Using unsorted sweep net samples to rapidly assess macroinvertebrate
biodiversity
Abstract
Macroinvertebrate biodiversity is routinely used to assess the
ecological condition of freshwater environments. Macroinvertebrates are
traditionally identified morphologically to mostly family level but
using DNA metabarcoding they can be rapidly and reliably identified to
species. Developing standardised, robust and cost-effective protocols
would enable DNA metabarcoding to be broadly used for routine freshwater
biological assessments leading to both potential cost savings as well as
increased taxonomic resolution. To further reduce the cost and time it
takes to process samples, we examine the feasibility of DNA
metabarcoding unsorted macroinvertebrates (macroinvertebrates and
debris) from sweep net samples collected from stream pool or edge
habitats. We processed these unsorted samples with a standardised method
and tested multiple primer sets widely used for invertebrate DNA
metabarcoding. We found that currently available DNA metabarcoding
primers are well suited for processing unsorted samples, though some
performed better than others. However, macroinvertebrate density
affected the number of species detected with DNA metabarcoding,
particularly the detection of rare taxa. These findings show that DNA
metabarcoding of unsorted net contents could streamline
macroinvertebrate sample processing for bioassessment, but the optimal
amounts of unsorted material for sub-sampling needs to be considered
when assessing macroinvertebrate biodiversity.