engleski

Chaetoceros peruvianus Brightwell, 1856: A generalistic/opportunistic approach to success in the northern Adriatic plankton

The northern Adriatic is a very suitable ecosystem for observing phytoplankton under a variety of different ecological conditions. This shallow basin is characterized by steep gradients of nutrient concentrations with an expressed N/P imbalance and sustained phosphate limitations. Here we characterize the non bloom forming, omnipresent, planktonic diatom Chaetoceros peruvianus Brightwell, 1856 with respect to its presumed life strategy in the northern Adriatic. Long term data of phytoplankton monitoring suggests omnipresence of C. peruvianus. To further understand the metabolic adaptation of C. peruvianus we report growth rates, phosphate uptake rates, alkaline phosphatase activity, alkaline phosphatase localization and activation patterns and characteristics of alkaline phosphatase enzyme activity. We observed cell cycle durations of about 24 h and only little differences between growth rates in F/2 medium and in P-limited medium. P uptake rates around 1.13 pm/cell/day could be perceived in F/2 medium as well as in P-limit medium. However, during the adaptation phase to P-limited conditions significantly lower P-uptake rates where observed. Cellular alkaline phosphatase activity was up to 20 am/s/cell. In P-limited conditions we could measure Km values of 64 μM. Observed morphological adaptations include the transition between different forms. All results combined suggest C. peruvianus to be a generalistic/opportunistic phytoplankton species

phytoplankton ; Adriatic Sea ; diatoms ; Chaetoceros ; APA ; P limitation

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