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

ASLO Aquatic Sciences Meeting – Granada 2015

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

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

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

R = r0 e –E/(kT) M3/4 R/M = r0’ e –E/(kT) M-1/4 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

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 Brown (2004) (b = 0.76) 20 orders of magnitude ASLO Aquatic Sciences Meeting – Granada 2015

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

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

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

… 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

} The variability of b and Ea for different organisms and processes O2 consumption by crustaceans as a function of temperature and size Respiration by crustaceans: Influence of O2 concentration b = 0.820 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

Same process, different taxon-specific rates salps copepods Krill (E. c.) Krill (E. s.) 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

Arctic zooplankton ln C = -3.4 + 0.63 ln M, r = 0.92 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

Different processes, different responses to temperature C, Ea = 1.292 N, Ea =1.685 P, Ea =1.802 And regarding the response to temperature changes, each metabolic process show specific sensitivity, as seen in these Arrhenius plots for Arctic zooplankton, for respiration (CLICK), and ammonia (CLICK) and phosphate excretion (CLICK) that indicate also a future change in the stoichiometry of regenerated elements by the rising temperatures by the predicted global warming.

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

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

Conclusions Pros and benefits of MTE: Drawbacks and pitfalls: 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. As a conclusion, the MTE has been enthusiastically received as explains a variety of processes related to the structure and function of everything, (CLICK. from the individual to the ecosystem with few assumptions and parameters. The predictions of biological and ecological processes can be remarkably accurate, and It works over many orders of magnitude. (CLICK) However, it has evident drawbacks and pitfalls like the high variability of real scaling exponents as compared to the theoretical ones, the limited capacity to explain deviations between predicted and experimentally observed rates, and the Incapacity to predict unstable regimes, mismatch mechanisms and environmental thresholds resulting from non-linear ecosystem changes. In my opinion, when looking at the tradeoff between pros and pitfalls, it seems clear that the limits and potentials of the MTE should not be pushed too far. In general, I would presume to suggest moderation on the enthusiastic support of new and fashionable ideas and theories, and a careful reflection before dismissing old ones. Probably because as one of the giants of the title taught me, in ecology the real fun consists in explaining the variability, not in finding the average. And that that can be extended to other ToE CLICK_CLICK.

THANKS! “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!