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Growth Patterns of a Chironomid Shredder on Fresh and Senescent Tag Alder Leaves in Two Michigan Streams

 

作者: R.Jean Stout,   WilliamH. Taft,  

 

期刊: Journal of Freshwater Ecology  (Taylor Available online 1985)
卷期: Volume 3, issue 2  

页码: 147-153

 

ISSN:0270-5060

 

年代: 1985

 

DOI:10.1080/02705060.1985.9665103

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

A chironomid,Brillia flavifronsJohannsen (Orthocladinii) previously thought to specialize on decaying wood, consumed Tag Alder leaves (Alnus rugosa(Du Roy)) in two Michigan streams, Schwartz Creek and the Ford River. Schwartz Creek's substrate is primarily sand and the principle allochthonous inputs are White Cedar (Thuja occidentalisL.) needles and wood. The Ford River's substrate contains cobble and gravel. The primary inputs are deciduous leaves, with the majority being Tag Alder. Fresh Tag Alder leaves are commonly found in streams in the western Upper Peninsula, owing primarily to high beaver activity and secondarily to wind activity. Substantial green leaf inputs occur at a time when the previous year's leaves have been processed. In Schwartz Creek,B. flavifronsmay be the primary shredder species, as the biomass ofB. flavifronsexceeded the biomass of all other shredder insect species combined on fresh green Tag Alder leaf packs and autumn senescent Tag Alder leaf packs. This chironomid appears to prefer to feed on fresh leaves: Larval mean biomass and field growth rates were significantly higher on fresh than on autumn leaves. In the Ford River,B. flavifronsis not the primary shredder, as the biomass of other shredder species exceeded the biomass ofB. flavifronson both leaf types. In the Ford River,B. flavifronsappears to prefer to feed on fresh leaves more than autumn leaves: Larval mean sizes were significantly higher on fresh than on autumn leaves. We hypothesize that (1) fresh green leaves are chemically richer and have surfaces that are richer in microflora and microfauna to account for the increased growth rates and/or higher mean biomass values forB. flavifronson fresh green leaves, and that 2) increased resource competition by other shredder species in the Ford River may account for the lower growth rates and/or lower mean biomass values ofB. flavifronsobserved on both leaf types in that river.

 

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