The bacterial isolates from normal and diseased branches of Kappaphycus alvarezii and Eucheuma denticulatum in the Philippines were examined for possible role in the development of the ice-ice disease. The numbers of bacteria on and in ice-iced branches were 10-100 times greater than those from normal, healthy ones. Grampositive bacteria predominated in almost all branch sources, but with an increasing proportion of agar-lysing bacteria in branches suffering from the ice-ice disease. These agar-lysing bacteria were composed of yellow and non-pigmented, spreading colonies identified to the Cytophaga-Flavobacterium complex and the Vibrio group. Among isolates which mainly appeared on ice-iced branches, two strains, designated as P11 (Vibrio sp.) and P25 (Cytophage sp.), which showed pathogenic activity, were obtained. These strains caused early ice-ice whitening of K. alvarezii especially when subjecting branches to environmental stress, such as reduced salinity and light intensity, suggesting that these bacteria were occasionally pathogenic. This paper offers new evidence of bacterial role in the development of so-called ice-ice disease among farmed species of Kappaphycus.

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This review paper presents information on the production status of economically important seaweed species in the Philippines, new culture technologies for Halymenia durvillei and also an examination of the present but limited use of Sargassum. The country recorded its highest production volume of seaweeds (mainly eucheumatoids) in 2011 amounting to 1,840,832 metric tons (fresh weight). In the subsequent years, the Philippines recorded a steady decline in production which can be attributed to epiphytism, loss of genetic diversity due to the culture methods used (i.e. vegetative propagation), political unrest in the main farming areas of the Southern Philippines, and the frequent occurrence of typhoons. The more than 200,000 ha of farmable areas along available coastlines remain to be tapped and evaluated in order to determine which areas are suitable for seaweed farming. The haphazard harvesting of Sargassum led to the proclamation of Fisheries Order No. 250 which prohibits harvesting of Sargassum. Exploitation of Gelidiela acerosa remains a concern as there is no currently available culture technology for the species. The lack of comprehensive records on Philippine seaweed production needs to be addressed and its diverse algal resources remain to be explored.

The most common perception of unfavorable environmental factors causing the ice-ice disease in the farmed seaweeds, Kappaphycus and Eucheuma, was demonstrated in this study for the first time using stressful conditions of abiotic factors in a continuous culture system. Light intensity of less than 50 /mol photon m -2 s-1 and salinity of 20%o or less induced ice-ice whitening characterized by short segments at midbranches which were similar to those observed in the Philippine seaweed farms, while temperatures of up to 33-35 C resulted in wide-scale whitening leading to complete damage of the branches. These effects were preceded by slow growth rates from an optimum of 3.7% d -1 to almost -2.0% d -1. Mechanical stress by wound injury did not result to ice-ice whitening similar to the above. Environmental factors observed to trigger ice-ice in the laboratory, although may not necessarily parallel those in the field, may act synergestically to produce similar effects.

Seaweed aquaculture beds (SABs) that support the production of seaweed and their diverse products, cover extensive coastal areas, especially in the Asian-Pacific region, and provide many ecosystem services such as nutrient removal and CO 2 assimilation. The use of SABs in potential carbon dioxide (CO 2 ) mitigation efforts has been proposed with commercial seaweed production in China, India, Indonesia, Japan, Malaysia, Philippines, Republic of Korea, Thailand, and Vietnam, and is at a nascent stage in Australia and New Zealand. We attempted to consider the total annual potential of SABs to drawdown and fix anthropogenic CO 2 . In the last decade, seaweed production has increased tremendously in the Asian-Pacific region. In 2014, the total annual production of Asian-Pacific SABs surpassed 2.61 × 10 6 t dw. Total carbon accumulated annually was more than 0.78 × 10 6 t y −1 , equivalent to over 2.87 × 10 6 t CO 2 y −1 . By increasing the area available for SABs, biomass production, carbon accumulation, and CO 2 drawdown can be enhanced. The conversion of biomass to biofuel can reduce the use of fossil fuels and provide additional mitigation of CO 2 emissions. Contributions