Effects of a laundry additive on the community structure of epidendric algae in Douglas Lake.

Abstract

Many organic chemicals have been detected in freshwater ecosystems and their effects on aquatic life have been documented extensively. Household cleaning products, such as detergents and fabric softeners, contain organic chemicals that have been detected in aquatic systems. These are manufactured in mass quantities and are introduced into the environment as solid waste or via ""down-the drain"" following consumer use (Belanger, 1994). Consequently, these chemicals end up in municipal wastewater treatment plants. If not readily degraded or totally removed in treatment facilities, they are likely to occur in treatment plant effluents which are discharged into surface waters (Belanger, 1994). This possible fate has prompted many investigations into the effects of household cleaning products on aquatic organisms. In this study, epidendric algae were exposed to fabric softener, a laundry additive that gives fabrics a soft feel and smooth surface. It also reduces static electricity and wrinkling. The softening agent commonly used in fabric softeners is a cationic quaternary ammonium surface-active ingredient (surfactant; QAS). Surfactants are organic compounds with both hydrophobic and hydrophilic ends that reduce the surface tension of water and adsorb onto its surface. Although they normally occur at lower concentrations, cationic surfactants generally are more toxic than any other class of surfactants (Stevenson, 1996). Most QASs are relatively insoluble in water, can complex with dissolved organics and adsorb firmly to solids. The adsorptive features of QASs enable them to be removed by treatment plant processes as complexes on solid surfaces of sludge. Moreover, the high occurrence of QAS sorption in aquatic systems limits their biodegradation and increases their potential to be toxic to aquatic organisms (Stevenson, 1996). The algae are ideally suited and regarded as ""universal indicators"" of water quality because they are ubiquitous in their distribution and are easily identified and sampled. Specifically, the composition of an algal community can be used as an indication of water quality or of changes in that quality (Hellawell, 1986). Some species within a normal algal community are more common whereas other species are less represented. This concept is significant in that it provides an ecological framework for comparing changes in the structure of algal communities that have been subjected to organic chemicals. Following are potential scenarios for change in community structure (Hellawell, 1986): (1) biomass changes, community structure does not--this scenario involves a decrease or increase in the size of the community without any modification of the relative proportion of individuals; (2) species same, community structure changes; biomass may change--the community may change in size but the composition shifts also; some species increase in relative importance; others decline; (3) species and community structure change; biomass may change-- in addition to the changes of the type found in the second scenario, new species join the community while others disappear. The purpose of this study was to determine which of these scenarios would occur after an algal community was exposed to a laundry additive containing a cationic quaternary ammonium surfactant.