Cigarette butt effects on diatom health in a stream ecosystem

Abstract

Cigarette butts are a prevalent form of litter containing numerous toxic chemicals. Because cigarette butts are frequently deposited on the ground and carried into water bodies, greater understanding of the toxic effects of cigarette butts in aquatic ecosystems is needed. We examined the toxicity of cigarette butts to algal growth and diatom health-especially pertinent because of the strong ecological role of these organisms. We modified the agar-based nutrientdiffusing substrate method by using cigarette butt leachate (at 10, 5, 2.5, and 1.25 butts/l concentrations), a whole cigarette butt, and a plain agar control. After incubating for 10 days in a small stream, the biofilms from the diffusing substrates were assessed for algal biomass and diatom health (chloroplast intactness and size of lipid bodies in two abundant species of Navicula). There were no significant differences among the cigarette butt treatments for algal biomass or diatom health; hence, evidence of toxic effects was not found. Other studies have demonstrated cigarette butt leachate toxicity to fish and aquatic invertebrates, but these studies were done in closed systems. In contrast, in open stream ecosystems, effluent may be quickly diluted and carried away by water flow, and the complex chemical environment of streams likely includes leachate from a variety of riparian leaves that fell into the stream (i.e., algae are naturally exposed to low concentrations of a wide variety of secondary chemicals). Our results do not preclude the finding of toxicity of cigarette butt effluent to algae, including diatoms, in standard toxicity tests.

Remediation Capacity of Different Microalgae in Effluents Derived from the Cigarette Butt Cleaning Process

“…Previous studies found a direct relationship between algal growth and Chla content [19][20][21]. Here, results of Chla indicate that microalgae growth was generally affected with a CB concentration of more than 2%.…”

The ecological impacts of discarded cigarette butts

“…To date, however, there are only two studies that has used continuously flowing water: Green et al [48] reported that smoked conventional butts decreased clearance rates of blue mussels (Mytilus edulis) (at 1 butt L -1 ) 2.5 times and reduced the biomass of benthic microalgae (at 0.25 and 1 butt L -1 ) by up to 3 times. On the contrary, Werdel et al [49] found that biofilm formation, in terms of algal biomass and diatom health, was unaffected in an experiment using a flowing stream with agar plates made with various concentrations of cigarette butt leachate. Such systems are relevant to understand ecoctoxicological effects of cigarette butts, but standardisation is required to facilitate comparison between different ecosystems.…”

“…There is a growing body of evidence of how microplastics affect aquatic biota [50], including animals and primary producers [51]. Studies assessing the impact of cigarette butts on primary producers, however, have been limited with only three studies on microalgae [25,49,52], one study on a marine macroalga [48] and no studies on plants in either habitat. Understanding impacts at the base of aquatic food webs would enable better predictions of impacts across multiple trophic levels in both freshwater and marine systems, but also in terrestrial habitats.…”