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Ecotoxicological information

Additional ecotoxological information

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Administrative data

additional ecotoxicological information
Type of information:
experimental study
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Published, investigative non-guideline, non-GLP study.
Reason / purpose for cross-reference:
reference to same study

Data source

Referenceopen allclose all

Reference Type:
Increase in the abundance of cladocera at pH 5.1 in experimentally-acidified Lake 223, Experimental Lakes Area, Ontario
Malley, DF & Chang, PSS
Bibliographic source:
Water, Air, and Soil Pollution 30 (1986) 629-638
Reference Type:
secondary source
SULFURIC ACID CAS No. 7664-93-9: SIDS Initial Assessment Report for 11th SIAM
Bibliographic source:
UNEP Publications

Materials and methods

Test guideline
no guideline available
Principles of method if other than guideline:
The pH of Lake 223, Ontario, Canada, was lowered from 6.7 in 1974 to 5.1 by 1981. Samples of cladocera were taken each year and the species composition and overall biomass were monitored.
GLP compliance:
Type of study / information:
Published paper describing experimentally derived results.

Test material

Constituent 1
Chemical structure
Reference substance name:
Sulphuric acid
EC Number:
EC Name:
Sulphuric acid
Cas Number:
Molecular formula:
sulfuric acid
Details on test material:
None available

Results and discussion

Any other information on results incl. tables

Total zooplankton biomass was not reduced by acidification and may have increased in 1980. Prior to acidification, mean ice-free season biomass was 269 mg/m2, during 1977 to 1980 it was 318, 218, 204 and 401 mg/m2 respectively. During 1981 to 1984 biomass was 279, 236 and 247 mg/m2. Although total biomass did not greatly change with acidification, total biomass of cladocerans increased during1918 to 1983. This occurred at the expense of calanoid copepods and to a lesser extent cyclopoid copepods. In 1974 adults of D. minutus were present at a biomass of 33 mg/m2. During 1981 to 1983 their biomass was 26, 17 and 24 mg/m2. Cladocerans also exhibited marked changes in species composition. The community in 1974 at pH 6.7 was dominated by Daphnia galeata mendotae with Diaphanosoma birgei and Bosmina longirostris also present, Holopedium gibberum was rare. At pH 5.1 Daphnia catawba, H. gibberum and B. longirostris were all abundant. D. birgei and D. g. mendotaehad dissappeared or become rare. D. catawba recorded for the first time in 1980 was usually the sole daphnid at pH 5.1, it replaced D. g.mendotaealmost entirely during the 1918 to 1983 period. Chaoborus has been incidentally samples along with the zooplankton, there is no evidence it changed markedly in abundance with acidification.

Applicant's summary and conclusion

The reported study is adequate in demonstrating the effects of lowering pH on the compostion and structure on cladocera.
Executive summary:

The zooplankton community was analysed by identifying the species and counting them. A NOEC for population repartition (from copepod to cladoceran dominance) was pH 5.59 (equivalent to 0.13 mg/L). This NOEC integrates not only reproductive success, but also prey/predator relationships, (presence/lack of suitable food as smaller invertebrates or aquatic plants/algae, presence/lack of fish predators). The NOEC also integrates the effects of successive one-tear exposures to pH 6.49, 6.13, 5.93 and 5.64.