"Mak-Pak" or "Mak-Pak Scale-Up" is a project for the industrial implementation and use of a packaging concept consisting of macroalgae in the food sector. The aim is to develop a biode-gradable, sustainable and edible packaging material from macroalgae as a dosage form and for "out-of-home" consumption. For this, different algae strains will be studied and the best conditions for high productivity will be researched. The growth and the complex reproduc-tion cycle play a major role in biomass production. This thesis intends to answer the ques-tion how different salinity treatments (10,15,20 and 30 PSU) affect the growth and photo-synthetic activity of germlings from Ulva lacinulata, Ulva californica and Ulva linza. By meas-uring the photosynthetic activity and growth, optimization of the experimental method was developed. The different salinities of 10,15,20 and 30 PSU showed significant differences in grow area and relative growth rate. The photosynthetic activity differed, but not signifi-cantly. Differences in the tolerability of different salt levels have been shown between spe-cies. The method of experimental setting was optimized and discussed. Based on the opti-mized method the question if it’s possible to use this method to differentiate between phases of the life cycle (between Gameto- and Sporophytes) was explored for Ulva califor-nica. In cultivation selective breeding plays a major role. Using the photosynthetic activity to differentiate between lifecycle stages seemed inconclusive and is discussed.