ITES PROFESSOR

Alonso Ramírez

Alonso Ramírez with a large shrimp in a trap at El Yunque.

The Luquillo Mountains are only about 20 miles from the municipality of Río Piedras and the climate in the rain forest is similar to urban areas of Puerto Rico, but the ecosystems of natural rivers and urban rivers couldn’t be more different. When Stream Ecologist Alonso Ramírez, Ph.D. first came to ITES in 2001, he was immediately attracted to investigating the natural pristine rivers and streams in El Yunque, but now his studies have moved to urban rivers, specifically the Río Piedras and Río Turabo in Caguas.

“Urbanization is rapidly increasing in Puerto Rico, and urban rivers are becoming the predominant type of river on the island. Before all rivers become impacted and degraded by urban development, we need to start understanding how rivers function and how to manage them,” says Ramírez.

Urban rivers are more flash-flood prone, what he calls “flashy.” They flood more often because the concrete in the watershed sends the rain water to the river quickly. “You don’t have the forest to absorb the water and slow down the movement from the land to the river, so when it rains all the water is driven into the river in minutes. Because it’s flashy, you get a lot less biodiversity and the ecosystem functions differently.” Ramírez points out that natural rivers are also subject to flash-flooding, but not nearly as quickly or as frequently. Another difference is the level of pollution. Urban rivers are subject to urban runoff, for example from oils from parking lots, gas stations and roads, and sewage from sewers that overflow during rainstorms. People also deliberately contribute to pollution in urban rivers. “People throw all sorts of things in the river, washing machines, refrigerators. There are things in there that you cannot really identify.”

Ramírez' students netting fish in the Río Piedras River.

Currently, Ramírez and graduate student Diana Martinó are surveying urban river fish. “The rivers in El Yunque are natural. You get native eels, gobiids, mountain mullets, and shrimps and crabs. The bottom line is that you get the native species—what you expect to find. When you move to urban rivers, everything is different, in particular upstream from dams and reservoirs. It’s like a huge aquarium. You get some native species, but not many. When you start sampling, you find aquarium fish species that have been dumped into the river. You get tilapias, orange cichlids, and catfish, for example. Urban rivers are like big fish tanks. Introduced species have completely altered the ecosystem. They’re competing with shrimp and native fishes and excluding native fauna.

To understand human impacts to urban rivers, Ramírez and graduate student Rebeca de Jesús are assessing the relation between land use and stream integrity in the Rio Piedras basin. “We have a visual assessment method to assess the physical condition of stream channels. Using this method, we learned that as urbanization increases, rivers become simpler. The channel structure is not as heterogeneous as it should be. You don’t have the complexity—the riffles, pools, woody debris, or undercut banks—things that fishes and shrimp need to live. We’re also using a biotic index that looks at the fauna living in the river. The results are clear—as the amount of urbanization increases in the Río Piedras, water quality and stream integrity decrease.

“We’re studying rivers as ecosystems. How their physical, chemical, and biological components are being modified by human activities and how those changes might end up affecting us. For example, Sofia Burgos, a doctoral student, is assessing how land use patterns on the watershed are altering the biodiversity of microorganisms living in rivers and how those changes in diversity alter ecosystem functioning, such as the metabolism of the river. We know how river ecosystems function in El Yunque, so we have a good reference for a natural river.”

This reference may soon change as a result of rapid urbanization around El Yunque and the rising demand for water. Although the forest itself is protected by its status as a National Forest, the shrimp and fish that live in the streams and rivers have migratory, or diadramous, life cycles that take them out of the reserve for a part of their lives. All native shrimp and fish have to migrate to the ocean to complete their life cycles, to reproduce or live as juveniles. Adult shrimp live in the river, release their larvae into the water column, and the tiny larvae, just one mm in size, float down to the estuary where they live for up to three months. Then they make their way back to the headwaters. Fish reproduce in the estuary or move to the ocean to reproduce, but they have to swim back upstream.

“The problem is that every single river in Puerto Rico is dammed. We were monitoring water intakes in El Yunque, and they were sucking shrimp larvae like crazy. Also, large dams, like Carraízo, extirpate all native fauna upstream by blocking migrations. People can eat these shrimp. Some shrimp, like Macrobrachium, can grow as large as a small lobster.”

Ramírez’ research program also includes an international component, and some of his students conduct research in Costa Rica as part of STREAMS project, funded by the National Science Foundation. A joint effort with the University of Georgia to study water quality and quantity issues in the Caribbean lowlands of Costa Rica, the project has scientific and educational components. Researchers work from La Selva Biological Station, owned by the Organization for Tropical Studies (OTS). “Rivers at La Selva have high levels of nutrients, much like polluted rivers, but it is all natural and surrounded by forest. There’s little volcanic activity in the area, but enough to modify the water. Stream water at La Selva has a particular chemical composition and a lot of phosphorous—and phosphorous is a major nutrient for rivers. We’re studying the effect of that pollution on a natural ecosystem. It’s a great way to understand how an ecosystem responds to pollution by nutrients. It’s also a great way to expose students to another environment and culture.”

In addition to his research program on stream ecology, Ramírez is project director of two undergraduate training programs at ITES. The Undergraduate Mentoring in Environmental Biology (UMEB) program matches six UPR, RP undergraduate students with research projects at ITES. UMEB students are focusing on a variety of systems, from forested to urban, and conducting scientific research as full members of an ITES faculty laboratory group. The Research Experience for Undergraduates (REU) program is a summer internship in ecology and evolution for Puerto Rican and mainland students. The program enrolls eight undergraduates who live for 10 weeks at El Verde Field Station. During the summer, students learn about conducting ecological research under the tutelage of faculty mentors from UPR and LTER.

aramirez@ites.upr.edu

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