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Lime application to condition soil to pH 11 controls growth of harmful vibrios and WSSV
(European Association of Fish Pathologists, 2023-05-26)
Shrimp farming has been devastated by several diseases. Disease outbreaks can be prevented by optimising environmental conditions or by eliminating risks factors including carrier organisms. These can be achieved through proper pond preparation. One important step in pond preparation is the application of hydrated lime.
This paper describes the effect of hydrated lime application to condition pond soil to pH 11 on the pond ecosystem, more specifically on soil pH and biota. The experiment was done using three 600 m<sup>2</sup> brackish water ponds. After hydrated lime application, the wet soil pH on the 1<sup>st</sup>-8<sup>th</sup> day was significantly higher (P<0.05) compared to the pH before liming to pH 11, and flushing after flooding for 24 h. Soil pH of 11 was observed 24-48h after lime application. Moreover, unwanted species like crabs and fish were found dead. Liming to pH 11 negatively affects the counts of green vibrio colonies thereby decreasing the percentage of green vibrios (PGV). In another experiment, three 750m<sup>2</sup> earthen ponds were used. The pond soils were previously positive for the Whitespot Syndrome Virus (WSSV), hydrated lime were applied to bring the pond soil pH to 11. After lime application, WSSV was not detected in the pond soils.
Results showed that increasing the soil pH to ≥11 positively affects the pond ecosystem. Liming encourages the proliferation of yellow vibrios and the eradication of carrier species (i.e. crabs) as well as predators (i.e. fish) in the ponds. Furthermore, liming to pH 11 may also eradicate White spot virus from the pond sediment. To implement a 1-unit increase in wet pH, hydrated lime should be applied at 2T/ha....
Reproductive quality evaluation of male Indian white prawn Penaeus indicus broodstock-fed diets supplemented with polychaete extracts (Marphysa sp.)
(Taylor and Francis, 2023-06-23)
The present study determined the effect of different polychaete extracts, namely, total soluble fraction (TSF), neutral lipid fraction (NLF) and polar lipid fraction (PLF), in the maturation and sperm quality of male ...
Behavior changes and \(\mathsf{LC_{50}}\) of dried garlic (Allium sativum) acute toxicity in Nile tilapia (Oreochromis niloticus) juvenile
(College of Agriculture and Food Science, University of the Philippines Los Baños, 2023-06)
Plant-based compounds are emerging substitutes for chemical treatments in aquaculture since they are known to cause less harm to both the environment and its organisms. Garlic (Allium sativum) is a popular herb that has a broad range of uses, especially in the control and treatment of bacterial and parasitic diseases. However, its toxicity to tilapia is not well-studied. Hence, this study was conducted to test the toxicity levels of garlic powder in juvenile Nile tilapia (Oreochromis niloticus) by determining the cumulative mortality and median lethal concentration (LC<sub>50</sub>). Test fish were exposed through immersion in 6 concentrations (150, 200, 250, 300, 350, and 400 mg L<sup>-1</sup>) of garlic powder with 25% allicin and a control in 96 h static bioassay. Within 24 h, test fish exposed to 250 mg L<sup>-1</sup> garlic and above, exhibited abnormal behaviors such as lethargy, gasping for air, and weak responses to environmental stimuli. Cumulative mortality was highest at 100% in 400 mg L<sup>-1</sup> garlic at 48 h. Mortalities were dependent on the concentration and duration of exposure. The 96 h LC<sub>50</sub> of garlic powder to O. niloticus is 225.86 mg L<sup>-1</sup> with lower and upper confidence limits of 210.37 and 242.50 mg L<sup>-1</sup>, respectively at 27°C....
Alternate day feeding as a cost-effective strategy for tank culture of the Pacific shortfin eel Anguilla bicolor pacifica
(College of Agriculture and Food Science, University of the Philippines Los Baños, 2023-09)
There is a growing interest in the aquaculture of tropical anguillid eels as an export commodity. However, studies on feeding strategies, and the present demand to reduce feed costs need to be addressed to ensure the ...
Complete genome sequence of Vibrio parahaemolyticus strain PH1273, isolated from aquacultured shrimp in the Philippines
(American Society for Microbiology, 2023-10-19)
We announce the complete genome sequence of Vibrio parahaemolyticus strain PH1273. This strain was collected from a Penaeus vannamei pond in the Philippines in 2015. Genome analysis revealed that it lacks the gene pirAB ...
Reproduction, early development, and larval rearing of the climbing perch Anabas testudineus (Teleostei: Anabantidae) in captivity
(College of Agriculture and Food Science, University of the Philippines Los Baños, 2023-06)
Induced spawning, early development, and larval rearing of the climbing perch Anabas testudineus were examined under captive conditions. Five female climbing perch [125.33 ± 3.27 mm standard length (SL); 70.67 ± 5.59 g body weight (BW)] were each paired with apparently mature males (108.50 ± 3.97 mm SL; 39.27 ± 4.70 g BW) and induced to spawn with 5,000 IU human chorionic gonadotropin (hCG) + 0.5 mL Ovaprim/kg BW. All hCG + Ovaprim-injected fish spawned 9 – 11 h after hormone administration but saline-injected fish (control group) failed to spawn. Mean egg production per female, fertilization and hatching rates, and larval production per female were 7,667 ± 1,313, 98.11 ± 1.63%, 61.01 ± 19.92%, and 4,435 ± 1,041, respectively. Fertilized eggs (1.52 – 1.96 mm in diameter) were almost spherical, non-adhesive, transparent, and buoyant due to a large, single oil globule (515 ± 33 µm in diameter). First cleavage appeared 30 min post-fertilization (MPF) and egg development lasted for 20 – 24 h post-fertilization (HPF) (29°C). Newly hatched climbing perch larvae [1.73 ± 0.08 mm in total length (TL)] with yolk volume (YV) and oil globule volume (OGV) of 0.545 ± 0.104 mm<sup>3</sup> and 0.072 ± 0.013 mm<sup>3</sup>, respectively had no pigmented eyes or functional mouth parts and digestive tract, and immobile with the yolk sac pointed upward. Eyes became pigmented and both mouth and anus opened in 1 d old larvae (2.09 ± 0.04 mm TL) in preparation for exogenous feeding. Except for body depth (BD) and pre-anal length (PAL), a general increase in TL (1.73 – 3.72 mm), eye diameter (ED) (0.164 – 0.378 mm), head length (HL) (0.205 – 0.923 mm), and mouth gape (MG) size (0.308 – 0.552 mm) was observed, coinciding with yolk resorption in 7 d post-hatched larvae. Climbing perch larvae were reared at four stocking densities (25, 50, 75, 100 larvae L-1) and fed solely on live food (Brachionus rotundiformis from days 2 to 12 and Artemia nauplii from days 13 to 40) or co-fed live food and microparticulate diet (MPD) (Artemia nauplii from days 2 to 15 and Artemia + MPD from days 16 to 40). Mean survival rates at lower densities (25 – 50 larvae L<sup>-1</sup>) were significantly higher than those reared at 75 and 100 larvae L<sup>-1</sup> (P < 0.05). Furthermore, climbing perch larvae co-fed Artemia nauplii and MPD showed better survival (28.67 – 81.00%) than those fed solely on live food (24.88 – 64.00%). However, at the end of the 40 d trial period, growth parameters did not vary significantly among densities (P > 0.05), except for the condition factor in larvae co-fed Artemia nauplii and MPD. Taken together, results demonstrate the effectiveness of hCG + Ovaprim for captive breeding and observations on the early development of climbing perch, and the feasibility of rearing the larvae at 25 – 50 L<sup>-1</sup> on a combination of Artemia nauplii and MPD under laboratory conditions....
Aquaculture governance: Five engagement arenas for sustainability transformation
(Elsevier, 2023-12)
A greater focus on governance is needed to facilitate effective and substantive progress toward sustainability transformations in the aquaculture sector. Concerted governance efforts can help move the sector beyond fragmented ...
Distribution pattern and habitat use of the protandrous shrimp Pandalus latirostris in relation to environmental characteristics in Akkeshi waters on the pacific coast of eastern Hokkaido, Japan
(Elsevier, 2023-09)
A sampling of the protandric shrimp, Pandalus latirostris, was conducted at fixed sites from July 2015 to March 2020 in Akkeshi Bay and the connecting Lake Akkeshi on the Pacific coast of eastern Hokkaido. Based on the ...
Effect of diet isotopic ratios on the \(\mathsf{\delta^{13}C}\) and \(\mathsf{\delta^{15}N}\) signatures of scallop-gut contents in a natural setting
(The Plankton Society of Japan, 2023)
The relationship between diet isotopic signatures and the extent of the tissue-diet isotope fractionation factors have been shown previously in controlled feeding studies, but this relationship remains poorly resolved for ...
Preliminary assessment of genetic variation in the Japanese endemic freshwater crab, Geothelphusa dehaani, based on mitochondrial DNA sequences
(Pensoft Publishers, 2023-06-27)
Geothelphusa dehaani, a freshwater crab species endemic to Japan, has the largest distribution range amongst the 19 known species in the country. Due to its low dispersal capability and restricted habitat to freshwater, ...