Marine Ecosystems under Toxic Pressure - Vulnerability of Coastal Ecosystems and Adaptation - page 37

Interactions between different environmental stresses can
be synergic, antagonistic or cumulative. They vary depending on the
trophic level (herbivore and predator) and the level of response
(individual, population and community) [CRA 08]. It is, therefore,
difficult to predict the impact that the effect of the climate, combined
with chemical stress observed at an individual level, will have on
other levels of biological organization [DE 11, PAI 98].
Many authors have found evidence that climate change has
affected the phenology of organisms and the geographical distribution
of species, as well as the composition and dynamic of communities
[LOV 05, PEN 01, ROO 03, WAL 01].
The toxico-kinetic accumulation and the toxicity of POPs and
pesticides in ecosystems are susceptible to increasing in response to
the increase in temperatures and salinity [CAP 06, GAU 00, HEU 01,
MOO 03, SCH 07, WAN 01, WAR 04]. A study carried out by
Maruya et al. [MAR 05] on an estuary-dwelling fish ( F. heteroclitus )
has thus found evidence that rates of elimination of several toxaphene
congeners are higher at 25°C than in water at 15°C. Similar results
have been observed among perch on elimination rates of different
PCB congeners over a seasonal cycle [PAT 07a] and on rainbow trout
when following hydroxylation rates for PCB [BUC 07].
In parallel with these processes, the increase in temperature can
also alter key physiological functions, aggravating the harmful effects
of contaminants [BRO 02, BRO 04]. Although the exact mechanisms
that underlie this relationship are not fully understood, several studies
indicate that the temperature causes changes in the metabolism and
notably in the activation of enzymatic systems implicated in the
detoxification processes [BUC 07, LYD 99]. Thus, Capkin et al.
[CAP 06] have shown that mortality rates in rainbow trout
( Oncorhynchus mykiss ) exposed to the insecticide endosulfan were
higher at 16°C than at 13°C. Monserrat and Bianchini [MON 95]
suggest a similar explanation for the increase in the toxicity of methyl
parathion for crabs ( Chasmagnathus granulata ) after exposure to
temperatures of 12-30°C. Conversely, DDT is generally considered to
be more toxic at low temperatures, which could be due to an increase