- What species are most affected during large-scale oil spills, and why?
- How does dissolved oxygen enter ocean water?
- What about the chemical nature of hydrocarbons and refined petroleum products makes it act as it does when spilled into the ocean?
- Describe the physiology of Daphnia magna
With BP’s recent oil well explosion in the Gulf of Mexico, the crash of the oil tanker into the Bay Bridge in San Francisco, and the Exxon Valdez dumping its contents off the coast of Alaska, Oil spills and their effect on the environment are of great concern. Big oil companies will downplay the impact on the environment, but often enough the results tend to be catastrophic.
Photos of affected wildlife tend towards the ones we can see- seabirds and marine mammals tend to make the news. Still, oil spills affect all organisms, not just ones that live near or on the surface of the ocean. The purpose of this experiment is to quantify exactly what that impact is on organisms that dwell below the surface.
- Daphnia magna (water flea) live culture and food (yeast, chorella algae)
- Cooking oil ( canola, vegetable, olive)
- Graduated cylinder or teaspoon
- 10 empty soda 2 or 3 liter bottles
- Scissors or straight razor
- Several gallons of distilled water, or water that has been sitting exposed to air for at least 48 hours.
- Small net or coffee filter to catch Daphnia.
Most of these materials can be found at either the grocery store or the hardware store- it’s also likely you have some of them around the house. The only ones more difficult to find are the Daphnia magna and the food. The Daphnia themselves can often be found at an aquarium shop, but the chorella- the food they eat- can be trickier. You can find places online to send you a ‘starter culture kit’ for about $20 which includes food ( see the link in the bibliography) which is the easiest method, although the survival rate through the mail can be negligible. If you do choose to go this route, make sure you have the phone number of the company in case the Daphnia expire en route.
- Take the 10 Soda bottles and cut the tops off just below where it starts to taper up toward the neck of the bottle.
- Fill one of the bottles with tap water, not more than halfway up (you don’t need to use the distilled water just yet)
- Start adding the oil in very small increments- ¼ tsp. or single ml’s. The idea is to have only enough oil to cover small parts of the surface, incrementally, until most or all of the surface is covered up.
- When you get a handle on the right amount of oil to add and what increments you will use, take your 10 bottles and fill them up to the same level.
- Add the same number of Daphnia to each container. 10 might be a good number to try, as you will be counting them daily, and more than that will be to hard to count, as they swim around constantly.
- Add food to each container, ideally chorella algae.
- Add different amounts of oil to each bottle. Even increments will mean easier and more meaningful graph representation.
- Each morning record the survival rates. If babies are born, you may actually have an increase in population. Do this for at least 10 days, or for how long the Daphnia survive.
- Record the data in a raw data chart. Graph it when the experiment is completed- it is probably best to use a line graph, with time as your X-axis. You will need a different line for each volume of oil added.
Terms/Concepts: Petroleum; Oil spill; Hydrocarbon; Oxygenation; Daphnia Magna; Chorella