This dataset comprises biological and biogeochemical measurements collected during a complete tidal cycle in the Bahía Blanca Estuary (Argentina). The dataset includes phytoplankton and mesozooplankton taxonomic composition and abundance, chlorophyll-a concentrations, dissolved inorganic nutrient concentrations (nitrite, nitrate and ammonia), and fatty acid profiles. Samples were collected at multiple time points spanning different tidal phases (high tide, flood, ebb, and low tide) to characterize short-term variability associated with tidal dynamics. The data provide an integrated description of plankton community composition and trophic-related variables in a turbid estuary and can be used for studies on estuarine ecology and trophic dynamics.This table reports chlorophyll-a and dissolved inorganic nutrient concentrations (nitrite, nitrate, and ammonium) measured during a tidal cycle in the Bahía Blanca Estuary (Argentina). Surface water samples (0.5 m depth) were collected using a Van Dorn bottle at discrete time points corresponding to different tidal phases. Chlorophyll-a and nutrient concentrations were quantified using an Agilent Cary 60 UV–Vis spectrophotometer.