[eng] The present study reports phytoplankton data obtained from four beaches of Santa Eulària del Riu from Ibiza Island during the summers of 2013 and 2014. A total of 79 microalgae taxa have been identified at species or genera level and 2 taxa at class level. This diverse community varies in time as well as in space. Few of them are recurrent and constitute the base of the phytoplankton community, in which the nanoflagellates are the dominant group. Most of the other taxa appear sporadically, and occasionally constitute a higher proportion of the whole phytoplankton community dominated by dinoflagellates or diatoms (depending on the sampling time). Based on total phytoplankton cell abundance we consider waters of Cala Llonga as oligotrophic, Santa Eulària waters with higher nutrient levels, and Es Riu and Es Canar with intermediate nutrient water levels. The general trend is the presence of a phytoplankton bloom during July. This bloom can be advanced or delayed depending on the study area. At Cala Llonga the phytoplankton bloom is observed during August. These phytoplankton blooms matches with summer conditions of high temperatures and water stability, also with the increase of recreational swimming and nautical activities. On the other hand, harmful blooms of specific taxa which involve red tides are a warming sign that these ecosystems are not in their natural conditions.