Algae. 2002; 17(4): 249-257.
Time-dependent Variation of Growth and Nutrient Uptake of Ulva pertusa Kjellman (Chlorophyta) from Intertidal Eelgrass Beds
Tae Seob Choi, Kwang Young Kim
Department of Oceanography, Chonnam National University
The growth of green macroalgal mats is becoming increasing common in many marine intertidal habitats. While the ecological consequences of such growth have been experimentally investigated on various tidal flats, such experiments have rarely been performed on intertidal seagrass beds. This study investigated the ecophysiological characteristics of Ulva pertusa Kjellman (hereafter Ulva) originating from an oligo-mesotrophic eelgrass beds, Haenam, southwestern coast of Korea. The nutrient uptake capacity and growth rate of Ulva were examined over time interval of 2, 4, 7 d. At end of experiment, chlorophyll a and tissue nutrient contents of Ulva were estimated to relate with increasing of nutrient in the culture medium. Growth rate of Ulva showed 0.028-0.063 d-1 according to variation of nitrate and phosphate concentrations. Change of growth rate as a function of time course was not significantly different and similar to change of nutrient uptake. Chlorophyll a concentration was positively related to increasing nitrate concentrations (r² = 0.999, p < 0.001). It was also related to the tissue nitrogen content of Ulva. In conclusion, we found that growth rate and nutrient uptake of Ulva did not susceptibly change for short term in laboratory experiment. Especially, Ulva should have a very reduced storage capacity of nitrogen so far as relationship between chlorophyll a with substrate concentration of nitrate and tissue nitrogen content. These results suggest that ulva from eelgrass beds is well adapted to oligotrophic water as adjusting its growth and nutrient uptake.
Keywords : carbon, chlorophyll, growth rate, nitrogen, nutrient uptake, phosphorus, Ulva