Page 16 - Food_chains_FULL

L

F W B

Balanced Ecosystem
If the population size of a species Top-level
changes within an ecosystem, the consumers
balance of the food web can be
disrupted. Over time, all levels of
2nd-level
the food web can be affected. consumers

This food web shows the feeding
relationships of organisms in an 1st-level
consumers
Alaskan marine ecosystem. If the
population of seals and sea lions
dramatically decreased, what impact
Producers
would it have on this food web?

orca (killer whale)

Without as many seals
seals/ sea lions sea o ers and sea lions to eat,
killer whales might
start feeding
krill/zooplankton small sh sea urchins
on more sea
otters, causing a
decline in their
populations.

phytoplankton/diatoms kelp forest

With fewer otters as predators, the number of
orca (killer whale) sea urchins would grow and eat more of the
kelp forests.

seals/ sea lions sea o ers The kelp forests are the habitat for many fish
larvae. Loss of this habitat would cause a
decline in the fish population.
krill/zooplankton small sh sea urchins

This example demonstrates that the original
change in the population of the seals and sea
lions could cause a chain reaction of events
that would alter the balance of the food web.
phytoplankton/diatoms kelp forest
14 © Copyright NewPath Learning www.newpathlearning.com