New Zealand Journal of Marine and Freshwater Research abstracts
Short communication
Tolerance and behaviour of the mysid shrimp Tenagomysis novae-zealandiae to low dissolved oxygen
Gregory Larkin*,1
Gerard P. Closs2
Barrie Peake3
1 Environmental Science Postgraduate Programme
2 Department of Zoology
3 Department of Chemistry
University of Otago
P.O. Box 56
Dunedin 9054, New Zealand
*Present address: 57 Banks Street, Invercargill, New Zealand. email: Gregl@es.govt.nz
Abstract Estuarine hypoxia (<4.0 mg O2 /litre) caused by eutrophication has been linked to mass mortality of fish and Crustacea. However, there is little information on the hypoxia tolerance of New Zealand’s estuarine mysid shrimps and/or if these species exhibit behavioural and physiological responses to low dissolved oxygen. Laboratory experiments demonstrated the native mysid shrimp Tenagomysis novae-zealandiae was tolerant of dissolved oxygen levels of 4.0 mg O2 /litre and 1.5 mg O2 /litre, but very sensitive to levels <0.5 mg O2 /litre. Mortality occurred within 22 min when dissolved oxygen levels decreased to 0.5 mg O2 /litre, although the 7 h LC50 value for T. novae-zealandiae was calculated to be 1.11 mg O2/litre. There was a clear relationship between T. novae-zealandiae activity and decreasing dissolved oxygen levels. Reduced activity appears to be a strategy of T. novae-zealandiae to tolerate moderate hypoxia (4.0 and 1.5 mg O2 /litre). However, this behaviour was unsuccessful at 0.5 mg O2 /litre, as all test organisms demonstrated erratic behaviour and escape responses immediately before loss of equilibrium and mortality.
Keywords hypoxia tolerance; mysid behaviour; estuarine hypoxia
New Zealand Journal of Marine and Freshwater Research, 2007, Vol. 41: 317–323
0028–8330/07/4103–0317 © The Royal Society of New Zealand 2007
M06027; Online publication date 18 September 2007. Received 9 June 2006; accepted 30 January 2007
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