Morfološke i fiziološke prilagodbe morskih dijatomeja iz rodova Thalassionema, Thalassiosira i Synedra na smanjenu koncentraciju fosfora

master's thesis

• Title (english): Morphological and physiological responses of marine diatoms belonging to genera Thalassionema, Thalassiosira and Synedra to phosphorous deficiency
• Author: Marija Fornažar
• Mentor: Mirta Smodlaka Tanković (mentor)
• Mentor: Sunčica Bosak (sumentor)
• Committee member: Sunčica Bosak (predsjednik povjerenstva)
• Committee member: Petar Kružić (član povjerenstva)
• Committee member: Nada Oršolić (član povjerenstva)
• Committee member: Zrinka Ljubešić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2021-04-15, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

U ovom radu istražene su različite prilagodbe dijatomeja rodova Thalassionema, Thalassiosira i Synedra na uvjete s ograničenom koncentracijom fosfora. Pratila se stopa rasta, morfološke promjene, aktivacija enzima alkalne fosfataze, kinetika enzimske reakcije, koncentracija anorganskog fosfora u kulturama i fluorescencija klorofila a. Vrste su se preliminarno odredile pomoću svjetlosnog mikroskopa te je vrstama Thalassiosira cf. eccentrica i Thalassionema cf. frauenfeldii identitet potvrđen i molekularnim metodama. Za sve vrste utvrđena je veća brojnost i stopa rasta u eksponencijalnoj fazi u uvjetima obogaćenim fosforom. U uvjetima s ograničenom koncnentracijom fosfora utvrđena je enzimatska aktivnost kod vrsta T. cf. eccentrica i T. cf. frauenfeldii, te morfološke promjene i smanjena fluorescencija klorofila kod vrste T. cf. eccentrica. Za vrstu Synedra sp. se promjena fluorescencije klorofila nije mogla izmjeriti. Rezultati eksperimenata ukazuju da vrsta Synedra sp. prikazuje obilježja ravnotežne vrste dok su T. cf. eccentrica i T. cf. frauenfeldii slabije kompetitorske vrste. Poznavanjem koncentracije anorganskog fosfora u ekosustavu mogli bi predvidjeti fitoplanktonski sastav danog područja čime možemo dobiti bolji uvid u lokalnu trofičku mrežu i ciklus ugljika kroz trofičke stepenice, mikrobni krug i samu biološku pumpu.

Abstract (english)

This thesis investigates the adaptations of diatoms belonging to genera Thalassionema, Thalassiosira and Synedra to a phosphorus deficient medium. Activation of alkaline phosphatase enzyme, chlorophyll a absorbance, phosphorus concentration, growth rate, cell abundance and morphological changes were monitored. Species were identified with light microscopy and molecular analysis confirmed the identities for Thalassiosira cf. eccentrica and Thalassionema cf. frauenfeldii. For Synedra sp. molecular determination was not possible. Higher cell abundance as well as greater cell growth rate in exponential growth phase was detected for all monitored species in phosphorus rich medium. In phoshorus deficient medium enzymatic activity was noted for T. cf. eccentrica and T. cf. frauenfeldii as were morphological changes and lower chlorophyll a fluorescence for T. cf. eccentrica. For Synedra sp. measurement of chlorophyll a fluorescence change wasn’t possible because phosphorus concentration was bellow detection levels. Synedra sp. characteristics depict a behaviour of an equilibrium species where T. cf. eccentrica and T. cf. frauenfeldii show characteristics of opportunistic species. Knowing phosphorus concentrations in the marine environment would enable better prediction of phytoplankton composition thus giving us a better understanding of the local food web and carbon cycling trough trophic interactions.

• Keywords: morske dijatomeje; Sjeverni Jadran; alkalna fosfataza; ograničenje fosforom; adaptacija
• Keywords (english): marine diatoms; northern Adriatic; alkaline phosphatase; phosphorus deficiency; adaptations
• Language: croatian
• URN:NBN: urn:nbn:hr:217:540573
• Study programme: Title: Ecology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra ekologije i zaštite prirode (magistar/magistra ekologije i zaštite prirode)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-04-19 08:45:00