Browsing by Author "Guanzon, Nicolas G. Jr."
Growth of Gracilaria sp. (Gracilariales, Rhodophyta) in brackishwater ponds at different stocking densities. TR de Castro & NGJ Guanzon -
The Israeli Journal of Aquaculture-Bamidgeh, 1993 - Society of Israeli Aquaculture and Marine BiotechnologyThe specific growth rate (% per day) and net production rate (g per m2 per day) of Gracilaria sp. cultivated in net cages in a brackishwater pond were determined at different stocking densities (200, 250, 300 and 350 g/net cage of 0.5 m2). The mean specific growth rates for the duration of the culture period were highest at stocking densities of 200 and 250 g per cage (P<0.05). The highest mean net production rate was obtained at a stocking density of 250 g per cage. The highest monthly mean specific growth rates and mean net production rates for all treatments were obtained in April, July and November; these were not significantly different from each other nor from the month of March (P>0.05), but were significantly different from the other months (P<0.05). Production was better during the dry season. Correlation analysis showed that water temperature, salinity, pH and total rainfall had no effect on the specific growth rate and net production rate (P>0.05). Results indicate that Gracilaria sp. can be grown in cages in brackishwater ponds at stocking densities of 200 and 250 g/net cage (400 and 500 g per m2, respectively).
ArticleEM Leaño, GD Lio-Po, LA Nadong, AC Tirado, RB Sadaba & NG Guanzon -
Aquaculture Research, 2005 - Blackwell Publishing LtdThis study was conducted to quantify and characterize the mycoflora associated with the ‘green water’ culture system of Penaeus monodon. Samples of water, tilapia gut and mucus, and shrimp hepatopancreas from three shrimp farms were collected during 15, 30, 45 and 60 days of culture (DOC). Results showed that high fungal loads were observed in tilapia gut (total: 117–1352 colony forming unit (CFU) 5 cm hind gut−1; yeasts: 0–136 CFU 5 cm hind gut−1) and mucus (total: 12–311 CFU (5 cm2)−1; yeasts: 0–88 CFU (5 cm2)−1), while minimal fungal populations were observed in water samples (total: 0–110CFU mL−1; yeasts: 0–5 CFU ml−1). Shrimp hepatopancreas harboured a very low number of filamentous fungi (0–27 CFU 0.1 g−1) and yeasts (0–7CFU 0.1 g−1) especially at 60 DOC. The filamentous fungal isolates were dominated by Penicillium and Aspergillus species, while the yeast populations were dominated by Rhodotorula and Saccharomyces species. The dominance of these fungi on tilapia mucus and gut and their presence in the rearing water might play an important role in the overall mechanisms involved in the control of luminous Vibrio in the ‘green water’ grow-out culture of P. monodon.