News from Belize — Blue Eyed Cichlids

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To enter the BFREE research station you have to cross a river. At the base of the Maya Mountains the Bladen River winds through the forested hills slowly making its way to the coast. Stepping into the river, bare feet sliding on the algae covered stones, the cool water refreshing our tired joints after a six mile hike through the hot tropical savanna, we were greeted by the magnificent sight of this shallow tropical river as it sped towards us through a canyon of trees.

As we waded through the water towards the station many different fish swam away as feet stirred up sediment on the river bottom, over the next few days this river would serve as both a respite from the bearing heat and swarming insects, and as an area to be studied.

The Bladen River winds its way out of the mountains and on to the savanna of central Belize, starting as a small stream and ending as a wide river. This river is home to a variety of fish, primarily, many different species of cichlids. This trip to Belize was not one of leisure, but rather of research. The Belize trip is the capstone of the Sewanee’s Rainforest and Coral Reef Ecology course; five days in the jungle, and five out on an island. Students must perform a project in each of these environments, and then, present their findings. For myself and my partners Maren Johnson and Winnie Davis our project would focus on cichlids in the Bladen River.

While snorkeling in the river on a daily basis to escape the heat we observed patterns in the behavior of Blue Eyed Cichlids. The Blue Eyed Cichlid is a small fish found in large numbers throughout the river, often seen in groups or solitarily, it is omnivorous and has a very obvious distinction between adults and juveniles. We observed that the fish seemed to prefer certain substrates as homes on the bottom of the river. To perform this study we wanted to quantify the levels at which the fish inhabit these substrates, looking at the differences between adults and juveniles. First, we distinguished the three main substrates: sand, rocks and organic matter. We hypothesized that all fish, regardless of age, would prefer to inhabit the rocky areas as the provide more cover, and that the juveniles would show a greater preference for the rocks than the adults.

To obtain this data we set up three 90 meter belt transects moving up river, one near either bank, and one in the middle of the river. We each swam one of these transects, and at every third meter we would record the depth, substrate and number of juveniles and adults in a one meter square.

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