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 presents mesozooplankton taxonomic composition and abundance data collected during a tidal cycle in the Bahía Blanca Estuary (Argentina). Samples were obtained by oblique tows in the surface layer (0.5–2 m depth) using a 200 µm mesh plankton net (30 cm mouth diameter) equipped with a Hydro-Bios mechanical flow meter at multiple tidal phases. Quantitative and qualitative analyses were performed using a Bogorov counting chamber under a Wild M5 stereoscopic microscope, and organisms were identified to the lowest possible taxonomic level. The dataset allows comparison of community composition across tidal conditions and supports analyses of short-term variability in estuarine zooplankton assemblages.