Table 2: Bacterial colonies vs. avg. temperature (Click to enlarge)
Table 3: Bacterial colonies vs. water temperatures (Click to enlarge)
First of all, there was a direct correlation between the average air temperature and the number of bacterial colonies counted. (See Table 2: Bacterial colonies vs. avg. temperature and Table 3: Bacterial colonies vs. water temperatures.) When the air temperature was higher, at the beginning of my expedition, there were more colonies. When the air temperature was lower, there were fewer colonies. What surprised me about this relationship was that it was exponential, not linear. This does make sense, though, since bacteria growth is often observed in an exponential ratio. There was also a direct correlation between the water temperature and the number of bacterial colonies counted. When the ocean water temperature was higher, at the beginning of the expedition, there were more bacterial colonies; when the water temperature was lower, there were fewer. This relationship was also exponential.
Table 4: Changes in parameters over time (Click to enlarge)
Another completely unexpected surprise came when my data demonstrated that there was absolutely no correlation between the estimated percentage of marine life and (1) the number of bacterial colonies; (2) the air temperature; (3) the water temperature; (4) the average air temperature; or (5) the amount of precipitation. However, the lowest estimated percentage of marine life was recorded after two weeks of rain, at the exact same time that an extremely large number of transparent bacterial colonies were observed. My second surprise came when I realized that there was absolutely no correlation between the number of anemones and (1) the number of bacterial colonies; (2) the air temperature; (3) the water temperature; (4) the average air temperature; or (5) the amount of precipitation. What did these unexpected results mean for my hypotheses, which were: (a) that ocean bacterial counts would decline proportionately with falling ocean water temperatures; and (b) that as ocean bacterial counts declined, the estimated percentage of marine life would increase?
My first hypothesis proved to be true. As ocean water temperatures declined, so did ocean bacterial counts, from a high of 155 colonies to a low of one colony. I also discovered that the number of bacterial colonies was related to the average air temperature. As the average air temperature declined, the number of bacterial colonies declined. I thought that the relationship between water temperature, air temperature, and bacterial counts would be linear and would appear as a straight line on a graph. However, the relationship was actually exponential, which is not totally unexpected, since bacteria grow exponentially when they have sufficient nutrients.
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An anemone and starfish
My second hypothesis was that as the number of bacterial colonies declined, the estimated percentage of marine life in my tide pool would increase. I proved this hypothesis to be absolutely false! In fact, the estimated percentage of marine life and the number of anemones observed was remarkably stable over the six-week period of my expedition. These two numbers did not correlate with water temperature, air temperature, average air temperature, or bacterial colony count. However, there was a slight decline in the estimated percentage of marine life following the two weeks of heavy rain. As you may recall, this is when I observed a different type of bacterial colony, perhaps carried in runoff from the storm drains.
My overall conclusions about the tide pools are that bacterial counts vary greatly over time, and directly correlate with average air temperature and ocean water temperature. In addition, my expedition has led me to believe that marine life in tide pools is very stable and not generally affected by bacterial counts or air and water temperature. However, an increase in bacteria from storm drain runoff after heavy rainfalls may adversely affect the tide pool population. It would be interesting to conduct another expedition to study tide pools over a longer period of time to confirm my findings, since it rains relatively infrequently in southern California. Discovering the types of bacteria that grew in the transparent colonies, and seeing if they can be linked to human/land waste from storm drain runoff, would be an interesting expedition for another day.
I have returned to my beloved tide pools often since the completion of this expedition, not to conduct further research but to visit an area of unique beauty, stability, and importance to both the human world and the world of the ocean. My thoughts are often riveted on how a certain event may affect the animals and plants that dwell partially in each world, tied irreversibly to mine as well as their own unique environment. My expedition has brought them into my sphere; perhaps it has also allowed me to venture into theirs.
"Then one can come back to the microscope and the tide pool... It is really the understanding and attempt to say that man is related to the whole thing..."
—John Steinbeck, The Log from the Sea of Cortez
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