The Last Sunset ... and Fish

As we all sit on the boardwalk to enjoy our last sunset at Palo Verde National Park, I couldn’t help but think back to just over a week ago, when I standing in the same place, fishing in the marsh for our last independent project. It was probably around 7:30 a.m.

            We were collecting fish at the Palo Verde protected marsh and also the outflow canal in the Bagatzí agriculture fields about 10km from Palo Verde. Our study aimed to see how agricultural landscapes may be affecting fish endurance and their response to predators. Why fish? For one, they are readily available at the rice fields and the marsh. But ultimately, because food production is so important worldwide, it’s important understand how our agriculture methods are affecting the environment around the land we cultivate. Agrochemical pollution is often seen in the ecosystems surrounding agriculture fields because of the intense use of pesticides, herbicides, and fungicides in crop growing. We sought out for some fish and results that could show how rice cultivation in Bagatzí is affecting them.

            Over a course of four days, we caught over one hundred fish and ran endurance tests to determine how long it took for them to become exhausted. We set up plastic containers as arenas for endurance tests, and used tongue depressors to follow fish around until they stopped swimming and were not responsive to the tongue depressor. We also noted how far each fish darted away when we first inserted the tongue depressor into the arena as well as measured their body lengths. After many hours of chasing fish and watching them jump out of the water during endurance tests, we got some results.

            The fish we collected from the rice fields were smaller than those from the protected marsh and also reached exhaustion faster. Bigger fish also tended to jump out of the water more than smaller fish, and also dart longer distances. Our results indicate that the agricultural landscape at the Bagatzí fields may be affecting fish size and endurance. Because we also found an association with jumping and darting with size, Bagatzí may also be indirectly affecting their ability to avoid predators.

            Besides a long paper that went along with our project, I gained a lot from our IP. It’s easy to pass on and agree with “pollution is bad” and “agrochemicals are bad”, but to go out into the field and actually find results of your own is incredible. Even if it was only four days; they were four, hardworking days that ended up telling a nice story we got to discover and write about ourselves. As I was looking out into the most beautiful sunset I was able to enjoy during our time at Palo Verde, I’m was saddened with the fact that only four days remain for me in Costa Rica. When will I be awake at 7:00a.m. for field work again? 
Yocelin Brito Bello
University of Illinois, Urbana-Champaign