Agar yield and gel strength of Gracilaria heteroclada collected from Iloilo, Central Philippines

Seasonality of yield and gel strength of agar from Gracilaria heteroclada was determined. Gel strength was high (510-794 gm cm-2) during early dry season (October-March) and low (43-101 gm cm-2) during the wet season (May-August). A negative correlation exist (P ≤ 0.05) between agar yield and gel-strength

Biomass and reproductive states of Gracilaria heteroclada Zhang et Xia collected from Jaro, central Philippines

Biomass production and reproductive states were investigated to determine the abundance of Gracilaria heteroclada Zhang et Xia at Jaro, central Philippines from March 1990 to February 1991. Biomass of Gracilaria heteroclada was highest in February (45 g/m2) and lowest in July (1.16 g/m2). Plant fertility was seasonal with the highest percentage of carposporphytic and tetrasporophytic plants occurring in January (48%) and in May (64%) respectively. Seawater temperature was significantly correlated with tetrasporophyte occurrence (r = 0.6586) but not with carposporophyte occurrence. There was no correlation of the occurrence of tetrasporophytes or carposporophytes with salinity or rainfall

Growing the reproductive cells (carpospores) of the seaweed, Kappaphycus striatum, in the laboratory until outplanting in the field and maturation to tetrasporophyte

Carposporophytes of the seaweed, Kappaphycus striatum, from the wild were made to shed spores in the laboratory and grown in multi-step culture method until they reached maturity. For each succeeding transfer onto increasingly bigger culture vessels, there was a marked increase in the growth of carposporelings. When plantlets were ready for outdoor culture, they were placed in aquaria and concrete tanks and later moved to the sea in net cage and long-line for grow-out culture. Successfully growing sporelings from carposporophytes in the laboratory until they reach market size seems to depend on the stage of sporelings and environmental factors such as photoperiod and temperature. In this study, carpospore progenies (diploids) also matured into tetrasporophytes and haploid progenies showed resistance to higher temperature

Clonal production of Kappaphycus alvarezii (Doty) Doty in vitro

Micropropagation has proven to be a reliable method to mass produce certain crops. This method also has been applied in macroalgae to produce clones for seaweed farming. Protocols for callus production and shoot regeneration from protoplasts have been established for some seaweed species like Kappaphycus alvarezii. Cells and larger tissues, whether in solid or suspension medium, have been used to propagate clones which were later tested for suitability for farming. Although clonal production was successful, the long duration of culture in vitro limits the production process making the growing of Kappaphycus in vitro an expensive technique to produce clones. In this study, K. alvarezii was grown in vitro to develop a more efficient protocol for the production of clones. Small sections of Kappaphycus were grown in suspension for 1 month under the same temperature, light, and salinity. The type of media, source of explants, length of explants, and stocking density that resulted in the highest growth rate and survival rate were determined. Growth rate of K. alvarezii is significantly higher in media with inorganic nitrogen added than in Grund medium or Ascophyllum nodosum medium only. The appearance of shoot primordia as early as 5 days was observed in media with higher nitrogen concentration. Growth rates of explants approximately 3 and 5 mm are significantly higher than 10 mm sections. Shoots develop significantly faster in explants from tips than sections from older branches. Growth rate of K. alvarezii grown at 0.5, 0.75, 1, 1.25 s 10 mL−1 of medium is not significantly different. This protocol could significantly reduce the (1) time of culture and (2) cost of plantlets production by not using plant growth regulators and formulated media in vitro. Nursery reared plantlets/propagules for farming would be affordable to the stakeholders for sustainability of seaweed production

Growth and agar quality of Gracilaria heteroclada (Zhang et Xia) grown in a filter tank

Gracilaria heteroclada Zhang et Xia was grown in filter tanks to determine the growth, agar quality and uptake pattern of nitrogen and to observe the water quality in recirculating water system with seaweed. Rapid uptake of nitrogen in G. heteroclada was observed within the first 24th of culture. Filling up of the nitrogen pools in the cell may have continued until the fifth day, the plants started to increase in weight, proportionate to the uptake rate of nitrogen duing the experiment. G. heteroclada stocked at 1 kg m-2achieved a specific growth rate (SGR) of approximately 10.4% d-1 during 15d of culture, at total ammonia-nitrogen and nitrite-nitrogen levels of 0.03-0.27 mg L-1 and 0.04-0.19mg L-1, respectively, in the filter tank. Approximately 11% of nitrogen in the water was removed by the seaweed

Seaweeds of Panay

This practical book on the seaweeds of Panay, Philippines, acquaints and provides information to members of the academe and research institutions, policy makers, fishermen and businessmen regarding the taxonomy, distribution, ecology and economic importance of these resources. It consists of 4 major parts: (1) Introduction, which reviews the literature, habitat, distribution, morphological structure and reproduction; 2) Classification, which describes the classes to which the seaweeds generally belong; 3) Collection and preservation, which explains the procedure used in treatment of specimens; and, 4) Taxonomic list. A glossary is included, covering technical terms used. All species listed and described in this book are macrobenthic and were collected in Panay and Guimaras Islands.2nd Ed

Solar irradiation as an alternative bleaching process for agar extracted from Gracilariopsis heteroclada in Iloilo, Philippines

The current industrial practice of using chemical bleach to achieve the pure white colour of agar is deleterious to both human and environmental health. This study evaluates the potential of solar irradiation as an alternative bleaching process for agar extracted from Gracilariopsis heteroclada in Iloilo, Philippines. The physico-chemical properties of agar obtained from alkaline-treated seaweed after exposure to different bleaching conditions (e.g. solar irradiation, hypochlorite solution, and ultraviolet and fluorescent lights) were examined and compared with commercial bacteriological agar. Photobleaching through solar irradiation produced agar with superior gel strength (1038.61 g cm−2), high 3,6-anhydrogalactose content (41.44%) and low total inorganic sulphate content (1.87%) without compromising agar yield (19.37%). Solar irradiation offers very promising results as a simple, low-cost, environmentally friendly alternative to the chlorine bleaching process for agar extraction.This study was funded by the Department of Science and Technology – Science Education Institute – Accelerated Science and Technology Human Resource Development Program (DOST-SEI ASTHRDP) and the University of the Philippines Visayas Thesis Support Grant. The authors would like to acknowledge the Institute of Fish Processing Technology, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, and the Seaweed Laboratory of the Southeast Asian Fisheries and Development Center – Aquaculture Department (SEAFDEC-AQD) for providing access to laboratory facilities

Monthly variation of agar quality of some gracilarioids from the Philippines (Rhodophyta, Gracilariaceae)

Species of the economically important gracilarioid seaweeds from the Philippines were studied to determine the monthly variation in agar quality. Yield, gel strength, melting and gelling temperatures, and sulfate contents were compared. Lowest agar yield was observed in Gracilaria changii in July (4.15%) and highest in Gracilariopsis heteroclada in March (20.84%). Gel strength was lowest in G. heteroclada in November (44 g cm-2) and highest in Gracilaria tenuistipitata in January (874 g cm-2). Melting temperature was lowest in G. heteroclada in November (68.7°C) and highest also in G. heteroclada in January (90.3°C). Gelling temperature was lowest at 34.4°C in G. changii and Gracilaria firma in November and December, respectively; and highest in G. heteroclada in October (45°C). Sulfate content was lowest in G. firma in November (0.16%) and highest in G. heteroclada in February (2.71%). The variation in the agar parameters could be due to different composition of agars of different species. Sulfate is significantly lower in Gracilaria firma. Yield is significantly higher in Gracilariopsis heteroclada. There is no significant difference in the gel strength, melting and gelling temperatures among species

Photosynthetic responses of ‘Neosiphonia sp. epiphyte-infected’ and healthy Kappaphycus alvarezii (Rhodophyta) to irradiance, salinity and pH variations

Understanding the physiological condition of seaweeds as influenced by biotic and abiotic stress is vital from the perspective of massive expansion and sustainability of seaweed-based industries. The photosynthetic responses ofNeosiphonia sp. epiphyte-infected (INF) and healthy (HEA) Kappaphycus alvarezii under various combinations of irradiance, salinity and pH were studied using photosynthesis-irradiance (P-E) curves. Measurements of algal photosynthetic rates, expressed in terms of amount of oxygen production per fresh weight biomass per unit time (mg O2 g−1 FW h−1), were carried out using the light-dark bottle technique. Neosiphonia-infected K. alvarezii (INF) had lower photosynthetic rates than healthy ones (HEA). Similarities (p > 0.05) in light-saturated photosynthesis rates (Pmax) and significant differences (p < 0.05) in initial slope of curve (α) between INF and HEAK. alvarezii suggest that both samples are adapted to similar light conditions and differs only on photosynthetic efficiency. Low Pmax (0.7–2.0 mg O2 g−1 FW h−1) and high initial saturation irradiances (Ek = 90–519 μmol photons m−2 s−1) of INF seaweeds resulted to their low photosynthetic efficiency (α = 0.002–0.010). Such decline in α is attributed to the epiphyte, as Neosiphonia sp. covered almost the entire surface of K. alvarezii. An increase in chlorophyll-a (35–42.1 vs. 27.7–31.5 μg g−1 FW, HEA) and phycobilin (1.96–2.39 vs. 1.16–1.58 mg g−1 FW, HEA) contents was also observed in INF samples, suggesting acclimation to low-irradiance conditions, as a result of competition for light between the epiphyte and host. Both INF and HEA K. alvarezii also exhibited broad photosynthetic tolerance to short-term changes in irradiance, with no photoinhibition at the highest irradiance of 850 μmol photons m−2 s−1. K. alvarezii had a euryhaline photosynthetic response, with optimum salinity of 35 psu. Photosynthetic rates increased with decreasing pH, revealing K. alvarezii’s ability to modify its photosynthetic affinity for acidic seawater conditions; yet, their underlying mechanism of response to pH shifts still need to be further examined.This research was funded in part by the University of the Philippines-Visayas (UPV) through the Office of the Vice-Chancellor for Research and Extension and Southeast Asian Fisheries Development Center Aquaculture Department. This research was the thesis submitted by the first author in fulfilment of her degree in Master of Science in Biology at UPV