Does fitness as used in biology been the same thing as survival

No, they are not the same.

Explanation:

The fittest individual is not necessarily the strongest, fastest, or biggest. Fitness also applies to the ability to find a mate and produce offspring. Survival is the form that an individual will leave the most copies of itself in the subsequent generations. Fitness does not include a measure of survival or lifespan.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

i think its c. amphipod