Unit:
Κατεύθυνση Βιολογική ΩκεανογραφίαLibrary of the School of Science
Author:
Triantafyllidis Anastasios
Supervisors info:
Αθηνά Οικονόμου-Αμίλλη, Ομότιμη Καθηγήτρια, Τμήμα Βιολογίας, ΕΚΠΑ
Ήρα Καραγιάννη, Επίκουρη Καθηγήτρια, Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών, Πανεπιστήμιο Ιωαννίνων
Αντωνία Γιαννακούρου, Ερευνήτρια Β’, Εργαστήριο Μικροβιακής Οικολογίας, Ινστιτούτο Ωκεανογραφίας,
Ελληνικό Κέντρο Θαλασσίων Ερευνών (ΕΛΚΕΘΕ)
Σουλτάνα Ζερβουδάκη, Ερευνήτρια Β’, Εργαστήριο Ζωοπλαγκτού, Ινστιτούτο Ωκεανογραφίας,
Ελληνικό Κέντρο Θαλασσίων Ερευνών (ΕΛΚΕΘΕ)
Original Title:
Κατανομή μικροβιακών παραμέτρων κατά μήκος ενός άξονα τροφικής διαβάθμισης στον Σαρωνικό κόλπο
Translated title:
Distribution of microbial parameters along a trophic gradient in Saronikos Gulf
Summary:
Heterotrophic bacteria play a key role in cycling of organic matter and nutrients in planktonic food webs, varying considerably depending on the environmental trophic status. They form the major host reservoir for viruses which are dynamic members in microbial processes. Viral abundance might rise with increasing eutrophication and the variation of host cell densities is a key factor for the understanding of virus spatial distribution patterns.
The study area, Saronikos gulf, is of particular interest since it hosts an industrial site and the Waste Water Treatment Plant of the city. Sampling was conducted seasonally, along a transect of four stations from the inner to the outer gulf. The aim was to determine seasonal dynamics of productivity and biomass stocks of the heterotrophic prokaryotes, as well as the virus-like particles and to relate these to variations in the physicochemical parameters.
In agreement with the higher nutrient and chlorophyll-a concentration at the inner gulf, bacterial production and abundance was higher (up to 151ngCl-1 h-1 and 1.2×106 cells ml-1). Towards the outer gulf bacterial concentration was lower, and only during late winter and spring, in the WWTP station values were as high as 1.02×106 cells ml-1, probably due to increased DOC input. Water-column integrated bacterial biomass was always lower than phytoplankton biomass at the inner station, while at the other stations the ratio was near or lower than 1. Viral abundance constantly peaked at the inner station up to 20.5x106 VLP ml-1 where seasonal variability was low. Similarly the virus-to-bacterium ratio demonstrated the numerical predominance of viruses over bacteria. This suggests allochthonous inputs and/or the existence of phytoplankton associated viruses. Except in December, a decreasing viral abundance pattern was observed towards the outer gulf.
Main subject category:
Science
Keywords:
planktonic food web, heterotrophic bacteria, virus-like-particles, Saronikos Gulf
