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Ecotoxicological information

Toxicity to other aquatic organisms

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Administrative data

Endpoint:
toxicity to other aquatic vertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable study which meets basic scientific principles
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Inhibition of carbon fixation as a function of zinc uptake in natural phytoplankton assemblages.
Author:
Davies AG & Sleep JA
Year:
1979
Bibliographic source:
J. mar. biol. Ass. U.K. 59: 937-949

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Photosynthetic inhibition (C fixation) test on phytoplancton communities in the field, designed for dose-response
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
The tests with zinc (plus 65Zn as a radioactive tracer) were carried out in natural sea water from Plymouth . The zinc background concentration in seawater was 0.4, 0.8 and 7.6 µg l-1 in the three samples

Test organisms

Test organisms (species):
other: multispecies test
Details on test organisms:
A series of three samples of varying biological composition were taken (100% diatoms - predominant species Rhizosolenia alata; 60% dinoflagellates/40% diatoms – predominant species Scrippsiella aff. trochoidea and R. stolterfothii; and 60% diatoms/40% dinoflagellates – predominant species as previous sample)

Study design

Test type:
static
Water media type:
saltwater
Limit test:
no

Test conditions

Test temperature:
14°C
Salinity:
35 ppt
Nominal and measured concentrations:
Nominal Zinc concentrations: 6 concentrations tested, 3 replicates / treatment

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
18 h
Dose descriptor:
NOEC
Effect conc.:
>= 7 - <= 13 µg/L
Nominal / measured:
estimated
Conc. based on:
dissolved
Basis for effect:
other: C fixation rate
Remarks on result:
other: estimated from graph
Key result
Duration:
18 h
Dose descriptor:
LOEC
Effect conc.:
>= 10 - <= 15 µg/L
Nominal / measured:
nominal
Conc. based on:
dissolved
Basis for effect:
other: C fixation rate
Details on results:
The lowest concentrations of zinc which caused detectable inhibition of carbon fixation ( i.e. rates lower than 90% of the mean control values) were reported as being in the range of 10 to 15 µg l-1. From the dose-response curves presented in the paper, estimated EC10 levels were in the range of 7 to 13 µg l-1.
Test details: only fixation rates lower than 90% of the mean control value can be ascribed to zinc inhibition
Dose-response: yes
Control data: graphed
Reported statistics and error estimates:
no statistics reported

Any other information on results incl. tables

no remark

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Relevant field study useful to check the protection level provided by the HC5 following from statistical extrapolation of single species tests data.
Executive summary:

Davies and Sleep (1979) studied the effect of zinc on carbon fixation rates of natural phytoplankton communities present in the English channel. A series of three samples of varying biological composition were taken in July 1978, at approximately weekly intervals, at the same location. The tests with zinc (plus65Zn as a radioactive tracer) were carried out in natural sea water. The zinc background concentration in seawater was 0.4, 0.8 and 7.6 µg l-1in the three samples. The lowest concentrations of zinc which caused detectable inhibition of carbon fixation ( i.e. rates lower than 90% of the mean control values) were reported as being in the range of 10 to 15 µg l-1. From the dose-response curves presented in the paper, estimated EC10 levels were in the range of 7 to 13 µg l-1.