Sinking and suspended particles in the South-west Pacific

Abstract

Sinking and suspended particles were sampled at Sites 11 and 12 in the Coral Sea, characterized by low seasonal variation in sea surface temperature (SST), and at Site 13 in the central Tasman Sea with a high range of seasonal SST variation. Sinking particles obtained at Site 12 had low annual mean total mass and organic matter (OM) fluxes with high carbonate content. Mean total mass flux at Site 13 was lower than those obtained around the same latitude of the boreal central Pacific. More carbonate-dominated and opal-depleted plankton communitygenerally characterized the sinking particles in the low to mid latitude of the austral western Pacific. To understand the relationship between sinking and suspended particles, suspended particles were taken in the upper 300 m of the water column. C _Organic /N atomic ratios in the suspended particles were generally 7–8, indicating that living organisms contributed a significant proportion. Although organic carbon (OC) flux by sinking particles at Site 13 was more than three times higher than that at Site 12 during May–June 1995, the total particle OC standing stock in the top 100 m was similar from 15ºS to 35ºS, indicating that OM is more recycled at the oligotrophic site 12, whereas higher new production yielded higher export production in the middle latitude site 13.