Suarez,-E.; Gasca,-R. (Diurnal variation of the zooplankton associated to Thalassia testudinum seagrasses in a reef lagoon at the Mexican Caribbean.). UNIV.-CIENC. 1990. vol. 7, no. 13, pp. 57-64. A reef lagoon off Puerto Morelos, Quintana Roo, Mexico, was studied. A definite migratory pattern was observed in different groups along a day-cycle; these patterns seem to be related to the trophic behaviour of the different taxa of this community. A total of 21 different taxa were found. The most abundant species were the amphipods followed by planktonic copepods.