Temporal consistency in the long-term spatial distribution of macroinvertebrate drift along a stream reach

Abstract

Previous studies of the spatial pattern of stream invertebrate drift have focused on spatial variation at microhabitat scales or landscape scales, or temporal variation over diel or seasonal scales. None have examined consistency in spatial variation over longer time scales (>1 year). This study examined invertebrate drift density and composition at fixed locations (terminal ends of 10 riffles) each month at day and night along a 1 km reach of a 2nd order stream over a period of nearly 2 years. Consistent differences in the density of macroinvertebrate drift between riffles over 2 years were observed. The only habitat characteristic observed to be related to invertebrate drift density was the length and size of riffles above sampling sites, with larger and longer riffles producing the highest drift densities. Consistent differences in the supply of drifting macroinvertebrates along a stream reach may have implications for the supply of colonists to substrate patches and the profitability of feeding positions for drift-feeding fish and other predators.

Effects of flow fluctuations on the daily and seasonal drift of invertebrates in a tropical river

“…The daily variation in the drift is a recurring pattern, with numerous studies showing that drift increases at night, especially just after sunset (Poff and Ward, 1991;Ramı´rez and Pringle, 1998;Hansen and Closs, 2007). Nevertheless, we did not observe a recurring pattern of daily drift in both wet and dry seasons.…”

Influence of peak flow changes on the macroinvertebrate drift downstream of a Brazilian hydroelectric dam

“…Numerous studies have shown that drift increases at night, especially just after sunset (Poff and Ward, 1991;Ramírez and Pringle, 1998;Hansen and Closs, 2007). However in the wet season with fixed flows, we observed no differences in drift between differing sampling periods (Figure 7).…”

“…The downstream transport of invertebrates is not constant and varies with season, day, and time of day (Brittain and Eikeland, 1988). Differences in drift densities may also vary by species and life cycle stage (Hansen and Closs, 2007). Macroinvertebrate drift is very important to aquatic ecosystem function, because it is a primary mechanism for the redistribution and colonisation of aquatic macroinvertebrates (Hay et al, 2008) and offers prey for predators such as fish (Flecker, 1992).…”

Using oligochaeta assemblages as an indicator of environmental changes

“…The flow regulation and stratification patterns developed in reservoirs frequently impact the biota downstream in four ways (Cortes et al 2002): i) alteration of physical and chemical characteristics associated with the release of water and sediment derived from the hypolimnion, that affect life history and density of macroinvertebrates (Cortes et al 2002); ii) alteration of available food resources to aquatic biota, specially through changes in the particulate organic matter (McAllister et al 2001); iii) creation of unstable environment due to daily changes in water level, increasing invertebrate drift (Hansen and Closs 2007); and iv) reduction of water released downstream, which modify abundance and diversity of benthic fauna (Bunn and Arthington, 2002). These effects have been demonstrated in several regulated rivers, where alterations in discharge have caused changes in the structure of the aquatic community (Pardo et al, 1998;Rosin et al, 2009).…”