Effect of Higher Plant Essential Oils for the Control of Red Tide Algae Cochlodinium polykrikoides under Laboratory Conditions.
Abstract
Effect of Higher Plant Essential Oils for the Control of Red Tide Algae Cochlodinium polykrikoides under Laboratory Conditions: Antialgal activity of Zataria multiflora, Satureja khuzistanica and S. rechingeri were evaluated. These plant species are easily cultivable and their algicidal activity make them suitable candidate as biocontrol. This study aimed to identify effective algicidal compounds, practically new algicidal agents from essential oils of plants that could inhibit the growth of red tide microalgae. Prepared essential oils of Z. multiflora showed the highest algicidal activity (LC50 1.35 µg.mL-1). Algicidal activities of essential oils of all plants exhibited dose dependency. Results of the assays showed that the growth of Cochlodinium polykrikoides was strongly inhibited by using different concentrations of the plants essential oils.
Introduction
Recently there has been a global increase in the frequency, magnitude and geographical extent of harmful algal blooms (HABs). This increase appears to be correlated with the degree of coastal pollution, the utilization of coastal water for aquaculture or global warming, and caused mass mortality of fishes and bivalves. In general, the mass mortality of fish not only results in economic loss, but also contributes to pollution of coastal waters (Kim et al., 2000; Kim et al., 2002; Camacho et al., 2007; Sole et al., 2006).
HABs are natural phenomena causing red discoloration of water and are commonly known as “red tides”. Although, referred to as “Red tides”, blooms are not only red, but can be brown, yellow, green, or milky in color (Kim et al., 2002; Kim et al., 2004; Verlecar and Desai, 2004).
Materials and Methods; Effect of Higher Plant Essential Oils
2.1. Culture of C. polykrikoides The dinoflagellate C .polykrikoides was obtained from the Persian Gulf and Oman Sea Ecological Research Institute (PGOSERI). All stock cultures were maintained in f/2 medium (An et al., 2008) before being transferred to natural sea water media supplemented with the f/2 medium (1000:1). They were grown in modified f/2 medium, at 26 ºC, 90 µmol photons m-2 s-1 with a 12:12 (h) Light: Dark cycle in incubators. The initial pH and salinity of the culture medium were adjusted to 8.0 and 32%, respectively. Prior to the experiment, C. polykrikoides was cultured up to the exponential growth (5 d following inoculation) to obtain a high biomass. The
microalgae were cultivated to the exponential growth phase for use. The density was monitored every two days by measuring cell numbers at a set time in the experiment.
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