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Environment International 31 (2005) 615 – 620 www.elsevier.com/locate/envint

Daphnia emergence: a sensitive indicator of fire-retardant stress in temporary wetlands
David G. Angeler*, Silvia Martın, Jose M. Moreno ´ ´
University of Castilla—La Mancha, Department of Environmental Sciences, Avda. Carlos III s/n, E-45071 Toledo, Spain Received 9 September 2004; accepted 15 October 2004Available online 14 November 2004

Abstract Fire-retardant formulations are increasingly used by fire managers to control wildland fires. Their extensive use requires an assessment of their impacts in those ecosystems that could be affected by them. Recent studies indicate the potential for environmental impacts when accidentally delivered to surface waters. Yet the response of temporary wetlands, suchas vernal pools, typical in Mediterranean areas, is unknown. This study reports on the emergence response of a wetland population of Daphnia curvirostris Eylmann (Cladocera, Crustacea) from sediments that were treated with a commercial fire retardant (Fire-TrolR 934). Three application levels were used: 1, 3 and 5 L mÀ2. The low and medium levels are in the range of manufacturer’s recommendationsof use in the field based on the fuel characteristics. The high level simulates local elevated concentrations that may result from inhomogeneous retardant delivery. Results indicate that emergence success decreases with increasing application rate, leading to a complete failure with application levels of 5 L mÀ2. This suggests that benthic–pelagic interactions in temporary wetlands—often theprimary way by which recolonization of isolated wetlands occurs—can be significantly impacted by fire retardants once they fill with fall/winter rains, thereby serving as a sensitive indicator of fire-retardant contamination. Results highlight a research need for establishing of criteria for effective, but environmentally safe use of fire retardants in the environment. D 2004 Elsevier Ltd. All rightsreserved.
Keywords: Environmental impact; Fire retardants; Fire-TrolR 934; Temporary wetlands; Mediterranean areas; Daphnia curvirostris, ephippia hatching

1. Introduction Two types of chemical products are in use for controlling wildland fires in nature. The first are suppressant foam formulations that have a relative short-term effectiveness and which are typically used to extinguishspreading fires. The second are retardant solutions, which remain effective even after the evaporation of the water carrier (McDonald et al., 1997), and are used either to control spreading fires or to prevent areas of high socioeconomic interest and/or wilderness value from fire outbreaks. Retardant composition when used in the environment is about 85% water, 10% fertilizers and 5% other ingredients,such as color additives, gum or clay thickeners, corrosion

* Corresponding author. Tel.: +34 925 26 8800; fax: +34 925 26 8840. E-mail address: david.angeler@uclm.es (D.G. Angeler). 0160-4120/$ - see front matter D 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.envint.2004.10.015

inhibitors and bactericides (Pyne et al., 1996). Application in nature is done either by ground or aerialmeans. Especially when dropped from airplanes, erratic atmospheric conditions (wind), and/or reduced visibility due to smoke may cause accidental delivery of the retardant to permanent or temporary aquatic ecosystems. Several studies have documented massive fish kills in streams that were contaminated with fire retardants (summarized in Boulton et al., 2003). Recent laboratory trials using algae andzooplankton (McDonald et al., 1995), amphipods (McDonald et al., 1997) and fish larvae (Buhl and Hamilton, 1998, 2000; Gaikowsky et al., 1996a,b) support the idea of retardant toxicity in surface waters (reviewed in Gimenez ´ et al., 2004). Studies of the effects of fire retardants in temporary wetlands located in a matrix of vegetation subject to fire are lacking. These types of wetlands, such...