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Gametogenic cycle of Crassostrea gigas in contrasting Mediterranean habitats: marine (Gulf of Tunis) and continental (Bizert lagoon) culture sites.

Dridi S, Romdhane MS, Elcafsi M - J Biol Res (Thessalon) (2014)

Bottom Line: The applied techniques gave similar results.The obtained results are probably related with the different environmental conditions of the studied habitats, temperature and food supply, in particular.The sexual cycle of the species was successfully completed in the marine area, stressing the invasive character of C. gigas.

View Article: PubMed Central - PubMed

Affiliation: Institut Supérieur de Pêche et d'Aquaculture de Bizerte, ISPA -BP 15, ERRIMEL, 7080 Bizerte, Tunisia.

ABSTRACT

Background: The gametogenic cycle of Crassostrea gigas, a species imported into the Mediterranean for aquaculture, has been studied (May 2005 to July 2006) in two contrasting habitats of Tunisia: the Bizert lagoon, where oyster farms have been developed since 1970, and the Gulf of Tunis, where oysters have been experimentally farmed during this study, to assess the potential of this latter marine area for sustaining oyster-culture.

Results: The sexual cycle of the species was described through the histological examination of the gonads, the estimation of oocytes diameter, and the assessment of its condition and gonadal condition indices. The applied techniques gave similar results. The gametogenic cycle of C. gigas was precocious and more intense in oysters farmed within the lagoon than in the marine area, considering as well gonadal growth, maturation stages and gametes release.

Conclusions: The obtained results are probably related with the different environmental conditions of the studied habitats, temperature and food supply, in particular. The sexual cycle of the species was successfully completed in the marine area, stressing the invasive character of C. gigas.

No MeSH data available.


Variation of gonadic stages (%) ofCrassostrea gigasin (A) Port aux Princes (PP) and in (B) Ferme Marine de Bizerte (FMB). Stages: 0- Undifferentiated gonads, I- Early gametogenesis, II- Gametogenesis, IIIA- Intensive gametogenic activity, IIIB- Gonadal maturation and IIID- Spent gonads.
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Fig2: Variation of gonadic stages (%) ofCrassostrea gigasin (A) Port aux Princes (PP) and in (B) Ferme Marine de Bizerte (FMB). Stages: 0- Undifferentiated gonads, I- Early gametogenesis, II- Gametogenesis, IIIA- Intensive gametogenic activity, IIIB- Gonadal maturation and IIID- Spent gonads.

Mentions: The six stages of gonadal development previously described for the species were detected at both stations. Their distribution in PP and FMB oyster populations showed rather similar temporal trends (Figure 2A & B), but with some differences related either to the month in which a stage started or ended, or to the percentage contribution of individuals per stage. The following pattern can be generally described for the studied oyster populations. Crassostrea gigas was at sexual resting (stage 0, undifferentiated gonads) from September to March at both stations; early gametogenesis (stage I) started earlier in FMB (December) but ended later in PP (April) lasting about three to four months. Gametogenesis (stage II), characterized by the rising number of spermatogonia against the wall of acinus in male and by the accumulation of vitells in the oocyte cytoplasm (previtellogenic oocytes) in females, expands from March to April (FMB) or May (PP). Intense gametogenic activity (stage IIIA) marked by the coexistence of spermatogonia, spermatocytes I and II and spermatides in the follicle of males, and of previtellogenic oocytes, adhering oocyte and peduncular oocytes (mature) in females, was observed from May 2005 to August 2005 and from April 2006 to June 2006, at both PP and FMB. The subsequent stage (stage IIIB) of gonadal maturation (homogenous aspect of gonads after the disappearance of spermatides running toward the center of the follicle in males, presence of numerous peduncular oocytes separated from the follicle lumen or going to be separated in females) was observed from April/May to July/August, whereas spent gonads (ruptured follicles, residual gametes, reappearance of connective tissues between the follicles and haemocytes invading gonadal tubules) were present from June (FMB) or July (PP) to September or October (FMB).Figure 2


Gametogenic cycle of Crassostrea gigas in contrasting Mediterranean habitats: marine (Gulf of Tunis) and continental (Bizert lagoon) culture sites.

Dridi S, Romdhane MS, Elcafsi M - J Biol Res (Thessalon) (2014)

Variation of gonadic stages (%) ofCrassostrea gigasin (A) Port aux Princes (PP) and in (B) Ferme Marine de Bizerte (FMB). Stages: 0- Undifferentiated gonads, I- Early gametogenesis, II- Gametogenesis, IIIA- Intensive gametogenic activity, IIIB- Gonadal maturation and IIID- Spent gonads.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4390001&req=5

Fig2: Variation of gonadic stages (%) ofCrassostrea gigasin (A) Port aux Princes (PP) and in (B) Ferme Marine de Bizerte (FMB). Stages: 0- Undifferentiated gonads, I- Early gametogenesis, II- Gametogenesis, IIIA- Intensive gametogenic activity, IIIB- Gonadal maturation and IIID- Spent gonads.
Mentions: The six stages of gonadal development previously described for the species were detected at both stations. Their distribution in PP and FMB oyster populations showed rather similar temporal trends (Figure 2A & B), but with some differences related either to the month in which a stage started or ended, or to the percentage contribution of individuals per stage. The following pattern can be generally described for the studied oyster populations. Crassostrea gigas was at sexual resting (stage 0, undifferentiated gonads) from September to March at both stations; early gametogenesis (stage I) started earlier in FMB (December) but ended later in PP (April) lasting about three to four months. Gametogenesis (stage II), characterized by the rising number of spermatogonia against the wall of acinus in male and by the accumulation of vitells in the oocyte cytoplasm (previtellogenic oocytes) in females, expands from March to April (FMB) or May (PP). Intense gametogenic activity (stage IIIA) marked by the coexistence of spermatogonia, spermatocytes I and II and spermatides in the follicle of males, and of previtellogenic oocytes, adhering oocyte and peduncular oocytes (mature) in females, was observed from May 2005 to August 2005 and from April 2006 to June 2006, at both PP and FMB. The subsequent stage (stage IIIB) of gonadal maturation (homogenous aspect of gonads after the disappearance of spermatides running toward the center of the follicle in males, presence of numerous peduncular oocytes separated from the follicle lumen or going to be separated in females) was observed from April/May to July/August, whereas spent gonads (ruptured follicles, residual gametes, reappearance of connective tissues between the follicles and haemocytes invading gonadal tubules) were present from June (FMB) or July (PP) to September or October (FMB).Figure 2

Bottom Line: The applied techniques gave similar results.The obtained results are probably related with the different environmental conditions of the studied habitats, temperature and food supply, in particular.The sexual cycle of the species was successfully completed in the marine area, stressing the invasive character of C. gigas.

View Article: PubMed Central - PubMed

Affiliation: Institut Supérieur de Pêche et d'Aquaculture de Bizerte, ISPA -BP 15, ERRIMEL, 7080 Bizerte, Tunisia.

ABSTRACT

Background: The gametogenic cycle of Crassostrea gigas, a species imported into the Mediterranean for aquaculture, has been studied (May 2005 to July 2006) in two contrasting habitats of Tunisia: the Bizert lagoon, where oyster farms have been developed since 1970, and the Gulf of Tunis, where oysters have been experimentally farmed during this study, to assess the potential of this latter marine area for sustaining oyster-culture.

Results: The sexual cycle of the species was described through the histological examination of the gonads, the estimation of oocytes diameter, and the assessment of its condition and gonadal condition indices. The applied techniques gave similar results. The gametogenic cycle of C. gigas was precocious and more intense in oysters farmed within the lagoon than in the marine area, considering as well gonadal growth, maturation stages and gametes release.

Conclusions: The obtained results are probably related with the different environmental conditions of the studied habitats, temperature and food supply, in particular. The sexual cycle of the species was successfully completed in the marine area, stressing the invasive character of C. gigas.

No MeSH data available.