Development of a chronic sublethal sediment bioassay using the estuarine amphipod Leptocheirus plumulosus (Shoemaker)

Abstract

Based on the need for a test to evaluate chronic sublethal toxicity in estuarine sediments, a 28‐d sediment bioassay with the estuarine amphipod Leptocheirus plumulosus (Shoemaker) was developed. The test was initiated with animals less than 2 weeks old (i.e., 425–600 μm sieved size class). Test endpoints included survival, growth (μg dry weight/d), and reproduction (number of neonates/surviving female). Factors with the potential to influence test animal performance (i.e., nontreatment factors) such as artificial sea salts, salinity, food ration, size at test initiation, intraspecific density, sediment grain size, and diet were evaluated. For example, intraspecific densities between 10 and 60 animals/beaker (i.e., 0.18–1.4 animals/cm2) did not affect survival, growth, or reproduction. Similarly, L. plumulosus were tolerant of a wide range of sediment grain sizes with only extremely fine grained (e.g., >75% clay) or coarse grained (e.g., >75% sand) material significantly affecting survival, growth, and reproduction. Test performance criteria included control survival (>80%) and reproduction (production of offspring in all control replicates), and response to a reference toxicant test with cadmium chloride in a control chart format.

Sediment Toxicity Testing with the Amphipod <i>Grandidierella Japonica</i> and Effects of Sediment Particle Size Distribution

“…The adverse effects of fine and coarse particles in sediment have also been reported for other amphipod species such as L. plumulosus [45], M. plumulosa [46], and Tiburonella viscana [47]. Although the underlying mechanisms are still unclear, the reduced growth in coarse sediment may be attributed to high energy consumption needed to manipulate large particles [45].…”