Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand
Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. Shell blistering induced by spionid polychaetes reduced the market quality of 10-40% of intertidal oysters in the Mahurangi Harbour, North Island in 1991, and, 22% of subtida...
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ftunivauckland:oai:researchspace.auckland.ac.nz:2292/738 2023-05-15T15:59:11+02:00 Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand Handley, Sean J. 1997 http://hdl.handle.net/2292/738 en eng ResearchSpace@Auckland PhD Thesis - University of Auckland UoA700225 Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm Copyright: The author Fields of Research::270000 Biological Sciences::270700 Ecology and Evolution::270702 Marine and estuarine ecology (incl. marine ichthyology) Thesis 1997 ftunivauckland 2013-12-07T08:29:45Z Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. Shell blistering induced by spionid polychaetes reduced the market quality of 10-40% of intertidal oysters in the Mahurangi Harbour, North Island in 1991, and, 22% of subtidally grown oysters in Admiralty Bay, South Island in1992-95. Polydora websteri induced the majority of shell blisters in the intertidal oysters. The larvae of P. websteri entered oysters through their mantle cavities. On experimental racks, the recruitment of P. websteri and blistering decreased with aerial exposure but was largely unaffected by sedimentation. Intertidal infestations are best managed by growing oysters at ELWN and at least 0.5m above the substratum. In Admiralty Bay, Boccardia knoxi bored the external shell of subtidal oysters inducing blistering after a lag period. Shell blistering was consistent with a hypothetical spring dispersive phase of planktotrophic B. konxi larvae. This hypothesis was confirmed later when these planktotrophic larvae were located and described during September 1996. In efforts to minimise infestations, experiments were conducted to increase the growth rates of oysters during the time of year B. knoxi larvae were absent. Oyster cultivators have long observed that the growth rates of oyster spat kept in the intertidal are stunted, and these oysters when transplanted to the subtidal, exhibit relatively rapid growth rates. Experiments in this study showed that the rate of growth was closely correlated with the duration of stunting period. Fouling and spionid infestations can be avoided by utilising an annual crop-rotation and using stunted spat to optimise growth and condition of subtidal oysters. Field and tank experiments showed an optimum stunting period of 8/9 months produced the fastest growth rates with minimal blistering. Energy-compensatory and energy-conserving mechanisms increased with the intertidal stunting period. The effect of stunting oysters with a limited diet in a tank indicated that food limitation rather than discontinuous feeding patterns caused the stunting effect. The effect of shell blistering on oyster condition was slight in subtidal oysters. Loss of condition was detected by three out of four condition indices - the dry weight gave the greatest power. Although loss of condition was considered biologically insignificant, by definition the measurable impact effectively rendered B. knoxi a parasite. Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. Thesis Crassostrea gigas Pacific oyster University of Auckland Research Repository - ResearchSpace Admiralty Bay New Zealand Pacific |
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University of Auckland Research Repository - ResearchSpace |
op_collection_id |
ftunivauckland |
language |
English |
topic |
Fields of Research::270000 Biological Sciences::270700 Ecology and Evolution::270702 Marine and estuarine ecology (incl. marine ichthyology) |
spellingShingle |
Fields of Research::270000 Biological Sciences::270700 Ecology and Evolution::270702 Marine and estuarine ecology (incl. marine ichthyology) Handley, Sean J. Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand |
topic_facet |
Fields of Research::270000 Biological Sciences::270700 Ecology and Evolution::270702 Marine and estuarine ecology (incl. marine ichthyology) |
description |
Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. Shell blistering induced by spionid polychaetes reduced the market quality of 10-40% of intertidal oysters in the Mahurangi Harbour, North Island in 1991, and, 22% of subtidally grown oysters in Admiralty Bay, South Island in1992-95. Polydora websteri induced the majority of shell blisters in the intertidal oysters. The larvae of P. websteri entered oysters through their mantle cavities. On experimental racks, the recruitment of P. websteri and blistering decreased with aerial exposure but was largely unaffected by sedimentation. Intertidal infestations are best managed by growing oysters at ELWN and at least 0.5m above the substratum. In Admiralty Bay, Boccardia knoxi bored the external shell of subtidal oysters inducing blistering after a lag period. Shell blistering was consistent with a hypothetical spring dispersive phase of planktotrophic B. konxi larvae. This hypothesis was confirmed later when these planktotrophic larvae were located and described during September 1996. In efforts to minimise infestations, experiments were conducted to increase the growth rates of oysters during the time of year B. knoxi larvae were absent. Oyster cultivators have long observed that the growth rates of oyster spat kept in the intertidal are stunted, and these oysters when transplanted to the subtidal, exhibit relatively rapid growth rates. Experiments in this study showed that the rate of growth was closely correlated with the duration of stunting period. Fouling and spionid infestations can be avoided by utilising an annual crop-rotation and using stunted spat to optimise growth and condition of subtidal oysters. Field and tank experiments showed an optimum stunting period of 8/9 months produced the fastest growth rates with minimal blistering. Energy-compensatory and energy-conserving mechanisms increased with the intertidal stunting period. The effect of stunting oysters with a limited diet in a tank indicated that food limitation rather than discontinuous feeding patterns caused the stunting effect. The effect of shell blistering on oyster condition was slight in subtidal oysters. Loss of condition was detected by three out of four condition indices - the dry weight gave the greatest power. Although loss of condition was considered biologically insignificant, by definition the measurable impact effectively rendered B. knoxi a parasite. Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. |
format |
Thesis |
author |
Handley, Sean J. |
author_facet |
Handley, Sean J. |
author_sort |
Handley, Sean J. |
title |
Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand |
title_short |
Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand |
title_full |
Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand |
title_fullStr |
Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand |
title_full_unstemmed |
Spionid Polychaete Worm Infestations of the Pacific Oyster Crassostrea Gigas in New Zealand |
title_sort |
spionid polychaete worm infestations of the pacific oyster crassostrea gigas in new zealand |
publisher |
ResearchSpace@Auckland |
publishDate |
1997 |
url |
http://hdl.handle.net/2292/738 |
geographic |
Admiralty Bay New Zealand Pacific |
geographic_facet |
Admiralty Bay New Zealand Pacific |
genre |
Crassostrea gigas Pacific oyster |
genre_facet |
Crassostrea gigas Pacific oyster |
op_relation |
PhD Thesis - University of Auckland UoA700225 |
op_rights |
Restricted Item. Print thesis available in the University of Auckland Library or may be available through Inter-Library Loan. https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm Copyright: The author |
_version_ |
1766394975524749312 |