Biologi reproduksi spesies timun laut stichopus quadrifasciatus massin, 1999 (aspidochirotida: stichopodidae) dl perairan Pulau Songsong, Kedah Darul Aman

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Date
2005
Authors
Vee Kwang, Sim
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Abstract
Stichopus quadrifasciatus Massin, 1999 is a nocturnal sea cucumber species that inhabits shallow water areas. The reproduction of S. quadrifasciatus in Pulau Songsong was investigated over a 1 %-year period from May 2002 to September 2003 by using the examination of macroscopic and microscopic appearances of gonad tubules, the monthly observations in the changing patterns of oocytes, the Gonad Index (GI) method, the Individual Weighted Maturity Index (IWMI) method, and the histological examination of gametogenesis. Physical and chemical parameters of sea water around the sampling site were obtained each month during the sampling of sea cucumber to determine the effects of exogenous environmental factors on the reproductive cycle of S. quadrifasciatus. The S. quadrifasciatus collected showed that the number of males and females were the same, indicating a balanced sex ratio of 1 : 1. The one-way ANOVA test conducted revealed that the monthly changing patterns in the number and length of gonad tubules were significant during the duration of the study (P < 0.05). New tubules appeared in June 2002 and May 2003, growing in size and in their extent of branching until finally reaching their maximum size and maturity in November 2002 and August 2003. Spawning occurred from December 2002 to May 2003, with the majority of the gametes released during March 2003. A four-stage gonad maturity scale based on the macroscopic appearance of the gonad tubules corresponded with the discrete stages of gametogenesis identified using histological methods. Gametogenesis was initiated in June 2002 and June 2003, with both oogenesis and spermatogenesis occurring simultaneously. This was then followed by the growing stage (July 2002 to October 2002 and July 2003 to August 2003), marked by active gamete development. Gl and IMWI for male and female S. quadrifasciatus each showed parallel seasonal cycles and synchronous development pattern, indicating the same spawning period between the male and female sea cucumber. The oocytes measured a mean size of 21.74 ± 8.42 !Jm during late May 2002 and increased gradually until reaching a peak of 90.53 ± 12.85 !Jm in late August 2002. The lowest value of mean size for the oocytes was reported in early April 2003 at 21.49 ± 3.20 !Jm. The Pearson Correlation test was applied to the monthly Gl with monthly mean gonad values and monthly oocytes size. The result showed that monthly Gl and monthly mean gonad values have a strong co-relationship with the Pearson value of 0.960 (P < 0.01). The monthly histological conditions however did not show any significant relationship to the monthly Gl values. The same result was also showed in the relationship between the monthly oocytes size and monthly Gl values. The Pearson values proved that the physical and chemical parameters of sea water in Pulau Songsong did not have any influence on the gonad development of S. quadrifasciatus (P > 0.05). However, the monthly nitrate values showed a relatively stronger Pearson relationship with the gonad development (r = 0.484) compared with the other parameters while the monthly chlorophyll-a values showed a relatively weaker relationship with the gonad development of S. quadrifasciatus (r = 0.358).
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Spesies timun laut , Stichopus quadrifasciatus MASSIN
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