Temporal scaling of benthic nutrient regeneration in a bivalve-dominated tidal flat

Beside light and temperature (1-5), nutrients such as ammonium (NH4+-N), phosphate (PO4 3--P), and silicate [Si(OH)4-Si] are a key factor in controlling the growth, abundance, and structure of primary producers in the ocean (6,7). Hence, it is important to investigate the availability, sources, and distribution of these nutrient species, as well as their spatial and temporal scaling. Biological processes strongly influence nutrient regeneration in different marine systems. In the open ocean, an important portion of reduced N-forms (e.g., NH4+-N), for instance, is made available in situ from waste products of plankton metabolism (8,9) and supports the so-called ''regenerated'' primary production (10). In coastal marine ecosystems, benthic nutrient regeneration is a major driving force in cycling biophilic elements (e.g., N, P, and Si) (11-13) and abundant macrofauna, for example, dense assemblages of bivalves, it has been shown, play a major role in these processes (14-16).