Development of new direct methods to quantify zooplankton feeding in situ, is necessary to gain a better understanding of the trophic interactions in aquatic ecosystems. We propose to develop a potentially powerful method, based on state-of-the-art molecu lar techniques, including quantitative real-time PCR and DGGE. Preliminary studies conducted collaboratively with the US host institution, Skidaway Institute of Oceanography (SkIO), have provided initial molecular methods, proof of concept data, and estab lished a functional working relationship between all of the proposed collaborators. The methods will be used to investigate complex interactions between key plankton species for Norwegian waters. The work will be conducted at SkIO, the National Mesocosm C enter at Univ. of Bergen (UoB) and in North Norwegian fjords, in close cooperation with the ongoing large-scale study of “complex adaptive systems” at SkIO. The proposed project will benefit from the US funded project, have a considerable potential to produce ground-breaking and broadly significant advancements in methodology and marine ecology, introduce new state-of-the-art competence in ecological methodology of high relevance to the Food Chain Research Center at UoB, devel op a fruitful cooperation with the internationally distinguished group from SkIO, and stimulate increased cooperation between Norwegian institutions, especially on new applications of molecular methods in aquatic ecology.