Centrifugation is an effective and inexpensive way to determine Batrachochytrium dendrobatidis quantity in water samples with low turbidity

TL;DR

A simple and affordable centrifugation method effectively measures the amount of a deadly amphibian fungus in clear water samples.

Contribution

A streamlined, cost-effective centrifugation method for quantifying Batrachochytrium dendrobatidis in low-turbidity water.

Findings

Centrifugation of water samples produced DNA concentrations highly correlated with expected Bd values.

The method is repeatable and provides a linear relationship between measured and actual Bd concentrations.

The technique is time- and cost-efficient, increasing accessibility for Bd research.

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.

The online version contains supplementary material available at 10.1007/s00442-024-05604-0.

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