A. Ojala, EFFECTS OF TEMPERATURE AND IRRADIANCE ON THE GROWTH OF 2 FRESH-WATER PHOTOSYNTHETIC CRYPTOPHYTES, Journal of phycology, 29(3), 1993, pp. 278-284
Effects of light and temperature on growth of two freshwater photosynt
hetic cryptophytes of different cell size were studied in batch cultur
es. For the smaller Cryptomonas 979/67, Steele's model and equation of
Platt et al. described the relationship between growth rate and photo
n flux density (PFD), whereas a hyperbolic tangent function gave a bet
ter fit for the larger Cryptomonas 979/62. Maximum growth rates given
by the three models were consistent with each other, but the hyperboli
c tangent function gave slightly lower estimates. Maximum growth rates
in relation to temperature were well described for both species by th
e model of Logan et al. The optimum temperature for growth for Cryptom
onas 979167 was ca. 24.5-degrees C and 19.0-degrees-C for Cryptomonas
979/62. The lethal temperatures were 30.4-degrees-C and 23. 1-degrees-
C for 979/67 and 979/62, respectively. The estimated maximum growth ra
tes were 1.38 div. .day-1 for Cryptomonas 979/67 and 0.87 div. .day-1
for Cryptomonas 979/62. There were interspecific differences in photoa
daptation strategies, as Cryptomonas 979/67 required relatively high P
FDs to show net growth, whereas Cryptomonas 979/62 grew at lower irrad
iances. Cryptomonas 979/67 showed photoinhibition soon after the satur
ation point, but Cryptomonas 979/62 tolerated a much wider range of ir
radiance. From their growth responses to light, Cryptomonas 979/67 app
ears to be a stenotopic and Cryptomonas 979/62 a eurytopic strain.