Description: The bioremediation capacity of the red macroalga Palmaria palmata was assessed by two experiments. First, uptake rates of P. palmata cultured in four treatments with varying levels and ratios of the N sources ammonium (NH4 +) and nitrate (NO3 −) (18/15, 0/30, 30/45, 50/65 μM) were measured over a 3-h period to evaluate N source preference. Secondly, P. palmata were cultured in five treatments with varying levels and ratios of ammonium and nitrate (300/12, 0/312, 500/12, 0/512, 250/262 μM) for 3 weeks to evaluate specific growth rates, protein content, and ammonia toxicity. Palmaria palmata had a higher affinity for NH4 + than for NO3 − as N source. However, in the single N source trials, NO3 − uptake was higher than that of NH4 +. The maximum specific growth rate of 11.99 % day−1 was observed in the 0/512 μM ammonium/nitrate treatment after 3 weeks, whereas the minimum specific growth rate of 2.21 % day−1 was observed in the 500/12 μM ammonium/nitrate treatment after 3 weeks. NO3 − supported higher growth rates, whereas NH4 + increased tissue N, and therefore protein content. Total protein content of the algal tissue was significantly higher in P. palmata of the NH4 + treatments, reaching up to 20.6 % DW, than of those from the NO3 -treatments. Palmaria palmata showed signs of poisoning after 3 weeks in the highest NH4 + treatment. This study indicates that P. palmata is a suitable species for ecological engineering in integrated multitrophic aquaculture systems as it shows a relatively high growth performance, high nutrient uptake rates, and elevated protein content under NH4 + supply.