Characterization of Photosynthetic Pigments by Leaf Age in Different Functional Groups in a Coastal Urban Wetland: Cienaga Las Cucharillas, Cataño, Puerto Rico

Undergraduate #272
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Ecology
Session: 1
Room: Exhibit Hall A

Georgianna E. Carmona Monge - University of Puerto Rico Rio Piedras Campus
Co-Author(s): Elix Hernandez, Environmental Sciences Department, University of Puerto Rico ; Elvira Cuevas, Department of Biology, Center for Applied Science and Conservation, University of Puerto Rico Rio Piedras, PR

Chlorophyll is a pigment that is present in terrestrial plants and its function is to absorb light which provides energy that is used in the processes of photosynthesis and chemical energy. Presence of heavy metals, such as lead, cadmium and arsenic, can affect the molecular and physiological processes of plants, therefore it can affect the concentration of chlorophyll in the plant and the production of photosynthesis. We wanted to determine how functional groups differ in their responses to anthropogenic heavy metal pollution based on their chlorophyll pigment concentration. To carry out this study, we chose four sites where high levels of Cd, Pb and As were reported in previous studies at the Cienaga las Cucharillas (18 26’25.27” N, 66 08’08.39” W), an urban coastal palustrine/estuarine wetland located in the western side of the San Juan Bay in the northern metropolitan area of Puerto Rico. At each site, two different species from different functional groups (trees, grasses, shrubs and ferns) were identified and selected for the study, for a total of eight species studied. Leaves of different maturity (young, adult and mature), under full sun exposure were collected from each species. Chlorophyll was extracted with 95% ethanol for two hours and read using a spectrophotometer using the formulas developed by Lichtentaler. Total chlorophyll concentrations were highest in adult leaves of Acrostichum aureum (2.369 mg/mL) and Dalbergia ecastaphyllum (4.184 mg/mL). We observed that for all the functional groups, the highest concentrations of pigments are concentrated in adult leaves, followed by young and then mature groups which contain the least amount of chlorophyll. Ongoing and future studies are focused on assessing temporal variation in chlorophyll and plant function.

Funder Acknowledgement(s): NSF- CREST Center of Innovation, Research and Education in Environmental Nanotechnology Grant Number HRD-1736093.

Faculty Advisor: Elvira Cuevas, epcuevas@gmail.com

Role: Plant collection on Cienaga las Cucharillas Chlorophyll extraction with 95% ethanol. Readings using a spectrophotometer using the formulas developed by Lichtentaler. Literature Review Result Analysis and conclusions (graphs)