Trophic level Primary consumers Secondary consumers Total biomass (kg) 9390 319 Tertiary consumers 139 Table 2. Total biomass of the different consumer levels found in the floodplain savanna of the Gorongosa National Park. Part 5: Estimation of producer biomass of the floodplain savanna of the Gorongosa National Park Trail camera photos do not provide you with the information you need to calculate producer biomass. Because of this, you must turn to the 10% rule to help estimate the producer biomass. The 10% rule refers to the phenomenon that approximately 10% of the energy of an organism in one trophic level is passed on to the trophic level above it when it is consumed. The remaining 90% is used in cell respiration or lost as heat. For example, if the producers contain 1000 kcal of energy, the primary consumers will only get 100 kcal of energy (10%) from the producers they eat. Because of this, the biomass required to support each trophic level is affected by the 10% rule. Using the information you provided in Table 2 above, calculate the total biomass of the producers. Complete the following table: Trophic level Total biomass (kg) Producers Primary consumers Secondary consumers Tertiary consumers Table 3. Total biomass of the different trophic levels of the floodplain savanna of the Gorongosa National Park. Calculate the ratio of the biomass between each trophic level. Use the table below to organize your calculations: Biomass ratio Ratio (%) Primary consumers/Producers Secondary consumers/Primary consumers Tertiary consumers/Secondary consumers Table 4. Biomass ratios of the trophic levels of the floodplain savanna of the Gorongosa National Park. Compare the biomass ratios between the trophic levels. How do these ratios compare to the 10% rule? What is a possible explanation for this?
The Correct Answer and Explanation is:
Part 5: Estimation of Producer Biomass in Gorongosa National Park
The 10% rule indicates that about 10% of the energy from one trophic level is passed on to the next trophic level when consumed. This means that in order to calculate the biomass of the producers, we can reverse-engineer it from the known biomass of the primary consumers.
Step-by-Step Solution:
Step 1: Calculating Producer Biomass
We know from Table 2 that the biomass of primary consumers is 319 kg. According to the 10% rule, the biomass of producers can be calculated as follows:Producer Biomass=Primary Consumer Biomass×10\text{Producer Biomass} = \text{Primary Consumer Biomass} \times 10Producer Biomass=Primary Consumer Biomass×10Producer Biomass=319 kg×10=3190 kg\text{Producer Biomass} = 319 \, \text{kg} \times 10 = 3190 \, \text{kg}Producer Biomass=319kg×10=3190kg
So, the total biomass of producers is 3190 kg.
Step 2: Calculating Biomass Ratios
Now, let’s calculate the biomass ratios between each trophic level based on the given data:
- Primary consumers / Producers:
Primary Consumer BiomassProducer Biomass=319 kg3190 kg=0.1 or 10%\frac{\text{Primary Consumer Biomass}}{\text{Producer Biomass}} = \frac{319 \, \text{kg}}{3190 \, \text{kg}} = 0.1 \text{ or } 10\%Producer BiomassPrimary Consumer Biomass=3190kg319kg=0.1 or 10%
- Secondary consumers / Primary consumers:
Since we know that secondary consumers have a biomass of 139 kg (from Table 2), we can calculate the ratio as follows:
Secondary Consumer BiomassPrimary Consumer Biomass=139 kg319 kg=0.436 or 43.6%\frac{\text{Secondary Consumer Biomass}}{\text{Primary Consumer Biomass}} = \frac{139 \, \text{kg}}{319 \, \text{kg}} = 0.436 \text{ or } 43.6\%Primary Consumer BiomassSecondary Consumer Biomass=319kg139kg=0.436 or 43.6%
- Tertiary consumers / Secondary consumers:
From the data, the biomass of tertiary consumers is 139 kg. So the ratio is:
Tertiary Consumer BiomassSecondary Consumer Biomass=139 kg139 kg=1.0 or 100%\frac{\text{Tertiary Consumer Biomass}}{\text{Secondary Consumer Biomass}} = \frac{139 \, \text{kg}}{139 \, \text{kg}} = 1.0 \text{ or } 100\%Secondary Consumer BiomassTertiary Consumer Biomass=139kg139kg=1.0 or 100%
Step 3: Complete the Biomass Table
| Trophic Level | Total Biomass (kg) |
|---|---|
| Producers | 3190 |
| Primary Consumers | 319 |
| Secondary Consumers | 139 |
| Tertiary Consumers | 139 |
Step 4: Complete the Biomass Ratio Table
| Biomass Ratio | Ratio (%) |
|---|---|
| Primary consumers / Producers | 10% |
| Secondary consumers / Primary consumers | 43.6% |
| Tertiary consumers / Secondary consumers | 100% |
Step 5: Comparison with the 10% Rule
The 10% rule suggests that only about 10% of the biomass from one trophic level is passed to the next. However, from our calculations, we see that:
- The ratio of primary consumers to producers (10%) aligns well with the 10% rule.
- The ratio of secondary consumers to primary consumers is much higher (43.6%), which exceeds the 10% rule.
- The ratio of tertiary consumers to secondary consumers is 100%, meaning no energy loss in this level, which is also an anomaly.
Possible Explanation:
These deviations from the expected 10% rule could be due to several factors:
- Efficiency in Energy Transfer: In natural ecosystems, energy transfer is not always strictly limited to 10%. Some organisms may be more efficient at assimilating energy from their prey.
- Incomplete or Low-Level Energy Loss: Not all energy is lost at each trophic level. For example, some species may have evolved strategies to maximize energy intake, resulting in higher than expected biomass at higher trophic levels.
- Data Representation: The data used for biomass may not perfectly represent energy flow, and this could account for the deviations observed.
These irregularities point to the complexity of real ecosystems, where the 10% rule serves as a general guideline but does not always perfectly apply in every case.
