Jm. Johnson et al., FACTORS AFFECTING PHOTOSYNTHESIS IN THE MOZAMBICAN SEAGRASSES CYMODOCEA-SERRULATA AND THALASSODENDRON-CILIATUM, Photosynthetica, 28(2), 1993, pp. 307-312
The effect of various environmental factors on net photosynthesis rate
s (P(N)) of the differentially depth distributed Mozambican seagrasses
, Cymodocea serrulata (R.Br.) Aschers and Magnus (Zannich), and Thalas
sodendron ciliatum (Forsk.) den Hartog, was examined. At saturating ir
radiances the deeper water species, T ciliatum, showed a maximum P(N)
(as measured by short term O2 evolution) of 12.67 +/- 3.33 mmol(O2) kg
-1(Chl) s-1 with added 40 mM NaHCO3 (0.89 mM dissolved CO2 at pH 8); t
he shallower species, C. serrulata, showed maximum rates of 21.67 +/-
4.17 (10 mM NaHCO3; 0.26 mM dissolved CO2). Saturating irradiances wer
e similar for both species. P(N) estimated by the lacunal gas discharg
e technique was 16.00 +/- 5.00 mmol(O2) kg-1(Chl) s-1 for C. serrulata
and 11.67 +/- 6.67 for T. ciliatum. P(N) of both species was reduced
by increased water depth, and the pattern of the effect of depth was s
imilar.