Detecting kelp-forest associated metazoan biodiversity with eDNA metabarcoding

Area of Science:

• Marine ecology
• Molecular ecology
• Biodiversity monitoring

Background:

• Environmental DNA (eDNA) metabarcoding offers a novel approach to assess marine biodiversity.
• Its application in Africa, particularly in sensitive ecosystems like kelp forests, remains limited.
• South African kelp forests host high, endemic biodiversity vulnerable to environmental changes.

Purpose of the Study:

• To evaluate aquatic eDNA metabarcoding for biodiversity detection in a South African kelp forest.
• To assess the spatial and temporal variability of eDNA signals.
• To highlight the potential of eDNA for future biomonitoring in the region.

Main Methods:

• Fine-scale spatial (1m, 8m) and temporal (4-hourly for 24h) sampling of aquatic eDNA.
• Targeted sequencing of two mitochondrial gene regions: cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (12S rRNA).
• Analysis of detected operational taxonomic units (OTUs) and community composition.

Main Results:

• Detected 880 OTUs across 75 metazoan families, including 44 fish OTUs from 24 families.
• Observed significant spatial and temporal variability in eDNA signals, but no distinct spatio-temporal community structure.
• Identified diverse taxa, including Placozoa, previously unreported in South Africa; species-level identification was limited (<3%).

Conclusions:

• Aquatic eDNA metabarcoding successfully detected a wide array of biodiversity in a South African kelp forest.
• The study underscores the understudied nature of this ecosystem's biodiversity.
• Optimized sampling strategies, enhanced barcoding efforts, and regional database development are essential for robust eDNA biomonitoring.