The Rise of Algae promoted eukaryote predation in the Neoproterozoic benthos

Area of Science:

• Paleoecology
• Marine Biology
• Microbial Ecology

Background:

• The Neoproterozoic Era saw increased marine algae proliferation, potentially impacting microbial predator evolution.
• Modern oxygen minimum zones (OMZs) offer analogous conditions to Neoproterozoic water columns for ecological studies.

Purpose of the Study:

• To investigate the ecological impact of algal particulate matter (APM) on microbial eukaryotes under anoxic conditions.
• To test the hypothesis that Neoproterozoic algal blooms stimulated predatory microbial eukaryotes.

Main Methods:

• Introduction of APM to marine sediments in a modern OMZ simulating Neoproterozoic oxygen levels.
• Analysis of microbial eukaryote gene expression, 18S rRNA abundance, and benthic foraminifera reproduction.
• Measurement of net growth efficiencies under simulated anoxic conditions.

Main Results:

• APM significantly stimulated microbial eukaryote gene expression, particularly for anaerobic metabolism and phagocytosis.
• Relative abundance of 18S rRNA from predatory microbial clades increased with APM addition.
• APM promoted benthic foraminifera reproduction under anoxia, exhibiting high net growth efficiencies.

Conclusions:

• Algal biomass exported to Neoproterozoic seafloors likely stimulated benthic predatory protists under anoxia.
• This stimulation enhanced carbon and energy transfer to higher trophic levels, contributing to early metazoan food webs.
• Findings support the role of algal blooms in shaping early marine ecosystems and the evolution of complex food webs.