Phytoplankton Composition and Saxitoxin Surveillance in Aquatic Species of Kedung Ombo Reservoir, Central Java, Indonesia | ||||
| Egyptian Journal of Aquatic Biology and Fisheries | ||||
| Article 126, Volume 29, Issue 4, July and August 2025, Page 2333-2352 PDF (532.6 K) | ||||
| DOI: 10.21608/ejabf.2025.445743 | ||||
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| Author | ||||
| Rahmawati et al. | ||||
| Abstract | ||||
| The rapid growth of Indonesia’s population and urban development has intensified water pollution, including eutrophication, which can trigger harmful algal blooms (HABs). In freshwater ecosystems, these events are referred to as cyanobacterial harmful algal blooms (CyanoHABs), some of which involve toxin-producing species capable of releasing saxitoxin (STX). This study aimed to investigate the phytoplankton community in the Kedung Ombo Reservoir, with a focus on Cyanobacteria that have the potential to form CyanoHABs, and to assess their relationship with water quality parameters and the possible presence of saxitoxin in aquatic organisms. Phytoplankton composition was analyzed microscopically, and the presence of saxitoxin was assessed using the Receptor Binding Assay (RBA) method. The phytoplankton community in the reservoir was found to consist of six phyla: Chlorophyta (40%), Cyanobacteria (35%), Bacillariophyta (16%), Euglenophyta (6%), Dinophyta (2%), and Charophyta (1%). Cyanobacterial genera with the potential to form CyanoHABs included Aphanizomenon spp., Microcystis spp., Phormidium spp., Dolichospermum spp., and Oscillatoria princeps. In addition, cyanobacterial cysts (akinetes) were detected in sediment samples at an average density of 53 cells/g dry sediment, suggesting a potential reservoir for future blooms under favorable environmental conditions. However, saxitoxin was not detected in any of the sampled aquatic organisms, which included snails (Pila ampullacea), carp (Cyprinus carpio), tilapia (Oreochromis mossambicus), and catfish (Clarias gariepinus). These results indicate no current risk of saxitoxin contamination in aquatic food resources from the reservoir, suggesting that food safety is not presently compromised. Nevertheless, the high nutrient levels and the presence of akinetes underscore the importance of proactive management strategies to safeguard aquatic resources and prevent the emergence of CyanoHABs in the future. | ||||
| Keywords | ||||
| Cyanobacteria; CyanoHABs; Cyanotoxin; Saxitoxin; Akinete | ||||
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