Centrifugation is an effective and inexpensive way to determine
Batrachochytrium dendrobatidis quantity in water samples with low
turbidity
Abstract
Batrachochytrium dendrobatidis (Bd) is a pathogenic chytrid fungus that
is particularly lethal for amphibians. Bd can extirpate amphibian
populations within a few weeks and remain in water in the absence of
amphibian hosts. Most efforts to determine Bd presence and quantity in
the field have focused on sampling hosts, but these data do not give us
a direct reflection of the amount of Bd in the water, which are useful
for parameterizing disease models, and are not effective when hosts are
absent or difficult to sample. Current methods for screening Bd presence
and quantity in water are time, resource, and money intensive. Here, we
developed a streamlined method for detecting Bd in water with low
turbidity (e.g., water samples from laboratory experiments and
relatively clear pond water from a natural lentic system). We
centrifuged water samples with known amounts of Bd to form a pellet and
extracted the DNA from that pellet. This method was highly effective and
the resulting concentrations across all tested treatments presented a
highly linear relationship with the expected values. While the
experimentally-derived values were lower than the inoculation doses, the
values were highly correlated and a conversion factor allows us to
extrapolate the actual Bd concentration. This centrifuge-based method is
effective, repeatable, and would greatly expand the domain of tractable
questions to be explored in the field of Bd ecology. Importantly, this
method increases equity in the field because it is time- and
cost-efficient and requires few resources.