattern of reproductive cycle with multiple spawning episodes and no resting stage in C. karachiensis. Although spawning in patella-gastropod occurred throughout the year but it was more intensified owing to the northeast monsoon characterized by low temperatures. It is hoped that this first-time study would provide underline information about an important gastropod species.
Keywords: Gonads annual, Development, Varying growth, Buleji and Paradise point, Patella-gastropod
