Temperature, will impact the distribution and abundance of animal

Temperature, the abiotic master
environmental factor, has a profound effect on the abundance and distribution
of animals on the earth, in particular ectotherms. Ectothermic animals cannot
physiologically regulate their body temperature, and are therefore especially
vulnerable to temperature changes to which they are not adapted but to which
they might be exposed on the warming earth. Predicted increases in ambient
temperature will acts as a leading factor which control the boundary of
habitats, locomotion, reproduction, development, immune defense and general
performance level of fishes and other ectotherms, and thereby will impact the
distribution and abundance of animal species and possibly distort the precise balance
of the ecosystems to which they belong. Fishes represent the most variable and
largest group among vertebrates. In northern latitudes, All fishes have to accommodate
large range of temperature changes between winter and summer. Heart muscle is
electrically excitable, i.e. a small voltage change of plasma membrane (cardiac
action potential, AP) sets the rate and rhythm of the heart, initiates
contraction and regulates force production of cardiac myocytes. Cardiac AP is
generated by a complex interaction between several ion channels in the cell
membrane. Hence, small disturbances in ion channel function cause cardiac arrhythmias,
conduction failure and compromise force of cardiac contraction. Moreover, thermal
plasticity of fish heart is substantial to maintain contractility and to avoid
disturbances in the electrical excitability that should be sensitive and stable
to temperature changes to produce temperature-dependent acceleration and
deceleration of heart rate (fH) and parallel changes in the
rate of impulse conduction over the heart. Strongly response of fishes to the
warming makes them as indicator for detecting and documenting climate-induced
modifications on aquatic ecosystems. To this end, effects of seasonal
acclimatzation on the electrical excitbility of roach (Rutilus rutilus) heart,
one of the most abundant fish species in Finnish lakes and coastal waters, is
examined.