Alternative approaches for monitoring aquatic ecosystems: a study on the effects of municipal sewage effluent on biota in the South Saskatchewan River
Date
1995
Authors
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ORCID
Type
Degree Level
Masters
Abstract
Assessments of nutrient enrichment and contaminant toxicity from treated
municipal sewage effluent were conducted on biota from the South Saskatchewan
River through field monitoring and artificial stream experimentation. Field studies
indicated that primary productivity was stimulated by nutrient enrichment, however,
standing crop measurements were strongly influenced by increased abundance of
invertebrates (i.e., chironomids). Periphyton quality was adversely effected by
contaminants in the effluent, resulting in reduced lipid energy storage and
physiological condition.
Invertebrate community structure and composition at sampling stations were
assessed through the use of diversity and similarity indices. Diversity indices were
successful in identifying changes in community structure immediately downstream
of the municipal effluent discharge, whereas the similarity index indicated a 51%
difference in community composition between upstream and downstream sites.
The evaluation of ecosystem processes based on invertebrate functional
feeding groups were used to assess the influence of municipal sewage effluent on
energy flow within the river. Energy storage within each group was measured by
both biomass and areal lipid content. The identification of increased biomass and
areal lipid content of gatherers and filter feeders immediately downstream of the
effluent discharge suggests organic enrichment effects, whereas a reduction in
scraper and predator biomass and lipid content indicated organic enrichment and
toxicological effects.
Measurements of invertebrate functional feeding groups provided
descriptive, and ecologically meaningful information. When combined with the
descriptive power of multivariate analyses, functional feeding group data was
useful as a rapid bioassessment approach in the evaluation of effluent impacts on
river ecosystems.
Artificial stream studies were conducted to address questions on chronic
effluent toxicity, and possible nutrient-toxicant interactions on growth and energy
storage of the common stream scraper, Baetis tricaudatis. Larvae exposed to effluent had a 100% increase in thorax length over control animals, indicating growth
stimulation of effluent exposed animals. Measurements of dry weight showed no
effects of effluent on B. tricaudatis, however food effects were significantly different
indicating that appropriate food levels were selected. Baetis tricaudatis exposed
to 1% and 10% municipal effluent concentrations were found to have reduced lipid
energy storage, indicating a reduction in physiological status. With increased food
availability, the level of lipid energy storage increased to those of control animals,
however, this was only apparent at the 1% effluent concentration, suggesting that
at 10% effluent concentrations, food quantity can not alleviate effects.
From a bioassessment perspective, this research provides important
information on alternative methods for evaluating effluent impacts on river
ecosystems. This research points out the importance of assessing energy flow
and storage within stream biota to better understand the types of impacts that
complex municipal sewage effluents have on riverine biota.
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Degree
Master of Science (M.Sc.)
Department
Toxicology
Program
Toxicology