REU in Tropical Ecology

Projects and Mentors

Summer 2024

Ecological responses to disturbance

Dr. Jesus Gomez, UPR, studies how disturbance affects species and functional group assembly.  His research focuses on: (1) community assembly rules, particularly how species diversity of arthropods and/or small vertebrates change in response to natural and anthropogenic disturbances; and (2) Predator-prey dynamics, with emphasis on the role of introduced species on food web structure and species distribution / habitat use. To address these questions he uses analytical tools like multivariate analysis, structural equation modeling, the Akaike information criterion (AIC), ANOVA, and Linear Mixed models. REU students can develop their independent projects developing hypotheses related to how disturbance affect communities in aquatic or terrestrial ecosystems.  Disturbance is a major driver of ecosystem dynamics in the Luquillo Mountains, taking the form of small events (e.g., landslides, floods) or major catastrophic occurrences (e.g., droughts, hurricanes).

Aquatic Insect Ecology

Dr. Alonso Ramírez, NCSU, works on the ecology of aquatic insects. His research program makes emphasis on the role that insects play within their ecosystems and how they respond to major disturbances (e.g., droughts and hurricanes). Students can develop their own independent research projects in areas such as: (1) Importance of insects on ecosystem processes (e.g., insects vs. decapods in processing organic matter); (2) Insect responses to hydrological disturbances (e.g., flooding); or (3) Insect and ecosystem recovery from hurricane impacts. Climate change predictions for the Caribbean indicate that droughts and hurricanes will become more frequent in the future.  In this context, it is critical to understand how those events might affect the functioning of stream ecosystems.  By focusing on insects, students can develop hypothesis-driven projects on the role of insects in their ecosystems and how they might be affected by disturbances created by drought (e.g., low oxygen, low flow) and hurricanes (e.g., open forest canopy, less detritus).

Chironomidae Ecology

Roberto Reyes is a Ph.D. student in the Biology department at the University of Puerto Rico, Rio Piedras.  He will be advising a student interested in working with aquatic insects of the family Chironomidae (non-biting midges). The selected student will have the opportunity to work in one of the following projects: (1) Chironomidae diversity on aquatic habitats around El Verde Field Station; (2) Mouth parts deformities in Chironomus sp. Florida larvae after exposure to sediments collected from urban streams; (3) Effect of fluctuating temperatures on the development, biomass, and behavior of Chironomus sp. Florida larvae. With these projects the students will have the opportunity to explore the different techniques used to collect these insects in the field, learn about their taxonomy and anatomical structures, and obtain laboratory skill to properly manage them under laboratory conditions.

Plant Population Ecology and Invasive Species Biology

Dr. James D. Ackerman, UPR, conducts research in 3 main areas in which REU students can develop their independent projects: (1) Natural history and the evolution of orchids; (2) Dispersion of plants and its relationship to land use history and recruitment; and (3) Invasive plant species biology. The first has its roots in evolutionary biology using Darwin's favorite model system, the orchids. As orchids are one of the most diverse groups of plants with a remarkable array of adaptations for survival and for specialized pollination, orchids are a good model system to gain insight in the diversification of flowering plants. The goal is to detect natural selection when reproductive success is rare and how these conditions affect the loss or gain of phenotypic variation. The second area involves the spatial aspects of reproductive success from seed germination to growth, development, flowering, fruiting, seed production and dispersal. This work links with studies of natural selection and evolution, but emphasizes ecological aspects at local and landscape scales combining field experiments with current and historical patterns of dispersion. For the third area, invasive species, tropical islands are prone to invasions and Puerto Rico is just beginning to see an explosion in the number of exotic species becoming naturalized and invasive. How such species affect ecosystems and what might be the pattern of spread is of great interest to the integrity natural areas. Data on distribution and reproductive ecology are often combined with species distribution models to address these problems.

Community responses to disturbance

Dr. Josué D. Santiago-Vera, Mount Mercy University, works on community ecology, using protozoa or aquatic invertebrates as model organisms to test the effect of disturbance to community structure. His research focus in studying species diversity, particularly how the community structure change in a natural habitat after any disturbance event (e.g., hurricanes, floods, droughts, anthropogenic etc.) or by recreating environmental changes under laboratory conditions to observe its effect on the community structure. Disturbance plays a major role in the community dynamics in the Luquillo Experimental Forest. Due to climate change, some disturbance events are predicted to increase. Disturbance such as droughts and hurricanes in Puerto Rico will become more frequent in the future. By focusing on either protozoa or aquatic invertebrates, students can develop hypothesis-driven research projects on how disturbance affect these organisms.

Stream temperature and ecosystem processes

Vamery González-Hernández is a Ph.D. student in the Department of Applied Ecology at North Carolina State University. She will be advising a student who is interested in working with the effects of stream temperature on ecosystem processes. Water temperature changes depending on land use and anthropogenic activities near the stream.  The goal is to assess how increases in water temperature alter stream ecosystem processes. The student will develop a project assessing ecosystem processes like organic matter decomposition. Techniques include the use of cotton strips as surrogates for organic matter and the use of sensors. 

Tropical Stream response to natural disturbances

Mariely Vega Gómez, a Ph.D. candidate at North Carolina State University, works on evaluating stream ecosystem responses to natural disturbances, particularly droughts and hurricanes, using aquatic insects as model organisms. Macroinvertebrates (aquatic insects visible with the naked eye) differ in their adaptations and traits, that coupled with their local habitat, determine their resistance and resilience to these events. Climate change projections for the Caribbean region suggest that these disturbances are expected to become more frequent and severe. At the El Yunque National Forest, students will explore and design a unique research project to assess how these disturbances impact the macroinvertebrate assemblage of tropical headwater streams.

Bryophyte diversity and ecology

Dr. Amelia Merced, UPR and IITF, works with bryophytes, a group of plants that includes mosses, liverworts and hornworts. Students in the REU program can develop research in areas of bryophyte biology and the ecological factors that influence the presence of bryophytes in the rainforest. Research in the Luquillo Experimental Forest consists of documenting the diversity of bryophytes and investigating the ecological factors that affect their distribution, including habitat and historical land use. Some specific questions to address are how bryophyte species richness and abundance relates to elevation, microclimate and distance from streams throughout the landscape. For epiphytic bryophytes, students can investigate how canopy cover and host tree characteristics affect bryophyte communities. Students can develop other projects in ecology, floristics and reproductive biology of bryophytes, and are encouraged to design field experiments and use herbarium or historical data in their project.

Stream food webs, droughts, and hurricanes

Dr. Pablo E. Gutiérrez-Fonseca from the University of Vermont is a field ecologist broadly interested in evaluating how freshwater ecosystems respond and are transformed by climate change and human activities.  In the Luquillo mountains, Dr. Gutiérrez-Fonseca studies the effects of hurricanes and droughts on aquatic communities (e.g., fish, shrimp, macroinvertebrates, algae), food webs and aquatic-terrestrial linkages. The REU Student will lead a project on the effects of increasing solar radiation on primary producers, and how energy flows towards the upper trophic level.  Light is expected to increase due to hurricane driven defoliation of the forest canopy. The student will develop an experiment to simulate pre- or post-hurricane conditions and will measure hurricane responses through changes in the growth rate of aquatic organisms, chlorophyll-a, and benthic organic matter.  Analysis of data in R, development of proposals and final articles, as well as presentations in symposiums and meetings after the REU program, are expected and highly encouraged.