Time-varying environmental control of phytoplankton in a changing estuarine system

LÓPEZ ABBATE, M. CELESTE; MOLINERO, JUAN CARLOS; GUINDER, VALERIA A.; PERILLO, GERARDO M.E.; FREIJE, R. HUGO; SOMMER, ULRICH; SPETTER, CARLA V.; MARCOVECCHIO, JORGE E.

THE SCIENCE OF TOTAL ENVIRONMENT

Elsevier

Lugar: Amsterdam; Año: 2017 vol. 609 p. 1390 - 1400

0048-9697

Estuaries are among the most valuable aquatic systems by their services to human welfare. However, increasinghuman activities at the watershed along with the pressure of climate change are fostering the co-occurrence ofmultiple environmental drivers, and warn of potential negative impacts on estuaries resources. At present, noclear understanding of how coastal ecosystems will respond to the non-stationary effect of multiple drivers.Here we analysed the temporal interaction among multiple environmental drivers and their changing priorityon shaping phytoplankton response in the Bahía Blanca Estuary, SW Atlantic Ocean. The interaction among environmentaldrivers and the number of significant direct and indirect effects on chlorophyll concentration increasedover time in concurrence with enhanced anthropogenic stress, changing winter climate and windpatterns. Over the period 1978?1993, proximal variables such as nutrients, water temperature and salinity,showed a dominant effect on chlorophyll, whereas in more recent years (1993?2009) climate signals (SAMand ENSO) boosted indirect effects through its influence on precipitation,wind,water temperature and turbidity.Turbidity emerged as the dominant driver of chlorophyll while in recent years acted synergistically with the concentration of dissolved nitrogen. As a result, chlorophyll concentration showed a significant negative trendand a loss of seasonal peaks reflecting a pronounced reorganisation of the phytoplankton community.We stressthe need to account for the changing priority of drivers to understand, and eventually forecast, biological responsesunder projected scenarios of global anthropogenic change.