Appendix D. Indicator species of the Trichoptera example.
Trichoptera indicator species were identified by indicator species analysis for the 5 space–time groups shown in Fig. 3. Combining indicator values and numerical dominance in each of the 5 groups, one obtains the following scenario:
• Time periods 1–2: group 2 rules along most of the transect. This group is dominated by the shredder Ceraclea diluta, the filterer Hydropsyche sparna, and the algae piercer Hydroptila delineata. The shredder Lepidostoma pictile characterizes this group thanks to a localized emergence during the first 10 days in a group of sites near the middle of the transect.
• Time periods 3–5: group 1 occupies most of the transect. Numerically, this group is dominated by the filterer Cheumatopsyche minuscula, with high numbers of the algae piercer Hydroptila valhalla. Together they form almost 60% of the total number of individuals in this group. The former species emerges during the whole period, while the latter is more concentrated around time period 4. Other species have been found to be significant indicators of this group due to high values of either specificity or fidelity.
• The 5 remaining time periods are characterized by a parcelling out of the transect, which becomes more finely partitioned, mainly among groups 3, 4, and 5. Group 3 is characterized by the algae piercer Oxyethira grisea. Group 4 is dominated by the filterer Cheumatopsyche pettiti and the algae piercer Oxyethira grisea. Group 5 is dominated by the grazer Neotrichia okopa, emerging mostly during periods 6 and 7. Another numerically important species is the filterer Cheumatopsyche minuscula, dominating group 1.