Answer:
Secondary consumer is Mackerel .
Explanation:
In this food chain ,
Phytoplankton is Primary Producer ,
Krill is Primary Consumer ,
Mackerel is Secondary Consumer and
Sea gull is Tertiary Consumer .
Primary producer is an organism that produces its own food.
Primary consumer is an organism that feeds on producer.
Secondary consumer is an organism that feeds on primary consumer.
Tertiary consumer is an organism that feeds on secondary consumer.
