Controls on planktonic metabolism in the Bay of Blanes, northwestern Mediterranean littoral

Carlos Duarte*, Susana Agusti, Dolors Vaqué

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Long-term and experimental approaches were used to examine the metabolic balance of the planktonic community in the Bay of Blanes (Spanish Mediterranean). Incubation measurements at weekly intervals for 6 yr revealed that community respiration, R, was consistently larger than gross primary production (GPP) by a factor of 2. The plankton community was net heterotrophic for 2/3 of the study period, with a median P/R ratio of 0.65. The biomass of autotrophs comprised, on average, 41% ± 3% of the planktonic biomass, and the total microplankton biomass was about 2.5-fold greater than that of the primary producers. The monthly average GPP and R were positively correlated with day length, and the planktonic respiration and gross production per unit microplankton biomass increased with increasing water temperature. Experimental nutrient additions had a greater effect on GPP than respiration rates; the increase in R along the nutrient gradient was 7.8% (± 0.4%) of the increase in GPP. As a result, net community production increased in parallel with GPP, shifting from net heterotrophic at low GPP to net autotrophic when GPP increased because of nutrient additions. Our results show that the R that would be supported by allocthonous inputs was 3.83 ± 0.67 μmol O 2 L-1 d-1, and the average GPP required to shift the community from net heterotrophic to net autotrophic was about 4 μmol O2 L-1 d-1. This is well above the average GPP recorded in the Bay of Blanes along this study (2.56 ± 0.13 μmol O2 L-1 d-1), explaining the net heterotrophic nature of the community.

Original languageEnglish (US)
Pages (from-to)2162-2170
Number of pages9
JournalLimnology and Oceanography
Volume49
Issue number6
DOIs
StatePublished - Jan 1 2004

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

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