Ekotoksikološki učinak natrijevog metasilikata na zelenu(Hydra viridissima Pallas, 1766) i smeđu hidru (Hydra oligactis Pallas, 1766)

master's thesis

• Title (english): Ecotoxicological effect of sodium metasilicate on green (Hydra viridissima Pallas, 1766) and brown hydra (Hydra oligactis Pallas, 1766)
• Author: Ana Šimičev
• Mentor: Goran Kovačević (mentor)
• Committee member: Goran Kovačević (predsjednik povjerenstva)
• Committee member: Božena Mitić (član povjerenstva)
• Committee member: Petra Korać (član povjerenstva)
• Committee member: Maja Matulić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2016-09-27, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Hidra je slatkovodni beskralježnjak iz koljena žarnjaka. Zelena se hidra ističe prisutnošću jednostaničnih endosimbiotskih algi u svojim gastrodermalnim mioepitelnim stanicama. Natrijev metasilikat sintetički je spoj koji kao rezultat antropogenog djelovanja dospijeva u okoliš te je poznavanje njegovog učinka na žive organizme važno za održivost ekosustava. U ovom radu istraživao se učinak natrijevog metasilikata na zelenu i smeđu hidru. Cilj istraživanja bio je odrediti postoji li razlika u toksičnosti spoja na dvije vrste hidri, te da li endosimbiotski odnos daje zelenoj hidri prednosti u odgovoru na nepovoljne uvjete okoliša. Hidre su tretirane s četiri koncentracije metasilikata te su tijekom tri dana promatrane morfološke, bihevioralne i reproduktivne promjene. Za analizu citološko - histoloških i morfometrijskih promjena izrađeni su standardni trajni preparati zelenih hidri. Utvrđeno je kako natrijev metasilikat u subletalnim koncentracijama u zelenih i smeđih hidri uzrokuje migraciju, smanjenu podražljivost, oštećenje lovki i promjenu oblika tijela. U zelenih je hidri štetan učinak najizraženiji bio prvi dan nakon tretiranja, a u smeđih hidri treći dan. Spoj je uzrokovao oštećenja staničnih slojeva i mezogleje te promjenu u položaju algi unutar stanica. Subletalne koncentracije natrijevog metasilikata izazvale su morfološka oštećenja i bihevioralne promjene u obje vrste hidri, a promjene su bile intenzivnije u smeđe hidre. S obzirom na to može se zaključiti kako endosimbiotske alge zelenoj hidri donose prednosti u prilagođavanju na uvjete u okolišu. Možemo zaključiti i kakav učinak bi ovaj spoj mogao imati na stanje vodenih ekosustava.

Abstract (english)

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.

• Keywords: topivi silikati; toksičnost; endosimbioza; slatkovodni ekosustavi
• Keywords (english): oluble silicates; toxycology; endosymbiosis; freshwater ecosystems
• Language: croatian
• URN:NBN: urn:nbn:hr:217:772662
• Study programme: Title: Experimental Biology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra eksperimentalne biologije (magistar/magistra eksperimentalne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-05-12 08:58:37