Foraging, feeding, and reproduction on silica substrate: Increased waterborne zinc toxicity to the estuarine epibenthic amphipod Melita plumulosa

Abstract

Artificial substrates consisting of fine milled silica with or without α-cellulose were evaluated for their capacity to support survival, growth, and fecundity in the amphipod Melita plumulosa. There were no significant differences in the survival and fecundity of adult amphipods maintained for up to 13 d on natural sediment, silica-only, or silica/α-cellulose substrate when fed two algal foods, Sera micron and Rotiselco-ALG. However, growth among juveniles maintained on the silica/α-cellulose mixture was significantly inhibited over 14 d compared with natural sediment. Addition of a microencapsulated shrimp feed, Frippak, to the algal foods improved juvenile growth over 28 d but still did not match the nutritive value of natural sediment. Fine silica without cellulose was subsequently used in acute and reproductive toxicity tests with waterborne zinc. With food, a 10-d median lethal concentration (LC50) of 140 µg Zn/L and a 10-d no-effect concentration (NEC) of 80 µg Zn/L were obtained for juvenile survival on silica. In contrast, a 10-d LC50 of 200 µg Zn/L and a 10-d NEC of 180 µg Zn/L were obtained for juveniles in water-only exposures. Similarly, exposure of adult females to Zn without food on silica compared with water-only exposures gave 10-d LC50s of 380 and 490 µg Zn/L and 10-d NECs of 130 and 370 µg Zn/L, respectively. The reproduction toxicity test indicated significant adult mortality at 92 µg Zn/L and significantly reduced fecundity at 22 µg Zn/L. We surmised that the toxicity of waterborne zinc to M. plumulosa increased when maintained on nutrient-depleted silica compared with water-only exposure because of increased energy expended through foraging, in concert with the likely increased exposure to Zn via the digestive tract and the gills.

Diffusive Gradients in Thin Films Technique Provide Robust Prediction of Metal Bioavailability and Toxicity in Estuarine Sediments

“…In these sediments, dissolved zinc concentrations in overlying waters (up to 75 ± 14 μg/L, Table S2 of the Supporting Information) indicated that dissolved zinc was likely affecting reproduction of M. plumulosa, as observed in previous studies. 45 However, the dissolved zinc concentrations were generally below those causing lethality (10-day LC 50 , lowest-observable-effect concentration (LOEC) and no-observable-effect concentration (NOEC) values are 220, 180, and 90 μg Zn/L for juveniles). 28 For this amphipod, dietary exposure to metals by ingestion of particles is an important exposure pathway, so it is likely that metal uptake from both overlying water and sediment was contributing to reproductive toxicity.…”

Review of the reproductive biology of amphipods and their endocrine regulation: Identification of mechanistic pathways for reproductive toxicants

“…Additional research is needed to identify a reproductionlinked biomarker in amphipods that may be applied in the field, because laboratory-based toxicity tests are not necessarily predictive of longer term ecological effects [20,21]. Forbes et al [22], in a study modeling effects of toxicants at the population level, demonstrated that impacts are likely equal to or less than effects on individual life-cycle traits, suggesting that risk assessments based on the latter are likely protective of population-level impacts.…”

Utilization of Marine Crustaceans as Study Models: A New Approach in Marine Ecotoxicology for European (REACH) Regulation

“…Amphipods are widely used in ecotoxicology, owing to their sensitivity to several contaminants such as metals (Zanders & Rojas, 1992;Liber et al, 2011;Mann et al, 2011;Strom et al, 2011), for the evaluation of sediments in marine and transition environments (Chapman & Wang, 2001) and have been employed to draw up sediment-quality guidelines (Macdonald et al, 2011). ASTM (1999) suggests for testing some amphipods species but unfortunately none of them occurs in the Mediterranean, making problematical their use for the laboratories of this region; on the whole, among the species considered in the guidelines the sole amphipod useful for the Mediterranean is Corophium orientale that is cited in the protocol ISO 16712 (2005).…”