Question

this change would have a direct positive impact and a direct negative impact on which organisms?
diatoms = negative impact; orca = positive impact
squid = negative impact; diatoms = positive impact
leopard seal = negative impact; copepods = positive impact
great white shark = negative impact; krill = positive impact

Explanation:

The question is about the impact of a change in a marine food web. In a food web, organisms are interconnected through feeding relationships. A direct positive impact means the organism benefits from the change, while a direct negative impact means it is harmed. Looking at the food web:

• Orca: If there is a change (e.g., increase in a food source it preys on, but in this case, we assume a general analysis based on the given options). If something that Orca preys on (like Leopard seal) has a change. But wait, the options are about which organism has a direct positive and negative. Let's re - analyze. If we consider the food web structure, Orca is a top - level predator. If there is a change that reduces its prey's predators (not likely here). Wait, no. Wait the options given in the left - hand side of the page: diatoms = negative impact (if something that preys on diatoms' consumers is affected). No. Wait, the question is "This change would have a direct positive impact and a direct negative impact on which organisms". From the food web:
• Krill: If there is a change (say a decrease in its predator (Fish, but Fish are also preyed on by Great white shark). But if we consider the options given in the original problem (left - hand side text which is part of the question, even though the user instruction didn't fully clarify, but from the left - hand side text "great white shark = negative impact; krill = positive impact".
• Great white shark: It is a predator. If there is a change (e.g., decrease in its prey (Fish) due to some factor, but according to the left - hand side text, it has a negative impact. Krill, which is preyed on by Fish (and Fish are preyed on by Great white shark). If the change is something that reduces the predation pressure on Krill (e.g., decrease in Fish population due to another factor), Krill would have a positive impact.

Answer:

Great white shark = negative impact; Krill = positive impact