Palaeontological evidence for community-level decrease in mesopelagic fish size during Pleistocene climate warming in...

Area of Science:

• Paleoclimatology
• Marine Biology
• Paleontology

Background:

• Mesopelagic fishes are vital to marine ecosystems and the biological carbon pump.
• Future of these fish under climate change is uncertain.
• Causes of commercial fish size reduction are debated.

Purpose of the Study:

• Investigate the impact of climate warming on mesopelagic fish size.
• Analyze changes during a Middle Pleistocene glacial-interglacial-glacial transition (814–712 kyr B.P.) with a 4°C seawater temperature increase.
• Examine fish size dynamics in the eastern Mediterranean Sea.

Main Methods:

• Analysis of fossil otoliths (fish ear bones).
• Reconstruction of fish community structure and size.
• Correlation of fish size trends with paleoclimatic data.

Main Results:

• Median size of lanternfishes decreased by approximately 35% at the community level during warming.
• Individual species exhibited varied size trends, some increasing, some decreasing.
• Warming likely induced shifts in species distribution and abundance.

Conclusions:

• Climate warming can lead to a decrease in average mesopelagic fish size.
• Ecological shifts, including range shifts and size-dependent effects, are key mechanisms.
• Understanding these impacts is crucial for predicting future marine ecosystem responses to climate change.