Question

Pacific salmon grow to adult size in the ocean and move into freshwater streams and lakes to reproduce and die. In this process, they transport energy and elements from the ocean to freshwater systems. However , returning salmon are often consumed by bears and therefore energy and elements are transported to terrestrial ecosystems. Discuss the flow of energy and elements with the above in mind.

Answer 1

Ans . An ecosystem is a community of living organisms and their abiotic (non-living) environment.

Salmon heavily affect the nutrient cycle in coastal ecosystems because they carry nutrients to other animals and bring MDN ( marine-derived nutrients) to the ecosystem. Macroinvertebrates (animals without a backbone that are big enough to see without magnification) are rich in the MDN that the salmon bring and they are soon eaten by the small fish in the stream and the nutrients passed on to the small fish. The nutrients the small fish ate are then passed on to salmon again , then the salmon are eaten by the eagles / bears ( top predators ) in the forest. The nutrients have been passed all the way from macroinvertebrates to the top predators in the ecosystem.

The death of salmon has important consequences, since it means significant nutrients in their carcasses, rich in nitrogen, sulphur, carbon and phosphorus, are transferred from ocean to terrestrial wildlife such as bears and riparian woodlands adjacent to rivers. This has knock-on effects not only for the next generation of salmon, but to every species living in the riparian zones the salmon reach.

The nutrients can also be washed downstream into estuaries where they accumulate and provide much support for estuarine breeding birds.