Southeast Asian Fisheries Development Center Aquaculture Department
SEAFDEC/AQD Institutional Repository http://repository.seafdec.org.ph
Institutional Reports Quarterly Research Reports
1980
Effect of substrate types on fecundity and nauplii production of ablated
Penaeus monodon Fabricius
Pudadera, Rosario
Aquaculture Department, Southeast Asian Fisheries Development Center
Pudadera, R., Primavera, J., & Borlongan, E. (1980). Effect of substrate types on fecundity and nauplii production of ablated Penaeus monodon Fabricius. SEAFDEC Aquaculture Department Quarterly Research Report, 4(2), 20–22.
http://hdl.handle.net/10862/2369
Downloaded from http://repository.seafdec.org.ph, SEAFDEC/AQD's Institutional Repository
Effect of substrate types on fecundity and nauplii production of ablated Penaeus monodon Fabricius
Rosario Pudadera, Jurgenne Primavera and Emeterio Borlongan
The survival, spawning, fe c u n d ity and nauplii production o f ablated Penaeus m onodon females reared in flo w th ro u g h broodstock tanks w ith w h ite coralline and black sand substrate fo r 62 days were assessed.
The survival o f prawns in broodstock tanks after 62 days was n o t significantly d iffe re n t between the tw o treatm ents in both experim ental runs. Female prawns were observed to have generally lower percentage survival (15.38% to 80.00%) than males (33.33% to 95.00%) as sim ilar
ly observed in other P. m onodon m aturation experiments. This may be a ttrib u te d p rim a rily to additional stress during eyestalk ablation, regular ovarian observations, spawning and processes such as tagging and measuring o f spent spawners. O ther causes o f m ortalities were m oulting stress and cannibalism o f weak and/or newly m oulted prawns. The sim ilar trend in m o rta lity rates in b o th substrates suggests th a t the variation in substrate material fo r the broodstock tanks is n o t the lik e ly cause o f prawn m o rta lity .
M a tu ra tio n rate o f the prawns is reflected b y th e ir to ta l number o f spawnings. Spawning rates were observed to be higher during the second run,(48 and 50 to ta l number o f spawnings) as compared to the firs t run w ith 28 and 29 spawnings. This can be due to more frequent ovarian exam inations durin g the second experim ent (n ig h tly compared to three times a week during the 1st experim ent). M a tu ra tio n to spawning was generally observed to peak three weeks fro m ablation, w ith a m in im u m o f 6 days. O n ly 16.67-51-72%, 14.28-33.33% and 0-33.33% were able to spawn fo r the second, th ird and fo u rth tim e. Subsequent spawnings usually occurred at an average o f nine days fro m firs t spawning. There were no significant differences observed between the rem aturation rates under the d iffe re n t treatments.
The cum ulative d a ily number o f nauplii produced under the tw o treatments shows the difference in the to ta l number o f nauplii fo r 62 days during experiments 1 and 2 (Figure 1).
Peak n auplii p ro d u c tio n , as reflected by sharp increments in Fig. 1, was generally observed on the th ird week a fte r ablation. A blated female in tanks w ith w h ite substrates consistently yielded s ig n ifica n tly higher (P < 0.05) to ta l nauplii production and average hatching rate (3.0 and 6.8 m illio n n a u p lii; 34.61% and 46.36% hatching rate fo r experiments 1 and 2, respectively) than those exposed to th e black substrate (1.9 and 5.0 m illio n n a u p lii; 15.77% and 32.34% hatching rate fo r experim ents 1 and 2, respectively). As a result o f the n ig h tly sampling over a 62-day period durin g the second experim ent, a tank w ith 30 females and 20 males produced 6.8 m illio n nauplii in contrast to o n ly 3.0 m illio n fro m a comparable tank w ith three times a week sampling during the firs t experim ent.
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Figure 1. C u m u la tiv e to ta l num ber o f n a u p lii p ro du ced b y Penaeus m o n o d o n exposed to b la c k and w h ite substrates d uring e x p e rim e n ts 1 & 2 fo r a d u ra tio n o f 6 2 days each.
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No significant differences in the physico-chemical parameters were observed throughout the experim ent. A lk a lin ity ranged fro m 94-136 ppm CaCO3 , pH fro m 7.0-8.2, while salinity was maintained between 28.6-33.6 ppt. Because of the flo w th ro u g h and well-aerated water system, to x ic compounds such as n itrite (0-0.471 ppm) and ammonia (0-0.512 ppm) were m ain
tained at low levels, w hile dissolved oxygen (6.29-6.84 ppm) was adequately provided. This strongly indicates th a t neither prawn m o rta lity nor the difference in nauplii production and hatching rate under the tw o treatments can be a ttrib u te d to these parameters.
It is lik e ly th a t some properties o f the substrates affected the broodstock such th a t the q u a lity o f eggs, as shown by the hatching rate, and consequently nauplii p ro d u ctio n , varies in the tw o treatm ents. Differences in the color o f the substrates may result in the variation o f lig h t q u a lity . W hile the w h ite substrate m axim ally reflected lig h t o f various wavelengths, the black substrate absorbed the entering lig h t.
Differences in the size o f substrates used in the upper fine layer may also have affected the a c tiv ity o f the prawn. Due to the bigger size o f the black sand, prawns were n o t observed to bu rro w in the substrate. In contrast, prawns in the w h ite coralline w hich had smaller size diam eter, sometimes burrowed though most o f the tim e they stayed on the substrate. Moreover, the 2-4 mm diam eter of coralline substrate is a good size fo r the biological cleaning o f the water.
A t present, the land-based broodstock tanks in SEAFDEC u tilize the w hite coralline sub
strate (2-4 mm diam eter o f upper layer) because o f: higher hatching rate o f eggs and nauplii p ro d u ctio n obtained fro m ablated P. m onodon; convenience in siphoning o u t debris and excess fo o d th a t tend to accumulate in the ta n k ; and contrast provided b y the w hite substrate (prawns being d a rkly pigmented) during n ig h tly observation o f ovaries.
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