Soil algae are the most important primary producers where vascular plants are absent, as in the Arctic and Antarctica. They give rise to species-rich microbial food webs in biological soil crusts (biocrusts). The terrestrial snow- and ice-free areas are in permanent expansion as glaciers retreat, leaving behind extensive areas of uncovered rock and new soil. Biocrusts stabilize the soil surface and have an important role in soil development. However, the microbial food webs and the nutrient and energy flow to higher trophic levels remain largely unexplored. Here, we characterized the microbial predator-prey dynamics of polar soils by combining molecular and traditional culturing techniques. Using high-throughput sequencing of environmental samples, we assessed the biodiversity and function of soil protists, applying a trait-based approach for acquiring and describing functional traits, i.e., the feeding behavior of heterotrophic protists in relation to microalgae. The study encompasses the analysis of biocrust samples of three polar regions. In the Arctic, one region was sampled - Svalbard in the Arctic Ocean (78°N) in July 2021. In Antarctica, two regions were studied, i.e. King George Island (62°S) in the South Shetland archipelago of Maritime Antarctica and the Thala Hills oasis in Enderby Land, East Antarctica (67°S), between January and March 2022.
The ingestion rates of the heterotrophic protist Polykrikos kofoidii feeding on three different species of Alexandrium were determined by means of incubation experiments in well-plates. In this experiment P. kofoidii was subjected to prey mixtures consisting of A. pseudogonyaulax (strain L4-B9) and A. catenella (strain Alex 5) or A. limii (strain Atay99Shio-02), whereby one prey was dyed with the fluorescent dye CMAC. The dye had no influence on the feeding behaviour of P. kofoidii and thus dye combinations of the same prey mixtures were combined. This dataset contains all data collected within this experiment including cell counts and ingested prey cells of P. kofoidii. The experiments were carried out on January 18, 2023 in the laboratories at the Alfred-Wegener-Institute in Bremerhaven, Germany.
The ingestion rates of the heterotrophic protist Polykrikos kofoidii feeding on different species of Alexandrium were determined by means of incubation experiments in well-plates. In the first experiment P. kofoidii was subjected to monoalgal prey consisting of either lytic goniodomin producing A. pseudogonyaulax (Limfjord, Denmark, strain L4-B9) or a non-lytic paralytic shellfish toxin producing Alexandrium catenella (Scottish east coast North Sea, strain Alex 5). In the second experiment P. kofoidii was subjected to prey mixtures consisting of A. pseudogonyaulax (strain L4-B9) and A. catenella (strain Alex 5) or goniodomin producing non-lytic A. limii (Shioya Bay, Japan, strain Atay99Shio-02), whereby one prey was dyed with the fluorescent dye CMAC. The experiments were carried out between December 2 and 5, 2022 and on January 18, 2023 in the laboratories at the Alfred-Wegener-Institute in Bremerhaven, Germany.