As a consequence of the environmental nutrient enrichment, significantly higher seagrass tissue P contents were found near nutrient sources, which reveals a physiological response of the biota to nutrient input. The epiphytic algae biomass and N content in the tissues mirrored only one of the two nutrient loading trends. We propose that changes in the phosphorus contents of T. hemprichii tissues, followed by epiphytic algae biomass and N content of the tissues, may be useful indicators of marine environmental degradation in studies designed to monitor the effects of nutrient loading on the coastal ecosystems.