The impact of environmental disturbances on the gastrointestinal bacterial community and the viability of aquatic gastropods
| dc.contributor.advisor | Herlemann, Daniel Philipp Ralf | |
| dc.contributor.advisor | Käiro, Kairi | |
| dc.contributor.advisor | Tammert, Helen | |
| dc.contributor.author | Kivistik, Carmen | |
| dc.contributor.department | Institute of Agricultural and Environmental Sciences | eng |
| dc.contributor.other | Beier, Sara (opponent) | |
| dc.date.accessioned | 2022-11-17T08:24:30Z | |
| dc.date.available | 2022-11-17T08:24:30Z | |
| dc.date.defensed | 2022-12-02 | |
| dc.date.issued | 2022 | |
| dc.description | A Thesis for applying for the degree of Doctor of Philosophy in Environmental Sciences and Applied Biology. | eng |
| dc.description | Väitekiri filosoofiadoktori kraadi taotlemiseks keskkonnateaduse ja rakendusbioloogia erialal. | est |
| dc.description.abstract | The freshwater salinization caused by global climate change and anthropogenic activities has received increasing attention in recent decades. Coastal freshwater areas and inland water bodies are affected by agriculture, road salt usage, urbanization and resource extraction, which increase the concentration of dissolved ions in freshwaters. Water salinity is an important factor distributing species along the salinity gradient according to their evolutionary adaptation. As a result of freshwater salinization, the habitats and the species composition are changing. The organisms' resistance to environmental changes can be facilitated by symbiosis with microorganisms. The gut bacterial community supports the digestion, plays a role in the immune control, reproduction and development, and increases the hosts' resistance to environmental disturbances. In this thesis, the impact of increased water salinity and antibiotic concentration solely and in combination with food source change on the gut bacterial community of freshwater organisms was examined. In parallel, the energy reserves of the host were measured, for estimating how organism copes with the stressful occurrences. It was found that the rise in water salinity can affect the gut microbiome, if the salinity increase exceeds the tolerable threshold (salinity ~3). Therefore, the disturbance intensity has the strongest impact on the gut microbiome. Salinity increase to 3 combined with an easily digestible, carbohydrate-rich food source resulted in the highest host's energy level. However, this combination had the strongest effect on gut bacterial diversity, by increasing the abundance of generalists and reducing overall bacterial richness. In order to find out from which source the gut colonizing bacteria come from, the water bacterioplankton and the biofilm (food source) bacterial community were examined. It turned out that the influence of water bacterioplankton was minimal, and the gut microbiome was more similar to food source, which is likely the main source of bacteria colonizing the digestive tract. The results of this work suggest that aquatic invertebrates and their gut microbiome can successfully tolerate mild salinization, even with changes in the food source. | eng |
| dc.description.abstract | Globaalsete kliimamuutuste ja inimtegevusega kaasnev mageveekogude soolastumine on viimaste aastakümnete jooksul pälvinud aina rohkem tähelepanu. Nii mageveelised siseveekogud kui ka merre suubuvate jõgede suudmealad on mõjutatud põllumajandusest, tee soolamisest, linnastumisest ja maavarade kaevandamisest tekkivatest kõrvalsaadusest, mis tõstavad magevees lahustunud ioonide kontsentratsiooni. Veekogu soolsus on oluline faktor, mis jaotab liigid soolsuse gradiendil vastavalt nende evolutsioonilisele kohanemisele. Mageveekogude soolastumise tagajärjel muutuvad elupaigad ja nende ökosüsteemide liikide kooslus. Organismi vastupanuvõimet keskkonnamuutustele võib hõlbustada sümbioos mikroorganismidega. Seedekulgla bakterite kooslus toetab organismi seedimist, mängib rolli organismi immunsuskontrollis, paljunemisel ja arengul ning suurendab peremeesorganimsi vastupanuvõimet keskkonnamuutustele. Antud töös käsitleti veekogu soolsuse, antibiootikumide sisalduse ning toidubaasi muutustest tulenevat mõju magevee tigude seedekulgla bakterite kooslusele. Nende tegurite mõju uuriti nii eraldiseisvalt kui ka omavahel kombineeritult. Paralleelselt hinnati peremeesorganismi energiavarusid, mis annab aimu, kuidas organism keskkonnamuutustest tingitud stressiga toime tuleb. Töö tulemusena leiti, et magevee soolastumine mõjutab organismi seedekulgla mikrobioomi, kui soolsuse tõus ületab talutava soolsuse läve (tigude puhul soolsus ~3). Soolsuse tõus kombineeritult kergesti seeditava ja süsivesikuterikka toiduallikaga tõstis generalistide arvukust ja vähendas üldist bakterite mitmekesisust soolestikus. Selleks et teada saada millisest allikast seedekulglat koloniseerivad bakterid pärinevad uuriti nii vee bakterioplanktonit kui ka toiduallikaks oleva biofilmi bakterite kooslust. Ilmnes, et peremeesorganismi ümbritseva vee bakterioplanktoni mõju seedekulgla mikrobioomi moodustamisel on minimaalne, ning soolestiku mikrobioom sarnanes biofilmi bakterite koosluses, seega peamine allikas seedetrakti koloniseerivate bakteritele on toiduobjekt. Antud töö tulemused viitavad sellele, et magevee teod ja nende soolestiku mikrobioom suudavad kerget soolastumist, sealhulgas koos toiduallika muutustega edukalt taluda. | est |
| dc.description.sponsorship | Publication of this thesis is supported by the Estonian University of Life Sciences. | eng |
| dc.identifier.isbn | 978-9916-669-80-8 | |
| dc.identifier.issn | 2382-7076 | |
| dc.identifier.uri | http://hdl.handle.net/10492/7835 | |
| dc.identifier.uri | https://doi.org/10.15159/emu.110 | |
| dc.publisher | Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Doctoral Theses of the Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Eesti Maaülikooli doktoritööd | est |
| dc.rights | © Carmen Kivistik, 2022 | |
| dc.rights.uri | https://www.riigiteataja.ee/en/eli/ee/Riigikogu/act/519062017005/consolide | |
| dc.subject | dissertations | eng |
| dc.subject | dissertatsioonid | est |
| dc.subject | Green University (thesis is related to EMÜ Green University iniciative’s aims) | eng |
| dc.subject | Roheline Ülikool (töö toetab EMÜ Rohelise Ülikooli põhimõtteid) | est |
| dc.subject | siseveekogud | est |
| dc.subject | teod | est |
| dc.subject | keskkonnahäiringud | eng |
| dc.subject | seedekulgla | est |
| dc.subject | mikrobioom | est |
| dc.subject | inland waterbodies | eng |
| dc.subject | snails | eng |
| dc.subject | environmental degradations | eng |
| dc.subject | digestive tract | eng |
| dc.subject | microbiome | eng |
| dc.title | The impact of environmental disturbances on the gastrointestinal bacterial community and the viability of aquatic gastropods | eng |
| dc.title.alternative | Keskkonnahäiringute mõju seedekulgla mikrobioomile ja peremeesorganismi seisundile veetigude näitel | est |
| dc.type | Doctoral Thesis | eng |
| dc.type.qualificationname | PhD |
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