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

2. ASLO Aquatic Sciences Meeting – Granada 2015

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. 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

6. 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

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

8. (⁓ - 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

9. (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

10. (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

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
Respiration by crustaceans:
Influence of O2 concentration
b = 0.820
Log O2 = log P
b = 0.581
Log O2 = log P }
15 º C Log O2 = log P
b = 0.731
Ea =0.599
18 º C Log O2 = log P
20 º C Log O2 = log P
Alcaraz, M. (1974)
ASLO Aquatic Sciences Meeting – Granada 2015

13. 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

14. Arctic zooplankton ln C = -3.4 + 0.63 ln M, r = 0.92
Alcaraz et al., unpublished
Arctic zooplankton
ln C = ln M, r = 0.92
Respiration
ln N = ln M, r = 0.86
N- excretion
ln P = 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
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.

16. 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

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

18. 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.

19. 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!