Particulate nutrient fluxes over a fringing coral reef: relevant scales of phytoplankton production and mechanisms of supply

Research at Ningaloo Coast, Western Australia, reveals that particulate organic nitrogen (PON) and carbon (POC) fluxes play a crucial role in reef nutrient budgets, with wave action and regional currents significantly influencing phytoplankton supply. Phytoplankton uptake rates were found to be near physical limits, with PON flux (2–5 mmol N m⁻² d⁻¹) comparable to dissolved nitrogen uptake, suggesting particle feeding may address reef nitrogen deficits. POC flux (14–27 mmol C m⁻² d⁻¹) matched net community metabolism, indicating its importance in reef metabolism. The study highlights the variability of phytoplankton supply over daily-to-seasonal scales due to dynamics in the Leeuwin Current (LC), which may deliver as much phytoplankton as sporadic upwelling events linked to the Ningaloo Current (NC). Introducing the 'ocean catchment' concept, the research suggests reefs depend on remotely sourced productivity, increasing vulnerability to human or climatic changes affecting offshore currents and plankton communities.

Wyatt, A., Lowe, R., Humphries, S., & Waite, A. (2010). Particulate nutrient fluxes over a fringing coral reef: relevant scales of phytoplankton production and mechanisms of supply. Marine Ecology Progress Series, 405, 113–130. https://doi.org/10.3354/meps08508