Fig. 1. 3D fluorescence spectra and contour maps of algae. (a) 3D fluorescence spectrum of Chlorella; (b) contour map of Chlorella; (c) 3D fluorescence spectrum of Aureococcus anophagefferens; (d) contour map of Aureococcus anophagefferens; (e) 3D fluorescence spectrum of Synechococcus elongatus; (f) contour map of Synechococcus elongatus;(g) 3D fluorescence spectrum of Prorocentrum donghaiense; (h) contour map of Prorocentrum donghaiense; (i) 3D fluorescence spectrum of Thalassiosira rotula; (j) contour map of Thalassiosira rotula; (k) 3D fluorescence spectrum of Dunaliella salina; (l) contour map of Dunaliella salina

Fig. 2. Fluorescence excitation spectra of Aureococcus anophagefferens at different growth periods

Fig. 3. Structural diagram of GBDT model

Fig. 4. Relationship between model accuracy and decision tree parameters. (a) Relationship between prediction accuracy and number of decision trees; (b) relationship between prediction accuracy and maximum number of leaf nodes

Fig. 5. Flowchart of GBDT-LR model

Fig. 6. Comparison of ROC curves of different classification models

Fig. 7. Comparison of classification results of various models under different growth periods. (a) Algae samples of first week; (b) algae samples of second week; (c) algae samples of third week; (d) algae samples after third week