Metabarcoding Insights Into the Trophic Behavior and Identity of Intertidal Benthic Foraminifera

Area of Science:

• Marine biology
• Protistology
• Molecular ecology

Background:

• Foraminifera are crucial to the benthic carbon cycle but their taxonomy and feeding habits are poorly understood.
• Morphological identification limits taxonomic precision and field studies on foraminifera feeding preferences are scarce.

Purpose of the Study:

• To apply metabarcoding for elucidating in situ feeding behavior of benthic foraminifera.
• To achieve accurate taxonomic assignment of foraminifera using the V9 region of the 18S rRNA gene.
• To investigate the trophic preferences of different foraminifera species in intertidal environments.

Main Methods:

• Collection of living foraminiferal specimens from Wadden Sea intertidal mudflats.
• DNA extraction from individual foraminifera and surrounding sediments.
• Metabarcoding analysis targeting the V9 region of the 18S (small subunit; SSU) rRNA gene.

Main Results:

• Three genetic types of foraminifera were identified: Ammonia sp. T6, Elphidium sp. S5, and Haynesina sp. S16.
• Foraminiferal intracellular eukaryote communities differed in relative abundance from surrounding sediment communities.
• Foraminiferal communities were primarily influenced by foraminifera species and secondarily by sediment depth, unlike sediment communities which were site-dependent.
• Ammonia sp. T6 appears to prey on metazoans, while Elphidium sp. S5 and Haynesina sp. S16 likely ingest diatoms.

Conclusions:

• Metabarcoding is effective for determining the in situ feeding behavior and taxonomic placement of benthic foraminifera.
• Different foraminifera species exhibit distinct trophic preferences, impacting benthic food webs.
• This study enhances understanding of the ecological roles and food web functions of foraminifera in intertidal ecosystems.