ASU Research E-Magazine: Build a Better Bioindicator

Policy makers, scientists, and the general public grow more concerned by the day about preserving biological diversity. Unfortunately, legislators and biologists seem to live in different universes. In the fast-paced world of politics, lawmakers have to make snap decisions on environmental policies. Biologists, however, often spend decades in the field doing the research on which those decisions are based.

A compromise exists. The idea is to study a representative sample of an ecosystem that can provide quick, yet reliable, information. In scientific terms, these sample species are known as bioindicators.

According to ASU biologist David Pearson, bioindicators are often chosen randomly, or based on their "cute-furry" factor. Such animals don’t always provide an accurate picture of what is really happening in the environment.

Pearson has compiled a set of guidelines to help solve this problem. Scientists can refer to the guidelines to choose an appropriate bioindicator. The ideal bioindicator, he says, should meet the following criteria:

Taxonomically well-known and stable: The researcher should be able to identify the species clearly and distinguish it from other species.

Biology and general life history well understood: The researcher should understand the species’ natural history, its habitats and its active period.

Populations are readily surveyed and manipulated: The researcher can find, observe, and mark the subjects easily.

Groups and related species should occupy a breadth of habitats and a broad geographical range: The group as a whole should live in several parts of the world, not just the area being studied. This way, research from one area will have value for study in other parts of the world.

Specialization of each population within a narrow habitat: The more specialized a species, the more sensitive it is to changes such as pollution and habitat modification. This sensitivity can serve as an early warning system for the whole ecosystem.

Patterns observed in the indicator taxon are reflected in other related and unrelated taxa: Data about the bioindicator should be applicable to other unrelated species in the ecosystem.

Potential economic importance: It is important to provide evidence that there is an economic benefit to studying the species in question, especially in countries where resources are scarce. This factor is often the "swing vote" that determines whether a study takes place.

Pearson says that these criteria vary in importance depending on the purpose of the study. Using this list, scientists can "grade" various species according to their usefulness as bioindicators.—Diane Boudreau