Seagrass meadows occur mostly along coastlines, that are under significant anthropogenic influence, such as nutrient enrichment. Understanding the effects of different nutrient species on seagrasses could inform impact assessment and management of seagrass meadows. This study aims to assess the impacts of two nitrogenous compounds on tropical seagrass species with a focus on inter-specific differences in their physiological responses. We anticipate that different seagrass species would exhibit distinct tolerance thresholds to varying nutrient loads. In an aquaria setting, shoots of three seagrass species (Thalassia hemprichii, Halophila ovalis and Cymodocea rotundata) collected from various meadows across Singapore were dosed in the water column with a range of NH4+ concentrations (0.0029 – 0.0274 mg/L) for seven weeks. A similar experiment set-up was used to assess nitrate effects (NO3-: 0.0029 – 0.051 mg/L) separately. Seagrass growth, photosynthesis (via leaf chlorophyll fluorescence), leaf area index and epiphyte biomass were measured. In general, our experiment saw increased seagrass mortality with NH4+ (c.f. NO3-). Our results also indicate a species-specific response towards both nitrogenous sources - H. ovalis exhibited greater changes with nitrogen loading while T. hemprichii showed greater resistance to nutrient loading. These insights aid in safeguarding and managing these increasingly threatened seagrass ecosystems.