Humic Substances Increase Survival of Freshwater Shrimp Caridina sp. D to Acid Mine Drainage

Aleicia Holland,Leo J Duivenvoorden,Susan H W Kinnear

doi:10.1007/s00244-012-9823-y

Aleicia Holland, Leo J Duivenvoorden + Show 1 more

Open Access

https://doi.org/10.1007/s00244-012-9823-y

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Abstract

Humic substances (HS) are known to decrease the toxicity of heavy metals to aquatic organisms, and it has been suggested that they can provide buffering protection in low pH conditions. Despite this, little is known about the ability for HS to increase survival to acid mine drainage (AMD). In this study, the ability of HS to increase survival of the freshwater shrimp (Caridina sp. D sensu Page et al. in Biol Lett 1:139-142, 2005) to acid mine drainage was investigated using test waters collected from the Mount Morgan open pit in Central Queensland with the addition of Aldrich humic acid (AHA). The AMD water from the Mount Morgan open pit is highly acidic (pH 2.67) as well as contaminated with heavy metals (1780 mg/L aluminum, 101 mg/L copper [Cu], 173 mg/L manganese, 51.8 mg/L zinc [Zn], and 51.8 mg/L iron). Freshwater shrimp were exposed to dilutions in the range of 0.5 % to 5 % AMD water with and without the addition of 10 or 20 mg/L AHA. In the absence of HS, all shrimp died in the 2.5 % AMD treatment. In contrast, addition of HS increased survival in the 2.5 % AMD treatment by ≤66 % as well as significantly decreased the concentration of dissolved Cu, cobalt, cadmium, and Zn. The decreased toxicity of AMD in the presence of HS is likely to be due to complexation and precipitation of heavy metals with the HS; it is also possible that HS caused changes to the physiological condition of the shrimp, thus increasing their survival. These results are valuable in contributing to an improved understanding of potential role of HS in ameliorating the toxicity of AMD environments.

Highlights

Acidification of freshwaters by anthropogenic means such as acid mine drainage (AMD) or aerial deposition is a global problem
This is a critical gap: as both low pH and high metal content are commonly recorded from AMD-affected systems, there may be an important role for Humic substances (HS) in reducing the toxicity of waterways polluted by AMD
The LC50 of 1.9% recorded during this study is considerably lower than the 2.7% recorded by Chapman and Simpson (2005), which used the Mount Morgan open pit water in tests with the freshwater shrimp Caridina indistincta

Summary

Introduction

Acidification of freshwaters by anthropogenic means such as acid mine drainage (AMD) or aerial deposition is a global problem. Unlike streams acidified by anthropogenic means, these systems may contain diverse populations of aquatic organisms. It has been suggested that the presence of high amounts of HS in naturally acidic waterways buffers the organisms present against the detrimental effects of low pH (Collier et al 1990; Dangles et al 2004). The ability of HS to increase survivorship to anthropogenically acidified waters such as those affected by acid mine drainage is unknown. This is a critical gap: as both low pH and high metal content are commonly recorded from AMD-affected systems, there may be an important role for HS in reducing the toxicity of waterways polluted by AMD

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