Cj. Dawes et al., Response of the tropical red seaweed Gracilaria cornea to temperature, salinity and irradiance, J APPL PHYC, 10(5), 1998, pp. 419-425
The agarophyte Gracilaria cornea, collected over 2.5 y in the Florida Keys,
shows adaptations to oceanic salinities and subtropical to tropical water
temperatures in its photosynthetic and respiratory responses as measured wi
th a respirometer. No seasonal pattern in responses to irradiance, temperat
ure, and salinity were evident between five collections over a 20-month per
iod, indicating the tropical nature of the populations from Bahia Honda and
Pigeon Keys. Concentrations of chlorophyll a (0.09 to 0.41 mg g d wt(-1))
and phycoerythrin (0.06 to 0.36 mg g d wt(-1)) were low and reflect the low
nutrient regime of the habitats, especially when compared to laboratory cu
ltured plants. Compensation and saturation irradiances were also low (11-38
and 90-127 mu mol photon m(-2) s(-1)), indicating acclimation to lower irr
adiances in their shallow (1-2 m depth) habitats where turbidity can be hig
h. In comparison with other subtropical and warm temperate species of Graci
laria, G. cornea had lower levels of pigment, but similarly high photosynth
etic efficiency, demonstrating shade adaptation; it had only limited tolera
nce to salinities below 20 parts per thousand and temperatures below 15 deg
rees C. Thus, G. cornea from the Florida Keys in mariculture would require
subtropical to tropical temperatures and stable oceanic salinities.