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VICTORIA LÓPEZ-RODAS Y COLS. AN. R. ACAD. NAC. FARM.

In aquatic ecosystems, the tolerance of microalgae and
cyanobacteria to environmental stress consequence of water
contamination is very relevant because these organisms are the
principal primary producers of aquatic ecosystems (4). Consequently,
survival and growth of phytoplankton living in contaminated
environments is an interesting topic from an ecological point of
view (5). There is a growing interest to study effects of crude oils
and oil components on microalgae (for example, see references
6-14). Usually, crude oil spills rapidly inhibits photosynthesis
and growth of these primary producers (10, 15). However, the
effects of crude oil on phytoplankton are very variable (16-19),
influence of dispersants (20). Recent experiments suggest that
different species show a different response against crude oil
contamination (15). Unfortunately, little is known about algal
response to crude oil contamination.

In order to add knowledge about microalgal response to crude oil
spill, we study a fascinating example of the extreme contamination
by crude oil in Arroyo Minero, Nirihuan de Arriba, Río Negro,
Argentina. A natural spill of crude oil has been pouring perhaps
during hundreds of years. Around 50 m of natural spill there is
and artificial spill from a tasting held made in 1915 for a possible
exploitation of the crude. Both spills are composed of crude oil mixed
with gas and fresh water. Both spill fall into the Arroyo Minero River
after flowed slowly a few meters.

Surprisingly, the crude oil spill area of Arroyo Minero River has
an abundant microalgal biomass living in contact with crude oil. The
main aim of this study was to describe the first known community
of microalgae living in permanently crude oil contaminated
environment.

2. MATERIALS AND METHODS

Sampling of water and phytoplankton was carried out in Arroyo
Minero, Nirihuan de Arriba, Río Negro, Argentina, on April 4th,
2008. Two samples points were studied: i) the spring of the natural
oil spill, and ii) Arroyo Minero river about 25 meters down water
from the petroleum spill.

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