Abstract
Meiofaunal abundance, biomass and secondary production were investigated over 13 months in an unpolluted first-order stream. Four microhabitats were considered: sediment and the biofilms on dead wood, macrophytes and leaf litter. The relative contribution of the microhabitats to secondary production and the influence of environmental factors on meiofaunal density distribution were estimated. We expected (1) meiofaunal abundance and biomass to exhibit seasonal patterns, with more pronounced seasonal fluctuations on macrophytes and leaf litter than in the other microhabitats, (2) annual secondary production to be highest in sediment; however, the relative contribution of the microhabitats to monthly secondary production would change during the year, and (3) a bottom-up driven influence on meiofaunal density distribution in the microhabitats. Meiofaunal annual mean abundance, biomass and secondary production were 7–14 times higher in sediment and on dead wood than on macrophytes and leaf litter. Significant seasonal patterns described the meiofaunal abundance in sediment and on leaf litter as well as the biomass in sediment, on macrophytes and leaf litter. Organisms in sediment and on dead wood contributed 48 and 43%, respectively, to secondary production m−2, but in regard to the stream area covered by the microhabitats, sediment had the highest share (80%). Significant determinants of the density distribution were AFDM, protozoans, bacteria and Chl-a, which influenced all meiofaunal groups. Our study clearly indicates that meiofaunal organisms in sediment and on dead wood have a remarkable share on total secondary production of lotic systems which is especially relevant for forested low-order streams.
Highlights
Meiofaunal abundance, biomass and secondary production were investigated over 13 months in an unpolluted first-order stream
Our study clearly indicates that meiofaunal organisms in sediment and on dead wood have a remarkable share on total secondary production of lotic systems which is especially relevant for forested low-order streams
Given that the ecological importance of meiofauna in freshwater habitats begins with the ability of these organisms to colonize essentially all submerged surfaces, in the present work we investigated the abundance, biomass and secondary production of a meiofaunal community over a 1-year period in four microhabitats of a single first-order stream (Furlbach, Germany)
Summary
Meiofaunal abundance, biomass and secondary production were investigated over 13 months in an unpolluted first-order stream. In small headwater streams surrounded by forest, the entry of coarse organic material is higher and dead wood and leaf litter are of greater importance than in larger streams (Vannote et al 1980; Richardson and Danehy 2007). The input of such organic matter and the growth of macrophytes as well as the discharge underly temporal dynamics that occur on scales lasting from days to years (Hildrew and Giller 1994; Robertson 2000; Leung et al 2012). E.g., rotifers and copepods, are able to migrate vertically deeper in the sediment at high flows, they are at risk of passive downstream displacement even with modest flooding (Palmer et al 1992)
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