Variation in biochemical composition during gonad maturation of the tropical abaloneHaliotis variaLinnaeus 1758 (Vetigastropoda: Haliotidae)

Abstract

Biochemical changes in the body components during gonad maturation of the tropical abalone Haliotis varia were investigated using wild collected specimens from the Gulf of Mannar, on the southeast coast of India. The gonadosomatic index (GSI) and the hepatosomatic index (HSI) showed negative correlations throughout the study period as well as during the progression of gonad maturation stages. The highest GSI for both the sexes were in the ripe stages followed by late maturing stages. The HSI ranged from 2.97 to 6.71 in females, and 3.55 to 5.09 in males. Among the biochemical components analysed, lipid and carbohydrate contents showed significant variations in the different tissues of H. varia during the progress of gonad maturation. The highest protein content was in the foot muscle and the lowest was in the digestive gland. Total lipids in the ovary were always higher compared with that of the testis and the values ranged from 12.60 to 26.49%, registering the highest value in the ripe ovary. Gonad carbohydrate content was lower when the lipid content was higher, suggesting the conversion of carbohydrate to lipids. The present study demonstrates the role of nutrient translocation between body parts as an essential part of the reproductive physiology of abalone.

Reproductive cycle and biochemical composition of Hexaplex trunculus (Gastropoda: Muricidae) from Bizerte lagoon, northern Tunisia

“…Confirming the key role of the reproductive tissues in energetic storage, the oscillations in the contents of proteins, lipids and carbohydrates were correlated with seasonal variations in the GSI, and consequently with the processes of gonad maturation and spawning. A similar interpretation has been made for H. trunculus (Vasconcelos et al 2009) and for other gastropod species, such as Buccinum undatum (Brokordt et al 2003), Haliotis varia (Najmudeen 2007), Patella depressa (Morais et al 2003), Stramonita haemastoma (Belisle & Stickle 1978), Turbo brunneus (Ramesh & Ravichandran 2008) and Turbo sarmaticus (McLachlan & Lombard 1980).…”

“…Interestingly, the monthly variation in the foot protein content of H. trunculus showed an evident decrease immediately before the spawning peak (March to April), which might suggest a possible mobilisation of protein reserves to support the reproductive effort. However, the irregular trend in the foot protein content of Haliotis varia was attributed to its involvement in growth and metabolism rather than in reproduction (Najmudeen 2007).…”

Ultrastructural studies of oogenesis in the variable abalone Haliotis varia (Vetigastropoda: Haliotidae)

“…As in other gastropods, yolk synthesis in H. varia involves the direct incorporation of extraoocytic precursors from the neighboring tissues to the intra-cellularly synthesized yolk vesicles. There was a significant negative correlation between biochemical composition of the digestive gland and ovary, especially lipids and carbohydrates, in connection with the maturation process in H. varia, indicating the transfer of these biochemical components from the digestive gland to the ovary (Najmudeen 2007a). …”

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“…Reproductive indices.-Reproductive indices provide indirect information that allows to evaluate the reproductive condition, and are commonly used as tools to evaluate gonadal development and determine the timing of reproductive activity (Boolootian et al, 1962;Litaay and De Silva, 2002;Morais et al, 2003;Najmudeen and Victor, 2004;Najmudeen, 2007;Abidli et al, 2012;Elhasni et al, 2013). Usually, a drastic decrease in a reproductive index is interpreted as spawning occurrence (Boolotian et al, 1962).…”

“…In this sense, if IG and MGI are calculated using the weight of the HGGC, the hepatic gland mask the gonad status outside spawning season. The GAIA also can mask the gonad development signal (underestimation) due to fattening of hepatic gland (Najmudeen, 2007) or when the gonad area remains unchanged because the trabeculae do not shrink after gametes are released (overestimation) (Ault, 1985). But in this case, the increasing trend of GAIA suggests gonads development prior to spawning season in autumn-winter, as well as the GIB.…”