Experiments on Underwater Plants and Oil Spills

Phytoplankton is underwater plants that are studied during marine oil spill experiments. They are at the bottom of the marine food chain but because they pull nutrients from the water column, experiments on phytoplankton can indicate oil spill impacts from an early stage. Oil remains in the water column for days, but resides in sediment for years. Early analysis of phytoplankton may be able to predict future impacts if the sediment is disturbed, releasing oil into the marine environment before full decomposition occurs.

Mesocosm Experiment

• In an experiment conducted in the Changjiang River Estuary in China, two mesocosms, which are temporary water enclosures that are as close to natural conditions as possible, were laid out. Oil was added to one mesocosm while the other remained uninfluenced. Environmental and biological parameters, such as temperature, salinity, organic carbon and phytoplankton abundance, were measured for both enclosures. The results indicated that growth rates for the smallest microphytoplankton and largest phytoplankton species were not inhibited, whereas the midrange-sized nanoplankton were inhibited in the oil-infused mesocosm.

Laboratory Experiment

• In a laboratory experiment conducted using Gulf of Mexico phytoplankton, eight different species were exposed to different concentrations and types of oil for 96 hours to determine the amount required to reduce cell growth by 50 percent, as compared to control samples. This experiment determined that Nigerian crude oil is the most toxic, Iranian and Empire mixed crude were less toxic and the Saudi Arabian and Venezuelan crude oil were the least toxic.

Experiments for Kids

• Oil spills can inhibit growth of underwater plants by blocking the sun's rays from seeping through the water column, which disrupts photosynthesis. Kids can demonstrate this effect with hydrilla plants, beakers, test tubes, funnels, water, a ruler and engine oil. Create two apparatuses and place the hydrilla plants under the clear funnel with the test tube upside down covering the funnel inside a beaker. Each beaker and test tube is filled with a specified amount of water. One set up is the control without oil and the other has a layer of oil on the surface of the water. During photosynthesis, carbon dioxide is absorbed and oxygen is produced. During this experiment, different amounts of oxygen are produced in the test tube, measured by the displacement of water within the tube.

Significance

• Experiments that mimic real-world conditions can indicate the impact of an oil spill on underwater plants at the bottom of the food chain. Laboratory experiments demonstrate toxicity levels of different types of oil, while experiments conducted by kids can show how oil inhibits photosynthesis.