Development of landscape ecological model system using glossostigma elanoides and hemianthus callitrichoides to remediate aquaculture pond contaminants

Abstract

The aquaculture industry has contributed significantly to the economic development of Malaysia. However, the large volume of water consumption and the effluent discharged into water sources has caused significant environmental problems that require urgent management and the introduction of more effective controls. For instance, water pollution caused by excess contaminants, rapid loss of natural habitats such as mangrove lands as well as degradation of ecosystems cause innumerable damage far beyond damage to the environment. Phytoremediation, which is the application of plant-based technologies, has become more acceptable as a means to examine the problems and provide sustainable solutions for such environmental issues. Accordingly, this research explores the efficacy of a landscape ecological model system to remediate aquaculture pond contaminants specifically heavy metals using selected aquatic plant species. To achieve this aim, we examine the contaminants available in shrimp and catfish aquaculture ponds in Perak. The results revealed that nutrients like nitrogen and phosphorus and heavy metals concentration varied dependent upon several factors such as the size of the farm, the quantity of food given, the chemicals added, and the cycles and periods of cultivation. In addition, the environmental condition itself like pH, salinity, conductivity, and dissolved oxygen also influence the toxicity of the heavy metals available. Through water sampling, heavy metals that exceed the limit of water quality standard for aquaculture, which are cadmium (Cd), copper (Cu), chromium (Cr), and lead (Pb) were assessed. The efficiency of potential aquatic plants which are Glossostigma elatinoides and Hemianthus callitrichoides to sequester Cd, Cu, Cr and Pb were also investigated. This model system was conducted over four different periods ranging four weeks and at the following three different concentrations:1 mg/L, 2 mg/L, and 3 mg/L. The findings suggested that the capability to sequester different concentrations of heavy metals for certain periods varied between different species. The results indicated that Glossostigma elatinoides was a good phytoremediator for Cd and Cr with the bioconcentration factor (BCF) values 5436.7±16.70 and 6070.4±3.98 respectively, whereas Hemianthus callitrichoides was a good phyoremediator for Cu and Pb with the BCF values 5291.1±30.19 and 1787.1±27.43 respectively. This highlights that aquatic plants have different capabilities to sequester different heavy metals since various factors are involved during the phytoremediation process. The expected outcome of this research is to introduce cost-effective and eco-friendly technologies to mitigate environmental pollution from a landscape ecology perspective. The plants used as phytoremediators can enhance the visual aesthetics of underwater gardens, create new habitats, improve the soil structure, and provide ecology restoration and revitalisation. Thus, phytoremediation should be recognised as a ‘tool’ in landscape ecological development especially in contaminated sites. This knowledge may push the boundaries of the landscape architecture profession as well as promoting the concept of sustainability. Keywords: Aquaculture; Phytoremediation; Landscape ecology; Heavy metals; Glossostigma elatinoides; Hemianthus callitrichoides; In vitro model system.