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A functional size-spectrum model of the global marine ecosystem that resolves zooplankton composition

Citation

Heneghan, RF and Everett, JD and Sykes, P and Batten, SD and Edwards, M and Takahashi, K and Suthers, IM and Blanchard, JL and Richardson, AJ, A functional size-spectrum model of the global marine ecosystem that resolves zooplankton composition, Ecological Modelling, 435 Article 109265. ISSN 0304-3800 (2020) [Refereed Article]

Copyright Statement

Copyright 2020 Elsevier B.V.

DOI: doi:10.1016/j.ecolmodel.2020.109265

Abstract

Despite their critical role as the main energy pathway between phytoplankton and fish, the functional complexity of zooplankton is typically poorly resolved in marine ecosystem models. Trait-based approaches—where zooplankton are represented with functional traits such as body size—could help improve the resolution of zooplankton in marine ecosystem models and their role in trophic transfer and carbon sequestration. Here, we present the Zooplankton Model of Size Spectra version 2 (ZooMSSv2), a functional size-spectrum model that resolves nine major zooplankton functional groups (heterotrophic flagellates, heterotrophic ciliates, larvaceans, omnivorous copepods, carnivorous copepods, chaetognaths, euphausiids, salps and jellyfish). Each group is represented by the functional traits of body size, size-based feeding characteristics and carbon content. The model is run globally at 5° resolution to steady-state using long-term average temperature and chlorophyll a for each grid-cell. Zooplankton community composition emerges based on the relative fitness of the different groups. Emergent steady-state patterns of global zooplankton abundance, biomass and growth rates agree well with empirical data, and the model is robust to changes in the boundary conditions of the zooplankton. We use the model to consider the role of the zooplankton groups in supporting higher trophic levels, by exploring the sensitivity of steady-state fish biomass to the removal of individual zooplankton groups across the global ocean. Our model shows zooplankton play a key role in supporting fish biomass in the global ocean. For example, the removal of euphausiids or omnivorous copepods caused fish biomass to decrease by up to 80%. By contrast, the removal of carnivorous copepods caused fish biomass to increase by up to 75%. Our results suggest that including zooplankton complexity in ecosystem models could be key to better understanding the distribution of fish biomass and trophic efficiency across the global ocean.

Item Details

Item Type:Refereed Article
Keywords:zooplankton, size spectrum model, functional traits, food webs, marine ecosystem, modelling
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Community ecology (excl. invasive species ecology)
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Assessment and management of pelagic marine ecosystems
UTAS Author:Blanchard, JL (Professor Julia Blanchard)
ID Code:143868
Year Published:2020
Web of Science® Times Cited:5
Deposited By:Ecology and Biodiversity
Deposited On:2021-04-07
Last Modified:2021-05-04
Downloads:0

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