Nippon Suisan Gakkaishi 68 (3), 356-361 (2002)

Effects of temperature, salinity and irradiance on the growth of the diatom Eucampia zodiacus caused bleaching of seaweed Porphyra isolated from Harima-Nada, Seto Inland Sea, Japan

TETSUYA NISHIKAWA

1Fisheries Technology Institute, Hyogo Prefectural Technology Center for Agriculture, Forestry, and Fisheries, Akashi, Hyogo 674-0093, Japan

The effects of temperature and salinity on the growth of Eucampia zodiacus isolated from Harima-Nada were examined for 42 different combinations of temperature 5-30°C and salinity 10-35 under 150μmolm−2s−1 and 12h:12h light:dark photo cycle. The growth of E. zodiacus was observed at 7°C to be ≥15 and most of the combinations examined. The maximum growth rate of 3.00d−1 was obtained with the combination of 25°C and 25, respectively. The range of optimum temperature and salinity is not in good accordance with the field data in Harima-Nada, when the spring bloom of E. zodiacus occurs.

The effect of irradiance on the growth of E. zodiacus was studied at 14 different irradiance conditions ranging from 5 to 385μmolm−2s−1 with 10h:14h light:dark photo cycle under 20°C. This species grew well at the irradiance of 10μmolm−2s−1 and higher, then the growth saturated at 150μmolm−2s−1. The irradiance-growth curve closely resembled the following formula μ=3.08(I-7.9)/(I+47.0), where μ is the specific growth rate (d−1) and I is the irradiance (μmolm−2s−1). The maximum growth rate of 3.08d−1 and Ks (value of I at which μ=μm/2) of 62.8μmolm−2s−1 were obtained in this experiment.


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