Our first Independent Projects of the course happened in Palo Verde National Park. We had lots of support from the professors, but the design and execution of the project was all up to the group. I was in a group of three, colloquially called “Team Fish.” As the name suggests, our project was studying fish, specifically looking at the effects of an agricultural landscape on the health and behavior of a common species of fresh water fish, Poecilia gillii.
We caught fish each day from three
different locations, each with different water quality and would return them to
their homes within a day. One site was inside Palo Verde National Park in the
marsh directly in front of the station, and the other two sites were in the
rice fields of the Bagatzí Agricultural project right outside the park. The
rice fields are irrigated with water from Lake Arenal, and we collected the
fish from these inflowing irrigation canals, as well as from the outflowing
drainage canals where the water drains from the fields.
Once the fish were collected, they
were put through a test of their anti-predator behavior. We scared the fish
with a very artistic and terrifying Great Egret on a stick, and timed how long
it took the fish to reach a large shaded area and where they crossed in relation
to the researcher. After their behavior exams, the fish went to the photo shoot
portion of their time with us. They were often very reluctant models, but
despite the trials of working with diva fish, we got good pictures. We analyzed
these pictures to get the length of the fish and to measure how much of the
red-orange pigment called carotenoids they had in their ventral fins. This
pigment is important in immune system functions as well as ornamentation, and
can be used as a way to measure health. After a long day of testing,
photographing, and analyzing fish photos, Team Fish would return the marsh fish
to their home and stay to watch the sunset on the pier.
All of our hard work paid off, and
we found out some interesting things. The health of the fish, as measured by
the level of carotenoids found in their fins, was affected by an agricultural
landscape. The fish from the marsh had the most carotenoids and the fish in the
outflow canals had the least, leading us to believe that the difference could be
because of the presence of agrochemicals in the water. The anti-predator
behavior was not affected by the agricultural landscape, with outflow fish
taking longest to reach shelter and inflow fish taking the shortest. This
difference could be caused by the difference in the abundance of predators at
each location, but is not likely due to agrochemicals.
Finishing the independent project
and looking back on all the work we accomplished in such a short amount of time
was a great feeling. We started the project a week before with our only plan
being that we wanted to catch fish in the rice fields, and ended up a week
later with an interesting question, a strong understanding of the topic, and
interesting results to share. As we worked on the final papers and packed up to
leave for San Jose, Team Fish and the rest of the group went to watch the
sunset from the marsh for the last time.
Living with a host family is such a
different experience than what we’ve done so far. We have our own rooms, get to
navigate the city buses to get to class, and talk in Spanish a lot. I can tell
my Spanish has improved in just the three days I’ve been here. With such a big
change, it’s easy to forget what I was doing just a few days earlier. Yet
sitting on the terrace at my host family’s house and watching the sunset over
the city with the family dogs by my side, I think of all those great sunsets
with Team Fish in the Palo Verde marsh and am proud again of all that we
accomplished.
Erin Gaschott
Grinnell College
No comments:
Post a Comment