Define the term trophic level in the context of an ecosystem.

An ecologist sampled a saltmarsh ecosystem and recorded the following population data:

• Number of cordgrass plants = 800
• Number of peregrine falcons that prey on curlews = 3
• Number of ragworms that feed on cordgrass = 250
• Number of curlews that feed on ragworms = 40

Draw and label a pyramid of numbers for this saltmarsh ecosystem.

The ecologist collected this data during the summer. Suggest two reasons why the population of ragworms might decrease significantly during the winter months.

The total biomass of the organisms decreases at each successive stage of this food chain. Explain the processes that lead to this loss of biomass between trophic levels.