Historic changes in freshwater insect communities on Mount Desert Island, Maine

Windmiller, Bryan; Mittelhauser, Glen

FIELD WORK: 2008 Following from abstract: 'We conducted an inventory of selected taxa of aquatic insects (whirligig beetles - Gyrinidae, predaceous diving beetles - Dytsicidae, burrowing water beetles - Noteridae, backswimmers - Notonectidae, giant water bugs - Belostomatidae, water scorpions Nepidae, and creeping water bugs - Naucoridae) in Acadia National Park on Mount Desert Island during 2008 and compared our inventory results with William ProcterÆs historic inventory effort conducted in the early to mid 1900s. We sampled these aquatic insect taxa in 16 diverse lentic water bodies in Acadia National Park and captured a total of 1,390 individuals of 46 species within our target taxa. Notonecta undulata (Notonectidae) was the most widely distributed of all target taxa (12 sites). Among the Gyrinidae, the most widely distributed species among our 16 sites at ANP were: Gyrinus sayi (11 sites), G. borealis (10 sites), and Dineutus nigrior (10 sites). Among the Hemiptera, Ranatra fusca (Nepidae, 10 sites) and Belostoma flumineum (Belostomatidae, 11 sites) were the most widespread. The composition of the dytiscid fauna differed greatly between sites; only two species were captured at more than 5 sites: Dytsicus verticalis (7 sites) and Acilius semisulcatus (6 sites). Schooner Head Marsh was the most diverse site with 25 target taxa documented. Seal Cove Beaver Pond (20 species) and Hodgdon and Duck Ponds (each with 16) were also diverse in target taxa documented. Duck Pond, which was only sampled in August, would likely have been the second most diverse site had it been sampled in May. Schooner Head Marsh and Hodgdon Pond were also the sites with the most unique species. The diversity and abundance of sampled Dytiscidae was much higher in fishless ponds than in ponds containing fish. Among the target taxa, we documented 15 species and one family (Noteridae) not recorded historically on Mount Desert Island and we did not find 10 species that were historically recorded by Procter. We discuss 4 species (1 Dytiscidae, 3 Notonectidae) that have likely increased in abundance and 2 species (both Gyrinidae) that have likely decreased in abundance on Mount Desert Island since the mid 1900Æs. Additionally, we added the family Hydrometridae (Hemiptera: water measurers) to the families of aquatic beetles and bugs known from Mount Desert Island and noted the absence, in both this effort and ProcterÆs collections, of creeping water bugs (Hemiptera: Naucoridae).' /STUDY LOCATIONS:/ /MOUNT DESERT ISLAND/Hodgdon Pond/Duck Pond/The Reservoir/Seal Cove Beaver Pond/Seawall Bog/Seawall Culvert/Seawall Pond/Echo Lake/Breakneck Beaver Pond/Eagle Lake Parking Lot/Duck Brook Vernal Pool/Duck Brook Beaver Pond/Beaver Dam Pond/The Tarn/Schooner Head Marsh/Route 3 Beaver Pond/ GIS Category 1: UTM coordinates are available for all study sites and appendix lists species for each study site.