Pigment fluxes from the Subtropical Convergence region, east of New Zealand: relationships to planktonic community structure

A preliminary sediment trap study using photosynthetic pigments as biomarker tracers of pelagic food web processes was conducted in three different water types (subantarctic, Subtropical Convergence, and subtropical), east of New Zealand, in winter and spring 1993. The presence of undegraded pigments in trap samples from water depths of 100-550 m indicate that phytoplankton cells were removed rapidly from surface waters, presumably mainly as sinking intact phytoplankton chains, marine aggregates, or as unconverted pigments in zooplankton waste products. Average pigment budget estimates indicate that <1% day(-1) of chlorophyll a standing stock and <4% of primary production were exported during winter and spring. Microzooplankton grazing (4% day(-1) chlorophyll a standing stock and 20-194% primary production) was potentially the most important process affecting particle retention in the upper water column and hence pigment fluxes across all three water types. Bacterial degradation, mesozooplankton grazing, and seasonal stratification were potentially important in subtropical waters in spring.