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QUESTION:
I’m looking for optimal ozone concentration to sterilize sea water used for shrimp postlarvae rearing, maturation and algae culture. Also a kit or instrument to test the ozone machine is adding the required amount of O3 to the system and if it disappears before it gets into the system.

Jaime Baquerizo baqueriziojaime@yahoo.com

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COMMENTS 1:

 

 

billc@cos-inc.com

Currently the system is under ozone action and I haven’t seen any probs in any of the area, larviculture, maturation or algae, but the system is set but no one knows the amount of ozone that is injected to the water (125 gpm), if it really is working effectively. The way we are using to measure if it is present in the water after the unit, is with a swimming pool chlorine test kit. One thing I’m sure is that it is not affecting the animals. I would like to know the right amount to be effective in treating seawater and find a method or instrument to measure if there is no residue before the seawater goes into LRTs.

COMMENTS 3:

 

 

Have you tried to use sodium thiosulfate as an indicator for the residual presence of ozone? In seawater you may have to add some edta but is should work. I think LaMotte has a test kit but something tells me it is for freshwater and not seawater. We use the sodium thiosulfate in our lab as an indicator.
Ozonation of brackish or seawater results in the production of different by-product oxidants to freshwater. Ozone reacts with bromide and chloride ions in saltwater to produce relatively stable oxidants that are toxic to aquatic organisms.Use of ozone in saltwater systems is usually restricted to batch treatment of water separate to the main recirculating flow. Activated carbon filtration can be used to remove residual ozone and other oxidants from ozonated saltwater.

Thanks for your reply on this "ozone case". Yes we pass through carbon filters when we repump ozone treated water into the system. I feel we've been using this system like "blind leading the blind", I don’t want to take more chances of risks. I know that O3 works and could be your friend if you know how to use it, I don’t want more "smelling testing", "odor verification" that the machine is injecting O3 to the system and that "has no residual" using the same senses methods.

In order for ozone to be effective, you have the get the ORP potential up to at least 750 mV. We let it go as high as 900 in situations where we knew there was a lot of bugs and organic material in the water. This takes a lot of ozone. The ORP probe was mounted in the outflow of the poly mix tank, and controlled the O3 injection. The ORP probe was a special one made by Phoenix probes just for this purpose. A standard ORP probe will die quickly in this environment.
As Larry said, you can run the outflow through an activated charcoal filter to kill the O3, but it chews up filters fast. And activated filters aren't cheap. If you can let the water breath for a bit, this also works. But you have to do it outdoors. We used the big holding tank to let the saltwater 'breath' and naturally dissipate the ozone. The ozonated water from the poly mix tank was injected in the bottom. Treated water was taken off the top of the tank. We kept it well stirred at the top by using submersible pumps in the tank.
We also used a standard ORP probe (along with pH and other probes) mounted in the outlet line to make sure the outflow level was below 200 mV. We found this to be a safe level for most critters. The chlorine test is also good. In our case, we had to use the ORP probes because ours was a continuous flow system, but we did spot checks with the chlorine test as well.I don't know much about raising shrimp, only read about it, and copy the Dallas and Julio, et. al. traffic whenever possible. But is it possible that the PL-1 were still very much dependent on algal feeds, and would simply starve to death if placed in the ozonated water? Maybe a combination of stress and lack of algae? I know that water with an ORP of 750 will kill any algae around, so is this a possible cause?

We've been using ozone in our commercial hatchery for more than 5 years with no problems during the whole cycle. Our system is based on a flow through system and has protected us from some problems in the area as red tides, we were the only hatchery producing PLs during this time, the only difference the ozone. Anyway, my concern is that I know we are injecting O3 to the seawate , before the reservoir, how much, what concentration 500, 600, 750, 100 mV right after the ozonifier only God knows. Sometimes agar plates for bacteria before and after O3 show difference, sometines don’t. That’s why I’m trying to find an instrument to calibrate the right concentration for O3 injection and no residual after carbon filters, aeration in the reservoir. I know that O3 is a great tool for production but can be very dangerous also, as spermatophores problems in maturation as an example.

Jaime, I see your problem. We eliminated that problem by having a reservoir where we recirculate the water through filters and ozone and only after we have reached a desired endpoint (750 vm) do we pass the water over the activated carbon to the animals. We set it up that way for exactly that reason.

I use a series of protein skimmers to remove ozone fter ozonating the water online in a recirculating system which rears Zoea thro' Mysis and subsequently Post larvae too. The half life of Ozone (L50) is substantially reduced with higher levels of dissolved and suspended organic matter in the water. The amount of ozone required and thereafter the amount of time required to remove it directly depends on how much organic matter (dissolved and suspended) you have in the rearing water at the given time.

The previous comment about bromine is a serious issue with ozone and salt water. If you are trying for real sterilization (not just feed good approaches), you will form hypobromous acid, which is very toxic and much more stable that ozone itself. Activated carbon will work, but you will get bacteria growing in the carbon and whether these are detrimental or probiotic bacteria or just irrelevant species is just a gamble. If you have enough organic material for froth flotation units (the correct name for "protein skimmers" that really skim surface active components and hydrophobic solids, may or may not be protein) to work after hard ozonation, you probably have some water quality issues that should be addressed before the use of ozone. Ozone in water can also be removed with UV light and this process creates an even stronger oxidizing action than ozone or UV alone. This process is in the category of Advanced Oxidation Processes (AOP) that are used industrially to oxidize very refractory organic chemical (often very toxic and nasty stuff).

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INDUCED SPAWNING, LARVAL DEVELOPMENT AND REARING OF TWO INDIGENOUS MALAYSIAN MAHSEER, TOR TAMBROIDES AND T. DOURONENSIS
Brett Ingram, Stephen Sungan, Geoff Gooley, Sih Yang Sim, David Tinggi, Sena S. De Silva-2005
Aquaculture Research, 36(10): 983 -
Abstract :
The Mahseers (Tor spp.) are highly valued freshwater fishes across the Himalayan and South-east Asian regions. Over exploitation of natural stocks because of high demand and the deteriorating environmental conditions have resulted in marked decline of mahseers in the wild. Malaysian mahseers, T. tambroides (Bleeker) and T. douronensis (Valenciennes), locally known as empurau, kelah or belian and semah, respectively, have significant cultural and economic importance but both species are now threatened in the wild because of environmental degradation and over fishing. A captive breeding programme was instigated to attempt to propagate these two species artificially for conservation and aquaculture purposes. Both pond-reared and tank-held T. tambroides and T. douronensis reached sexual maturity in captivity and were successfully induced to spawn using hormone treatments. Ovaprim (0.5 mL kg1) was the most successful hormone treatment for both species. Pre-treatment of fish with Ovaplant (2868 g kg1, 27 weeks before spawning induction) greatly improved the success rate of spawning induction. Repeat spawning (within 4 months of initial spawning) was induced in some captive fish. Use of formalin baths improved hatching by preventing fungal infections. Embryonic development and hatching are described. Juveniles were reared in static greenwater ponds. Tor tambroides reached 142179 g (max 270 g) in 60 weeks. These results represent the first successful captive spawning and rearing of both species. Options for future research to improve production are discussed.
(PO Box 3268, Mornington, Victoria, Australia; email of S.S. de Silva: sena@deakin.edu.au)

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ARTIFICIAL SPAWNING OF CARP (CYPRINUS CARPIO L.): DIFFERENCES BETWEEN FEMALES OF POLISH STRAIN 6 AND HUNGARIAN STRAIN W TREATED WITH CARP PITUITARY HOMOGENATE, OVOPEL OR DAGIN
Elbieta Brzuska-2005
Aquaculture Research 36 (10): 1015-
Abstract :
Investigations of the effects of controlled reproduction were conducted on carp females of Polish strain 6 and Hungarian strain W after ovulation stimulation with carp pituitary homogenate (CPH) (0.3 mg+2.7 mg kg1 body weight), Ovopel (1/5+1 pellet kg1 body weight) or Dagin (1 dose kg1 body weight). In both strains, the highest percentage of spawning females was found after the Ovopel treatment. After treatments with CPH and Dagin this percentage did not differ in strain 6; however, after Dagin, it was higher in fish of strain W. After CPH or Ovopel stimulation the females of line 6 yielded eggs of higher weight compared with line W. After the Dagin treatment the weight of eggs obtained from females, both strains was similar but much lower than after the two remaining agents. The quality of eggs expressed both by the percentage of fertilization and that of living embryos after 24 and 36 h incubation was similar in the two strains only in the group treated with Ovopel. After CPH application eggs of better quality were obtained from strain 6 compared with strain W; however, after the treatment with Ovopel, eggs of much better quality were noted in strain W. In general, the best effects of reproduction were recorded in the case of Ovopel and the poorest in that of Dagin. Females of strain 6 yielded eggs of a higher weight but the percentages of spawning females were higher in strain W after each of the applied spawning agents. A new approach to this problem consisted in investigating the interaction between ovulation stimulators and origin of females of fish treated with Dagin.
(Polish Academy of Sciences, Institute of Ichthyobiology and Aquaculture, Goysz, 43-520 Chybie, Poland; email of E. Brzuska: golysz@fish.com.pl, zigr@bb.onet.pl)

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EFFECTS OF TANK COLOUR ON LARVAL SURVIVAL AND DEVELOPMENT OF MUD CRAB SCYLLA SERRATA (FORSKÅL)
Abed Golam Rabbani, Chaoshu Zeng-2005
Aquaculture Research 36 (11): 1112 -
Abstract :
Hatchery culture of mud crabs has not yet achieved commercial viability despite decades of research efforts. Further research is therefore needed to better understand larval culture requirements of the crab. Based on anecdotal observations, an experiment was carried out to test whether the background colour of the culture vessel affected larval culture success. Newly hatched larvae of Scylla serrata were reared in culture vessels of five colours, i.e., black, dark green, maroon, sky blue and white. Larval survival and development were monitored daily until all of them either moulted to the first crab stage or died. The results showed clear effects of background colour on larval survival. A general tendency of higher larval survival in darker-coloured backgrounds was evident. In particular, overall zoeal survival for larvae reared in black vessels was significantly higher than those reared in white ones. Background colour also appeared to affect larval development. Larvae reared in darker backgrounds generally had shorter development times and more synchronized moulting. A significant delay in zoeal development was observed in larvae reared in white vessels. Dark backgrounds possibly facilitated more efficient feeding, reduced settlement of larvae at the bottom of the vessels as well as minimized stress. This result appears to be the first to demonstrate that background colour can significantly affect larval survival and development of a crustacean species.
(Tropical Crustacean Aquaculture Research Group, School of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia; email of C. Zeng: chaoshu.zeng@jcu.edu.au)

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EFFECTS OF INCUBATION TEMPERATURE ON DEVELOPMENT AND YOLK SAC CONVERSION EFFICIENCIES OF SPOTTED WOLFFISH (ANARHICHAS MINOR OLAFSEN) EMBRYOS UNTIL HATCH
Terje Sund, Inger-Britt Falk-Petersen-2005
Aquaculture Research 36 (11): 1133
Abstract :
Two egg batches of spotted wolffish, Anarhichas minor Olafsen, were incubated at 4, 6 and 8°C. Embryo samples were fixed and compared on each 100th daydegree until hatching (up to 1000 daydegrees). Embryos, yolk sacs and chorions were dissected and the sizes, wet and dry weights were recorded separately. Comparisons of gross morphologies and measured parameters showed increasing and generally significant differences with time between the incubation temperatures. Lower temperatures produced longer and more differentiated larvae at hatch with a smaller yolk sac. Even though some unexpected deviations were registered among batches and experimental groups, it was clear that temperature affected embryo survival and time of hatching. Overall survival was best at 6°C, in agreement with results from earlier studies. Yolk conversion efficiencies measured around the hatching point were generally high, ranging from 60% to 78%, varied between the two batches and probably reflected the developmental variations between embryos and larvae at the respective ages (daydegrees). The hatching process was apparently an energy-demanding period; yolk conversion efficiencies of unhatched embryos of similar age at each temperature were always higher. Temperature is one environmental factor that can be manipulated in hatcheries to induce hatching of viable larvae at an optimal stage of differentiation with respect to first-feeding success and early survival.
(Barentslab A/S, Hammerfest, Norway; email of I-B Falk-Petersen: ingerf@nfh.uit.no)

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GENE TRANSFER FOR JAPANESE FLOUNDER FERTILIZED EGGS BY PARTICLE GUN BOMBARDMENT
Ryosuke Yazawa, Ikuo Hirono, Eiichi Yamamoto, Takashi Aoki-2005
Fisheries Science 71 (4): 869 -
Abstract:
Fish transgenesis has progressed considerably. However, the technique of gene transfer for most marine aquaculture species has not been established. A method to introduce foreign genes into fertilized eggs of Japanese flounder Paralichthys olivaceus by particle gun bombardment was developed by the authors. A recombinant plasmid which contains the Japanese flounder keratin gene promoter linked to the green fluorescence protein (GFP) gene was introduced into fertilized eggs by particle gun bombardments twice at 250 psi. In each experimental group, 25 00035 000 eggs were treated. However, the survival rate was 12.8% which is lower than that of the control groups (56.8%). Of 26065205 the embryos survived for 24 h, 4361 GFP positive embryos were obtained in one experiment, giving a final gene transfer efficiency of 1.4%. All GFP-positive embryos developed and hatched normally. GFP expression was observed in epithelial tissue throughout the developmental stages. At 3 months after gene transfer, foreign DNA was detected by genome polymerase chain reaction analysis in 37 of 69 fry (53.6%). These results suggest that the particle gun method is an effective method to use with fertilized Japanese flounder eggs.
(Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477; email of T. Aoki: aoki@s.kaiyodai.ac.jp)

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EFFECT OF DIETARY FATTY ACIDS ON THE BODY TISSUES OF LARVAL AND JUVENILE COBIA AND THEIR PREY
J.P. Turner, J.R. Rooker-2005
Journal of Experimental Marine Biology and Ecology 322 (1): 13-27
Abstract:
Polyunsaturated fatty acids (PUFAs) have been used as biomarkers in pelagic ecosystems although previous studies have failed to quantify the timing of conservation of dietary PUFAs in pelagic fishes and invertebrates. Here we investigated the influence of diet upon the timing of conservation of PUFAs throughout multiple trophic exchanges in larval and juvenile cobia (Rachycentron canadum) and their prey. Cobia, rotifers (Brachionus plicatilis), and Artemia (A. franciscana) were fed laboratory processed or natural diets resembling prey and dietary modification of fatty acid signatures was quantified using two-source mixing models. Specimens were collected throughout the experiment to track dietary influences over time. Cobia larvae underwent significant dietary modification of PUFAs after 24 h and conserved > 90% of dietary PUFAs after an average of 6 days. Similar results were identified in juvenile cobia as significant dietary modification of PUFAs took place after 3 days and > 90% were conserved after an average of 12 days. In addition, no significant ontogenetic changes in PUFA signatures were identified in juvenile cobia throughout the 30-day experiment. PUFA signatures in prey items (rotifers and Artemia) underwent significant dietary modification in 24 h, with over 90% incorporation after 5–7 days. Results from this study support the premise that fatty acids are promising dietary indicators and may be useful for future studies examining trophic relationships in marine ecosystems and habitat use of marine fishes.
(Texas A&M University at Galveston, Department of Marine Biology, Galveston, TX 77551, United States; email of J.P. Turner: jpturne1@uno.edu)