Risk of Ammonia Toxicity During Sediment Bioassays With the Estuarine Amphipod Leptocheirus Plumulosus

Abstract

Abstract-High levels of ammonia in sediment toxicity tests can potentially confound test results. At issue is whether the observed toxicity is due to elevated ammonia or the presence of more persistent anthropogenic contaminants. To evaluate the risk of ammonia toxicity, information on (1) the exposure-response relationship and (2) the probability of exposure are needed. Preliminary exposureresponse data were obtained for two different sieved size classes of the estuarine amphipod Leptocheirus plumulosus representing juveniles (425-600 m) and subadults (not reproductively active) (600-1,000 m) in 4-d water-only exposures with ammonia (NH 4 Cl). Resulting LC50 values were 44 (juvenile) and 89 mg NH 3 -N/L (subadult). Results from 4-d tests were used to establish exposure concentrations for two spiked-sediment studies: (1) a 10-d static exposure starting with subadults measuring survival and growth and (2) a 28-d exposure with daily renewal of overlying water starting with juveniles and measuring survival, growth, and reproduction. Risk of ammonia toxicity to L. plumulosus during sediment toxicity tests was characterized via a Monte Carlo simulation using the exposure-response curves from laboratory spiked-sediment studies and published porewater ammonia values for 322 marine sediments. Results indicate a significant potential for ammonia induced interference in the 10-d test (e.g., 2-18% probability of significant mortality due to ammonia alone). Risk in 28-d tests appears to be minimal due to rapid dissipation of ammonia via renewal of overlying water.

Responses of Estuarine Benthic Invertebrates to Sediment Burial: The Importance of Mobility and Adaptation

“…The water replacements were performed to reduce build-up of NH 4 + concentrations in the containers. In preliminary trials with Macoma balthica, Streblospio benedicti and Leptocheirus plumulosus, we determined that the NH 4 + concentrations in our experiments were well below levels considered harmful to L. plumulosus (Moore et al, 1997). Comparable NH 4 + tolerance data for M. balthica and S. benedicti are not available.…”

Physiological responses and scope for growth of <i>Ruditapes decussatus</i> from Ria Formosa, southern Portugal, exposed to increased ambient ammonia

“…Huber et al (1997), working with M. lateralis, and Moore et al (1997), using the amphipod Leptocheirus plumulosus in sediment toxicity testing, reported no observed effects on growth at TA-N concentrations of <100 mmol l -1 and 0.7 mmol l -1 respectively. Our results, however, show that the short time exposure (~3 h during the physiological measurements) of R. decussatus to much lower concentrations of TA-N (48 µmol l -1 or 1.1 µmol l -1 NH 3 ) resulted in physiological stress.…”

“…The development of sediment toxicity tests with amphipods (Kohn et al, 1994, Moore et al, 1997 and the bivalve Mulinia lateralis (Huber at al., 1997) using mortality and growth as endpoints have provided information on tolerance to ammonia, but none has examined the effects of ambient ammonia on the physiological responses that can lead to decreased performance and ultimately death.…”

Current approaches and future directions for contaminant-related impact assessments in coastal environments: Brazilian perspective

“…Redmond et al, 1996), ammonia (e.g. Carr et al, 1996b;Moore et al, 1997), sulfides (e.g. Thompson et al, 1991;Knezovich et al, 1996), particle size distribution (e.g.…”