Every now and then we catch a Boa Constrictor, Drake Bay, Costa Rica!
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Purpose: The question that was to be asked by this project was: “Does reef color affect the attraction of organisms?” It was decided that this would be a good project idea because it was noticed that many of the reefs the class visited were very colorful and each had a different number and kind of fish. The hypothesis that was collaborated was that the darker reefs would attract a greater abundance of organisms because it mimics the coloration of a natural reef. (When the materials that were need were gathered, as you will see in the next section, it was decided that the order of the colored reefs should be: red, blue, multi-colored, yellow, and white.)
Materials: For this project the following materials are needed:
- 20 conchs
- 3 colors of paint (red, yellow, and blue)
- paint brush
- tape measure
- beach marking tape
- snorkel gear
- data slates (for recording collected information)
- 1 day to get the investigation set up
- 4+ days of data collecting (takes approximately 30 minutes for each collection)
Methods: If you are thinking of performing this experiment in San Salvador, it is important to make sure that all the materials listed above are able to be gathered quickly and easily. (We found it difficult to locate all the necessary items (paint) because some of the items are hard to get a hold of, since they need to be imported.) If the paint et al. are able to be gathered then you can proceed with the next step which is to decide on a location to perform the investigation. The section of beach needs to be at least 60 meters long. It is preferable that no other investigations of this sort are being conducted within 20 meters of each side of the project. The next stage (if it hasn’t been done already) is to search for your 20 conchs and to get them painted. The five lightest conchs need to be set aside for the white and multi-colored reefs. The next step is to paint 5 conchs yellow, 5 red, and 5 blue. Four of each of these colors will be used to construct the individual colored reefs, while the extra of each will be used to build the multi-colored reef. Let the conchs dry thoroughly, this may take a few hours. While the conchs are drying, you can set up your investigation zone. To begin, measure out the shoreline markers. These should be placed 15 meters apart along the shoreline. It is now time to set the reefs up, one person needs to stay on the shore holding the measuring tape, while the others in the group take the measuring tape and the painted conchs out to the water, one reef at a time. The reefs should be set up 35 meters from the shore (See Figure #1), once the desired distance is reached the conchs need to be arranged in a manner so that 3 shells are on the ground with their lips pointed out, so that fish and other organisms can swim inside for shelter and habitat. The 4th conch should be set on the top of the triangle of shells to provide the artificial reef with height. Once the reefs have been set up, they will need about 24 hours before you should take your first artificial reef collection data.
Figure 1. Set up of the study site.
(SEE:GDS POWERPOINT FOR FIGURE)
To check the reefs, it is preferred that the reefs are checked at a variety of times (morning, afternoon, and night or near dusk), this ensures that you are getting a wide variety of time options for different reef fish to find habitation. When recording is taking place, the number and type of fish that are seen need to be noted at each of the independent reefs. (It is a good idea to keep fish identification books close by, and have a couple of people look at the reefs, for it is easy to miss, a fish or two, especially when they are mostly juveniles and sometimes hard to see.
At the end of the investigation, once all of the data has been collected and tabulated, it is necessary to perform some statistical tests to analyze what was seen at the reefs. For this experiment, the Chi-square and a Spearman Rank Order Test were used.
Results: For a complete list of results please refer to Nikki Nagel’s Tropical Marine Ecology Lab Notebook (I did not have it at the time of publication.)
The first chart (#1) seen here shows the diversity of the different colored reefs throughout the week. Red had a total of 10 different organisms in the form of 6 different species. Blue had a total of 5 different organisms in the form of 3 different species. Yellow had a total of 4 different organisms in the form of 4 different species. White had a total of 4 different organisms in the form of 1 species. Multi-colored had a total of 6 organisms in the form of 3 species.
Chart #1: Diversity of Reefs throughout the week.
(SEE: GDS POWERPOINT FOR CHART)
The graph (#1) of Abundance of Organisms per Artificial Reef shows the number of organisms that were present at each of the check points during the week. Red was the leader everyday but the first. The multi-colored reef ended up with the second most organism abundance. Then the rest went white, blue, and yellow respectively in terms of organism abundance.
Graph #1: Line graph of the Abundance of Organisms per Artificial Reef
(SEE: GDS GRAPH IN POWERPOINT)
The bar graph of Total Organisms per Day (Graph #2) shows that the total number of organisms increased from the first day of recording to the last, based on a shear number count.
Bar Graph #2: Total number of organisms per day at the check point.
(SEE: GDS POWERPOINT)
The Spearman Rank order Results are also seen in table #2.
Table #2: Spearman Rank Order Test Results.
(SEE: GDS POWERPOINT)
When analyzing the data, it is seen that there is an increase of organisms at each checkpoint throughout the week of the investigation. The rank order of abundance by color turned out to be: red, multi, white, blue, and yellow. When the Chi square test was preformed to analyze the data, it was found that reef coloration does not have any affect on the ratio of abundance/diversity. Df = 4, Chi-Square = 0.737, and P Value = .946.
When the Spearman rank order test was preformed it showed that there is a correlation between some colors and their abundance, but not enough data was collected to make this conclusive.
Conclusion: As we came to the end of the project, we were disappointed in the results that we received. Our tests showed that the results do not fully support our hypothesis, and organisms seemed to be randomly distributed throughout the color reefs. There are many reasons that this may be the case. The fish were so small that they might be attracted to anything that looked like it would provide shelter. Also, a longer period of time for observations would have been much more telling of the organisms that may have been attracted to the reefs.
We also did not take into consideration a source population or other artificial reefs that may have been around. If this experiment were going to be performed again, placing the reefs around a source population may be a good idea. It may be that the fish from the source populations would prefer a certain color of reef over another, thus giving better results.
Another problem that we had was that the paint that was placed on the conchs did not have the adhesive properties that we expected. In fact the yellow paint started to chip and peel as we put it into the water. We thought that the fish might also smell or sense the paint and be afraid to go near it. This could have had a large effect on our results. Finding a brand of paint that is salt water tolerable would be a good idea.
The last thing that may need to be changed is the size of the reef. The four shells may have been fine for small fish, but too small for large fish. A greater reef size may aid results and give a more telling picture of what is really going on.
Over all, coming up with the investigation and watching the reefs gather fish was a great learning experience. There are some changes to be made that could make this a much more telling experiment. I believe that this could be a very interesting topic to put more research into, if we were allowed more time, and had better resources.
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