AUTHOR=Muñoz Pamela T. , Rodríguez-Rojas Fernanda , Celis-Plá Paula S. M. , López-Marras Américo , Blanco-Murillo Fabio , Sola Iván , Lavergne Céline , Valenzuela Fernando , Orrego Rodrigo , Sánchez-Lizaso José Luis , Sáez Claudio A. 

TITLE=Desalination effects on macroalgae (part A): Laboratory-controlled experiments with Dictyota spp. from the Pacific Ocean and Mediterranean Sea

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1042782

DOI=10.3389/fmars.2023.1042782

ISSN=2296-7745

ABSTRACT=Desalination brines from direct seawater intake that get discharged to coastal areas may produce stress responses on benthic marine communities mostly due to its excess salinity, and especially on sessile organisms; in this context, macroalgae have been  under-studied in desalination ecotoxicological investigations.  In this study, we assessed short and long-term cellular tolerance responses in two brown species of the macroalgae genus Dictyota through controlled laboratory conditions. D. kunthii was collected from the eastern Pacific Ocean (average salinity ~34 psu), whereas D. dichotoma from the Mediterranean Sea (average salinity ~37 psu). Each macroalgae species was exposed for up to 7 days to two increased salinities conditions, +2 and +7 psu above their natural average salinity. Photosynthetic parameters and oxidative stress measurements were determined. Results showed that in both Dictyota species, high salinities induced reduced photoinhibition (Fv/Fm,), but an increased primary productivity (ETRmax) and light requirement (EkETR), especially after 7 days. Conversely, the photosynthetic efficiency (αETR) decreased in hypersalinity treatments in D. dichotoma, while there were no changes in D. kunthii. The reactive oxygen species (ROS) hydrogen peroxide (H2O2) was greater at high salinities at 3 days for D. dichotoma and after 7 days in D. kunthii, while lipid peroxidation decreases under hypersalinity with time in both species. Despite the evident H2O2 accumulation in both species against hypersalinity, it did not produce oxidative damage and important impairment in the photosynthetic apparatus. These results contribute to understand tolerance strategies at the cellular level of Dictyota spp., which may be considered as potential candidate for biomonitoring desalination impacts in the field.