OFF THE SHOULDERS OF GIANTS: BENEFITS, PERILS AND PITFALLS OF ToE ’ S IN ZOOPLANKTON STUDIES.

1. OFF THE SHOULDERS OF GIANTS: BENEFITS, PERILS AND PITFALLS OF ToE’S IN ZOOPLANKTON STUDIES. Miquel Alcaraz Institut de Ciències del Mar, CSIC ASLO Aquatic Sciences Meeting – Granada 2015

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3. NEW IDEAS AND ToE DIVERSITY – BIODIVERSITY: A PUZZLING DUALITY THE UNIFIED NEUTRAL THEORY OF BIODIVERSITY AND BIOGEOGRAPHY METABOLIC THEORY OF ECOLOGY

4. THE METABOLIC THEORY OF ECOLOGY The theory proposes to predict the ecological characteristics at individual, community and ecosystem levels • Theoretically founded on the fact that metabolism controls ecological processes at all levels. • All the characteristics of organisms, communities and ecosystems, vary predictably with body size, temperature and chemical composition. • If combined with evolution and population genetics, it could be a real ecological ToE ASLO Aquatic Sciences Meeting – Granada 2015

5. Scaling metabolism from individuals to ecosystems O2 a R = Rate R0 = Normalization constant M = Body mass b = Allometric exponent P V = V0 Mb(1) Alcaraz, M. (1974) R = Rate V0 = Normalization constant E = Activation energy in eV k = Boltzmann’s constant T = Absolute temperature in ºK Kleiber, M. (1932) V V = V0 e -E/(kT)(2) A { -K A. Clarke (2003 ASLO Aquatic Sciences Meeting – Granada 2015 Alcaraz, M. (1974)

6. JOINT EFFECT OF SIZE AND TEMPERATURE • By combining eq. (1)and(2) R = r0 e –E/(kT) M3/4 R/M = r0’ e –E/(kT) M-1/4 Biomass-specific metabolic rate, Alcaraz, M. (1974) ASLO Aquatic Sciences Meeting – Granada 2015

7. The MTE: Many pros… How remarkably explains the variability of ecological processes at broad scales MAXIMUM PRODUCTION RATE (g ind-1 year-1) AND INDIVIDUAL MASS (b = 0.76) Brown (2004) 20 orders of magnitude ASLO Aquatic Sciences Meeting – Granada 2015

8. TURNOVER RATE (d-1) AND INDIVIDUAL MASS (⁓ - 1/4) b = -0.22 Brown (2004) 20 orders of magnitude ASLO Aquatic Sciences Meeting – Granada 2015

9. EGG DEVELOPMENT TIME Ea = -0.68 Ea = -0.73 (Ea ⁓ - 0.63) b = -0.22 b = -0.27 (b ⁓ - 1/4) Brown, J.H. (2004). Data from Gillooly & Dodson 2000 ASLO Aquatic Sciences Meeting – Granada 2015

10. AMPHIBIAN SPECIES RICHNESS Ea = -0.70 Ea = -0.71 Brown, J.H. (2004) (slightly higher than 0.63) ASLO Aquatic Sciences Meeting – Granada 2015

11. … And some drawbacks and pitfalls Problems to predict the effects of global warming on ecosystem’s structure and function (Size-metabolic rate exponent: b ≅ 0.75 (3/4) Activation energy: Ea≅ 0.63 EV) • Differential response of metabolic processes • Shifts in ecosystem structure (individual size and taxonomic composition) • Non-linear ecosystem responses ASLO Aquatic Sciences Meeting – Granada 2015

12. The variability of b and Ea for different organisms and processes O2 consumption by crustaceans as a function of temperature and size b = 0.820 Respiration by crustaceans: Influence of O2 concentration Log O2 = -0.094 + 0.820 log P b = 0.581 Log O2 = 0.520 + 0.581 log P } 15 º C Log O2 = 0.152 + 0.723 log P b = 0.731 Ea =0.599 18 º C Log O2 = 0.171 + 0.755 log P 20 º C Log O2 = 0.350 + 0.720 log P Alcaraz, M. (1974) ASLO Aquatic Sciences Meeting – Granada 2015

13. Same process, different taxon-specific rates salps salps copepods Krill (E. s.) Krill (E. s.) Krill (E. c.) Krill (E. c.) copepods C Alcaraz et al. (2014) Salp-krill shift: - The carbon ingested by zooplankton will increase by a factor of 7 - The vertical carbon export (as fecal pellets) will increase by a factor of 10. ASLO Aquatic Sciences Meeting – Granada 2015

14. Alcaraz et al., unpublished Arctic zooplankton ln C = -3.4 + 0.63 ln M, r = 0.92 Respiration ln N = -4.3 + 0.69 ln M, r = 0.86 N- excretion ln P = -7.6 + 0.86 ln M, r = 0.84 P- excretion ASLO Aquatic Sciences Meeting – Granada 2015

15. Different processes, different responses to temperature C,Ea = 1.292 N, Ea =1.685 P, Ea =1.802

16. Different processes, different thermal windows Metabolic balance, P = I – R Ingestion, I Respiration, R Balance, I-R ASLO Aquatic Sciences Meeting – Granada 2015 Alcaraz et al. (2013)

17. Hysteresis Duarte et al. (2012) ASLO Aquatic Sciences Meeting – Granada 2015

18. Conclusions • Pros and benefits of MTE: • Explains a variety of processes with few assumptions and parameters • The predictions of biological and ecological processes can be remarkably accurate • It works over many orders of magnitude • Drawbacks and pitfalls: • The high variability of real scaling exponents as compared to the theoretical ones • A limited capacity to explain deviations between predicted and experimentally observed rates • Incapacity to predict unstable regimes, mismatch mechanisms and environmental thresholds resulting from non-linear ecosystem changes.

19. “For most topics that concern ecology, I like poets more than lawyers, and feel more inclined to fantasy, feeling and inspiration than to rigour, consistency and even responsibility. In my views on environmental problems, I feel more attracted by the origin of the troubles than by their solutions, at least in the way the problems are usually being faced at present.” Ramon Margalef (1979 THANKS!