סמינר מחלקתי של יואב להן- חישה מרחוק בקנה מידה של נחילי מדוזות

Multi-scale remote sensing of jellyfish swarms

Monday May 26th 2025 at 14:00 

Wolfson Building of Mechanical Engineering, Room 206 

Abstract:

The study of jellyfish swarms, which comprise large amounts of individuals that spread over broad

areas, is a multi-scale scientific endeavor. Focusing on seasonal swarms of the jellyfish

Rhopilema nomadica in the eastern Mediterranean, we show how integration of remote sensing

observations from multiple platforms enables a broad perspective on the dynamics of jellyfish swarms, providing new insights over a wide range of spatial and temporal scales - from the behavior of individuals to the spatial characteristics and biogeochemical importance of the bloom as a whole.

At the smallest scale, jellyfish swimming behavior is characterized through Lagranian tracking the

trajectories of multiple adjacent individuals as appear in videos taken by drones hovering over the

bloom. At the regional scale, time varying spatial characteristics of the jellyfish bloom are extracted from aerial images taken from light airplanes. Finally, based on comparison with consecutive satellite images of surface chlorophyll concentrations, which is used as a tracer to transport by the currents, we link the displacement of the jellyfish swarm to fine scale (~1-100 km) circulation patterns.

This research sheds new light on the characteristics of Rhopilema nomadica blooms in the

eastern Mediterranean, and emphasizes the advantages of incorporating multi-platform remote

sensing observations in regional studies of jellyfish blooms worldwide.

Bio:

Yoav Lehehn is faculty member at the Charney School of Marine Sciences in the University of Haifa. In his scientific work, Yoav is studying marine systems through synergy between in-situ measurements and remote-sensing data from airplanes, satellites and drones. Yoav’s current research focuses on promoting data-based oceanic research by automating the process of ocean data integration; development and implementation of Lagrangian methods and image analysis tools for interpretation satellite and drone imagery; and harnessing drone technology to support marine research, with emphasis on small-scale ocean dynamics and motion of marine organisms.