Monitoring of Irgarol 1051 concentrations with concurrent phytoplankton evaluations in East Coast areas of the United States Lenwood W. Hall Jr. a, * , William D. Killen a , Ronald D. Anderson a , Piero R. Gardinali b , R. Balcomb c a University of Maryland, Maryland Agricultural Experiment Station, Wye Research and Education Center, P.O. Box 169, Queenstown, Maryland 21658, USA b Southeast Environmental Research Center, Department of Chemistry, Florida International University, University Park Campus, Miami, Florida 33199, USA c Ciba Specialty Chemicals Corporation, Expert Services Group, 540 White Plains Rd., Tarrytown, New York 10591, USA Abstract The objectives of this study were to measure: (1) Irgarol and GS26575 (major metabolite) during the peak 2004 boating season at selected marinas and reference areas in the Carolinian Zoogeographic Province of the Eastern United States; (2) Irgarol and GS26575 at selected stations during the summer months in the Back Creek/Severn River area in Maryland in 2003 and 2004; and (3) structural and functional characteristics of resident phytoplankton communities concurrently with Irgarol and GS26575 monitoring in Back Creek/Severn River area. Irgarol concentrations from 14 marinas in the Carolinian Province ranged from non-detectable (<1 ng/L) to 85 ng/L; concentrations were less than 16 ng/L at all reference sites. The probability of exceeding the plant 10th centile for Irgarol (251 ng/L) was less than 0.6% for all marinas and 0.01% for all reference areas. These data suggest low ecological risk from Irgarol exposure for both marina and reference areas in the Carolinian Province. Irgarol concentrations ranged from 5 ng/L at the Severn River reference site to 1,816 ng/L in Port Annapolis marina during the two year study. Ecological risk from Irgarol exposure was high for the Port Annapolis marina sites based on a probability of exceeding the plant 10th centile. However, risk was low for Severn River and Severn River reference sites. Functional and structural measures of resident phyto- plankton communities in the Back Creek and Severn River did not suggest that these target species are impaired in the Port Annap- olis marina area where probabilistic analysis predicted adverse effects from Irgarol exposure. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Irgarol 1051; Antifouling paint; Chesapeake Bay; Carolinian Province; Marinas; Phytoplankton 1. Introduction The growth of marine organisms on boat hulls (foul- ing) is a marinerÕs curse. Fouling of ship and boat hulls results in increased hydrodynamic drag leading to loss of speed and decreased fuel efficiency (Callow, 1986). Fuel efficiency decreases as fouling progresses thus increasing pollution by burned fuels. Controlling fouling on boat hulls is a longstanding problem that has serious economic and environmental consequences. Antifouling paints—paints containing substances that control the settlement and growth of target organisms on submerged surfaces—are commonly used. Commercial and recrea- tional vessels of all sizes use antifouling paint to control the growth of an estimated 4,000 to 5,000 fouling plant and animal species (Evan and Smith, 1975). 0025-326X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2005.02.025 * Corresponding author. Tel.: +410 827 8056; fax: +410 827 9039. E-mail address: lh43@umail.umd.edu (L.W. Hall Jr.). www.elsevier.com/locate/marpolbul Marine Pollution Bulletin 50 (2005) 668–681