NSF GK-12 Graduate Fellows Program
Award # DGE-0139171
University of North Carolina at Wilmington
Harmful Algal Blooms
by Tika Knierim, Department of Chemistry
This activity is aligned with the 2001 North Carolina
Standard Course of Study for 8th Grade Science: Goal # 1 & 2
Algal species
sometimes make
their presence known
as a massive
“bloom” of cells that
may discolor the
water
These “blooms”
alter marine habitats
Every coastal state has reported major blooms
Although they are referred
to as harmful algal blooms,
not all HABs are toxic
Toxic blooms are caused
by algae that produce potent
toxins that can cause massive
fish kills, marine mammal
deaths, and human illness
There are several types of toxins produced by these harmful
algae. . .commonly the toxins affect the functioning of nerve and
muscle cells
Toxic blooms have been responsible for causing diarrhea,
vomiting, numbness, dizziness, paralysis, and even death
The key is how the toxins move through the food web
The key to this scenario is bioaccumulation!!
BIOACCUMULATION is the process by which compounds
accumulate or build up in an organism at a faster rate than they
can be broken down.
Some organisms, such as krill, mussels, anchovies, and
mackerel, have been found to retain toxins in their bodies
Today we are going to do a little
activity in order to better understand
the concept of bioaccumulation and
how toxins are transferred through the
food chain.
Each person will be assigned one of the following
organisms:
Krill:
Fish:
Seal:
Killer Whale:
There is an outbreak of a Harmful Algal Bloom within the
boundaries of this classroom, and there is algae (green beads)
spread all over the area. The only organisms that are able to eat
the algae are the krill. The fish can then eat the krill, the seals
can eat the fish, and the whale can eat the seals. Each organism
(person) will receive specific instructions as to how they will
react to this bloom.
The krill will have 30 seconds to “graze” the area and “eat” as
much algae (place algae into “food bag”) as possible.
The fish will then do what is indicated on their card. . .the fish
will “eat” the krill by tagging them and taking their food bag.
Once a krill is tagged, he/she should sit down to indicate that they
have been eaten. The living krill can continue to “graze” during
this time.
Once the fish have accomplished their tasks as indicated by the
cards, the seals will then do as their cards say, and so on.
Now that everyone has “eaten. . .”
This Harmful Algal Bloom contained toxic algae!!!
If you consumed the large green beads, you have consumed toxic
algae!
Sort the toxic algae from the non-toxic algae small green beads
Count the total number of algae
Count the number of toxic algae
Calculate the amount of toxic algae you consumed as a percent of
your total consumption:
100 x (# of large green) / (total #)
Are there any krill that are still alive?
If you (krill) ate ANY toxic algae, you are now dead
Are there any fish still alive?
If you consumed 20% or more toxic algae, you are now
dead
Are there any seals still alive?
If you consumed between 20-30% toxic algae, you are now
sick
If you consumed over 30% toxic algae, you are now dead
If the killer whale ate between 20-30% toxic algae, you are now
sick
If the killer whale are over 30% toxic algae, you are now dead
So how many of us are still alive at this point?
How many are sick?
References
• www.bigelow.org/edhab/tracingtoxins.html