Issuu

Proof only

Preliminary Survey on Foraminiferal Responses to Pollutants in Torrecillas Lagoon Puerto Rico Michael Martínez-Colón1 and Pamela Hallock

College of Marine Science-University of South Florida 140 7th Ave. S, St. Petersburg, FL 33701 † foram3438@yahoo.com ABSTRACT.—Torrecilla Lagoon, part of the San Juan Bay Estuary system, is a moderately-polluted estuary on the northern coast of Puerto Rico. Foraminiferal assemblages from two 30 cm cores were dominated by Ammonia spp. and Quinqueloculina rhodiensis. The latter taxon exhibits a relatively high occurrence of deformed tests (up to 18%). Analyses for potentially toxic-element in bulk sediment samples of one core show concentrations below recognized toxicity levels except for copper. Copper concentrations (50-138 ppm) fall between previously established Effect Range Low and Effect Range Median values, representing potential for occasional detrimental effects to the aquatic environment. Organic matter content (loss-on-ignition) ranging from 10-23%, coupled with the presence of framboidal pyrite, indicate low oxygen conditions. Ammonia spp. showed no significant variation in size with depth in core. Ammonia-Elphidium index values, a previously established indicator of hypoxia, are 69-100, reflecting relative few Elphidium. Species diversity indices indicate temporal variability in abundance and distribution of foraminifers. Foraminiferal assemblages and organic matter in sediments indicate that Torrecilla Lagoon has undergone episodes of hypoxia. KEYwORDS.—Pollution, Foraminifera, Potentially Toxic Elements, Estuary, Eutrophication, Puerto Rico

Environmental studies have characterized and quantified anthropogenic sources of pollution (i.e., sewage discharge, boat marinas, hydroelectric plants, etc.) entering the San Juan Bay Estuary (SJBE) system in northern Puerto Rico, and, to a lesser degree, on its sub-systems (e.g., Torrecilla Lagoon). These studies have found that the bay contains elevated concentrations of Potentially Toxic Elements (PTEs) (As, Cd, Hg, Ni, Th, and Zn) in the sediments; high, oxygendepleting nutrient loads; low dissolved oxygen (DO) levels; pathogens; and high sedimentation rates; all of which have been classified as major environmental threats to the SJBE (Ellis 1976; Marsh 1992; Hunter & Arbona 1995). Torrecilla Lagoon (TL) sediments have been found to be contaminated with As (17 μg/g), Hg (0.05 μg/g), and Pb (20 μg/g) (Webb et al. 1998). Benthic foraminifers can be useful bioindicators for PTE pollution (e.g., Alve, 1995; Nigam et al. 2006). In polluted areas, foraminifers can display not only a wide variety of morphological deformities but also changes in assemblage makeup and species abundance (Schafer 2000; du Chatelet

et al. 2004). However, no direct relationship has been established between either natural stressors (i.e., salinity) or anthropogenic stressors (i.e., PTEs, pesticides), and tests deformities or community structure (e.g., Alve 1995; Debenay et al. 2001). Benthic foraminifers are potentially sensitive to PTE exposure due to their high surface-tovolume ratios and relationship with sediments and pore waters. Seiglie (1968, 1975) investigated the impacts of eutrophication (from sewage disposal and leakage) and temperature changes (by hydrothermal plants) on benthic foraminiferal assemblages along southwest and northern coastlines of Puerto Rico. Seiglie (1975) concluded that Ammonia catesbyana (= becarii) forma tepida (Cushman) dominated areas of sewage discharge and noted abnormal morphologies of Quinqueloculina rhodiensis (Parker) influenced by eutrophication and thermal pollution (deformed chambers). This study examines two short sediment cores from TL, Puerto Rico, with the goal of assessing foraminiferal assemblages and determining relative influences of

Proof only 1