Chemotactic response (CR) of the four chytrid types (Chytridium sp., Rhizophydium sp. type I and type II a and b) to different attractants tested as individual standards and mixtures: (a) carbohydrates; (b) amino acids; (c) fatty acids; (d) others (quaternary ammonium compounds and polyol glycerol); and (e) mixtures of standards and host extracts obtained from the specific diatom host cultures grown under standard culture conditions (10 °C, 12:12 h light:dark (L:D), 50 μmol·photons·m‒2·s‒1; host extract I) and a 24 h light regime, including 6 h UV exposure (host extract II). Furthermore, mixtures simulating the presence of stressed diatoms hosts were also tested (mix I: salinity of 10; mix II: salinity of 40; mix III: temperature of 20 °C and mix IV: 24 light + UVR). The CR values were calculated as described in Section 4.4.1.1, including the data given in Table 3 The individual concentrations of each standard and mixture are given in Table 2.