DNA metabarcoding has been widely used to access and monitor species.
However, several challenges remain open for its mainstream application
in ecological studies, particularly when dealing with a quantitative
approach. In a from the Cover article in this issue of Molecular
Ecology, Cédric et al. (2021) report species-level ichthyoplankton
dynamics for 97 fish species from two Amazon river basins using a clever
quantitative metabarcoding approach employing a probe capture method.
They clearly show that most species spawned during the rainy season when
the floods started, but interestingly, species from the same genus
reproduced in distinct periods (i.e., inverse phenology).
Opportunistically, Cédric et al. (2021) reported that during an intense
hydrological anomaly, several species had a sharp reduction in spawning
activity, demonstrating a quick response to environmental cues. This is
an interesting result since the speed at which fish species can react to
environmental changes, during the spawning period, is largely unknown.
Thus, this study brings remarkable insights into basic life history
information that is imperative for proposing strategies that could lead
to a realistic framework for sustainable fisheries management practices
and conservation, fundamental for an under-studied and threatened realm,
such as the Amazon River basin.