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Effects of delayed metamorphosis on larval survival, metamorphosis, and juvenile performance of four closely related species of tropical sea urchins (genus Echinometra).

Rahman MA, Yusoff FM, Arshad A, Uehara T - ScientificWorldJournal (2014)

Bottom Line: Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species.Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec.Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.

ABSTRACT
We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins, Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22-24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis.

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Related in: MedlinePlus

Effects of delayed metamorphosis on larval survival (%) of Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Larvae attained metamorphic competence within 24 days after fertilization were on month 0 (control). Each value represents the mean ± SD of six replicate experiments from each species with 400 larvae per replicate for each delayed period. Results of one-way ANOVA (F value and P value) are presented above each set of bars. Columns with the same letter represent means that are not significantly different (Tukey's test, P > 0.05).
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fig1: Effects of delayed metamorphosis on larval survival (%) of Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Larvae attained metamorphic competence within 24 days after fertilization were on month 0 (control). Each value represents the mean ± SD of six replicate experiments from each species with 400 larvae per replicate for each delayed period. Results of one-way ANOVA (F value and P value) are presented above each set of bars. Columns with the same letter represent means that are not significantly different (Tukey's test, P > 0.05).

Mentions: Majority of the larvae of all four species attained the state of metamorphic competence (bottom dwelling mode of life) at 22–24 days after fertilization and was evidenced by the presence of a large adult rudiment and a high percentage of metamorphosis (>90%) in trial assays with coralline red algal covered stones. Larval survival of Em, Ea, Eo, and Ec were highest at 24 days, when competent was attained (0 delayed period), and no significant differences were noted among the four species (Tukey's test, P > 0.05) (Figure 1). But the four species differed in survival rates as the delay period increased (Figure 1). One-month delayed larvae of Em and Ea did not differ significantly in survival rates, but Em differed significantly (Tukey's test, P < 0.05) from Ec and Eo, while both Ec and Eo did not significantly differ. Moreover, extending the competent phase of larval period 3 to 4 month resulted in striking decreases of survival in a manner that Em exhibited significantly higher (Tukey's test, P < 0.05) values followed by Ea/Eo (no differences between Ea and Eo) and Ec in that order (Figure 1).


Effects of delayed metamorphosis on larval survival, metamorphosis, and juvenile performance of four closely related species of tropical sea urchins (genus Echinometra).

Rahman MA, Yusoff FM, Arshad A, Uehara T - ScientificWorldJournal (2014)

Effects of delayed metamorphosis on larval survival (%) of Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Larvae attained metamorphic competence within 24 days after fertilization were on month 0 (control). Each value represents the mean ± SD of six replicate experiments from each species with 400 larvae per replicate for each delayed period. Results of one-way ANOVA (F value and P value) are presented above each set of bars. Columns with the same letter represent means that are not significantly different (Tukey's test, P > 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927581&req=5

fig1: Effects of delayed metamorphosis on larval survival (%) of Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Larvae attained metamorphic competence within 24 days after fertilization were on month 0 (control). Each value represents the mean ± SD of six replicate experiments from each species with 400 larvae per replicate for each delayed period. Results of one-way ANOVA (F value and P value) are presented above each set of bars. Columns with the same letter represent means that are not significantly different (Tukey's test, P > 0.05).
Mentions: Majority of the larvae of all four species attained the state of metamorphic competence (bottom dwelling mode of life) at 22–24 days after fertilization and was evidenced by the presence of a large adult rudiment and a high percentage of metamorphosis (>90%) in trial assays with coralline red algal covered stones. Larval survival of Em, Ea, Eo, and Ec were highest at 24 days, when competent was attained (0 delayed period), and no significant differences were noted among the four species (Tukey's test, P > 0.05) (Figure 1). But the four species differed in survival rates as the delay period increased (Figure 1). One-month delayed larvae of Em and Ea did not differ significantly in survival rates, but Em differed significantly (Tukey's test, P < 0.05) from Ec and Eo, while both Ec and Eo did not significantly differ. Moreover, extending the competent phase of larval period 3 to 4 month resulted in striking decreases of survival in a manner that Em exhibited significantly higher (Tukey's test, P < 0.05) values followed by Ea/Eo (no differences between Ea and Eo) and Ec in that order (Figure 1).

Bottom Line: Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species.Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec.Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.

ABSTRACT
We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins, Echinometra sp. A (Ea), E. mathaei (Em), Echinometra sp. C (Ec), and E. oblonga (Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22-24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis.

Show MeSH
Related in: MedlinePlus