Speaker
Description
In freshwater biomonitoring, a common assumption is that members of the ordersEphemeroptera, Plecoptera, and Trichoptera(collectively known as (EPT) are generally more sensitive to environmental degradation than other insect orders (non-EPT), and this assumption underlies the widespread use macroinvertebrate indices that specifically focus on these taxa. However, while EPT are often good indicators of land-use change in the watershed, there are many counter-examples. Here, we endeavored to evaluate the association between proportions of EPT in macroinvertebrate samples and land-use in the surrounding watershed as a robust indicator of land use change specifically remains limited. We used a database containing freshwater insect abundances from 83 studies that compare sites with more versus less intense land use and examined how EPT and non-EPT taxa respond.
We found that land use intensification suppressed the EPT abundance ratio (EPT abundance relative to total insect abundance) more strongly than the EPT richness ratio (EPT richness relative to total insect richness), with urban habitats imposing the strongest and most consistent effects. With EPT, family-level responses were heterogeneous; some families strongly responded to land use while others did not, challenging the assumption of using EPT as a coherent indicator. Beta diversity analyses showed that compositional change among the EPT emerged through loss of some taxa (but not gains in others), indicating that nestedness rather than taxon replacement. For non-EPT taxa, we found roughly equal contributions from both nestedness and turnover (some taxa are lost and others gained).
These findings show evidence of both the mechanisms and the limits of EPT as a bioindicator, and illustrate the need for more nuanced interpretations of community wide compositional shifts by dissecting the reasons for observed changes.
| Status Group | Doctoral Researcher |
|---|---|
| FOR TALKS: Poster Presentation Option | No, I prefer to present only as a talk. |