Publication Date:
2024-03-12
Description:
Zooplankton plays a notable role in ocean biogeochemical cycles. However, it is often simulated as one generic group and top closure term in ocean biogeochemical models. This study presents the description of three zooplankton functional types (zPFTs, microâ, mesoâ and macrozooplankton) in the ocean biogeochemical model FESOMâREcoM. In the presented model, microzooplankton is a fastâgrowing herbivore group, mesozooplankton is another major consumer of phytoplankton, and macrozooplankton is a slowâgrowing group with a low temperature optimum. Mesoâ and macrozooplankton produce fastâsinking fecal pellets. With three zPFTs, the annual mean zooplankton biomass increases threefold to 210 Tg C. The new food web structure leads to a 25% increase in net primary production and a 10% decrease in export production globally. Consequently, the export ratio decreases from 17% to 12% in the model. The description of three zPFTs reduces model mismatches with observed dissolved inorganic nitrogen and chlorophyll concentrations in the South Pacific and the Arctic Ocean, respectively. Representation of three zPFTs also strongly affects phytoplankton phenology: Fast nutrient recycling by zooplankton sustains higher chlorophyll concentrations in summer and autumn. Additional zooplankton grazing delays the start of the phytoplankton bloom by 3 weeks and controls the magnitude of the bloom peak in the Southern Ocean. As a result, the system switches from a lightâcontrolled Sverdrup system to a dilutionâcontrolled Behrenfeld system. Overall, the results suggest that representation of multiple zPFTs is important to capture underlying processes that may shape the response of ecosystems and ecosystem services to onâgoing and future environmental change in model projections.
Description:
Plain Language Summary:
Zooplankton plays an important role in the ocean food web and biogeochemical cycles. However, it is often represented in very simple forms in mathematical models that are, for example, used to investigate how marine primary productivity will react to climate change. To understand how these models would change when more complicated formulations for zooplankton are used, we present here a new version of the model with three (instead of only one) zooplankton groups. We find that this more complicated representation leads to higher zooplankton biomass, which is closer to observations, and this stimulates growth of phytoplankton since zooplankton also returns nutrients into the system. In addition, zooplankton grazing controls the seasonal cycle of phytoplankton, as we show for one example in the Southern Ocean.
Description:
Key Points:
Nutrient recycling by zooplankton stimulates net primary production in the biogeochemical model REcoMâ2.
Modeling zooplankton functional types (zPFTs) leads to a switch from a lightâcontrolled Sverdrup system to a dilutionâcontrolled Behrenfeld system.
Implementing multiple zPFTs improves the modeled zooplankton biomass and zooplanktonâmediated biogeochemical fluxes.
Description:
Helmholtz Young Investigator Group Marine Carbon and Ecosystem Feedbacks in the Earth System [MarESys]
Description:
https://doi.org/10.1594/PANGAEA.779970
Description:
https://doi.org/10.1594/PANGAEA.785501
Description:
https://doi.org/10.1594/PANGAEA.777398
Description:
https://www.nodc.noaa.gov/OC5/woa18/woa18data.html
Description:
http://sites.science.oregonstate.edu/ocean.productivity/index.php
Description:
https://doi.pangaea.de/10.1594/PANGAEA.942192
Keywords:
ddc:577.7
;
Southern Ocean
;
zooplankton
;
ocean food web
;
biogeochemical cycles
;
modeling
Language:
English
Type:
doc-type:article
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