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As greenhouse gases accumulate and ocean pH continues to fall, the brain function of apex predators is quietly changing. Dr. Yung-Che Tseng at the Marine Research Station (MRS), Institute of Cellular and Organismal Biology, used the bigfin reef squid (Sepioteuthis lessoniana), a common predator in the western Pacific Ocean surrounding Taiwan, to investigate how projected year-2100 ocean acidification affects the neurophysiology of cephalopod optic lobes. Their findings reveal that chronic exposure to seawater at pH 7.8 substantially reduces predatory willingness and prolongs prey capture time by up to 2.5-fold. Electroretinogram (ERG) recordings performed at the MRS have verified that basic visual function is maintained in these conditions. It is therefore inferred that the behavioral deficits observed are not the result of sensory failure, but rather the disruption of higher-order neural integration circuits.

At the molecular level, prolonged acidification led to extensive downregulation of nicotinic acetylcholine receptor subunits in the optic lobes, accompanied by mitochondrial dysfunction and suppression of oxidative phosphorylation pathways. These findings indicate that metabolic constraint is the main reason for behavioral impairment. The study also indicates that chronically acidified squid have a robust compensating response, including large-scale vesicular transport and other cellular maintenance processes. The combined results indicated that squid, which are often referred to as the “marine primates”, have a remarkable capacity to endure multiple levels of neural adaptation and metabolic reorganization in response to prolonged environmental stress.

The study was published in Communications Biology (2026, 9: 229). It was co-led by Prof. Garett J. P. Allen, a former postdoctoral fellow at Academia Sinica now based at Acadia University, Canada, and was carried out in collaboration with the Faculty of Fisheries at Kagoshima University, the High Throughput Genomics Core at the Biodiversity Research Center of Academia Sinica, the Imaging Core Facility at National Taiwan University College of Medicine, and the Department of Aquaculture at National Taiwan Ocean University. The research was supported by Academia Sinica and the National Science and Technology Council, Taiwan (NSTC 112-2628-B-001-013-MY3).