Background
Fish schooling is a common social behavior among many fish species. It is complex in nature, requiring quick reaction times and cooperation of each individual fish's lateral line system to detect movement in surrounding water so that a group of fish may move as a group (Partridge, 1982). Reasoning for this behavior, along with the structure and function of a fish school, have been explored. With disturbances in an ecosystem, like Hurricane Irma, it raises questions regarding the behavior of fish schooling in relation to the structure of the reef ecosystem, which is what this experiment attempts to answer.
There are several important factors that have been determined to incline fish to school. Some advantageous possibilities for schooling include mating, foraging, and reduced energy expenditure. Also, fish schooling could help fish species in predator interactions (defense, reduction of encounters, predator surveillance, mimicry) (Larsson, 2012). Larson additionally found that fish schooling involves many group dynamics with the OLS and health. Even though many have explored the possibilities of why fish school, there is still a certainty about schooling behavior that are not yet decided.
Background Cont.
Certain definitions are required to understand the independent variables for experimentation. According to Mochamed Arif Zainul Faud (2010), rugosity is a measurement that refers to the surface roughness of a coral reef. He suggests a method of using a chain to measure surface roughness and also provides an equation to apply to a scale of rugosity: C=1-d/l. "d" is the distance the chain covers factoring in the contour of the reef and "l" is the total distance the chain covers on a flat surface.
Some fish species spend their time swimming in different levels of the water. Currents and water movement above a reef make it easier for certain fish to forage in the water column. The water column can provide resource enrichment, evident from the change in species diversity from even the reef front to the back reef. Comparing the water column foragers and the benthic foragers, there are also certain morphologies that belong to each group (Davis and Birdsong, 1973). When introducing the factor of predation, the water column is more vulnerable to predators, which is why the level in which fish species forage could affect fish schooling behavior. The concept of "space sharing" on coral reefs and in other ecosystems has also been explored in the context of evolutionary biology, which speaks to animal relationships in a community (Smith and Tyler, 1972) .
Hypothesis 1
On reefs with different rugosity (low, medium, and high), fish schooling behavior will be different.
Predictions for Hypothesis 1
- On reefs with low rugosity, fish schooling behavior will increase
- On reefs with high rugosity, fish schooling behavior will increase
Reasoning: When a reef has more structure and surface roughness, I predict that fish schooling behavior is not as necessary. If schooling is used for structure, then the reef structure should be able to act as such. In contrast, if there is less structure provided by the reef, then the fish need to create structure themselves and will increase schooling behavior.
Hypothesis 2
As you change levels in the water column, fish schooling behavior will change.
Predictions for Hypothesis 2
Hypothesis 2:
- moving up in the water column will increase schooling behavior
- moving down in the water column will decrease schooling behavior
Reasoning: With more reliance on the reefs for structure and protection, the fish that spend most of their time around the reef will not need the structure and protection of schooling. When this is flipped and fish spend most of their time closer to the surface of the water where they are more vulnerable to predators, they will rely more on schooling for daily activities.
Methods
1. Video Taping
- 30 meter transect videos at 3 different reefs based on rugosity (low, medium, and high rugosity)
- rugosity will be measured using a chain. Using the equation for rugosity mentioned earlier, the reef will be categorized as low, medium, or high rugosity.
- videos will need to be recorded so that each level in the water column may be observed
2. Analysis of Videos
- watch videos, record identification of fish species and schooling behavior (schooling or no schooling)
- differentiation of levels of the water column will need to be made while watching the videos
- isolation of relevant fish species (French Grunt, Sergeant Major, Striped Parrotfish)
Available Data: Some videos already recorded
3. Statistical Analysis
- frequency of schooling behavior will determine the amount of fish schooling behavior
- frequency will be recorded for each species in each experiment dealing with either rugosity or level in water column
- statistical tests will follow
References
Davis, W.P. & Birdsong, R.S. (1973) Coral Reef Fishes That forage in the Water Column. Helgolander Wiss. Meeresunters. 24, 292. Retrieved from https://doiorg.libproxy.clemson.edu/10.1007/BF01609520
Faud, M. A. C. (2010) Coral Reef Rugosity and Coral Biodiversity. International Institute for Geo-Information Science and Earth Observation. Retrieved from https://webapps.itc.utwente.nl/librarywww/papers_2010/msc/nrm/fuad.pdf
Larsson, M. (2012) Why do Fish School? Current Zoology. 58(1), 116-128. Retrieved from https://doi.org/10.1093/czoolo/58.1.116
Smith, C. L. & Tyler, J. C. (1972) Space resource sharing in a coral reef fish community. Los Ang. County Mus. Sci. Bull. 14, 125-170.
Partridge, B. (1982). The Structure and Function of Fish Schools. Scientific American, 246(6), 114-123. Retrieved from http://www.jstor.org/stable/24966618