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Titre du document / Document title

Viruses and protists cause similar bacterial mortality in coastal seawater

Auteur(s) / Author(s)

FUHRMAN J. A. ; NOBLE R. T. ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

Univ. Southern California, dep. biological sci., Los Angeles 90089-0371, ETATS-UNIS

Résumé / Abstract

Mesocosms filled with 80 liters of coastal seawater from Santa Monica, California, were used twice (June and November) to budget bacterial production and loss, as well as to assess the relative significance of viral lysis and protist grazing in bacterial mortality. Bacterial abundance was ∼6 x 109 cells liter-1 in June and 2 x 109 in November, with viral abundances ∼2 X 1010 particles liter-1 in June and 1.5 x 1010 in November. Incorporation of [3H]thymidine and leucine yielded essentially identical production estimates and allowed calculation of total bacterial mortality in these closed systems. Bacterial growth rates were 1-2 d-' in June and 1-3 d-1 in November. Three independent lines of evidence indicated that bacterial mortality attributed to grazing by protists was about equal to that attributed to viruses : size fractionation of disappearance of labeled DNA, with a 50% reduction after protists were removed ; comparison of protist grazing rates estimated with fluorescently labeled bacteria and virus production-based bacterial lysis rates, with 40-50% of the total ascribed to viruses ; and model-based interpretation ofthe 3.3-4.6% of bacteria visibly infected with assembled intracellular viruses, suggesting that 24-66% of loss is due to infection. Redundant production and loss measurements as well as the independent loss process estimates agreed within ∼30%, yielding a reasonably balanced budget. We believe the loss of bacteria to viruses reflects a significant dissipation of energy in this ecosystem and that viruses and protists contribute similarly to bacterial mortality.

Revue / Journal Title

Limnology and oceanography    ISSN  0024-3590   CODEN LIOCAH 

Source / Source

1995, vol. 40, no7, pp. 1236-1242 (34 ref.)

Langue / Language

Anglais

Editeur / Publisher

American Society of Limnology and Oceanography, Waco, TX, ETATS-UNIS  (1956) (Revue)

Mots-clés anglais / English Keywords

Bacteria

;

Growth rate

;

Biological productivity

;

Population dynamics

;

Mortality

;

Predation

;

Zooplankton

;

Protozoa

;

Virus

;

Seasonal variation

;

Marine environment

;

Coastal zone

;

North Pacific

;

California

;

Pacific Ocean

;

United States

;

North America

;

America

;

Mots-clés français / French Keywords

Bactérie

;

Taux croissance

;

Productivité biologique

;

Dynamique population

;

Mortalité

;

Prédation

;

Zooplancton

;

Protozoa

;

Virus

;

Variation saisonnière

;

Milieu marin

;

Zone côtière

;

Océan Pacifique Nord

;

Californie

;

Océan Pacifique

;

Etats Unis

;

Amérique du Nord

;

Amérique

;

Mots-clés espagnols / Spanish Keywords

Bacteria

;

Tasa crecimiento

;

Productividad biológica

;

Dinámica población

;

Mortalidad

;

Rapiña

;

Zooplancton

;

Protozoa

;

Virus

;

Variación estacional

;

Medio marino

;

Zona costera

;

Océano Pacífico Norte

;

California

;

Océano Pacífico

;

Estados Unidos

;

America del norte

;

America

;

Localisation / Location

INIST-CNRS, Cote INIST : 2892, 35400005502530.0060

Nº notice refdoc (ud4) : 2940358



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