Question 1: Define 'trophic level' and explain its relevance in an ecological context.

Answer: A trophic level is a position in a food chain or food web that an organism occupies, based on how it obtains its food. It is relevant because it helps understand energy transfer and the impact of fishing at different levels.

Question 2: Describe how overfishing at higher trophic levels can affect the overall health of an aquatic ecosystem.

Answer: Overfishing at higher trophic levels can reduce predator populations, leading to an increase in prey species, which may cause imbalances and disrupt the stability of the ecosystem.

Question 1: Calculate the biomass of fish at the top predator level if the biomass of the primary producer level is 10,000 kg and the transfer efficiency between each trophic level is 10%. Use the formula: Biomass at level n = Biomass at level 1 × (efficiency)^ (n - 1).

Answer: 10,000 kg × (0.10)^{n-1} (depending on level n, e.g., for level 4: 10,000 × 0.10^{3} = 10 kg)

Question 2: If the biomass of phytoplankton is 8000 kg and the transfer efficiency to zooplankton is 15%, what is the biomass of zooplankton?

Answer: 8000 kg × 0.15 = 1200 kg

Question 1: Identify three variables that should be considered when establishing sustainable fishing quotas.

Answer: Fish population size, reproductive rates, and ecosystem impact

Question 2: State two safety precautions that should be observed during commercial fishing operations to protect both workers and the environment.

Answer: Use of protective gear and adherence to environmental regulations

Question 1: In a certain lake, overfishing has led to a 60% reduction in fish at trophic level 3 over five years. Describe how this change might affect the populations at trophic levels 2 and 4.

Answer: A reduction in trophic level 3 fish may lead to an increase in prey species at level 2 due to less predation, and a decrease in predators at level 4 due to less food availability.

Question 1: Explain how sustainable fishing practices can be informed by understanding trophic levels and biomass transfer efficiencies. Include at least two strategies that could be used in fisheries management.

Answer: Understanding trophic levels helps identify which species are critical for ecosystem stability. Biomass transfer efficiencies indicate how much energy is passed up the food chain, guiding quotas to prevent overfishing at vulnerable levels. Strategies include setting catch limits based on biomass assessments at different trophic levels and implementing marine protected areas to allow populations to recover, ensuring long-term sustainability.

Question 1: Describe two technological innovations that help monitor fish populations and promote sustainable fisheries.

Answer: Use of satellite tracking to monitor fishing activities and remote sensing technology to assess fish stock levels