**4. Conclusions**

Due to their relatively short life cycles, high turnover rates, high abundance, taxonomic diversity [13–17], the lack of larval dispersion and their quick reactions to


#### **Table 2.**

*Bizerte lagoon nematodes response to ECs. NS (not studied).*

*Marine Free-Living Nematodes as Tools for Environmental Pollution Assessment: A Special Focus… DOI: http://dx.doi.org/10.5772/intechopen.104721*

environmental changes [16, 17] compared to more slowly macrofauna responds [64]. Nematodes, the dominant meiobenthic taxon (>50% in the littoral zones, [35]), was well chosen as indicators of ecological risk assessment of emerging contaminants and reliable models in ecotoxicology. The laboratory experiments results revealed that some nematodes can be considered sensitive species to a contaminant type studied. Others were found to be more resistant to all exposure levels, while a number were classified as opportunistic species since they proliferate only under conditions highly unfavorable to life.
