High-resolution spatio-temporal quantification of fish predator-prey interactions over ecosystem scales with multispectral underwater sensing and optimality of human visual perception with natural daylight

• Main Author: Pednekar, Shourav
• Other Authors: Makris, Nicholas C., Massachusetts Institute of Technology. Department of Mechanical Engineering
• Format: Thesis
• Language: unknown
• Published: Massachusetts Institute of Technology 2023
• Subjects: Arctic; Barents Sea; Global warming; Nordic Seas
• Online Access: https://hdl.handle.net/1721.1/151924

Marine ecosystems face simultaneous pressures from human activities, ocean industrialization, potential global warming and changing habitats. Continuous monitoring of marine biodiversity and ecosystem processes is needed to assess the individual fish species survivability in such conditions. The increasing use of computer modeling and simulations based on significantly under-sampled data of the marine environment, however, leads to unconstrained and potentially unstable predictions of key processes. To address this issue, we demonstrate a technology enabling synoptic quantification and distinction of multispecies fish population densities over ecosystem scales with continuous spatial and temporal resolution. This enables high-resolution quantification of predator-prey interactions in space and time over ecosystem scales. We present an example of an event in the Barents Sea where a massive cod predatory swarm of approximately 1.9 million individuals attacks a defending coherently moving linear capelin prey structure extending over 14 km containing approximately 23 million individuals. Capelin are a keystone species of the Arctic ecosystem. Cod are their primary predator, but cod populations have collapsed everywhere except in the Nordic Seas due to overfishing causing significant changes in ecosystem balance in those regions. We provide high-resolution spatial density images finely sampled over time of cod convergence on capelin prey, estimated capelin consumed, capelin survived and satiated cod predators quantifying the detailed spatio-temporal dynamics of predation. From these we estimate 58% of the entire capelin group was consumed by the swarming cod within 4 hours where the detailed imagery of behavioral shoal structure show capelin in the highest density regions have the highest probabilities of survival. Other interactions we quantified between predatory juvenile cod and pre-spawning capelin groups indicate a variety of behavioral mechanisms with varying levels of efficiency are at work for both the ...