The role of bacteria in the nutrition of silver carp was studied by in-vim tests, which confirmed earlicr results that the potentially important source of nitrogen in bacteria is not utilized by the fish. Cultures of aerobic and anaerobic bacteria, recovered from a fish pond, were incubated with digestive fluids from the gut contents and from tissues surrounding the alimentary tract (Organ of Leydig) respectively. Growth of aerobic isolates was not affected by the digestive fluids whereas growth of all anaerobes was inhibited. A susceptibility test revealed a bacteriostatic rather than bactericidal effect of the digestive fluid on the bacteria. During 42 h incubation at approximately 20 "C of gut fluid, trypsin activity decreased between 14% (in fore-gut fluid) and 62% (in mid-gut fluid). The addition of aerobic bacteria (to the mid-gut fluid) or anaerobic bacteria (to the fore-gut fluid) did not accelerate the degradation of trypsin.

Soil function assessments (SFA) are becoming increasingly important as a tool to integrate soil-related issues in decision-making processes in order to maintain soil quality. We present the SEPP (Soil Evaluation for Planning Procedures) tool, which calculates a level of fulfillment for 14 soil functions based on the information generally collected in soil pit descriptions. By using a statistical modeling approach based on support vector machine classification, we investigate how and to what extent topography, as representated by local terrain parameters and landform classes computed with the GRASS GIS tool r.geomorphon algorithm, controls soil parameters and hence the output of the SEPP tool. A feature selection procedure is applied which highlights those topographic attributes best suited for modeling the various soil function fulfillment levels. By evaluating the model for each soil function using cross-validation we show that the prediction accuracy varies from function to function. While some terrain attributes are directly implemented in the SFA algorithms of SEPP, others are implemented indirectly due to the link between topography and land use. Minimal curvature and slope were found to be first indicators of function fulfillment level for a number of soil functions.

Information (databases, classifications, and maps) on soils in the Alps is rather scattered and not readily available, especially for non-agricultural areas and those above the timberline (Baruck et al., 2016;Schaber & Geitner, 2020). However, results from several case studies indicate a remarkable diversity of soils in high-mountain regions,

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