Large-Scale Spatio-Temporal Patterns of Mediterranean Cephalopod Diversity

Area of Science:

• Marine Biology
• Ecology
• Fisheries Science

Background:

• Species diversity is crucial for ecosystem functioning and resilience.
• Cephalopod diversity patterns are less understood compared to other taxa like fish.
• Understanding diversity drivers is key for conservation efforts.

Purpose of the Study:

• To analyze spatio-temporal trends of cephalopod diversity in the Mediterranean Sea over 19 years.
• To investigate the influence of environmental factors on cephalopod diversity.
• To challenge previous assumptions about eastward diversity decline.

Main Methods:

• Utilized 19 years of data from the MEDITS bottom trawl survey.
• Applied generalized additive models to analyze diversity patterns.
• Used species richness and Shannon Wiener index as diversity descriptors.
• Examined local and regional environmental variability.

Main Results:

• Cephalopod diversity did not show a consistent eastward decrease; high diversity was found in the western basin, Adriatic, and Aegean Seas.
• Species richness was high in the eastern Ionian Sea.
• Overall diversity remained stable over two decades.
• Diversity exhibited a hump-shaped trend with depth (200-400m) in most regions.
• Higher Chlorophyll a concentrations and warmer temperatures correlated with increased species diversity.

Conclusions:

• Cephalopod diversity in the Mediterranean is complex and regionally variable.
• Environmental factors, particularly Chlorophyll a and temperature, significantly impact cephalopod diversity.
• Depth plays a crucial role, with peak diversity observed in mid-water depths.
• Findings highlight the need for region-specific conservation strategies for cephalopods.