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:
To calculate the biomass of the producers and the biomass ratios between each trophic level using the 10% rule, let’s break it down step by step:
Step 1: Estimating the Biomass of Producers
From Table 2, we know the biomass at the higher trophic levels:
- Primary consumers = 9390 kg
- Secondary consumers = 319 kg
- Tertiary consumers = 139 kg
Using the 10% rule, we know that only 10% of the energy is passed from one level to the next. Therefore, the biomass of the producers can be calculated as the total biomass of the primary consumers divided by 10% (or multiplied by 10, since 10% means the producers supply the primary consumers with 10 times their biomass).Producer biomass=Primary consumers biomass×10=9390 kg×10=93,900 kg\text{Producer biomass} = \text{Primary consumers biomass} \times 10 = 9390 \, \text{kg} \times 10 = 93,900 \, \text{kg}Producer biomass=Primary consumers biomass×10=9390kg×10=93,900kg
Thus, the biomass of the producers is 93,900 kg.
Step 2: Calculating Biomass Ratios
Now let’s calculate the biomass ratios between each trophic level.
1. Primary consumers / Producers:
Ratio (Primary consumers/Producers)=Primary consumers biomassProducers biomass=939093,900=0.1 or 10%\text{Ratio (Primary consumers/Producers)} = \frac{\text{Primary consumers biomass}}{\text{Producers biomass}} = \frac{9390}{93,900} = 0.1 \, \text{or} \, 10\%Ratio (Primary consumers/Producers)=Producers biomassPrimary consumers biomass=93,9009390=0.1or10%
2. Secondary consumers / Primary consumers:
Ratio (Secondary consumers/Primary consumers)=Secondary consumers biomassPrimary consumers biomass=3199390≈0.034 or 3.4%\text{Ratio (Secondary consumers/Primary consumers)} = \frac{\text{Secondary consumers biomass}}{\text{Primary consumers biomass}} = \frac{319}{9390} \approx 0.034 \, \text{or} \, 3.4\%Ratio (Secondary consumers/Primary consumers)=Primary consumers biomassSecondary consumers biomass=9390319≈0.034or3.4%
3. Tertiary consumers / Secondary consumers:
Ratio (Tertiary consumers/Secondary consumers)=Tertiary consumers biomassSecondary consumers biomass=139319≈0.436 or 43.6%\text{Ratio (Tertiary consumers/Secondary consumers)} = \frac{\text{Tertiary consumers biomass}}{\text{Secondary consumers biomass}} = \frac{139}{319} \approx 0.436 \, \text{or} \, 43.6\%Ratio (Tertiary consumers/Secondary consumers)=Secondary consumers biomassTertiary consumers biomass=319139≈0.436or43.6%
Step 3: Completing the Tables
Now, we can fill in the tables with the calculated values.
Table 3: Total Biomass of the Different Trophic Levels
| Trophic level | Total Biomass (kg) |
|---|---|
| Producers | 93,900 |
| Primary consumers | 9,390 |
| Secondary consumers | 319 |
| Tertiary consumers | 139 |
Table 4: Biomass Ratios of the Trophic Levels
| Biomass ratio | Ratio (%) |
|---|---|
| Primary consumers / Producers | 10% |
| Secondary consumers / Primary consumers | 3.4% |
| Tertiary consumers / Secondary consumers | 43.6% |
Step 4: Comparison to the 10% Rule
According to the 10% rule, we would expect the biomass to decrease by approximately 90% at each trophic level (i.e., each level should have about 10% of the biomass of the level below it). However, the actual biomass ratios we see in the floodplain savanna are as follows:
- Primary consumers have 10% of the biomass of the producers, which aligns with the 10% rule.
- Secondary consumers have only about 3.4% of the biomass of the primary consumers, which is significantly lower than expected based on the 10% rule.
- Tertiary consumers have about 43.6% of the biomass of the secondary consumers, which is far higher than expected.
Explanation for Deviation from the 10% Rule:
The biomass ratios not perfectly following the 10% rule can be explained by several factors:
- Efficiency of Energy Transfer: The 10% rule is a generalization. In reality, energy transfer between trophic levels can vary depending on factors like organism size, diet, and metabolic efficiency.
- Overlapping Niches: Trophic levels might overlap in terms of their food sources. For instance, secondary consumers may also consume primary producers or may not strictly follow the typical food chain structure, leading to a higher biomass than expected.
- Species Composition and Ecosystem Factors: The species in the Gorongosa floodplain savanna may have adapted to different ecological conditions, with some species being more energy-efficient at certain trophic levels, altering the typical pattern of biomass distribution.
In conclusion, the ratios indicate some unusual energy dynamics in the Gorongosa ecosystem, likely influenced by complex ecological interactions, species behaviors, and environmental factors that may not fully follow the classic 10% energy transfer model.
