The diet of deep-sea macrobenthic isopods (Crustacea, Malacostrace) and polychaetes (Annelida) with focus on the importance of foraminiferans for their nutrition

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The limited investigations studying the functioning of abyssal ecosystems still leave many unanswered questions. This is also the case for the Southern Ocean deep sea, a habitat with high abundances of protozoan foraminiferans, peracarid crustaceans (namely isopods) and polychaete worms. To gain knowledge on their ecological interactions, the proposed project aims at 1) investigating the diet of abyssal isopods and polychaetes, focusing on the role of foraminiferans, 2) the establishment of molecular methods to identify invertebrate gut contents, and 3) revealing possible mechanisms connected with distinct feeding preferences which might underlie the high degree of diversity found in deep-sea taxa. Epibenthic sledge samples from four previous Polarstern expeditions (ANDEEP I-III and SYSTCO) as well as new material will be analysed. To answer the targeted questions, selected methods will be employed including microscopic gut content analysis, studying functional morphology of mouthparts as well as the designing and optimisation of genetic primers to conduct gut content analyses based on PCR methods (which are even applicable if the gut content is not identifiable by microscopy). The latter include the testing of different universal primers to develop a suitable method for the analyses of an organism’s general diet as well as the application of foraminiferan specific primers to define the role of different foraminiferan species in the diet of isopods and polychaetes. The results will not only deliver information on the diet of deep sea macrobenthos of the Southern Ocean including the role of foraminiferans, but also provide an innovative tool to analyse the diet of various organisms in the future.