Macroinvertebrate assessment of water quality in White Clay Creek based on specimens identified by amateurs, professionals, and barcoding

Insects identified three ways, by a student, professional entomologists, and DNA barcoding (cox1 gene) were compared in their ability to assess water quality in White Clay Creek, PA. Riffles were collected quantitatively from two stations known to have good (St11, MAIS score=14 of 20) and fair (St12, MAIS=7) water quality. Of the 1786 specimens examined, 84% were successfully barcoded (including early instars). A 2% genetic divergence in barcode data was used to separate species for all insect families except Chironomidae (5%). Professionals identified fewer species relative to barcoding (i.e., 45 vs 128 insect species, respectively), and this was apparent for almost every insect order: Diptera 23/86, Ephemeroptera 6/16, Plecoptera 1/6, Trichoptera 9/14, and Coleoptera 6/6. The relative abundance of EPT was greater at St11 (51% vs 25%) and chironomids were more abundant at St12 (63% vs 30%). Barcoding revealed that EPT species richness was higher at St11 (24) than St12 (18) but chironomid species richness was higher at St12 (64) than St11 (38). Contrary to bioassessment predictions, barcoding indicated higher total species richness in the more degraded site. Thus, barcoding appears useful for both assessing water quality and increasing our knowledge of taxa, especially for complex groups such as chironomids.