Microbial community structure in two anchialine caves on Mljet Island (Adriatic Sea)

Autor: Krstulovic, Nada, Solic, Mladen, Santic, Danijela, Marsic-Lucic, Jasna, Ordulj, Marin, Stefanija Šestanović
Jazyk: angličtina
Rok vydání: 2013
Předmět:
Zdroj: Marin Ordulj
Acta Adriatica
Volume 54
Issue 2
Publons
ResearcherID
ISSN: 0001-5113
1846-0453
Popis: The microbial abundances, including bacteria, viruses, and heterotrophic nanoflagellates, were determined for two anchialine caves located on the Island of Mljet (Adriatic Sea): Bjejajka Cave and Lenga Pit. Both caves are situated approximately 100 m from the coast with extensive subterranean connections to the sea, resulting in noticeable marine and terrestrial, influences. Because of the shallow settings of the studied caves, they represent habitats with a minimal light or complete darkness where photosynthesis is minimal or not possible. Thus, during the surveys there was no evidence of cyanobacterial cells in either caves, but the presence of bacteria, viruses and heterotrophic nanoflagellates (HNF) was established. Further, bacterial abundance was higher in caves in comparison to surrounding open seawater. In the surrounding seawater the predominance of the LNA group over HNA is determined, which also indicates the differences in relation to the studied caves. In fact, the dominance of HNA group of bacteria in caves together with higher total bacterial abundance indicates that the caves are of higher trophic level than the surrounding seawater. With regard to bacterial diversity, both caves had a unique makeup of bacterial populations and low diversity, with the chemolithoautotrophic Epsilonproteobacteria representing the most abundant taxonomic group. To examine the mechanisms regulating bacterial abundance in these habitats, we observed the relationship between bacteria and heterotrophic nanoflagellates (HNF) and between bacteria and viruses. The importance of predation in controlling bacteria (top down control) and, consequently, the domination of bottom up control of HNF were observed in both caves
Istraživanja abundancije mikroorganizama, uključujući bakterije, viruse i heterotrofne nanoflagelate (HNF) su provedena u anhialinim špiljama Bjejajka i Lenga na otoku Mljetu. Špilje su smještene na oko 100 m udaljenosti od obalne linije s podzemnom vezom s morem te su pod znatnim utjecajem mora kao i kopnenih staništa. S obzirom na položaj istraživane špilje predstavljaju staništa s minimalnim prodorom svjetlosti ili potpunim mrakom što ukazuje na izostanak procesa fotosinteze. Tijekom istraživanja ni u jednoj špilji nije utvrđeno prisustvo cijanobakterija odgovornih za procese fotosinteze, ali je utvrđena značajna brojnost bakterija, virusa i heterotrofnih nanoflagelata. Štoviše brojnost bakterija u špiljama je bila veća od brojnosti bakterija u okolnom moru. Jednako i odnosi HNA i LNA bakterija ukazuju na razlike između špilja i okolnog mora. U okolnom moru je utvrđena dominacija LNA bakterija u odnosu na HNA dok je u špiljama utvrđeno prevladavanje HNA bakterija što zajedno s većom ukupnom brojnošću bakterija ukazuje na viši trofički stupanj u špiljama u odnosu na okolno more. Preliminarnim ispitivanjem raznolikosti bakterija u špiljama je utvrđeno najbrojnije prisustvo kemolitoautotrofnih bakterija taksonomske skupine Epsilonproteobacteria. U svrhu studiranja mehanizama regulacije bakterijske abundancije u istraživanim su špiljama analizirani odnosi između bakterija i heterotrofnih nanoflagelata i između bakterija i virusa. Važnost predacije u kontroli bakterija (top down kontrola) je utvđena u obje ispitivane špilje.
Databáze: OpenAIRE
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