Papers by Gerald Quinitio
Kalikasan, The Philippine Journal of Biology, 1980
The acute toxicity of dispersant Mardeus-455 added to water accommodated fractions (WAF) were eva... more The acute toxicity of dispersant Mardeus-455 added to water accommodated fractions (WAF) were evaluated in Gold-saddle rabbitfish Siganus guttatus fry after 72 h exposure under laboratory conditions. Mortalities of fry exposed to different concentrations of dispersed oil were recorded every hour for the first 6 h, every 3 h for the next 12 h, and every 6 h thereafter. Results showed that the higher the ratio of dispersant and WAF, the higher the mortality of the rabbitfish fry which may be due to the enhanced availability of polyaromatic hydrocarbons (PAH). The LC50 was computed at 3.692% of the oil volume. The application of dispersant in cleaning oil spills must be limited to reduce its harmful effect in the marine environment. Assessing toxicity of dispersed oil in fish fry may help understand the extent of environmental damage after cleaning oil spill using dispersant.
The shell is the most conspicuous and variable part of a bivalve and is largely affected by envir... more The shell is the most conspicuous and variable part of a bivalve and is largely affected by environmental conditions. Thus, this study was conducted to describe the changes in the shell shape of the horse mussel Modiolus metcalfei from Dumangas, Iloilo. Allometric changes in shape, sex-induced shape differences, and asymmetry were investigated using geometric morphometric methods. A total of 12 landmarks where used to obtain biological shape information from 60 horse mussel individuals. Multivariate analysis of variance revealed significant differences of shell shapes between sexes (Wilk’s λ=0.01, p=1.26E-219). Generally, males have an expanded shell but compressed mid-shell region while females have compressed shell but expanded midand postero-ventral region. Moreover, the multivariate regression of shape on centroid size was statistically significant (p<0.001, Goodall’s F-test). Smaller individuals were slender and elongate while larger individuals were slightly rounded and cur...
Mem. Fac. Fish. Kagoshima Univ., 2010
Aquaculture Research, 2012
Possible application of mibolerone for induced
This paper summarizes the results of the experiments on the induced breeding and larval rearing o... more This paper summarizes the results of the experiments on the induced breeding and larval rearing of milkfish (Chanos chanos) during the 1979 season. Milkfish larvae could be reared successfully without the use of trochophore larvae of oysters as feed during the first few days. In order to induce the ovulation of wild adult milkfish a higher dose of human chorionic gonadotropin hormone is required.
Results of the study indicate that the survival rate and increase in body weight did not differ s... more Results of the study indicate that the survival rate and increase in body weight did not differ significantly at different salinity levels or at different stocking density manipulation methods. A significant interaction between salinity and stocking density manipulation could not be demonstrated statistically. There apparently is no need to reduce the salinity of the water used in storing milkfish Chanos chanos fry in order to attain higher survival as commonly believed. Sufficient food and maintenance of good water quality are more important than salinity for higher survival of fry during storage.
In cultured grey mullets, MugiJ cephaJus L., mortalities caused by a dinoflagellate like parasite... more In cultured grey mullets, MugiJ cephaJus L., mortalities caused by a dinoflagellate like parasite were observed under normal rearing conditions. Moribund fish were abnormally swimming near the water surface and exhibited haemorrhagic areas on the head, around the mouth and on the body surfaces. Their gills displayed whitish spots as well as haemorrhagic areas and showed excessive mucus production. Microscopic examination of these whitish spots revealed structures highly resembling the trophonts of AmyJoodinium attached to the gill filaments. The most consistent feature of this parasitic infestation was lamellar disintegration or degeneration. Early stages of the infestation showed epithelial lifting and lamellar detachment, eventually leading to the disruption of the lamellae and lamellar tissue degeneration. The parasites were associated with large necrotic areas in the gills and caused degeneration of the gill ray tissues. Hyperplasia of the gill epithelium and lamellar fusion were also observed, with the parasites enclosed by the fused lamellae. These structural alterations may have caused osmoregulatory and respiratory difficulties which ultimately led to the observed mortalities.
is therefore apparent that in order to evaluate, assess or predict the potential effect of pollut... more is therefore apparent that in order to evaluate, assess or predict the potential effect of pollution to fisheries, it is necessary to collect data and information regarding specific fishing gears and their target organisms, i.e., a meaningful assessment of the relationship between environmental pollution and capture process. In this study, we investigated the effect of pollutants on the capture efficiency of fishing gears. We examined how pollution affects the following: amount of catch, income, duration and frequency of fishing, and fish species caught.
Clarias macrocephalus is endemic yet dwindling freshwater foodfish in the Philippines. Induced br... more Clarias macrocephalus is endemic yet dwindling freshwater foodfish in the Philippines. Induced breeding protocol was developed by monitoring the size and maturation of eggs at 0-48 h after a simultaneous injection of luteinizing hormone-releasing hormone analogue (LHRHa; 0.0005 0.10 μg/g BW) and pimozide (PIM; 1 μg/g BW). Based on its similar osmotic pressure with catfish plasma, eggs were fixed in 1% phosphate-buffered formalin. Mean egg diameter of fish that were induced to mature increased during ovulation. Oocyte maturation, indicated by oocytes with germinal vesicle breakdown (GVBD), was observed at least 12 h post-injection in fish given 0.01 0.10 μg LHRHa + 1 μg PIM/g BW, followed by ovulation 4 h thereafter. Results showed that a simultaneous injection of C. macrocephalus with 0.05 μg LHRHa + 1 μg PIM/g B W at 1800-1900 h followed by stripping at 16-20 h post-injection resulted in high ovulation, fertilization and hatching rates.
Bulletin of The European Association of Fish Pathologists, 2008
Viral nervous necrosis caused by betanodaviruses is one of the most devastating diseases in cultu... more Viral nervous necrosis caused by betanodaviruses is one of the most devastating diseases in cultured marine finfish. In the Philippines, mass mortalities occurred in sea bass, Lates calcarifer larvae and grouper, Epinephelus coioides broodstock. The virus was isolated using SSN-1 fish cell line and confirmed by PCR. Cytopathic effect started to develop in the cell line 2 days post infection (p.i) with tissue filtrates until the cells completely disintegrated and detached from the flask at 5 days p.i. and the viral protein was detected by immunofluorescence. Sequence analysis revealed that VNN isolated from the brain of grouper broodstock and sea bass larvae were 98.6 % similar. Sequence analysis between the Philippine isolates and red-spotted grouper nervous necrosis virus (RGNNV) genotype is 96.9% similar as compared to 72.0% and 64.0% similar with the barfin flounder nervous necrosis virus (BFNNV) and tiger puffer nervous necrosis virus (TPNNV) genotypes, respectively. These resul...
Gonad development of rabbitfish Siganus guttatus from an oil spill affected (Taklong Island) and ... more Gonad development of rabbitfish Siganus guttatus from an oil spill affected (Taklong Island) and unaffected (Ave Maria Sanctuary) area in Guimaras province were monitored from November 2007 to December 2008. There were instances wherein samples could not be collected in both sites at the same period since tidal change was not abrupt so that the fish did not migrate to the seagrass bed where they fed and eventually get caught in the barrier net. Male rabbitfishes sampled from both area had 23-400 g body weight (BW) and 6.15-29.00 cm total length (TL) while females had 25-753 g BW and 6.50-31 cm TL. The fish were dissected and gonads
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Papers by Gerald Quinitio