Lecture 23 - Secondary Production Flashcards
Biomass from primary production moves to 1 of 2 fates:
What are they?
- Consumed by herbivores
2. Degraded by detritus feeders
Define secondary production
Secondary production is the formation of living mass of a heterotrophic population or group of populations over some period of time.
Define gross secondary productivity (or assimilation rate)
Gross productivity (or assimilation rate)= Respiration rate + Net productivity A = R + P
R = resting energy + activity P = Growth + Reproduction
What percent of assimilated energy goes into net productivity? Why is this useful?
Useful to predict if species is gonna grow →
Productivity efficiency = P/ A = P/(R+P)
Define basal metabolic rate. How is it measured? What’s its relationship with organism size?
Basal metabolic rate: The amount of energy expended by an animal at rest in a neutral-temperature environment in a post-absorptive state
The animal is placed in a respirometry chamber and the decrease in dissolved O2 due to consumption by animal is used to measure metabolic rate.
Larger organisms have a greater basal metabolic rate.
Define Field metabolic rate. What organisms have the lowest need to spend energy?
Field metabolic rate: amount of energy used per unit of time in an organism under normal living conditions.
Larger organisms have higher field metabolic rate.
Reptiles have the lowest need to spend energy in time.
Define net secondary productivity
the P in A = R + P
Net Productivity
= Somatic growth (body growth) + natality (how many offsprings there are across time) - weight loss= net change in biomass + losses by mortality
Dead biomass still counts as productivity as it contains energy
Compare the productivity efficiency of birds and insects.
Productivity efficiency
Birds: 99% energy is used up in respiration, so PE = 1% → increase biomass slowly
Insects: 70% , PE= 30% → increase biomass more quickly
Define trophic efficiency
Trophic efficiency (transfer efficiency/ecological efficiency) = fraction of energy passed from one trophic level to the next = Net productivity at trophic level i+1 / Net productivity at trophic level i
What’s the mean trophic efficiency of aquatic food webs?
10%
___ and ___ are critical parts of energy flow in all ecosystems but they are often ignored.
Decomposers and Detrivores
Which system of primary production is most removed by herbivores? Why?
Aquatic
More diffusion
Why do you think less primary production is removed by herbivores on land?
Lots of plants filled chemicals that deter herbivory.
What are two diagram names to show trophic levels?
Eltonian or Ecological Pyramids
