Nutrient limitation in Ellis Fjord, eastern Antarctica

The occurrence of high chlorophyll-a concentrations (up to 11.6μgl-1) at shallow depths within Ellis Fjord, eastern Antarctica, during spring and summer, coincided with the development of a stratified water column. Macronutrient concentrations during periods of high chlorophyll-a levels were very low. Phosphate concentrations decreased to 0.2 μM, nitrate to 0.4 μM and silicate to 3.9 μM. High rates of nutrient depletion early in the season can be explained by strong sea-ice algal mat development. An Si:N:P uptake ratio of 25.5:13.8:1 indicates a strong demand for silicate. Minimum silicate levels were below those necessary for maximum diatom growth and probably contributed to the successional shift from diatoms to phytoflagellates. © 1995 Springer-Verlag.