Are Fragrance Encapsulates Taken Up by Aquatic and Terrestrial Invertebrate Species?

The uptake potential of fragrance encapsulates by aquatic or terrestrial organisms was investigated. Because of their size of <5 mm and their polymeric nature, fragrance encapsulates fall under the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection definition of microplastics. After use, fragrance encapsulates enter the sewer system and reach the sewage treatment plant (STP), where >90% of them are likely to be removed by sorption to the sludge. When the STP-generated sludge is used as fertilizer for agricultural soils, this may lead to potential exposure of terrestrial invertebrates to fragrance encapsulates, especially those feeding on particles of a similar size as the fragrance encapsulates. Two aquatic (Corbicula fluminea [water exposure] and Hyalella azteca [water and dietary exposure]) and one terrestrial invertebrate (Eisenia andrei [soil exposure]) species were exposed to 50 mg/L (or mg/kg) double fluorescence-labeled fragrance encapsulates (diameter 5-50 µm). The results showed that fragrance encapsulates are available to aquatic and terrestrial invertebrates but that species-specific differences regarding the ability to ingest fragrance encapsulates may exist. The benthic grazer H. azteca showed no ingestion of fragrance encapsulates, whereas the capsules were readily ingested and egested by the unselective freshwater filter feeder C. fluminea as well as the terrestrial decomposer E. andrei. No signs of bioaccumulation of fragrance encapsulates were indicated by microscopic assessment. Environ Toxicol Chem 2022;41:931-943. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Testing the bioaccumulation potential of manufactured nanomaterials in the freshwater amphipod Hyalella azteca.

Standardized experimental approaches for the quantification of the bioaccumulation potential of nanomaterials in general and in (benthic) invertebrates in particular are currently lacking. We examined the suitability of the benthic freshwater amphipod Hyalella azteca for the examination of the bioaccumulation potential of nanomaterials. A flow-through test system that allows the generation of bioconcentration and biomagnification factors was applied. The feasibility of the system was confirmed in a 2-lab comparison study. By carrying out bioconcentration and biomagnification studies with gold, titanium dioxide and silver nanoparticles as well as dissolved silver (AgNO3) we were able to assess the bioaccumulation potential of different types of nanomaterials and their exposure pathways. For this, the animals were examined for their total metal body burden using inductively coupled mass spectroscopy (ICP-MS) and for the presence of nanoparticulate burdens using single-particle ICP-MS. The role of released ions was highlighted as being very important for the bioavailability and bioaccumulation of metals from nanoparticles for both examined uptake paths examined (bioconcentration and biomagnification). In 2018 a tiered testing strategy for engineered nanomaterials was proposed by Handy et al. that may allow a waiver of bioaccumulation fish studies using inter alia invertebrates. Data gained in studies carried out with invertebrates like the developed Hyalella azteca test may be included in this proposed tiered testing strategy.

Development of a low-cost technology for mass production of the free-living nematode Panagrellus redivivus as an alternative live food for first feeding fish larvae.

The free-living nematode Panagrellus redivivus is a suitable food source for first feeding fish. In the present report, a new method for the mass production of P. redivivus is presented. The technique involves multiplication of the nematode in monoxenic (single microorganism: Saccharomyces cerevisiae) solid culture (fluid media supported by 1- to 4-cm(3) sponge cubes) in autoclavable plastic bags (size range: 50 x 30 cm to 75 x 67 cm). Two growing media were tested: oat-meal medium (OM), which is an oat-based medium (16.7% oat-meal flour in 0.8% saline solution), and purified ingredient medium (PIM), a semi-synthetic medium (1.64% meat peptone, 0.94% yeast extract, 12.6% corn starch, 0.24% glucose, 1.48% sunflower oil, in 0.8% saline solution). The bags were inoculated with 350 nematodes/g medium. After an average period of 12 days (11-13 days) at 25 degrees C, the average yield (number of nematodes/g medium) was 241 x 10(3) for OM and 333 x 10(3) for PIM in 12-l bags (50 x 30 cm). The production scale has currently reached a bag volume of 50 l (75 x 67 cm); using PIM and the conditions described above, it was possible to harvest more than 1.3 x 10(9) nematodes/bag (291 x 10(3) nematodes/g medium). In PIM, when sun flower oil was replaced with the same amount of fish oil or cod liver oil, yields of 259 x 10(3) and 290 x 10(3) nematodes/g medium, respectively, were attained. The technology for mass production and formulation of P. redivivus should enable fish-hatchery operators to rely on a cheap, standardised, and permanently available live food product for first feeding fish larvae.