Physiology of Finfish and Shellfish (2+1)

5.1.3. Acclimation

Acclimation will be used to designate the process of brining the actual to a given steady state by setting one or more of conditions to which it is exposed for an appropriate time before a given test. Such condition may be fixed or cycled depending on circumstances. The most significant aspect of acclimation an opposed to acclimation is that it allow the organism to acquire an adjustment, say to higher temperature in advance of event if that event is appropriate to seasonal cycle. Thus acclimatization provides for anticipatory adjustment as well as reactive adjustment.

1. Lethal factors: An environmental identity act as lethal factor when its effect is to destroy the integration of organism. Properly speaking such destruction should be independent of metabolic rate to be the result of lethal factor. The lethal effect of any identity may be separated into two components a) the incipient lethal level, that level of the identity concerned beyond which organism can no longer like for an indefinite period of time. b) effective time, the period of time acquired to bring about at lethal effect at a given level of the identity beyond the incipient lethal.
2. Controlling factors: Controlling factors comprise one of two categories which govern the metabolic rate what are considered here as controlling factors are what Blackman termed 'tonic effects. Controlling factors govern the metabolic rate by this influence on state of molecular activation of the component of the metabolic chain. Controlling factors place bound to two levels of metabolism. They permit a certain maximum in the absence of a limiting factor through their influence on the later of chemical reactions. The controlling factors also demand certain minimum metabolic rate which is taken is necessary to release the energy required for the repair reactions needed to keep the organism in being.
3. Limiting factors: It makes up the second category of identity that govern the metabolic rate. They are Blackman's factors of supply in his original treatment of limiting factors and the category to which Leibig's law of minimum applies. Both the term and concept of the factor have been widely used in this connection. The usage here is simply to restrict the definition to what was the major border of Blackman's exposition. It operates by restricting the supply or removal of materials in metabolic chain. Thus a reduction in the supply of oxygen below a certain level it can be said that oxygen supply is limiting.
4. Masking factors: A masking factor is an identity which modifies the operation of second identity on organism. An organism achieves all its physiological regulation by the exploitation of marking factor through the channeling of energy by some anatomical device. For example, deep sea fishes with swim bladder have pressures of gas in these bladder for in excess of pressure that could be generated by releasing all the atmospheric gases held in blood. To make this gas available at high pressure, the fish exploit a second physical law, namely the property of dissolved gases to diffuse down a pressure gradient.
5. Directive factors: These allow or require a response on part of organism directed in some relation to gradient of factor in space or time. The factor elicits the well known forced movement. They also provide for the animal's guidance in moving about the environment in relation to physical obtader and for its interaction with other organism. The directive factor also trigger physiological process without mediation of senses, as in effect of photoperiod on the pituitary. Directive factors operate by impingement of energy on some appropriate target. The energy absorbed initiates a signal which appropriately metabolism into the appropriate response.