Nicola Castelnuovo

This study investigates underwater debris in a freshwater lake using remotely operated vehicles (ROVs) during two distinct survey periods: 2019 and 2024. The primary objective was to count and document visible debris (metal and plastic) on the lakebed based on ROV video recordings. A total of 356 debris items were observed in 2019, while only 39 items were recorded in 2024. The notable decrease in debris visibility in 2024 is likely attributed to dense algal growth during the survey months, which hindered the visual identification of objects on the lakebed. The study highlights the challenges of monitoring underwater debris in freshwater systems, particularly during periods of high algal activity, which can significantly impact visibility and detection efforts. While ROVs have proven effective in identifying submerged debris in clear water, this research underscores their limitations under reduced visibility conditions caused by algal blooms, turbidity diminishing the video quality. The results provide valuable insights into the temporal variation in debris visibility and contribute to ongoing efforts to improve freshwater debris monitoring techniques.

In the Anthropocene era, lake ecosystems are facing significant human-related pressures, resulting in a decline in both biodiversity and habitat quality. Restoration initiatives can effectively enhance the resilience of freshwater environments. This research delves into various established and novel method aimed at encouraging the growth of a macrophyte, Vallisneria spiralis, in the littoral zone of Lake Como, a southern alpine Italian lake. For this aim, Vallisneria spiralis was collected and placed in tanks filled with four different types of 3D-printed biodegradable substrates. Remarkably, the plant demonstrated a growth rate of 4 mm per day, increasing from an initial number of 12 plants to 400 after four months, with a total surpassing 700 specimens by the conclusion of the study. Following their introduction into the natural environment, the survival rate of plants positioned on substrates that remained stable and in contact with the lakebed reached 85.7%. This research is the first to indicate that Vallisneria spiralis could be a viable option for restoration projects in coastal lake habitats, particularly when utilizing biodegradable substrates. The hope is that this study can serve as a valuable model for future restoration initiatives and improve sustainability of freshwater ecosystems.