Journal Article 27YLU75U4W Humic Substances Phosphorus Research Support, Non-U.S. Gov't climate change convolutional neural networks deep learning deep-mixing harmful algal blooms imaging flow cytometry lake browning large-scale lake survey long-term monitoring mesocosm multiple stressors multispectral imaging flow cytometry nutrient gradient plant trait pollen pollen grain size pollen variability pollinator species identification trait variability