Gaya fish color project

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One of the more charismatic parts of a coral reef ecosystem is the fish community. We observed that many fish used specific coloration and patterns for possible camouflage on different parts of the reef. However, there are potentially many factors which influence the coloration and patterns of fishes (sexual selection and species recognition, for example). In our experiment, we examined to what extent fish coloration is associated with certain substrates (corals, rocks, and sand). We hypothesized that colorful fish would be associated with a more colorful background (corals); lightly colored fish, with light backgrounds (sand); and darkly colored fish, with dark backgrounds(rocks and corals).

We used a 1m x 1m square plot to sample coral, rock, and sand habitats at Padang Point, Pulau Gaya, Sabah, Malaysia. We chose the sites by using random spinning and 10s swims to reach a random site within a habitat. 3 observers recorded the number of fish that visited the plots over 10 minutes, recording overall appearance(dark, light, or colorful), pattern(solid, striped, or spotted), and color. All 3 observers consolidated the data for each plot, and the data was analyzed using R. We used chi-squared tests to assess whether the appearance, patterns, and colors of fish were randomly distributed or were distributed with a specific pattern.

We found that the appearances, patterns, and colors of fish follow a non-random pattern of distribution among different areas of the reef. The p-value for the chi-squared test of the fish overall appearance data was p < 2.2e-16, suggesting that fish appearance is highly dependent on substrate type. Dark fish dominated the coral, while light fish were more prevalent in the sand. In the rock region, dark and light fish were most common (Figure 1). Colorful fish were rather rare in all substrates, but occurred most frequently in the sand. The p-value for the chi-squared test of the fish pattern data was p = 0.00103, suggesting that fish patterns also depend upon substrate type. Solid-patterned fish were common in all areas, but striped fish were most common in the rock, while spotted fish occurred most on sand (Figure 2). The p-value for the chi-squared test of the fish color data was p = 1.577e-13, suggesting that colors of fish are non-randomly distributed throughout the reef. Black was the most common color on corals and rocks, while tan dominated in sands (Figure 3). Our results show that there is a specific distribution of patterns of fishes according to their habitat substrates.

We hypothesized that fish would associate with substrates that were similar to their overall appearance, patterning, and coloration, and our results allow us to accept our hypothesis. The p-value related specifically to the patterns of fish is higher than the other two p-values, although still significant; this can be attributed to high number of solid-patterned fish in all areas. We can determine that camouflage techniques play a crucial role in the coloration and appearance of fishes, although other factors cannot be ruled out as not influencing coloration patterns.

Fig.1: Plot of Overall Fish Appearance
Fig.2: Plot of Fish Patterning
Fig. 3: Plot of Fish Colors