Share this“I don’t know what happened! Yesterday, this (insert your choice: frog, fish, xenole, lobster, sea urchin, etc.) looked fine. I walked in this morning and it was dead!”
How often has that statement occurred in your facility? “Aquatics” is a new realm for many research facilities and institutions. The husbandry is different. The species characteristics are different. Unlike laboratory mammalians, amphibians and fish require very specific microenvironments. Their basic life functions are influenced by and interrelated to one entity - the water. They eat, breathe, and eliminate waste through it. Many use gills for gas exchange, osmoregulation, acid-base balance, and nitrogenous waste excretion. Some can absorb and excrete directly through their skin. But one detail is not so different... like mammals, stress, and/or lack thereof, plays a major role in how aquatic species subsist.
It is essential to the scientific value of the research that stress and discomfort be minimized. Stress causes biochemical, physiological, and behavioral changes. It can affect growth, digestion, reproduction, osmoregualtion, healing, and disease immunity. 1
In the research setting, some stresses are unavoidable. Surgery, transport, handling, oocyte expression, anesthesia are just a few examples of inevitable stresses. With the help of the hormone cortisone, all animals can manage some stress. It is when several stressful situations occur simultaneously that the arbitrary threshold is crossed and the animal becomes compromised. (See Figure 1) And, given that animals are designed to hide stress, too often excess can quickly lead to disease, even death, before it is realized and a fix can be implemented. The objective is to reduce secondary stress to keep the animal levels manageable.
But the question remains: What is stress for an aquatic animal? Many stresses in the aquatic environment, especially water conditional factors, are invisible to the eye. To make matters more complex, many water parameters affect one another; and some stresses are simply misconstrued assessments from inaccurate human emotional interpretation of the situation.
