A Day In the Life Of A Reef Fish: Fish Activity Changes During The Day
About Coral Reef Fish Phases
A dive on a coral reef during the day presents a scene of a kaleidoscope of activity by reef fish of many different species, sizes, colors and behaviors, all seeming to be moving everywhere at the same time. There is a pattern and order to this activity that represents fish phases but it is not readily apparent because it is usually seen for less than an hour (the time-limit for most dives) and during mid-portion of the day.
Coral reef fishes regularly change their behavior and activities in response to cyclic (repeating) changes in environmental conditions on the reef. In marine science these are referred to as the temporal (with time) changes in environmental parameters that alter (or drive) the phases of daily life on the reef. There are many of these environmental parameters and they change frequently. The most prominent are the water currents, which normally change direction every six hours in response to the high and low tidal cycles, and daylight and darkness. There are also changes that are monthly, timed with the phases of the moon’s cycle.