How are macroinvertebrates of slow flowing lotic systems directly affected by suspended and deposited sediments?
The effects of suspended and deposited sediments on the macroinvertebrates are well documented in upland streams but not in slower flowing lowland rivers. Using species found in lowland lotic environments, we experimentally evaluate mechanisms for sediments to affect macroinvertebrates, and in one experiment whether salinity alters the effect of suspended sediments. Suspended kaolin clay reduced feeding of Ischnura heterosticta (Odonata: Coenagrionidae) at high turbidity (1000-1500 NTU) but had no effects on feeding of Hemianax papuensis (Odonata: Aeshnidae) and Micronecta australiensis (Hemiptera: Corixidae). In freshwater (0.1 mS/cm), survival of Ischnura aurora was poor in clear water, but improved with suspended kaolin. Growth and feeding of I. aurora were unaffected by suspended sediments and salinity. Burial (1-5 mm) of eggs with kaolin or sand reduced hatching in Physa acuta (Gastropoda: Physidae), Gyraulus tasmanica (Gastropoda: Planorbidae) and Chironomus cloacalis (Diptera: Chironomidae). Settling sediments may pose greater risk to lowland lotic invertebrates than suspended sediments.
Kefford
Ben J
BJ
Biotechnology and Environmental Biology, School of Applied Sciences, RMIT University, PO Box 71, Bundoora, Victoria 3083, Australia. ben.kefford@rmit.edu.au
Zalizniak
Liliana
L
Dunlop
Jason E
JE
Nugegoda
Dayanthi
D
Choy
Satish C
SC
D000704:Analysis of Variance; D000818:Animals; D005247:Feeding Behavior / Q000502:physiology; D019015:Geologic Sediments / Q000032:analysis*; D007448:Invertebrates / Q000502:physiology*; D007616:Kaolin; D045483:Rivers / Q000737:chemistry*; D054712:Salinity
D007616:Kaolin