New Zealand Journal of Marine and Freshwater Research abstracts
Upper thermal tolerances of twelve New Zealand stream invertebrate species
JOHN M. QUINN*
G. LAURA STEELE
CHRISTOPHER W. HICKEY
MAGGIE L. VICKERS
NIWA
National Institute of Water and Atmospheric
Research
P.O. Box 11-115
Hamilton, New Zealand
Abstract The upper thermal tolerances of 12 New Zealand
freshwater invertebrate taxa were compared using a laboratory lethality testing
protocol. Temperatures that were lethal to 50% of the test organisms (LT50s),
following acclimation to 15deg.C, generally declined over the 4 day period of
the tests. LT50 values after 48 and 96 h exposure ranged from 24.5 to
> 34deg.C and 22.6 to 32.6deg.C, respectively, indicating that
temperatures that occur in summer in many NZ streams and rivers may limit the
distribution and abundance of some of these invertebrate species. Larval
insects included both the most sensitive species (a plecopteran and two
Ephemeroptera) and the most tolerant (the larvae of the elmid beetle
Hydora sp.) in this study. The two molluscs studied (
Potamopyrgus
antipodarum (Prosobranchia: Hydrobiidae) and
Sphaerium
novaezelandiae (Bivalvia: Sphaeriidae)) showed high thermal tolerance,
whilst two crustaceans (
Paratya curvirostris (Atyidae) and
Paracalliope fluviatilis (Eusiridae)) were moderately tolerant. The
effect of a higher acclimation temperature (20deg.C) on thermal tolerance was
also investigated for the three most sensitive species. This appeared to
increase the thermal tolerance of the two Ephemeroptera (
Deleatidium
spp. and
Zephlebia dentata (both Leptophlebiidae)) but to reduce the
tolerance of the plecopteran
Zelandobius furcillatus
(Gripopterygidae).
Keywords benthic invertebrates; streams; temperature
tolerance; lethality; thermal; laboratory tests
New Zealand Journal of Marine and Freshwater Research, 1994: Vol. 28:
391-397
0028-8330/94/2804-0391 $2.50/0 (c) The Royal Society of New Zealand
1994
PDF file of entire paper: medium quality (583K); (scanned from paper original: notes about this process)
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