On the Swedish west coast the Japanese wireweed represents one of the most prominent changes in modern history. Many scientists consider the alga negative for the ocean’s ecosystem. The problem is that the Japanese wireweed is an opportunistic brown alga and in many perspectives very competitive in contrast to the alga bladder wrack. On the other hand, there is no real comparison between these two algae’s effects on the ocean’s ecosystems. The question whether the Japanese wireweed is negative as a replacement for bladder wrack, is still not answered. This leads to the purpose of the research. The project aims to compare the degree of covering epiphytes and the animals’ populations between these two algae, to see possible differences between them.