INVESTIGADORES
FERREYRA Gustavo Adolfo
artículos
Título:
Non-synergistic effects of water-soluble crude oil and enhanced ultraviolet-B radiation on a natural plankton assemblage
Autor/es:
SARGIAN, P., B. MOSTAJIR, K. CHATILA, G.A. FERREYRA, E. PELLETIER AND S. DEMERS
Revista:
MARINE ECOLOGY PROGRESS SERIES
Editorial:
Inter-Research
Referencias:
Año: 2005 vol. 294 p. 63 - 77
ISSN:
0171-8630
Resumen:
The present study demonstrates the effects of the water-soluble fraction (WSF) of a crude
oil, enhanced ultraviolet-B radiation (UVBR: 280 to 320 nm), and the combination of WSF and enhanced
UVBR on a natural plankton assemblage (<150 ìm) isolated from the lower St. Lawrence Estuary.
To study the separate and dual effects of WSF and UVBR, 12 microcosms (9 l) were immersed in
the water column of larger mesocosms (polyethylene bags; 1800 l), providing 4 treatments, each in
triplicate: (1) NUVBR + WSF (natural UVBR with WSF), (2) HUVBR + WSF (enhanced UVBR with
WSF), (3) NUVBR (natural UVBR without WSF), and (4) HUVBR (enhanced UVBR without WSF). During
5 d we monitored the incident radiation, WSF and nutrient concentrations, abundance and production
of heterotrophic bacteria and phytoplankton. Strong deleterious effects of WSF and lower effects
of UVBR were observed on the phytoplankton assemblage, with a decrease in growth rates accompanied
by an increase in mean cell size which reflected a perturbation of the cell division cycle. Using the
NUVBR treatement as reference conditions, the above effects resulted in a reduction of 84, 79 and
60% of total abundance of the phytoplankton fraction <20 ìm in the HUVBR + WSF, NUVBR + WSF
and HUVBR treatments, respectively. Significant higher values of bacterial abundances were observed
in the WSF-added treatments compared to NUVBR without WSF. However, bacterial thymidine
incorporation exhibited diel variations, suggesting cumulative UVBR-induced DNA and/or PAHinduced
DNA damages, and possible repair mechanisms with the co-occurrence of more available
growth substrates from stressed phytoplankton. The absence of significant differences between both
WSF-added treatments under the 2 different UVBR conditions suggests that there is no additive interaction
between WSF and UVBR. This study provides therefore the first evidence of a non-synergistic
interaction between both stresses, and suggests that UVBR-induced effects on marine microorganisms
can be completely masked by the strong deleterious effects of soluble petroleum hydrocarbons.