Question 1: Define 'trophic level' and explain its significance in ecological food chains.

Answer: A trophic level is a position an organism occupies in a food chain, determined by how many energy transfer steps it is from the primary producers. It is significant because it helps understand energy flow and biomass distribution in ecosystems.

Question 2: Describe two major impacts of overfishing on trophic levels within marine ecosystems.

Answer: Overfishing reduces populations of top predators, causing trophic cascades that disrupt ecosystem balance, and leads to the decline of species at higher trophic levels, affecting biodiversity and energy transfer.

Question 1: The biomass of a fish species is 5000 kg in a protected marine area. If 10% of this biomass is removed annually through sustainable fishing, what is the annual biomass removal? Provide your answer in kilograms.

Answer: 500 kg (calculation: 10% of 5000 kg = 0.10 × 5000 kg = 500 kg)

Question 2: If the energy transfer efficiency between trophic levels is approximately 10%, how much energy (in joules) is transferred from a primary consumer that consumes 2000 joules of energy from producers?

Answer: 200 joules (calculation: 10% of 2000 J = 0.10 × 2000 J)

Question 1: Design a simple outline for a sustainable fishing experiment to assess the impact of fishing on fish populations at different trophic levels. Include variables to be controlled and safety precautions.

Answer: The experiment should include selecting multiple fishing sites with similar environmental conditions; variables to control include fishing gear, timing, and fishing quotas. Variables to measure are fish population sizes and biomass before and after fishing. Safety precautions include wearing protective gear, handling equipment properly, and ensuring compliance with legal fishing limits.

Question 1: A study reports that in a certain marine ecosystem, the biomass of phytoplankton is 8000 kg, zooplankton is 1200 kg, small fish is 300 kg, and large predatory fish is 50 kg. Interpret these data in terms of energy transfer efficiency and trophic levels.

Answer: The biomass decreases at higher trophic levels, reflecting energy transfer inefficiency (~10%). The large biomass of phytoplankton indicates primary producers dominate energy capture, while the small biomass of large fish suggests energy loss through trophic transfer. This pattern highlights the importance of maintaining healthy phytoplankton populations for ecosystem stability.

Question 1: Explain how understanding trophic levels can help develop sustainable fishing quotas and reduce overfishing. Include at least two specific examples.

Answer: By understanding trophic levels, fishery managers can set quotas that prevent overharvesting top predators and maintain balanced ecosystems. For example, limiting catch of large predatory fish helps preserve their populations, and regulating catches at lower trophic levels prevents disruption of energy flow.