Performance of DNA metabarcoding vs morphological methods for assessing
intertidal turf diversity
Abstract
The increasing climate-driven replacement of kelp forests by turf algae
highlights the need for efficient biodiversity monitoring.
Traditionally, monitoring turf communities involves species
identification based on morphology, which is challenging due to their
reduced dimensions and highly variable morphology. Molecular methods
promise to revolutionize this field, but their real-world effectiveness
needs to be evaluated. Here, we evaluate the performance of DNA
metabarcoding (COI and rbcL markers) and morphological identification
(in situ and photoquadrat identifications) to describe intertidal turf
communities along the Portuguese coast. When comparing metabarcoding
with in situ and photoquadrat identification, it was found that both COI
and rbcL markers detected more taxa than the other two (277 and 140 vs
28 and 34 taxa, respectively). Metabarcoding also showed greater
discrimination of turf communities between shores and regions, matching
our knowledge of the geographical and climatic patterns for the region.
However, certain taxa that were identified by in situ and photoquadrat
approaches were not detected through metabarcoding, likely due to lack
of reference barcodes or taxonomic resolution. Our multi-marker
metabarcoding approach was more efficient than morphology-based methods
in characterizing turf communities along the Portuguese coast,
differentiating morphologically similar species, and detecting
unicellular organisms. Additionally, although not the primary focus, the
COI marker identified metazoans, which can be used in future ecological
studies on species co-occurrence and algae-animal interactions.
Metabarcoding emerges as a valuable tool for monitoring these
communities, particularly in long-term programs requiring accuracy,
speed, and reproducibility.