The macroinvertebrate colonization of leaf bags: Is there a pattern?

Abstract

There have been many studies of litter decomposition and the macroinvertebrates associated with litter. Nevertheless, the reasons why invertebrates colonize leaf bags are still a matter for discussion. Although invertebrates use leaves as food, it has been shown that they may use the leaf bags as a substrate. In this study, we investigate whether macroiiivertebrates colonize leaf bags despite aburidant natural leaf litter in the streams aiid whether they discriminate between leaves occurring naturally in the streams (Alnus glutinosa) and alien species iin this case, the South American Hura crepitans). We found no differences in the relative abundance of chredders between Alnus and Hura leaf baga. In relation to the relative abundance of shredders in the leaf bags and in the streambed, we found all the possible combinations. In two streams there were no differences between the benthic samples and the leaf bags, in another stream, the relative abuiidance of shredders was higher in the benthic samples, and in a further stream, the relative abundance of shredders was higher in the leaf bags. It seeins therefore, that when there ia an abundant supply of high quality food in the streams, there is no reason for the aggregation of shredders in the leaf bags. © Asociación Española de Limnología.