02454nas a2200217 4500008004100000022001300041245010000054210006900154300001000223490000700233520173500240100002401975700002201999700002002021700002602041700002402067700002402091700002102115700003302136856006702169 2017 eng d a0075951100aThe dynamics of Chaoborus americanus in an Adirondack lake following the reintroduction of fish0 adynamics of Chaoborus americanus in an Adirondack lake following a38-450 v653 a

Acid deposition during the 20th century led to the gradual elimination of fish in Brooktrout Lake (Adirondack Mountains, New York State). Thereafter, the lake was colonized by Chaoborus americanus, a dipteran with an aquatic larval stage that typically resides in the pelagic zone in fishless lakes. During subsequent chemical recovery from acidification, the lake was stocked with Brook Trout (Salvelinus fontinalis). For seven years following this reintroduction we examined the re-adaptation of the food chain. The C. americanus abundance and distribution was quantified utilizing a combination of hydroacoustics, traditional vertical net tows and Schindler-Patalas trap collections. Hydroacoustic backscattering signals were repeatable and correlated (r = 0.86, p = 0.003) with C. americanus abundance. Backscattering, depth, month and year were used to develop a random forest model that predicted the C. americanus density (r2 = 0.67,  p< 0.05). The hydroacoustic signal revealed a clear but limited diurnal vertical migration of C. americanus. The signal continued in the presence of the fish population beginning with reintroduction in 2005 and extending through 2011. In 2012, the hydroacoustic signal no longer was present in the lake, suggesting that the fish had eliminated the C. americanus population, which was verified with net tows. Using novel and traditional survey methods, we demonstrate that the reintroduction of fish can alter the lake community structure significantly through the extirpation of the major component of the pelagic zone.

1 aFarrell, Jeremy, L.1 aSiegfried, C., A.1 aDaniels, R., A.1 aSutherland, James, W.1 aBoylen, Charles, W.1 aBloomfield, Jay, A.1 aQuinn, Scott, O.1 aNierzwicki-Bauer, Sandra, A. uhttps://linkinghub.elsevier.com/retrieve/pii/S0075951116300949