In a study of variability in copepod catch during a tidal cycle at 17 stations in the St. Andrew Bay System of Florida, the coefficient of variation (c. v.) for the total copepod count of a single oblique tow was found to be 43%. The c. v. for counts of three different species ranged between 51-56%. The least variation occurred in the index of community diversity (c. v. 17%). Tests of catch variance against estimates of error arising from collecting and counting the copepods indicate that, at most stations, variation in catch resulted from irregular distribution of the plankton in the water....