Agar production from Gracilariopsis heteroclada (Gracilariales, Rhodophyta) grown at different salinity levels

Gracilariopsis heteroclada grown in fiber glass tanks at four salinity levels was treated with three different concentrations of aqueous NaOH. Yield, gel strength, gelling and melting temperatures of the extracted agar were determined. Plants grown at salinities of 24 and 32 ppt and treated with 3% NaOH produced the strongest gel (850 g cm^-2) and weakest gel (300 g cm^-2), respectively. Statistically significant differences in gel strength, dynamic gelling and melting temperatures were observed between the various treatments. The interactive effect of salinity and NaOH was significant in gel strength, gelling and melting temperatures of the gel from G. heteroclada.

URI

http://hdl.handle.net/10862/1457

Suggested Citation

Hurtado-Ponce, A. Q. (1994). Agar production from Gracilariopsis heteroclada (Gracilariales, Rhodophyta) grown at different salinity levels. Botanica Marina, 37(2), 97-100. https://doi.org/10.1515/botm.1994.37.2.97

DOI

10.1515/botm.1994.37.2.97

Type

Article

ISSN

0006-8055

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Impact of AMPEP on the growth and occurrence of epiphytic Neosiphonia infestation on two varieties of commercially cultivated Kappaphycus alvarezii grown at different depths in the Philippines

Borlongan, Iris Ann G.; Tibubos, Keneth R.; Yunque, Dianne Aster T.; Hurtado, Anicia Q.; Critchley, Alan T. (Springer, 2011)

Two varieties of the carrageenophyte Kappaphycus alvarezii (Tungawan, TUNG; and Giant tambalang, GTAM) from Zamboanga Sibugay, Philippines were used to test the efficacy of Acadian Marine Plant Extract Powder (AMPEP) as source of nutrients for growth, and to determine if applications had any effect on the percent occurrence of an epiphytic infestation of the red alga Neosiphonia sp. at four different depths in the sea. Results showed that the use of AMPEP significantly (P < 0.05) increased the growth rate of both Kappaphycus varieties tested but decreased the percent occurrence of Neosiphonia sp. The percent occurrence of Neosiphonia sp. infection (6–50% at all depths) of both Kappaphycus varieties with AMPEP treatment was significantly lower than the controls (i.e., 10–75% at all depths). Both the growth rate of the cultivated seaweed and the percent occurrence of the epiphytes decreased as the cultivation depth increased. Plants dipped in AMPEP and suspended at the surface had the highest growth rates (i.e., 4.1%, TUNG; 3.1%, GTAM) after 45 days; those without AMPEP dipping had the highest percent occurrence of Neosiphonia infection (viz. 70–75%). The occurrence of Neosiphonia infestation was found to be correlated with changes in irradiance and salinity at the depths observed. The results suggested that both varieties of K. alvarezii used in this study have the fastest growth rate when grown immediately at the water surface. However, in order to minimize damage caused by the occurrence of epiphytic Neosiphonia, K. alvarezii should be grown within a depth range of 50–100 cm. These observations are important for the improved management of Kappaphycus for commercial farming. Furthermore, the use of AMPEP treatments for enhancement of growth and reduction deleterious Neosiphonia sp. infections is encouraging.
Polyculture of milkfish Chanos chanos (Forsskal) and the red seaweed Gracilariopsis bailinae (Zhang et Xia) in brackish water earthen ponds

Guanzon, Nicolas G., Jr.; de Castro-Mallare, Teresa R.; Lorque, Felizardo M. (Wiley-Blackwell, 2004)

Growth, net production, and survival rates of milkfish cultured with Gracilariopsis bailinae at two stocking density combinations (T₁– 30 fingerlings 100-m⁻² pond+1-kg G. bailinae 4-m⁻² net cage, T₂– 30 fingerlings 100-m⁻² pond+2-kg G. bailinae 4-m⁻² net cage) in brackish water earthen ponds over four culture periods were determined. The control (T₃) was stocked at 30 fingerlings 100-m⁻² pond. Specific growth and production rates of G. bailinae were also calculated. There were no significant differences in mean growth, survival, and net production rates of milkfish between the three treatments. Irrespective of stocking singly or in combination with G. bailinae, significantly higher mean growth and mean production rates for milkfish were obtained during the third culture period of year 1 than those obtained from the other culture periods. Survival rates were not significantly different among the four culture periods. There were no significant differences in mean specific growth and mean net production rates between the two stocking densities of G. bailinae. Significantly higher mean specific growth and mean net production rates of red seaweed were also obtained during the third culture period of year 1 than those obtained from other culture periods. The production of milkfish and red seaweed was higher during the dry season. Growth rates of milkfish was positively correlated with temperature and salinity, while net production rates were positively correlated with temperature and total rainfall, but was inversely correlated with dissolved oxygen. G. bailinae growth and net production rates were positively correlated with water temperature and salinity. Results show that milkfish can be polycultured with G. bailinae grown in net cages in brackish water ponds at stocking density combination of 30 fingerlings 100-m⁻² pond+1-kg G. bailinae 4-m⁻² net cage.
Yield and agar quality of three red seaweed Gracilaria species grown in tanks at three salinities

Ferrer, Maria Salvacion R.; Marasigan, A. N. (Bureau of Agricultural Research, Department of Agriculture, 2007)

Gracilaria changii, G. firma and G. tenuistipitata were collected from the eastern coast of Sorsogon in southeastern Philippines and grown in concrete tanks at the SEAFDEC Aquaculture Department in Iloilo in May-June and in September-October 1994 at a stocking density of 1 kg/m² and at three salinities (15, 25, and 35 ppt). In the first run, the highest specific growth rates per day were 2.5% at 25 ppt for G. changii, 3.6% at 35 ppt for G. firma, and 3.2% at 15 ppt for G. tenuistipitata. In the second run, the highest daily growth rates were 1.4% for G. changii, 1.2% for G. firma, and 3.3% for G. tenuistipitata, all at 15 ppt. Nutrient and light limitation in the second run led to lower and even negative growth rates. Gracilaria changii and G. firma were euryhaline but grew best at 25–35 ppt; G.tenuistipitata was not euryhaline and grew best at 15 ppt. The highest growth rates in tanks were at salinities close to those in the natural habitat: G. changii at 25 ppt, G. firma at 35 ppt, and G. tenuistipitata at 15 ppt. The estimated potential production (dry weight kg/m²-yr) in tanks was 1.65 kg G. changii at 25 ppt, 2.49 kg G. firma at 35 ppt, and 2.35 kg G. tenuistipitata at 15 ppt. Agar yields from three Gracilaria species varied from 5% to 23%, on average lowest in G. tenuistipitatata, and were generally higher at 25 ppt and 35 ppt than at 15 ppt. Agar gel strengths were also strongly affected by salinity and were highest at 35 ppt. Gracilaria tenuistipitata had very high gel strength (average 782 g/cm² but as high as 1,082 g/cm² comparable to agarose), well above the specified 750 g/cm² for the international market. Gracilaria changii and G. firma had average gel strengths of 516 and 558 g/cm², well within the range (400–600 g/cm²) for commercial agar used in the food industry. The sulfate contents were lower at 15 ppt and were even 0% in several instances, especially in G. tenuistipitata. The gelling temperature of 32°C and melting temperature of 97.3°C qualifies G. tenuistipitata for the international market. Gracilaria changii and G. firma had melting temperatures of 93–95°C but gelling temperatures of just 29°C. Farming techniques for these seaweeds should be developed to produce enough raw material for profitable commercial processing.