Global warming and environmental pollution threaten aquatic ecosystems. While interactive effects between both stressors can have more than additive consequences, these remain poorly studied for most taxa. Especially chronic exposure trials with vertebrates are scarce due to the high time- and monetary costs of such studies. We use the recently-established fish model Nothobranchius furzeri to assess the separate and combined effects of exposure to the pesticide chlorpyrifos (at 2 µg/L and 4 µg/L) and a 2 °C temperature increase. We performed a full life-cycle assessment to evaluate fitness-related endpoints including survival, total body length, maturation time, fecundity, critical thermal maximum (CTmax) and locomotor activity. Exposure to 4 µg/L chlorpyrifos slowed down male maturation, reduced fecundity and impaired growth of the fish. While the temperature increase did not affect any of the measured endpoints on its own, the combination of exposure to 2 µg/L CPF with an increase of 2 °C reduced growth and severely reduced fecundity, with almost no offspring production. Together, these findings suggest that climate change may exacerbate the impact of environmental pollution, and that interactive effects of chronic exposure to multiple stressors should be considered to predict how populations will be affected by ongoing global change.

Agricultural management in Europe faces increasing pressure to reduce its environmental footprint. Implementing precision agriculture for weed management could offer a solution and minimize the use of chemical products. High spatial resolution imagery from real time kinematic (RTK) unmanned aerial vehicles (UAV) in combination with supervised convolutional neural network (CNNs) models have proven successful in making location specific treatments. This site-specific advice limits the amount of herbicide applied to the field to areas that require action, thereby reducing the environmental impact and inputs for the farmer. To develop performant CNN models, there is a need for sufficient high-quality labelled data. To reduce the labelling effort and time, a new labelling method is proposed whereby image subsection pairs are labelled based on their relative differences in weed pressure to train a CNN ordinal regression model. The model is evaluated on detecting weed pressure in potato (Solanum tuberosum L.). Model performance was evaluated on different levels: pairwise accuracy, linearity (Pearson correlation coefficient), rank consistency (Spearman’s (r_s) and Kendal (τ) rank correlations coefficients) and binary accuracy. After hyperparameter tuning, a pairwise accuracy of 85.2%, significant linearity (r_s = 0.81) and significant rank consistency (r_s = 0.87 and τ = 0.69) were found. This suggests that the model is capable of correctly detecting the gradient in weed pressure for the dataset. A maximum binary accuracy and F1-score of 92% and 88% were found for the dataset after thresholding the predicted weed scores into weed versus non-weed images. The model architecture allows us to visualize the intermediate features of the last convolutional block. This allows data analysts to better evaluate if the model “sees” the features of interest (in this case weeds). The results indicate the potential of ordinal regression with relative labels as a fast, lightweight model that predicts weed pressure gradients. Experts have the freedom to decide which threshold value(s) can be used on predicted weed scores depending on the weed, crop and treatment that they want to use for flexible weed control management.