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Coral Reefs

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Snorkeling For Parrotfish! (Photo by Todd Livdahl)

            The methods presented here were developed to assess the question: is there an optimal foraging strategy being employed by Rainbow Parrotfish (Scarus guacamaia)? I observed Rainbow Parrotfish in John Smith’s Bay, Bermuda in October, 2004: once at 10 am and again at 4 pm. I snorkeled above them, but maintained enough distance so as not to disturb their normal foraging habits by causing them to move away from me. Thus, I was usually several feet above them, but located away from them so as not to disturb their normal behavior by appearing like a predator, or casting my shadow on them.  I observed a single fish for a one minute interval, noting how many times it grazed during that period, as well as for how many seconds each graze lasted. The number of seconds to a graze also coincided with the number of seconds the fish grazed in one location with movement between grazing sites after each grazing period. Thus, the number of grazes per minute also is indicative of the number of different sites the fish grazed at during that minute. I recorded this information on an underwater slate, and kept track of the time using a water-proof stopwatch.

            I then analyzed the data by grouping the number of grazes data and performing a chi square test using a Yeats conversion. I also compared the mean to the variance of the number of grazes to see if a pattern emerged. Finally, I plotted the data to see if trends emerged.

 

 Looking for those Parrotfish, materials in hand