Temporal dynamics of the depth diversity gradients
The DDG measures of the different richness components show different degrees of invariability (IV ) as measure for stability. TheIV of Gamma richness (mean=7.14, sd=3.69), ofD(α,max) (mean=6.62, sd=4.11), ofR(α,max) (mean=6.36, sd=2.87), ofR(β,max) (mean=5.89, sd=2.06) and ofR(γ,max) (mean=6.52, sd=2.97) were high in comparison to the IV of D(β,max)(mean=1.56, sd=0.48) and of D(γ,max) (mean=1.78, sd=0.53).
For all lakes depth-independent gamma richness showed a small but significant trend (p  < 0.1) towards more species (Supporting information). Analysing all lakes together, the DDG measures revealed no significant common trend (p  > 0.05) (Supporting information). For individual lakes slopes of significant linear models of the Dmax andRmax over years showed mostly positive trends (richness increasing and peaking at shallower depths, see Supporting information). The D(α, max) shows two significant positive trends (peak shifting towards water surface – lake Starnberg and lake Tegernsee) and two significant negative trends (peak shifting to deeper waters – lakes Großer Alpsee and Woerthsee). TheD(β, max) increases significantly at Lake Riegsee, while D(γ, max) increases for lakes Riegsee, Staffelsee Nord and Tegernsee. For total gamma richness, lakes Chiemsee, Staffelsee Nord, Staffelsee Süd and lake Starnberg show positive trends (Table 2).