Benthic-pelagic Coupling in an Intertidal Mudflat in the Bahía Blanca Estuary (SW Atlantic)

GEORGINA ZAPPERI; MARÍA JULIA PIOVAN; JORGE MARCOVECCHIO; PAULA PRATOLONGO; MARÍA JULIA PIOVAN; PAULA PRATOLONGO; GEORGINA ZAPPERI; JORGE MARCOVECCHIO

JOURNAL OF COASTAL RESEARCH

COASTAL EDUCATION & RESEARCH FOUNDATION

Lugar: Florida; Año: 2016 vol. 32 p. 629 - 637

0749-0208

Benthic-pelagic coupling was evaluated in a shallow, turbid, and nutrient enriched estuary in the SW Atlantic. We analyzed the annual trends in turbidity, nutrients, and Chl-a concentration in the water column, and related those changes to benthic fluxes of dissolved inorganic nutrients, estimated through microcosms incubation experiments, as well as seasonal variations in the abundance and composition of macrobenthic communities. Peak Chl-a concentration in the water column, occurred in July, after turbidity reached its minimum value in June. Dissolved nutrients decreased after the peak of Chl-a. Benthic fluxes of NH4+ towards the column were very high after the diatom bloom in the Laeonereis flats, while the crab beds performed as sinks. Both subsystems were sinks of NO3- + NO2- before the bloom, and fluxes reversed in the post bloom period. Neohelice granulata and Laeonereis acuta were the most represented macrobenthic species in both subsystems. L. acuta?s density in Laeonereis flats was highest in June, while N. granulata?s density in the crab beds was highest in December. These changes in abundance coincide with changes in the benthic fluxes. These results suggest that benthic-pelagic coupling, mediated by biological activity, may play a significant role in creating the window of lower turbidity that allows phytoplankton bloom. As bloom develops, dissolved nutrients in the water column are consumed, and organic matter is produced. As a counterpart, the local coupling between remineralization in the surface sediments, and benthic flux to the water column as dissolved nutrients allows the recovery of nutrient levels and supports primary production in the forthcoming cycle.