We studied if functional traits related to resource preemption (light and inorganic nutrients) exert control on space preemption of tropical seagrass meadows. Additionally, we studied if space preemption changed under different eutrophication scenarios. We took seagrass abundance data to study space preemption, seagrass traits data to study their effect on space preemption and eutrophication indicators to evaluate the level of eutrophication at each site/sampling event. The data was collected in Unguja Island (Zanzibar Archipealgo, Tanzania) in seven sites/sampling events (Harbor, Chapwani, Changuu, Bweleo, Fumba, Mangroves and Marumbi). Each site/sampling event comprised a subtidal seagrass meadow (2-4 meters depth) of around 2500 square meters, delimited by the coastline and a fringing reef. The data was taken between the 26.09.2016 to the 05.10.2016. In each site/sampling event, five 50 meters transects were deployed perpendicular to the coast and paralel to each other, approximately separated by 50 meters. The areas enclosed beweeen the transects were names A, B, C and D. Dissolved inorganic nitrogen and phosphate in pore water were collected as an indicator of eutrophication. We took one sediment pore water sample per transect from each site/sampling event using 30 cm PVC cores. The cores were pushed into the sediments, and after extraction an Eijkelkamp rhizon connected to a 20 ml syringe was placed in a hole corresponding to a depth of 5 cm below the sediment surface. Making vacuum with the syringe, the water was pulled out of the sediment cores. These samples were immediately filtered (0.45 µm pore size, Whatman GF/F filters) in pre-rinsed polyethylene bottles, frozen (−20°C) and transported to the Leibniz Centre for Tropical Marine Research. Analysis was performed using a continuous flow injection analyzing system (Skalar SAN++-System). The measuring procedure had a relative standard deviation < 3.5% with reference to the linear regression of an equidistant 10-point calibration line from NIST standards. Final concentrations are given in micromolar.