Long-term increase in mesozooplankton biomass in the Sargasso Sea: Linkage to climate and implications for food web dynamics and biogeochemical cycling

摘要: [1] Changes in zooplankton biomass and species composition over long time scales can have significant effects on biogeochemical cycling transfer of energy to higher trophic levels. We analyzed size-fractionated mesozooplankton (>200μm) from biweekly monthly day night tows taken 1994 2010 the epipelagic zone at Bermuda Atlantic Time series Study (BATS) site oligotrophic North subtropical gyre. During this 17-year period total increased 61% overall, although a few short-term downturns occurred course series. The overall increase was nighttime compared daytime, resulting an calculated diel vertical migrator biomass. largest seasonal late-winter spring (February–April). Associated with larger late-winter/spring shift timing annual peak during latter half (from March/April distinct March for all size fractions combined, April 2–5 mm fractions). Zooplankton positively correlated sea-surface temperature, water column stratification, primary production, negatively mean temperature between 300 600 m. Significant correlations exist multidecadal climate indices–the Oscillation plus three different Pacific Ocean indices, BATS biomass, indicating connections patterns forcing ecosystem response. Resultant changes include magnitude both active carbon flux by migration passive fecal pellets as components export flux. most likely mechanism driving is bottom-up control smaller phytoplankton, which has also production BATS, translating up microbial food web into mesozooplankton. Decreases top-down or expansion range tropical northward result warming may play role.