Temperature effects, freeze resistance, and warm bodied fishes

Chapter 13

Homeostasis

state of steady internal conditions maintained by living things through physiological processes

• negative feedback loops keep systems in check

effects of temperature on fishes lives

affects metabolism and digestion

signals reproductive maturation and behavior

Thermoconformers

body temperature is that of the environment

• big difference between what fish can tolerate and what is optimal

Thermal Tolerance

the range of temperatures over which a species can survive

Stenothermal

little tolerance to variation in temperature

Eurythermal

able to tolerate a wide range of temperatures

LT50

time to 50% sampled population mortality at a given temperature

CTmax

temperature at which individual shows loss of equilibrium

Acclimation

becoming accustomed to a condition

Allozymes

alternative form of enzymes that function better at specific temperatures

HSF

heat shock factor

• regulates heat shock proteins (HSP)

heat shock elements (HSE)

HSF bind to HSE throughout the genome

heat shock proteins (HSP)

act as molecular chaperones and stabilize new or repair damaged proteins

Marine fish show increased Na-K activity at

higher temperatures

Freshwater fish show increased Na-K activity at

lower temperatures

How does temperature affect swimming?

• more muscle fibers must be recruited at lower temperatures

• harder to recruit muscle fibers at lower temperatures

  • more rigid and difficult to contract

  • slower to relax

• max sustainable swimming velocities reduced at lower temps