Vertical distribution of hard shell phytoplankton in the Antarctic Ocean in summer

第2回極域科学シンポジウム　共通セッション「海氷圏の生物地球化学」 11月16日（水） 統計数理研究所 3階リフレッシュフロ

Spatial and temporal variation of zooplankton in Sepanggar bay, Sabah

Zooplankton spatio-temporal distribution and the community dynamics corresponding to environmental changes were studied in Sepanggar Bay, Sabah. Samples were taken in horizontal tows using a 140 µm net at nine stations during four study periods; June, October 2017 and March, June 2018, coinciding with the SW, NE and intermonsoon seasons. Zooplankton were enumerated and identified to the lowest taxonomic level possible. All in-situ parameters measured in this study were significantly different among monsoons (p < 0.05), but not spatially. In total, 110 zooplankton taxa were observed and copepods were dominant (70% of total composition) and were most abundant during intermonsoon (40610 ± 48437 inds. /m3). Similarly, maximal zooplankton abundance was during Intermonsoon with the mean of 47628 ± 55488 inds. /m3. Zooplankton abundance showed significant monsoonal variation among seasons (p=0.01). Chlorophyll-a concentration peak period coincided with zooplankton abundance peaks, which was during Intermonsoon. Temperature showed positive correlation with total zooplankton and copepod abundances. In summary, the zooplankton abundance and composition is more sensitive to the changes in monsoon than that in space

Mesoscale eddies drive increased silica export in the subtropical Pacific Ocean

Mesoscale eddies may play a critical role in ocean biogeochemistry by increasing nutrient supply, primary production, and efficiency of the biological pump, that is, the ratio of carbon export to primary production in otherwise nutrient-deficient waters. We examined a diatom bloom within a cold-core cyclonic eddy off Hawai`i. Eddy primary production, community biomass, and size composition were markedly enhanced but had little effect on the carbon export ratio. Instead, the system functioned as a selective silica pump. Strong trophic coupling and inefficient organic export may be general characteristics of community perturbation responses in the warm waters of the Pacific Ocean