Laboratory assay of sediment phytotoxicity using the macrophyte Vallisneria americana

Abstract

In contrast to their ecological importance, submersed rooted macrophytes have been overlooked in environmental science. Presently, the array of standard phytotoxic bioassays includes only one free‐floating vascular macrophyte (Lemna) and several algal species. A short‐term and inexpensive assay was studied for feasibility in evaluating sediment quality. Cloned ramets of the macrophyte Vallisneria americana were used to test phytotoxicity of sediments collected at different locations in the Detroit River. Ramets were planted in sediment samples and placed in greenhouse aquaria. After a week of exposure, ramets of V. americana were destructively sampled and preserved. The leaf and root surfaces areas were determined, and plant biomass was recorded for each ramet. An index of the leaf‐to‐root surface area ratio was a reliable predictor of sediment phytotoxicity; the ratio of leaf‐to‐root mass was also useful but proved less consistent. Ramets grown in sediments that were relatively less contaminated with organic compounds had lower values of the leaf‐to‐root surface area ratio, while plants grown in more contaminated sediments had greater values. Results of analyses of variance indicated that the index of leaf‐to‐root surface area ratio responded to sediment quality but was not significantly affected by either variation in plant genotype or interaction between sediment and plant genotype. There was a significant correlation (p < 0.001) between rank‐ordered results of the present greenhouse study and results of leaf‐to‐root surface area ratios for plants previously surveyed in the field.

Herbicide Exposure and Toxicity to Aquatic Primary Producers

“…Responses of rooting plants to herbicide exposure through the sediment are expected to be most strongly in their belowground parts, since in this case these parts of the plant are most directly exposed to the herbicide. Sensitivity of Vallisneria americana to sediment-associated contaminants could be assessed by changes in their shoot-to-root ratios, with plants grown in sediments contaminated with organic compounds having larger shoot-to-root ratios compared to plants grown in cleaner sediments (Biernacki et al 1997). Although root endpoints were more sensitive than shoot endpoints for M. spicatum exposed to linuron via sediment, shoot biomass declined more (1.8x lower than control) compared to root biomass (1.5x lower; Burešová et al 2013).…”

The Phytotoxic and Genotoxic Effects of Olive Oil and Milk Industry Wastewater onElodea canadensis

“…Measuring components of basic plant traits, such as growth, survival or reproduction is typically quite simple and repeatable. For example, Biernacki et al [1996Biernacki et al [ , 1997a showed the leaf-to-root surface area ratio in Vallisneria americana, which was a reliable index of environmental quality in aquatic ecosystems. Similarly, patterns of fluctuating asymmetry in plant leaves has been proposed as a useful measure of sub-lethal environmental stresses in wetland and terrestrial systems [Rettig et al, 1997].…”