menu.header.image.unacom.logo
 

Journal Articles - UP - MSI

Permanent URI for this collectionhttps://repository.unesco.gov.ph/handle/123456789/50

Browse

Filters

1988 - 198911990 - 19951

Settings

Author: search.filters.author.Belda, C. A.

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Phosphate acquisition in the giant clam-zooxanthellae symbiosis
    Belda, C. A.; Yellowlees, D. (Springer, 1995-12)
    The effect of phosphate on the giant clam Tridacna gigas and on its symbiotic dinoflagellate Symbiodinium sp. was compared with that on cultured Symbiodinium sp. originally isolated from the same clarn species. Incubation of whole clams in elevated phosphate (10 μM) reduced their capacity for phosphate uptake, but the uptake capacity of the clam's zooxanthellae population was not influenced. In addition, there was no change in the zooxanthellae density and the N:P ratio, of these algae. On the other hand, cultured zooxanthellae were influenced by the phosphate regimen of their culture medium. Compared with controls (0 μM P), addition of 10 μM phosphate to the culture medium caused an increase of 100% in cell density and decreases of 50% in the N:P ratio, and 80% in the phosphate-uptake capacity of the zooxanthellae. Zooxanthellae freshly isolated from the clams exhibited properties similar to those of zooxanthellae cultured in the absence of phosphate. These results demonstrate that the zooxanthellae population of T. gigas have limited access to the inorganic phosphate in sea water and the phosphate reserves within the animal host.
  • Thumbnail Image
    Notes on the induced spawning and larval rearing of the Asian moon scallop, Amusium pleuronectes (Linné), in the laboratory
    Belda, C. A.; Del Norte, A. G. C. (Elsevier, 1988-08)
    Sexual and chemical stimulations were effective in inducing the scallop, Amusium pleuronectes (Linné), to spawn sperm only, whereas thermal stimulation was not at all successful. Chemical stimulation consisted of serotonin injections into the ripe gonads. Fertilizable eggs were obtained by stripping gametes from the ovaries. Cleavage of zygotes (72.4 μm mean diameter) occured 1 h after fertilization. Trochophores (58.9–111.2 μm in length) and straight-hinge veligers or D-veligers (80.0–130.2 μm) were observed in less than 24 h. Five days after fertilization, the umbone stage (101.6–169.1 μm) was reached. Crawling pediveligers (174.0–250.0 μm) appeared after 9 days. Seawater in the culture vessels was changed 24 h after fertilization and every other day thereafter. The larvae were fed on Isochrysis galbana (Tahitian strain) at an initial concentration of 30 cells/gml.