Ecological processes in the New Caledonia Lagoon based on a particle coagulation model
Abstract
The abundance and size distribution of particulate matter, the size spectrum, depends on physical and biological processes occurring in a system. Here, we used a particle coagulation-disaggregation model and observations from a limited size range (2-200 μm) to gain information on particle production and removal processes and to extrapolate the measured size spectrum to the entire particulate matter spectrum (0.2 μm-2 cm). Sampling was done along a transect in the SW lagoon of New Caledonia, extending from a mesotrophic urban bay to oligotrophic waters beyond the reef. Particulate primary production was insufficient to simulate the observed size spectrums, and required new particulate matter to form from a colloidal (<0.2 μm) pool. Coagulation of particles >1 μm was by differential settling rather than shear. Particles <10 μm were primarily removed by microbial decay, while larger particles were removed by sinking. Stickiness tended to increase with distance from shore. The disaggregation rate decreased offshore, suggesting that biological rather than physical mechanisms dominated. Beyond 200μm, the modeled size spectrum decreased more rapidly than predicted by a power-law fit to the data. Relative to the power-law fit, the coagulation model predicted smaller sedimentation fluxes that were consistent with primary production rates. By incorporating physical and biological processes, the coagulation model provides a robust method to estimate processes occurring within and beyond a measured size spectrum.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMOS33C1693C
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0466 BIOGEOSCIENCES / Modeling;
- 4815 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Ecosystems;
- structure;
- dynamics;
- and modeling;
- 4863 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Sedimentation