A new visual index for assessing zooplankton biomass and its utility in assessing prey availability for megaplanktivores

Hannah M Moloney; Asia O Armstrong; Guy M W Stevens; Christine L Dudgeon; Joanna L Harris; Kathy A Townsend; Anthony J Richardson

doi:10.1093/plankt/fbag027

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A new visual index for assessing zooplankton biomass and its utility in assessing prey availability for megaplanktivores

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A new visual index for assessing zooplankton biomass and its utility in assessing prey availability for megaplanktivores

Hannah M Moloney, Asia O Armstrong, Guy M W Stevens, Christine L Dudgeon, Joanna L Harris, Kathy A Townsend and Anthony J Richardson

Journal of Plankton Research, Vol.48(3), pp.1-8

2026

DOI: https://doi.org/10.1093/plankt/fbag027

PMID: 42212007

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Abstract

plankton

blooms

marine

planktivores

prey abundance

Zooplankton are vital links in marine food webs, yet their biomass remains challenging to quantify across broad spatial and temporal scales. This study introduces the Zooplankton Visual Index–a simple, rapid and scalable semi-quantitative method for evaluating zooplankton biomass through underwater observations. Following the establishment of a standardized protocol, validation against in situ net samples demonstrated that index levels increased consistently with measured biomass and predictable shifts in community composition. We then applied the validated index to a 9-year dataset of reef manta ray (Mobula alfredi) sightings in the Maldives. Increased M. alfredi abundance significantly correlated with higher index levels, confirming that the index effectively captures the food environment as an important predictor of behavior and habitat use. Thus, the Zooplankton Visual Index provides an accessible and validated tool for assessing prey availability, enabling researchers, non-specialist field staff and citizen science programs to contribute to broad-scale ecological research and conservation efforts for marine megaplanktivores.

Details

Title: A new visual index for assessing zooplankton biomass and its utility in assessing prey availability for megaplanktivores
Authors: Hannah M Moloney (Corresponding Author) - University of the Sunshine Coast
Asia O Armstrong - University of the Sunshine Coast
Guy M W Stevens - Manta Trust (United Kingdom)
Christine L Dudgeon - University of the Sunshine Coast
Joanna L Harris - Manta Trust (United Kingdom)
Kathy A Townsend - University of the Sunshine Coast
Anthony J Richardson - Commonwealth Scientific and Industrial Research Organisation
Publication details: Journal of Plankton Research, Vol.48(3), pp.1-8
Publisher: Oxford University Press
Date published: 2026
DOI: 10.1093/plankt/fbag027
ISSN: 1464-3774
PMID: 42212007
Copyright note: © The Author(s) 2026. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Grants: Australian Government Research Training Program (RTP) Scholarship, RTP, Department of Education (Australia, Canberra)
Grant note: This study was made possible due to funding from the Save Our Seas Foundation, Carl F. Bucherer and the logistical support and funding from the Four Seasons Resort at Landaa Giraavaru, Maldives.
Organisation Unit: School of Science, Technology and Engineering
Language: English
Record Identifier: 991233192702621
Output Type: Journal article

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