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Hydrobiologia (2011) 673:137151 DOI 10.1007/s10750-011-0768-3
PRIMARY RESEARCH PAPER
Life history strategies and production of caddisies in a perennial headwater stream in Patagonia
Cecilia Brand Mara Laura Miserendino
Received: 22 December 2009 / Revised: 13 May 2011 / Accepted: 21 May 2011 / Published online: 3 June 2011 Springer Science+Business Media B.V. 2011
Abstract Synchrony, one of the main traits of population life histories, refers to the degree to which individuals complete a certain stage of the life cycle at the same time. It can be governed by temperature, variations in temperature, photoperiodic cues, detritus inputs, or discharge regimes. We investigated life cycles and secondary production of ve caddisy species in a second order stream in the Patagonian Mountains. In addition, we analyzed what environmental variables were implied in the caddisy assemblage variation. Mastigoptila sp. (Glossosomatidae) and Eosericostoma aequispina (Helicophidae), Myotrichia murina (Sericostomatidae), Brachysetodes quadridus (Leptoceridae), and Neoatopsyche brevispina (Hydrobiosidae) showed univoltine life cycles, with an extended recruitment with no overlapping cohorts and a relatively well-synchronized imaginal emergence taking place during spring summer seasons. However, Myotrichia murina (Sericostomatidae) displayed a complex life cycle with mixed populations taking 1012 months to develop, and pupae being collected almost continuously. The
annual secondary production per species varied from11.06 (E. aequispina) to 310.5 mg m-2 year-1 (M. murina), being overall caddisy production(0.5 g m-2 year-1) similar to that reported for cold springs in other regions. The highest growth rates (K) were observed during late winter and spring (mostly September) and ranged from 0.70 to 3.70% day-1 in M. longicornuta and N. brevispina, respectively. Redundancy analysis indicated that seasonally dynamic variables, water temperature, discharge, and detritus biomass were the main predictors of caddisy assemblage variation; consequently at this cold stream (mean annual 5.9C), with a regular availability of food supply, these parameters ruled Trichoptera life histories and secondary production. As documented for other mountainous temperate areas, synchrony would be a dominant trait on life histories of Trichoptera species inhabiting Patagonian streams.
Keywords Life cycles Trichoptera Biomass
Mountain rivers Voltinism Secondary production
Introduction
The life history of an organism reects a suite of interacting factors which includes genetic information, inter-specic relationships, and environmental characteristics (Butler, 1984). They are regulated mainly by river temperature (Komzk & Sedlk,
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C. Brand...