Hydroacoustic assessment of pelagic stages of freshwater insects

0150321 - HBU-Z 20003028 RIV FR eng J - Journal Article
Kubečka, Jan - Frouzová, Jaroslava - Čech, Martin - Peterka, Jiří - Ketelaars, H. A. M. - Wagenwoort, J. - Papáček, M.
Hydroacoustic assessment of pelagic stages of freshwater insects.
Aquatic Living Resources. Roč. 13, č. 13 (2000), s. 361-366. ISSN 0990-7440. E-ISSN 1765-2952
R&D Projects: GA AV ČR IAA6017901; GA ČR GA206/97/0072; GA ČR GA206/99/0405
Institutional research plan: CEZ:MSM 123100004
Subject RIV: DA - Hydrology ; Limnology
Impact factor: 0.942, year: 2000

Two independent surveys showed that aquatic insects can generate echoes comparable with the echoes of small fish. In the open water of two fishless mountain acidic waters of the Czech Republic, a very distinct population of well defined single targets resembling fish (target strength -66 to -50 dB at 120 kHz) was discovered. These targets were found in the depth range of 5-7 m during the day (June-July 1997). At night, most targets were recorded by horizontal beaming (depth < 3m). Towing of ichthyoplankton nets in these horizons revealed the presence of water bugs - Corixidae (Heteroptera), mostly genus Glenocorisa. Target strengths of water bugs was also verified by direct observations in an experimental tank, where it was possible to track side, dorsal and ventral aspects. In three Dutch reservoirs, Petrusplaat, Honderd-en-Dertig and De Gijster the targets of ascending dipteran pupae (Chironomidae, Procladius signatus) with target strength of -74 to -65 dB were observed by vertical beaming.
Permanent Link: http://hdl.handle.net/11104/0047859