Multi-scale habitat associations and predictive habitat modeling of Heterosternuta sulphuria (Coleoptera: Dytiscidae) in Ozark streams




Role of Geodata Crawler:
GeodataCrawler was used to calculate watershed area, land-use/land-cover types (like impervious surfaces and canopy cover) and other environmental variables related to climate and hydrology. GeodataCrawler was used to collect this data at multiple spatial scales at targeted sites in the Ozarks and Ozark Highlands regions where H. sulphuria was collected in the field, and then also at 18,000 stream segments where probabilities of beetle occurence were predicted.


Publication:
Flannery JN. 2016. Multi-scale habitat associations and predictive habitat modelling of Heterosternuta sulphuria (Coleoptera: Dytiscidae) in Ozarks streams. Honors Thesis. Dept. of Mathematics, J. William Fulbright College of Arts and Sciences, University of Arkansas. 29 pp.

Funding Source:
University of Arkansas Honors College

Contribution to Education:
Undergraduate Honors Thesis submitted by Jeremiah N. Flannery to the Fulbright College of Arts and Sciences, University of Arkansas in 2016.

Abstract:
Heterosternuta sulphuria is an endemic predaceous diving beetle occurring in streams on the Ozark Plateau. Current information for H. sulphuria including high frequency of occurrence in relatively small watersheds and potential flightlessness suggests numerous populations could be isolated and at risk to localized extirpations. A better understanding of the habitat and distribution of this species is needed to support conservation actions; this need is bolstered because the distribution of this species is overlayed on a region experiencing rapid urban growth. We developed hypotheses regarding multi-scale associations of H. sulphuria and its habitat across 63 watersheds across Arkansas and analyzed these associations with generalized linear modeling. Fifteen scalar variables that represent urban development, forest cover, population, farming, and stream slope were found to be best predictors of H. sulphuria occurrences. These were used to project the distribution of H. sulphuria at 18000 sites across the two counties in northwestern Arkansas that have undergone the greatest population growth in recent years, and a broader area of the Ozarks in three states. Regression analysis showed watershed area to be by far the most important characteristic in determining presence of the beetle, and following that was urban development. Based on our results, conservation actions for H. sulphuria across small watersheds should involve proactive measures to protect streamside management zones from the land development, such as vegetated riparian buffer strips and other means to limit stream disturbances.

Professional Presentations:
2016 Honors Thesis Defense, Fayetteville, Arkansas


Other Products:
Habitat suitability map of H. sulphuria in the Ozarks showing it to be more widespread than previously thought
Habitat suitability map of H. sulphuria in the Ozarks