Subject: Plankton abundance "What if"

Jennifer D. Philips (jphilips@soest.hawaii.edu)
Thu, 29 Oct 1998 09:10:12 -1000



>Dear Jen,
>=A0=A0=A0=A0=A0=A0=A0 What if the population of the plankton went down?= =A0 Would the
>population go down or would they try to eat another animal.=A0 Please answer!
>My teacher told me you would know.=A0 Thankyou.
>
>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Sincerely,
>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Lakeside Student


Lakeside Student -

That's a good question, particularly because this is an issue to be concerned about when humans start over harvesting the main prey species of many whales:  krill.  Baleen whales feed mostly on krill and small fish.  If the abundance of these organisms goes down for some reason, whatever that reason might be, whales would certainly have a hard time.  Lets say, for example, that the abundance of Antarctic Krill went down because humans started to harvest the krill more.  All the great whales feed on this krill species in the Antarctic at some time or another, not to mention the multitude of other marine species that rely on krill (seals, penguins, fish, etc.).  Almost certainly, the populations of the whales would go down too.  Whales may be able to switch their diet concentration to another species of prey, but this would probably only occur after the population has already suffered an initial decline.  The new prey species would probably not be able to support whale populations as they are now.  Their populations would probably remain down until the krill or some other extremely abundant prey returned. 

The ecosystem is very fragile and complex.  Each part of the system serves an important role.  The removal of a part, or change of a part in one direction or another, effects the entire system.  After the removal or change, the system will find a new equilibrium, but the resulting ecosystem WILL be different than it was before.  Humans are very effective in in causing changes to the ecosystems of the world. 

I hope this answers your question!  Write back anytime.

Aloha -
Jen Philips


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Jennifer D. Philips     
jphilips@soest.hawaii.edu

Marine Mammal Research Program
HIMB, University of Hawaii at Manoa
PO Box 1106      = ;  
Kailua, HI  96734
voice:  (808) 247-5063
fax: (808) 247-5831
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