The Effects of Sodium Percarbonate Generated Free Oxygen on Daphnia—Implications for the Management of Harmful Algal Blooms

Robin Thoo,Waldemar Siuda,Iwona Jasser

doi:10.3390/w12051304

Abstract

Increasing frequencies and durations of harmful algal blooms are a nuisance in many aquatic ecosystems. This has led to the use of a variety of control methods to prevent their appearance or to disperse them following their establishment. Most of these methods are not selective; consequently, research into alternative selective methods has been ongoing. Reactive oxygen species generated following the addition of hydrogen peroxide have been shown to selectively target the cyanobacterial component of harmful algal blooms in experimental and field settings. This study assesses the effects of increasing concentrations of reactive oxygen species from the addition of sodium percarbonate on zooplankton in a small experimental setting using a natural plankton sample. It was found that the genus Daphnia showed moderate sensitivity to sodium percarbonate. Preliminary evidence suggests that the size of an individual may affect the probability of survival, with larger individuals having a lower likelihood of survival. Lower survival rates of large Daphnia were hypothesized to have been caused by higher relative filtration rates of larger individuals. From the zooplankton data obtained, we suggest that a safe concentration of sodium percarbonate for Daphnia individuals would be below 10.0 mg·L−1 sodium percarbonate (2.8 mg·L−1 hydrogen peroxide).

Highlights

Phytoplankton forms the base of the aquatic pelagic food web [1]
A total of 1944 individuals belonging to seven different systematic groups were counted: four from the order of Cladocera, namely Daphnia (1610), Bosminidae (2), Chydoridae (1) and Scapholeberis
Daphnia were the most numerous zooplankton group by far; it was decided that further detailed analyses were only to be performed on this genus (Table 2), though the actual number of animals from all identified groups are provided in the Table S1 in the Supplementary Materials

Summary

Introduction

Phytoplankton forms the base of the aquatic pelagic food web [1]. These photosynthetic organisms are a key component of freshwater aquatic ecosystems, and the majority of other aquatic environments [2]. Eutrophication is undesirable for water bodies for a number of reasons, ranging from ecological and economic concerns to pure aesthetics [3] It is not the only phytoplankton component that causes blooms to be a nuisance, but the proliferation of cyanobacteria are a particular cause of concern because of the large number of negative effects that can result when their abundance becomes too high. Such issues include but are not limited to: shading and outcompeting other phytoplankton species and macrophytes, interfering with large zooplankton feeding by clogging and providing poor quality food, forming scum on water surfaces, and eventually producing toxins which may be harmful for other organisms and humans [3,4,5,6,7,8]. Owing to the mixed or heterogeneous community of organisms within a fluid medium (notwithstanding stratification due to temperature, light and temperature gradients, and so on) a major complication in combatting harmful algal blooms (HABs), and an even

Methods

Results

Discussion

Conclusion