Michael Martínez-Colón Puerto Rico Sea Grant Program- Final Report (Grant no. R-21-1-08)
July 28, 2011
A. Executive Summary Title: Benthic Foraminifera as Bio-indicators of Heavy Metal Pollution: Torrecilla Lagoon (San Juan Bay Estuary), Puerto Rico. Date: 7/28/2011 Project Number: R-21-1-08 Investigators and Affiliation: Michael Martínez-Colon and Pamela Hallock-Muller College of Marine Science- University of South Florida
Dates Covered:
2/1/08 – 1/31/11
Summary of Impacts: Objectives1. Determine the distribution and bio-availability of metals at Torrecilla Lagoon. Objective partially achieved. Sample analysis is still in progress. 2. Determine the effects of metals on the spatial/temporal distribution of foraminifers at Torrecilla Lagoon. Objective partially achieved. (1) Core sediment samples could not be dated because of the high organic matter content and possible bioturbation (anthropogenic). Vertical variations in metals concentrations are evident. (2) Spatial temporal distribution of key metals has been determined for season one samples; analysis of season two samples is still in progress. 3. Determine specific morphological deformities in Ammonia spp. that are induced by bio-available metals in controlled culture experiments. Objective achieved. Three experiments were conducted at different copper concentrations (0.10, 0.20, and 0.30 micromol). Experiments show a change in morphology towards a more pronounced trochospiral shape in 10% of specimens. This is considered a deformity under these concentrations. 4. Develop a cost-effective pollution indicator, which will lay groundwork for utilization of foraminiferal assemblage and deformity assessment in future long-term environmental monitoring programs in Puerto Rico and other tropical coastal environments. Objective not achieved. This objective will be addressed once Objective 2 is finalized. Advancement of the fieldTorrecilla Lagoon (TL) is a moderately-polluted estuary on the northern coast of Puerto Rico. Foraminiferal assemblages (Ammonia spp. and Quinqueloculina rhodiensis) from 30 cm cores contain a relatively high occurrence of deformed tests, especially among the miliolids, while rotaliids show fewer deformities. Preliminary results for potentially toxic element analysis from bulk sediment samples show concentrations below toxicity levels except for copper. Copper concentrations (50-138 ppm) fall between the Effect Range Low and Effect Range Median values, representing possible to occasional detrimental effects to the aquatic environment. The distribution of foraminifers and abundance of Ammonia spp. appear to be related to hypoxiic events coupled with pH and salinity variability. Ammonia-Elphidium index values, a previously established indicator of hypoxia, are 83-97, indicating common stress from hypoxia. Diversity indices indicate temporal variability in abundance and distribution of foraminifers. Foraminiferal assemblages, coupled with diversity and hypoxia indices, as well as organic matter concentrations indicate 1