The Effects of Sedimentation on the Aquatic Biota

Authors
W.H. Griffiths
B.D. Walton
Resource Date:
1978
Page Length
86

A review of the effects of sedimentation on aquatic biota is presented. The detrimental effects of increased suspended and settled sediments on fish, bottom invertebrates, and primary productivity are documented. It is shown that the upper tolerance level for suspended sediment is between 80-100 mg/l for fish, and as low as 10-15 mg/l for bottom invertebrates. Recovery of the aquatic biota from increased sedimentation is dependent on the severity of sediment additions and the discharge level of the rivers or streams. Recovery from short-term additions of sediment is usually complete within one year. The use of remote sensing and biomonitoring to locate sources of sedimentation is discussed. Remote sensing can generally be used to identify point sources of sedimentation, define flow patterns, choose sampling stations, interpret ground survey data, and maintain permanent records of changes in water quality. Biomonitoring can be used to monitor water quality, especially with regard to sedimentation, since alterations in the environment are reflected by the indigenous biota. The sedimentation characteristics of the Alberta Oil Sands Environmental Research Program (AOSERP) study area are presented and observations are made on the potential for erosion and sediment production. The AOSERP study area is divided into twelve hydrological zones and each zone is classified for erosion potential. The zones having a high erosion potential are: (1) lower Ells basin and eastern slopes of Birch Mountains (Zone 1); (2) tributaries immediately north of Fort McMurray (Zone 6); (3) Christina River basin (Zone 7); (4) Hangingstone and Horse River basins. (Zone 8); (Fort MacKay River basin (Zone 9); (6) Dunkirk River basin (Zone 10); and (7) upper Ells River basin (Zone 11). Road construction, pipeline construction, general construction (urban and industrial sites), vegetation removal, overburden removal, and pit excavation, tailing ponds, settling ponds, and diversion channels were identified as possible sources of unnatural increases of suspended and settled sediments in the AOSERP study area. The effect of development activities on the hydrological regime and the aquatic biota is shown. The scale of the disturbance and the length of the recovery period are also predicted. Development activities such as road building and pipeline construction will affect a number of the watershed basins; therefore, they were classified as having regional effect and were considered to be of greatest concern.