The temperature of each zone represents a cyclic pattern over a twenty-four hour period (figure 1). The low temperatures, which occur during the night time hours dips to about 75 degrees (F). The yellow zone temperature is more constant (~80-85 degrees F) during the time it is submerged by the high tide waters. Small short fluctuations in temperature occur for each most often during high temperature times of the days, except for the yellow zone when under high tide water (figure 1).
Figure 2- Intertidal zone temperatures for all four zones over the study period combined.
The temperatures of the intertidal zones are different at the four zones over the same time period (figure 2). They have the same cyclic pattern occurring at the same times of the days. During the 17,18, and 20 the white zone reached the highest temperatures, and during the 19 the black zone reached the highest temperatures. Grey reached the third highest temperatures generally, and the yellow zone had the lowest high temperatures generally. The low temperatures were very similar with the yellow and gray zones typically being slightly cooler than black and white zones. The small, short fluctuations in temperatures appear to be consistent for all of the time zones.
Table 1-Scheffe analysis of zone on temperature for two twenty-four hour periods (A and B).
Scheffe analysis indicated a significant difference between the gray-black, gray-white, yellow-black, and yellow-white zones average temperatures over two twenty-four hour periods. There was not significant differences between gray-yellow and black-white zones average temperatures for either day (table 1).
Figure 3- Interaction bar plot for temperatures Table 2- ANOVA table for temperatures between the two days. between the two days.
The average temperatures of each zone for both twenty-four hour period was similar (figure 3). In fact they were found not to be significantly different with a .4350 P-value (table2).
Analysis of Variance
Source DF SS MS F P
Factor 3 58007.2 19335.7 831.02 0.000
Error 1148 26711.0 23.3
Total 1151 84718.2
Table 3- One-way ANOVA for Yellow, Grey, Black, and White Zones
A One-way ANOVA test for the average high temperatures of each zone indicated that there was a difference between the zones with the P-value of less than .0001 (table 3).
Two-sample T for Black vs. White Two-sample T for Yellow vs. Gray
N Mean StDev SE Mean N Mean StDev SE Mean
Black 288 110.45 4.27 0.25 Yellow 288 94.39 4.29 0.25
White 288 112.61 3.66 0.22 Gray 288 103.76 6.56 0.39
T-Test of difference = 0 (vs not =): T-Test of difference = 0 (vs not =):
T-Value =-6.51P-Value= 0.000 DF = 574 T-Value=-20.27 P-Value=0.000 DF =574
Table 4- Two-sample T-test for Black vs. White and Yellow vs. Gray zones
A significant difference between black and white zones and yellow and gray zones was not found when averaging the temperatures for the entire day (table 1). Therefore a two-sample T-test was run using the average high temperature between these zones and found both to be significantly different (P-value less than .0001) (table 4).
Discussion
Our study of the temperature of intertidal zones shows clear evidence of a cyclic patter over a twenty-four hour period, with highest temperatures occurring during the early afternoon (figures 1 and 2). The tide level played a significant role in affecting the yellow zone, while only slightly affecting the temperature of the gray zone. Short spikes and drops in temperature occurred occasionally at every zone and is believed to be caused by cloud cover during that time.
Scheffe analysis indicated differences between average temperature of each of the zones except the black and white zones and the yellow and gray zones (table 1). This analysis was conducted with two twenty-four hour periods, which were similar in average temperatures and not found to be different (figure 3 and table 2). Therefore, I believe this pattern in temperature between the zones would be similar during the typical June in San Salvador, Bahamas.
To analyze the temperature that poses the most stressful physical disturbance I decided to analyze the average temperature of the hottest times of the day. Using a one-way ANOVA I found there also to be a significant difference between the zones average high temperature (table 3). Furthermore, I found a significant difference between the black and white zones as well as the yellow and gray zones using the average high temperature, which I didn't find using the total average temperature because the night time cool temperature deweighted the high temperatures (table 4).
One interesting find was that white zone was significantly hotter than the black zone during the hottest times of the day, as opposed to my hypotheses that black would be hotter. I suggest that the lichen cover holds enough moisture to cool the rock down as why this is the case. Perhaps less lichen is present in the white zone. During one of the four days the black zone was hotter than the white zone, but the other three days the white was hotter. I cannot explain why this would occur. A study of a longer time range would be interesting to see if there is some sort of pattern that would cause this. Or perhaps it had to do with the tides.
Temperature appears differ greatly between the zones, which would cause great physical stress to many organisms. Further research on the living communities of these zones would help to determine the extent of stress temperature has on organisms. Also, research on other physical variables such as salinity and moisture content on the surface of the rock would determine if temperature alone is the cause of physical stress in the upper intertidal zones.
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