Subject: orca and environment

Rui Prieto (rprieto@dop.uac.pt)
Mon, 21 Sep 1998 15:22:24 -0000

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>Dear Sir,
>I have been searching unsuccessfully for information about how
>the environment affects the orca whale.  Please e-mail any
>info.
>Thank you for your help.


Hi!

The environment affects us all in many ways. In the case of the Orcas, you
can imagine several influences that the surrounding environment will have on
them. I will give you some examples, and you can imagine other ways, just by
trying to remember what they need to live.

Imagine, for instance, that the seawater starts to warm over the normal
average for a given season and area (that has been discussed by many people
because of "El Nino"). In that case some fishes may move to colder waters,
where they feel better, or their eggs may not hatch because the higher
temperatures spoil them. In either case, that means that less fish will be
available for the Orcas to eat, and they may face problems of food shortage.
So, temperature can affect them...

There are some organisms in the sea, that are poisonous. Amongst them are
some very small ones (almost invisible to the naked eye) we call
Dinoflagellates, which cause a phenomenon sometimes called "red tides", that
is very dangerous. The reason for that is that they are reddish, and when
they encounter the right conditions will reproduce in great numbers, causing
the sea to become reddish. When in such great numbers, the fish that eats
them will become poisoned, and the bigger fish that eats this poisoned fish
will become poisoned as well, and so on... The Orcas are on the top of that
"food chain" and will by their turn become poisoned. If the toxin (poison)
is ingested in big quantities, the animals may become ill, or even die. As
you can see, the Orcas are also affected by the organisms that surround
them.

We put many things into the environment, as by-products of our technological
development. Between these, there are several chemicals that we dump in the
sea causing an "invisible pollution". That is the case with some organic
compounds that are soluble in the fats (but insoluble in the water). If a
group of Orcas live nearby an area polluted with these compounds, they will
eat contaminated fish, and these chemicals will be stored in the fat of the
Orcas. If someday they need to use their fat reserves for some reason (let's
say, because they can't find food) the chemicals will enter in the blood
stream and affect some of the organs, causing them to fail. Then the animal
may become weakened or ill. As you see, pollution in the environment also
affects the Orcas.

If you try, you will find other ways in that the environment affects the
Orcas,

best wishes,

Rui


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