Effects of Organic Herbicides on Phototrophic Microbial Communities in Freshwater Ecosystems - Reviews of Environmental Contamination and Toxicology - page 116

robust (Schmitt-Jansen and Altenburger 2005a ), they cannot fully replace model
ecosystems (microcosms, mesocosms, or enclosures) or ield investigations. The
reason is that SSD approaches focus on short-term or midterm effects and tend to
ignore important ecological factors (Brock et al. 2004 ), such as the indirect effects
that result from community interactions (i.e., interactions among zooplankton,
benthic grazers, heterotrophic microbial communities, etc.).

4.2.2 Using Molecular Tools in Ecotoxicology

Although molecular biology has revolutionized the understanding of microbial
ecology in various environments, including water ecosystems, its use in ecotoxicol-
ogy has probably been underused, although we did ind a few studies that employed
molecular techniques such as PCR-DGGE (e.g., Dorigo et al. 2007 ; Tlili et al. 2008 ;
Pesce et al. 2009 ) or 18S rRNA cloning and sequencing (Dorigo et al. 2002 ). New
sets of 18S rRNA primers that are more speciic to different taxonomic levels (e.g.,
Chlorophycea and Bacillariophyceae; Valiente Moro et al. 2009 ) could prove to be
highly valuable for studying the phototrophic community dynamics, after pesticide
exposure. Cutting-edge molecular tools such as (meta)genomics or microarrays also
offer new and powerful possibilities for assessing pesticide effects on microbial
community (including phototrophic communities) diversity and functionality.

4.2.3 Understanding the Ecological Consequences

of Tolerance Acquisition

For many research scientists the only realistic approach to obtain aquatic ecotoxi-
cology data consists of performing in situ studies (Boudou and Ribeyre 1997 ). Field
studies, however, may yield more useful results, although distinguishing between
pollutant effects and those related to other physical, chemical or biological environ-
mental variables can be very challenging. As mentioned above (Sect. 3), PICT is
one of the tools best adapted to achieve this goal because tolerance to one toxicant
is less sensitive than is other community characteristics to natural variations at sam-
pling sites (Schmitt-Jansen et al. 2008 ). To improve PICT methodology, special
attention should be paid to cotolerance patterns and to developing new short-term
tests designed to evaluate tolerance capacities, especially with a view to broadening
the range of toxicants monitored (Blanck 2002 ; Tlili and Montuelle 2011 ).

4.3 Ecosystem Recovery

Finally, interest in restoring chemically polluted ecosystems is growing, especially
through environmental policies such as the European Water Framework Directive
(EU 2000 ). In this Directive, the EU commits its members to achieve good