Secondary production and consumer energetics
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Secondary production and consumer energetics. The consumer energy budget Determinants of energy flow Ecological efficiencies Definition of secondary production Measurement of secondary production Predicting secondary production For individual populations For guilds of consumers

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Secondary production and consumer energetics
Secondary production and consumer energetics

  • The consumer energy budget

  • Determinants of energy flow

  • Ecological efficiencies

  • Definition of secondary production

  • Measurement of secondary production

  • Predicting secondary production

    • For individual populations

    • For guilds of consumers

    • For the entire community of consumers



I = A + E

Ingestion (I)

Assimilation (A)

Egestion (E)


I = A + E

A = R + P (+ U)

Respiration (R)

Ingestion (I)

Assimilation (A)

Growth (G), or Production (P)

Egestion (E)

(Excretion (U))


I = A + E

A = R + P (+U)

Respiration (R)

=loss of useful energy

Ingestion (I)

=loss to prey

population

Assimilation (A)

=energy available to consumer

Growth (G), or Production (P)

=energy available to predators

Egestion (E)

=input to detritus

(Excretion (U))




Body size affects energetic rates m 0 25
Body size affects energetic rates(~M-0.25)

Peters 1983



Metabolic rates are evolutionarily flexible
Metabolic rates are evolutionarily flexible

Data on flatworms from Gourbault 1972


Ecological efficiencies
Ecological efficiencies

A/I = assimilation efficiency

P/A = net growth efficiency

P/I = gross growth efficiency





Bacterial growth efficiency depends on food quality
Bacterial growth efficiency depends on food quality energy)?

Del Giorgio and

Cole 1998


Bacterial growth efficiency depends on temperature
Bacterial growth efficiency depends on temperature energy)?

Rivkin and Legendre 2001


Introduction to secondary production
Introduction to secondary production energy)?

  • “All non-photosynthetic production (growth), regardless of its fate”

  • NOT the same as biomass accumulation

  • NOT just the production of herbivores

  • Much better studied than other parts of the consumer energy budget

    • Easier to measure

    • Historically considered more important


Secondary production is aquatic and empirical
Secondary production is aquatic and empirical energy)?

  • 167 papers published on subject in 2005

  • 52% marine or estuarine, 35% freshwater, 3% terrestrial

  • 55% microbial, 39% invertebrate, 7% vertebrate

  • Very little theoretical work

  • Are generalizations about secondary production really generalizations about aquatic ecosystems?


How do we estimate secondary production
How do we estimate secondary production? energy)?

  • Tracer methods

  • Demographic methods

  • Turnover methods

  • Empirical methods



Controls on prediction of secondary production
Controls on/prediction of secondary production energy)?

  • Individual populations

  • Guilds of consumers

  • Entire communities


Predicting secondary production 1 individual populations
Predicting secondary production: energy)?(1) individual populations

  • Marine benthic invertebrates

  • Log10(P) = 0.18 + 0.97 log10(B)

  • - 0.22 log10(W) + 0.04 (T)

  • – 0.014 (T*log10depth)

  • R2 = 0.86, N = 125

Tumbiolo and Downing 1994


Predicting secondary production 1 individual populations1
Predicting secondary production: energy)?(1) individual populations

  • Marine benthic invertebrates

  • Log10(P) = 0.18 + 0.97 log10(B)

  • - 0.22 log10(W) + 0.04 (T)

  • – 0.014 (T*log10depth)

  • R2 = 0.86, N = 125

Tumbiolo and Downing 1994


Predicting secondary production 1 individual populations2
Predicting secondary production: energy)?(1) individual populations

Q10 ~ 2.5

Tumbiolo and Downing 1994


Predicting secondary production 1 individual populations3
Predicting secondary production: energy)?(1) individual populations

Tumbiolo and Downing 1994


Predicting secondary production of individual populations
Predicting secondary production of individual populations energy)?

  • Feasible if you know mean annual biomass, body size, and temperature

  • Very imprecise

  • If you’re going to measure mean annual biomass, why not just estimate production directly?


Predicting secondary production 2 guilds
Predicting secondary production: (2) guilds energy)?

(aquatic bacterial production as a function of phytoplankton production – Cole et al. 1988)


Predicting secondary production 2 guilds1
Predicting secondary production: (2) guilds energy)?

(aquatic invertebrate production in experimentally manipulated streams (Wallace et al. 1999)


Predicting secondary production 2 guilds2
Predicting secondary production: (2) guilds energy)?

(terrestrial animal production as a function of primary production – McNaughton et al. 1991) (V=vertebrates, I=invertebrates)



Nutrients affect production of guilds
Nutrients affect production of guilds supply

Cross et al. 2006


Predicting secondary production or ingestion 2 guilds
Predicting secondary production (or ingestion): (2) guilds supply

Aquatic is white (left) or blue (center and right); terrestrial is black (left) or green (center and right)

(Cebrian and Lartigue 2004)


Terrestrial aquatic differences
Terrestrial/aquatic differences supply

  • Herbivores ingest a higher proportion of NPP in aquatic systems (higher nutrient content of NPP)

  • Herbivore production possibly much higher in aquatic systems (higher ingestion, higher assimilation efficiency?, less homeothermy so higher net growth efficiency)


Predicting secondary production of guilds
Predicting secondary production of guilds supply

  • Predictable (and linear?) from resource supply

  • Too imprecise to be very useful as a predictor

  • Maybe strong terrestrial/aquatic differences arising from nutrient content of primary producers

  • Nutrients as well as energy affect guild production



Predicting secondary production 3 entire communities1
Predicting secondary production: (3) entire communities supply

S = R + L, so R = S – L

(S = net supply of organic matter, L = non-respiratory losses)


Predicting secondary production 3 entire communities2
Predicting secondary production: (3) entire communities supply

S = R + L, so R = S – L

εng = P/(P + R), so P = εng(P + R)

(εng = net growth efficiency,

S = net supply of organic matter, L = non-respiratory losses)


Predicting secondary production 3 entire communities3
Predicting secondary production: (3) entire communities supply

S = R + L, so R = S – L

εng = P/(P + R), so P = εng(P + R)

Therefore, P = εng(P + S – L)


Predicting secondary production 3 entire communities4
Predicting secondary production: (3) entire communities supply

S = R + L, so R = S – L

εng = P/(P + R), so P = εng(P + R)

Therefore, P = εng(P + S – L);

Rearranging, P(1- εng) = εng(S – L)


Predicting secondary production 3 entire communities5
Predicting secondary production: (3) entire communities supply

S = R + L, so R = S – L

εng = P/(P + R), so P = εng(P + R)

Therefore, P = εng(P + S – L);

Rearranging, P(1- εng) = εng(S – L)

And P = (S – L)εng/(1 – εng)


Predicting secondary production 3 entire communities6
Predicting secondary production: (3) entire communities supply

P = (S – L) εng/(1 – εng)

A = (S – L)/(1 – εng)

I = (S – L)/(εa(1 - εng))

εa = assimilation efficiency, εng = net growth efficiency,

S = net supply of organic matter, L = non-respiratory losses



Predicting secondary production of entire communities
Predicting secondary production of entire communities supply

  • Secondary production is large compared to primary production (if NGE=30%, secondary production = 43% of NPP)

  • Decomposers see a lot of consumer tissue (not just plant tissue)

  • Secondary production is larger in systems dominated by heterotherms than in systems dominated by homeotherms

  • Energy available for ingestion and assimilation by consumers is greater than primary production (if NGE=30% and AE = 20%, A=143% of NPP, I = 714% of NPP)


Conclusions
Conclusions supply

  • It’s easier to predict the secondary production of an entire community than a single population

  • Consumer activity is tightly linked with other processes that control the movement and fate of organic matter

  • When considered at the community level, secondary production (maybe) is controlled by the same factors that control primary production: supply of energy and nutrients, and their retention


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