[eng] The coasts of the Balearic Islands are subjected to touristic pressure, and this leads
to the input of contaminating agents such as components of sunscreens. Studies
related with impacts of these contaminants in marine ecosystems are limited and
their effects on Posidonia oceanica are unknown. It is important to know their
effects on P. oceanica because the sea grasses have several ecosystem services. In
addition, the effects of components of sunscreens are also unknown on
nitrogen(N2)-fixers associated to P. oceanica. The N2-fixers contribute to satisfying
the needs of this phanerogam by converting atmospheric nitrogen into inorganic
forms of nitrogen that the phanerogam can assimilate. Temperature could influence
the response of marine species to these pollutants, so it is essential to study their
effects in the context of climate change (increase in sea surface temperature). This
study consisted in measuring and evaluating the effects of sunscreens on P.
oceanica and its associated community of N2 fixers under different temperature
levels by determining the response such as primary production, chlorophyll a, b,
and total content, N2 fixation and alkaline phosphatase activity rates. Sunscreen
favoured NPP at ambiental temperature. However, added sunscreen at elevated
temperature decreased the chlorophyll a and total chlorophyll content. N2-fixation
was not significantly different between treatments. Alkaline phosphatase activity
was not high in treatment with added sunscreen, but it was at elevated
temperature and without added sunscreen.