Species Sensitivity Distributions (SSD) with invertebrates

Species Sensitivity Distributions (SSDs) are used in ecological risk assessment to represent the sensitivity of different species to particular chemicals. Toxicity data (LCx, ECx, NOEC/LOEC) of several species are collected and displayed on a distribution curve in order to demonstrate the variability of the sensitivities of different species. One of the aims of the SSDs is to determine the HC5 value (Hazard Concentration for 5% of species) - i.e. the concentration at which only 5% of the species are negatively affected.

Aquatic invertebrates have a central role in SSDs, as they often react sensitively to chemicals released in the environment and at the same time fulfil ecologically important functions. SSDs with aquatic freshwater invertebrates are therefore a valuable tool for assessing environmental risks from chemicals.

Advantages of SSDs with invertebrates:

• High ecological relevance due to inclusion of different species
• Consideration of interspecific sensitivity differences
• Possibility to derive regulatory endpoints on a well-founded statistical basis

The challenge often involves the availability of comparable, good quality toxicity data. Especially for the risk assessment it is important to not just introduce commonly used standard test organisms but also test organisms which are considered more sensitive and which are more likely to be exposed to the substances released into the environment. This includes for example test organisms of the EPT-taxa (Ephemeroptera, Plecoptera, Tricoptera).

At Fraunhofer IME, we offer a selection of acute and chronic test systems with aquatic invertebrates from lentic and lotic habitats and are therefore able to collect and evaluate corresponding toxicity data in-house. Depending on the requirements we are able to perform tests with various test organisms from our own lab cultures or from the field. With our expertise, we are able to adapt different test organisms from the field to laboratory conditions and finally conduct tests under laboratory conditions indoor but also outdoor (e.g. in a microcosm design). The use of field collected test organisms enables us to determine the sensitivities of species less easily and less frequently tested. While most of the laboratory tests are conducted with freshwater organisms originating from lentic habitats we are also able to perform laboratory testing with test organisms from lotic habitats under stream conditions (for further information see also:  Chronic Testing of Lotic Invertebrate Species). Besides the commonly applied endpoints (i.e. Immobilisation, Reproduction, Length, Emergence (depending on test organism and test design)), we are able to investigate additional endpoints, e.g. measurements of head capsule, determination of development stage of larvae or changes in behavior and appearance.

At our facility, we have the possibility to carry out the accompanying chemical analysis for the ecotoxicological studies in-house. In addition, we are able to conduct the performed studies under non-GLP and GLP conditions.

The following test organisms can be tested at our facility (please see pdf for further information on respective test designs and test systems). The used test systems are usually water-only exposure systems. However, we also offer a various number of laboratory tests in water-sediment systems and/or with peak exposure patterns.

Crustacea

• Cladocera (Daphnia magna, Daphina longispina, Daphnia pulex, Chydorus sphaericus, Ceriodaphnia dubia)
• Amphipoda (Hyalella azteca, Gammarus pulex)
• Isopoda (Asellus aquaticus)
• Anostraca (Thamnocephalus platyurus)

Gastropoda

• Lymnaea stagnalis
• Potamopyrgus antipodarum

Insecta

• Diptera (Chironomus riprarius, Chaoborus crystallinus, Culex pipiens)
• Ephemeroptera (Cloeon dipterum, Baetis sp., Ecdyonurus sp., Epeorus sp.)
• Plecoptera (Protonemura sp.)
• Trichoptera (Hydropsyche sp., Sericostoma sp.)
• Hemiptera (Notonecta sp.)

Rotifera

• Brachionus calyciflorus