Ecotoxicological effect of sodium metasilicate on green (Hydra viridissima Pallas, 1766) and brown hydra (Hydra oligactis Pallas, 1766)

Šimičev, Ana (2016) Ecotoxicological effect of sodium metasilicate on green (Hydra viridissima Pallas, 1766) and brown hydra (Hydra oligactis Pallas, 1766). Diploma thesis, Faculty of Science > Department of Biology.

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Abstract

Hydra is a freshwater invertebrate from the phylum Cnidaria. In its gastrodermal myoepithelial cells green hydra harbours endosymbiotic unicellular algae. Sodium metasilicate is a synthetic compound which is released in the environment as a product of human activities. Therefore, knowing the effects it has upon living organisms is important for sustainability of ecosystems. The aim of this research was to determine its effects on green and brown hydra and to compare the changes in the two hydra species. Hydras were treated with four concentrations of metasilicate and morphological, behavioral and reproductive changes were observed during the next three days. For cyto-histological analysis standard preparations of green hydra were made. The results have shown that sublethal concentrations of sodium metasilicate caused migration, reduced reactivity to mechanical stimuli, changes in body contraction and damage of tentacles. Effects were the strongest on the first day after treatment in green hydra and on the third day in brown hydra. The compound caused damage of cellular layers and mesoglea, and changed distribution of algae inside cells. Sublethal concentrations of sodium metasilicate caused morphological and behavioral changes in both species of hydra, and they were more intense in brown hydra. Green hydra showed better adaptability to unfavourable environmental conditions and we can conclude about the effect this metasilicate could have on aquatic ecosystems.

Item Type: Thesis (Diploma thesis)
Keywords: oluble silicates, toxycology, endosymbiosis, freshwater ecosystems
Supervisor: Kovačević, Goran
Co-supervisor: Gračan, Romana
Date: 2016
Number of Pages: 49
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Grozdana Sirotic
Date Deposited: 19 Jan 2017 11:50
Last Modified: 19 Jan 2017 11:50
URI: http://digre.pmf.unizg.hr/id/eprint/5431

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