Elemental Composition of Liver and Kidney Tissues of Rough-Toothed Dolphins (Steno bredanensis) E. A. Mackey, 1 R. D. Oflaz, 1 M. S. Epstein, 1 B. Buehler, 1 B. J. Porter, 1 T. Rowles, 1,2 S. A. Wise, 1 P. R. Becker 3 1 National Institute of Standards and Technology, Mailstop 8395 Gaithersburg, Maryland 20899, USA 2 National Oceanic and Atmospheric Administration, Office of Protected Resources, Eastwest Hwy., Silver Spring, Maryland 20910, USA 3 National Institute of Standards and Technology, 219 Fort Johnson Rd., Charleston, South Carolina 29412, USA Received: 17 July 2002 /Accepted: 11 November 2002 Abstract On December 14, 1997, 62 rough-toothed dolphins (Steno bredanensis) stranded on Cape San Blas, on the Florida coast of the Gulf of Mexico. Approximately 30 animals died either on the beach or in rehabilitation facilities. Two were successfully rehabilitated and released. Liver, kidney, blubber, and muscle tissues were collected from 15 animals that died on the beach. Portions of the liver and kidney from each dolphin were analyzed using instrumental neutron activation analysis and inductively coupled plasma mass spectrometry to deter- mine mass fractions of 37 elements. Levels of several electro- lytes (Na, Cl, K, Br, Rb, I, Cs) and of the essential trace elements Fe, Cu, and Zn in both tissues were similar to those found in other Odontoceti. Mass fractions of Ca ranged from 60 mg/kg to 1,200 mg/kg (wet mass basis), indicating signifi- cant inhomogeneity in the kidney tissues of several animals. Necropsy reports noted that the kidneys of many of these animals contained fibrous nodules. The measured Ca inhomo- geneity may be due to mineralization of the fibrous kidney tissue. Hepatic levels of Hg and Se were at the high end of the ranges generally found in livers of other Odontoceti and were slightly higher in animals with fibrous kidneys than in the others. Mass fractions of Se, Ag, and Hg in liver tissues increased with the size and age of the animals indicating accumulation of these elements in the liver with age. Results also indicate that Se and Hg accumulate in rough-toothed dolphin kidney. Accumulation of these elements with age has been reported commonly for marine mammals and other spe- cies. Rough-toothed dolphins are widely distributed pelagic marine mammals of the class Cetacea, suborder Odontoceti, family Delphinidae, and subfamily Steninae. These dolphins range in length from approximately 1 m for neonates to 2.8 m for adult males, are dark gray to light brown in color, and often have long white scratches and scars. Rough-toothed dolphins feed primarily on fish (Steiner 1995) and squid (Baker 1987; Santos and Haimovici 1998) in offshore deep waters. They are found in temperate and tropical waters in various locations around the world, including the Pacific Ocean (Van Waerebeek and Guerra 1988; Wahlen et al. 1985); the Gulf of Mexico (Davis et al. 1998; Delgado 1994); the Gulf of California (Heyning 1986); the Caribbean Sea (Perkins and Miller 1983); the Med- iterranean Sea (Watkins et al. 1987); and the Atlantic Ocean near Brazil (Lodi 1992; Santos and Haimovici 1998; Ott and Danilewicz 1996), near the Azores (Steiner 1995), near South Africa (Ross et al. 1985), and near the Cape Verde islands (Hazevoet and Wenzel 2000). Baker (1987) noted that rough- toothed dolphins are also found in the Indian Ocean, Red Sea, and Bay of Bengal and that they travel in groups consisting of 10 to 20 animals. Groups consisting of as many as 50 to 60 dolphins also have been reported (Poss 1998; Steiner 1995; Texas Cooperative Research Unit 1994). Rough-toothed dol- phins have been observed in the company of other Odontoceti such as bottle-nosed dolphins (Poss 1998) and spinner dolphins (Baker 1987). Rough-toothed dolphins strand less frequently than other marine mammal species. Geraci and Lounsbury (1993) re- ported that strandings of these dolphins occur only rarely, or every 1 to 5 years along temperate regions of the U.S. coast- line. There have been previous reports of one rough-toothed dolphin stranded with other ondontocetae on the Italian coast (Diguardo et al. 1995); a mass stranding on the Washington and Oregon coast, USA (Ferrero and Hodder 1994); a mass stranding in Belize (Perkins and Miller 1983); and a mass stranding (16 animals) on the Florida coast of the Gulf of Mexico in 1961 (Texas Cooperative Research Unit 1994). On December 14, 1997, 62 rough-toothed dolphins live- stranded on the Gulf Coast of Florida, at Cape San Blas, near Apalachicola (www.mote.org/terri/hh99.phtml). All animals were returned to the Gulf of Mexico, but approximately half of the animals stranded again later the same day. Attempts were made to rehabilitate 16 of these, and 2 were rehabilitated successfully at the Mote Marine Laboratory Mammal Center and released to the wild on March 25, 1998 (www.mote.org/ terri/dec161.htm). Of the remaining 15 animals that re- stranded, 12 died on the beach and an additional 3 that could Correspondence to: E. A. Mackey; email: mackey@nist.gov Arch. Environ. Contam. Toxicol. 44, 523–532 (2003) DOI: 10.1007/s00244-002-2039-9 ARCHIVES OF Environmental Contamination and T oxicology © 2003 Springer-Verlag New York Inc.