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Atkinson A, Rossberg AG, Gaedke U, Sprules G, Heneghan RF, Batziakas S, Grigoratou M, Fileman E, Schmidt K, Frangoulis C. Steeper size spectra with decreasing phytoplankton biomass indicate strong trophic amplification and future fish declines. Nat Commun 2024; 15:381. [PMID: 38195697 PMCID: PMC10776571 DOI: 10.1038/s41467-023-44406-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 12/12/2023] [Indexed: 01/11/2024] Open
Abstract
Under climate change, model ensembles suggest that declines in phytoplankton biomass amplify into greater reductions at higher trophic levels, with serious implications for fisheries and carbon storage. However, the extent and mechanisms of this trophic amplification vary greatly among models, and validation is problematic. In situ size spectra offer a novel alternative, comparing biomass of small and larger organisms to quantify the net efficiency of energy transfer through natural food webs that are already challenged with multiple climate change stressors. Our global compilation of pelagic size spectrum slopes supports trophic amplification empirically, independently from model simulations. Thus, even a modest (16%) decline in phytoplankton this century would magnify into a 38% decline in supportable biomass of fish within the intensively-fished mid-latitude ocean. We also show that this amplification stems not from thermal controls on consumers, but mainly from temperature or nutrient controls that structure the phytoplankton baseline of the food web. The lack of evidence for direct thermal effects on size structure contrasts with most current thinking, based often on more acute stress experiments or shorter-timescale responses. Our synthesis of size spectra integrates these short-term dynamics, revealing the net efficiency of food webs acclimating and adapting to climatic stressors.
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Affiliation(s)
- Angus Atkinson
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL13DH, UK.
| | - Axel G Rossberg
- School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Ursula Gaedke
- Institute of Biochemistry and Biology, University of Potsdam, 14469, Potsdam, Germany
| | - Gary Sprules
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada
| | - Ryan F Heneghan
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Stratos Batziakas
- Hellenic Centre for Marine Research, Former U.S. Base at Gournes, P.O. Box 2214, Heraklion GR-71003, Crete, Greece
| | | | - Elaine Fileman
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL13DH, UK
| | - Katrin Schmidt
- University of Plymouth, School of Geography, Earth and Environmental Sciences, Plymouth, PL4 8AA, UK
| | - Constantin Frangoulis
- Hellenic Centre for Marine Research, Former U.S. Base at Gournes, P.O. Box 2214, Heraklion GR-71003, Crete, Greece
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de Juan C, Calbet A, Saiz E. Shifts in survival and reproduction after chronic warming enhance the potential of a marine copepod to persist under extreme heat events. JOURNAL OF PLANKTON RESEARCH 2023; 45:751-762. [PMID: 37779672 PMCID: PMC10539201 DOI: 10.1093/plankt/fbad037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/31/2023] [Indexed: 10/03/2023]
Abstract
The study of a species' thermal tolerance and vital rates responses provides useful metrics to characterize its vulnerability to ocean warming. Under prolonged thermal stress, plastic and adaptive processes can adjust the physiology of organisms. Yet it is uncertain whether the species can expand their upper thermal limits to cope with rapid and extreme changes in environmental temperature. In this study, we reared the marine copepod Paracartia grani at control (19°C) and warmer conditions (25°C) for >18 generations and assessed their survival and fecundity under short-term exposure to a range of temperatures (11-34°C). After multigenerational warming, the upper tolerance to acute exposure (24 h) increased by 1-1.3°C, although this enhancement decreased to 0.3-0.8°C after longer thermal stress (7 days). Warm-reared copepods were smaller and produced significantly fewer offspring at the optimum temperature. No shift in the thermal breadth of the reproductive response was observed. Yet the fecundity rates of the warm-reared copepods in the upper thermal range were up to 21-fold higher than the control. Our results show that chronic warming improved tolerance to stress temperatures and fecundity of P. grani, therefore, enhancing its chances to persist under extreme heat events.
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Affiliation(s)
- Carlos de Juan
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM), CSIC Pg. Marítim de la Barceloneta 37–49, 08003 Barcelona, Spain
| | - Albert Calbet
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM), CSIC Pg. Marítim de la Barceloneta 37–49, 08003 Barcelona, Spain
| | - Enric Saiz
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM), CSIC Pg. Marítim de la Barceloneta 37–49, 08003 Barcelona, Spain
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Saiz E, Griffell K, Isari S, Calbet A. Ecophysiological response of marine copepods to dietary elemental imbalances. MARINE ENVIRONMENTAL RESEARCH 2023; 186:105940. [PMID: 36905722 DOI: 10.1016/j.marenvres.2023.105940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 06/18/2023]
Abstract
We assessed the effects of nutrient imbalanced diets on the feeding, reproduction and gross-growth efficiency of egg production of the copepod Paracartia grani. The cryptophyte Rhodomonas salina, cultivated under balanced (f/2) and imbalanced growth conditions (N and P limitation), served as prey. Copepod C:N and C:P ratios increased in the imbalanced treatments, particularly under P limitation. Feeding and egg production rates did not differ between the balanced and N-limited treatments but decreased under P limitation. We found no evidence of compensatory feeding in P. grani. C gross-growth efficiency averaged 0.34 in the balanced treatment and declined to values of 0.23 and 0.14 for the N- and P-limited treatments, respectively. Under N limitation, N gross-growth efficiency increased significantly to a mean value of 0.69, likely as a result of increasing the nutrient absorption efficiency. P gross-growth efficiency reached values > 1 under P limitation, involving the depletion of body P. Hatching success was >80%, with no differences among diets. Hatched nauplii, however, had lower size and slower development when the progenitor was fed a P-limited diet. This study highlights the effects of P limitation in copepods, which are more constraining than N, and the presence of maternal effects driven by prey nutritional composition that ultimately may affect population fitness.
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Affiliation(s)
- Enric Saiz
- Institut de Ciències del Mar (ICM-CSIC), Pg. Marítim de la Barceloneta 37-49, 08003, Barcelona, Catalonia, Spain.
| | - Kaiene Griffell
- Institut de Ciències del Mar (ICM-CSIC), Pg. Marítim de la Barceloneta 37-49, 08003, Barcelona, Catalonia, Spain
| | - Stamatina Isari
- Institut de Ciències del Mar (ICM-CSIC), Pg. Marítim de la Barceloneta 37-49, 08003, Barcelona, Catalonia, Spain
| | - Albert Calbet
- Institut de Ciències del Mar (ICM-CSIC), Pg. Marítim de la Barceloneta 37-49, 08003, Barcelona, Catalonia, Spain
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