Effect of biodeposition of an invasive polychaete on organic matter content and

BRUSCHETTI MARTIN; BAZTERRICA CIELO; FANJUL EUGENIA; LUPPI TOMAS; IRIBARNE OSCAR

JOURNAL OF SEA RESEARCH

ELSEVIER SCIENCE BV

Año: 2011

1385-1101

The reef-forming polychaete Ficopomatus enigmaticus is the main benthic suspension-feeding species of the 24Ficopomatus enigmaticus is the main benthic suspension-feeding species of the 24 Mar Chiquita lagoon (37¡ã 40¡ä S, 57¡ã 23¡ä W; Argentina) and exerts a strong top-down control on phytoplankton 25¡ä S, 57¡ã 23¡ä W; Argentina) and exerts a strong top-down control on phytoplankton 25 biomass. A large portion of the ingested material is rejected as faeces, and a fraction of the material filtered is 26filtered is 26 packed and discarded as pseudofaeces, which could be deposited on the sediment or horizontally displaced by 2727 water flow. In this work we evaluate the effect of this biodeposition on the organic matter (OM) content and 28flow. In this work we evaluate the effect of this biodeposition on the organic matter (OM) content and 28 productivity of the sediment between reefs. Laboratory experiments show that the OM from biodeposition 2929 was 21 times higher than the sediment between reefs and with low C per mg matter/N per mg matter. 3030 Sediment traps underneath live reefs showed higher OM content compared to traps underneath dead reefs 3131 but only in areas with low water currents, suggesting the importance of hydrodynamic conditions for this 3232 process. In situ mesocosms showed that F. enigmaticus decreased up to 45% the phytoplankton biomass, up to 33In situ mesocosms showed that F. enigmaticus decreased up to 45% the phytoplankton biomass, up to 33 50% the turbidity and up to 20% the particulate OM of the water column and, consequently enhanced up to 3434 50% the OM deposited on the bottom. But there were no differences in the OM of sediment with increased 3535 distance from the reefs. Sediment gross primary production was lower in the sediment closer to reefs, but 3636 when adults of the high-density local crab that live underneath reefs were excluded, the productivity 3737 increased, suggesting that the activity of the crabs could be counteracting the reef effect on sediment. In 3838 summary, biodeposits of F. enigmaticus can enrich the sediment, but crab activity and water currents can 39F. enigmaticus can enrich the sediment, but crab activity and water currents can 39 disperse the suspended and/or deposited material, decreasing the OM content of sediment close to the reefs. 4040 However, these effects (suspension feeding and biodeposition) are linked, and could increase flux of particles 41flux of particles 41 from water column to the bottom of the lagoon, increasing the benthic¨Cpelagic coupling.¨Cpelagic coupling.