Colonization of experimentally disturbed patches by stream macroinvertebrates in the Acheron River, Victoria

Abstract

Twenty-five patches (1 m^) of natural stream substratum in the Acheron River. Victoria, were physically disturbed by kicking and raking during winter 1986 and summer 1987. The macroinvertebrate composition of these disturbed patches was examined at various times over the following 71 days, and compared with adjacent undisturbed control patches sampled concurrently.The disturbance did not alter the particle-size distribution (>150 nm) of the disturbed patches. Organic material was reduced in the disturbed patches by about 70% in each season, but returned to control levels within 21 days in winter and 8 days in summer.The total number of species, and the density of species and individuals were all significantly reduced by the disturbance. Recovery of species density was complete after 21 days during winter and 8 days during summer, and the density of individuals recovered after 71 days during winter and 8 days during summer. The differences were due to the slower colonization rate of Chironomidae in winter, either because of a lower drift rate, or a slower recovery of detritus in winter.Individual species showed variations in colonization patterns, most increasing steadily at various rates, with some declining after an initial rapid increase (e.g. Baetis spp.). In the latter case, the density changes were mirrored in the control patches, emphasizing the need to take control samples concurrently with experimental samples.In each season, the species remaining immediately following the disturbance, and those subsequently colonizing the disturbed patches were in the same rank order (Spearman Rank correlation) as their occurrence in the control patches, suggesting that no taxa were differentially affected by the treatment.No evidence was found to allow the application of the Intermediate Disturbance Hypothesis to explain species diversity at the scale of this study. It appears that current hypotheses developed to explain the relationship between diversity and disturbance in sessile communities do not apply to highly mobile communities in streams.

Effects of outdoor education stream classes on substrate movement and macroinvertebrate colonization

“…In contrast, the marked rocks at the class site subjected to OE stream classes experienced more frequent substrate disturbance via student-activity and spates. Significant differences (P < 0.05) in mean macroinvertebrate abundance, mean taxa richness, mean EPT abundance, and mean clinger abundance between the class site subjected to OE stream classes and the unused site at the end of the study are consistent with findings in other studies of anthropogenic disturbance in which disturbance caused a decrease in macroinvertebrate colonization (Clifford 1982;Reice 1985;Robinson and Minshall 1986;Doeg et al 1989;Death 1996;Matthaei et al 1996; Wright and Li 1998; McCabe and Gotelli 2000; Laing 2008;Robinson et al 2011). Thus, our results indicate that the greater frequency of student-induced substrate movement as a result of OE stream classes at the class site suppressed macroinvertebrate colonization of rocks.…”

Assessment of Temporary Streams: The Robustness of Metric and Multimetric Indices under Different Hydrological Conditions

“…However, the post-flood increase in macroinvertebrate abundance was within the values recorded during the pre-flood period. Such resilience studies in temporary streams have been reported previously (e.g., Doeg et al, 1989;Grimm & Fisher, 1989;Lake & Schreiber, 1991). The main factor that may account for the apparent high resilience of the stream macroinvertebrate community was the rapid decrease in discharge from 1515 to 258 l s −1 .…”

“…The effect of these hydrological events is one of the principal environmental factors influencing the structure and function of macroinvertebrate communities in Mediterranean streams (Langton & Casas, 1998;Prenda & Gallardo-Mayenco, 1996;Prenda & Gallardo-Mayenco, 1999;Puig et al, 1991;Ubero-Pascal et al, 2000). Another characteristic of these systems is the rapid capacity to recover following these natural disturbances (Boulton et al, 1988;Closs & Lake, 1994;Doeg et al, 1989;Grimm & Fisher, 1989).…”

Relative importance of surface and subsurface movement on benthic community recovery in the Makaretu River, North Island, New Zealand

“…A number of experimental studies have explored the length of time for community recovery after disturbance (e.g., Cairns et al 1971;Doeg et al 1989;Death 1996) and a few have assessed the significance of different sources of colonists to this recovery (e.g., Townsend & Hildrew 1976;Williams & Hynes 1976;Williams 1977). However, none has investigated benthic colonisation patterns in North Island, New Zealand gravel bed rivers.…”