Ostracodes and pollen preserved in a 75.9-m-long sediment core (PI-6) recovered from Lake Petén Itzá, Guatemala in 2006 were used to assess the magnitude and velocity of aquatic and terrestrial community responses during the last 85,000 years. The composite sediment sequence from three holes was recovered from a water depth of 71 m, and subsampled every ~ 20 cm for biological analysis. Our ostracode data (adults and juveniles) includes information on species abundances and richness, diversity index, DCA species scores along the first two DCA axes, stratigraphic DCAs (axes 1 and 2), ecological change and rates of ecological change. The following pollen data are provided as well: Taxa richness, diversity (pollen sum), DCA taxa scores along the first two DCA axes, stratigraphic DCAs (axes 1 and 2), ecological change and rates of ecological change.