THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA
In the late 1950s, oyster populations in the Chesapeake and Delaware Bays suffered mortality from the parasite, Haplosporidium nelsoni that is now present from Florida to Maine. In 2001 and 2002, H. nelsoni caused oyster mortality in the Bras d’Or Lake, Cape Breton, N.S. Temperature and food availab...
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ftdalhouse:oai:DalSpace.library.dal.ca:10222/76352 2023-05-15T15:46:49+02:00 THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA Beresford, Roderick Department of Biology Doctor of Philosophy Dr. Jeff Davidson Dr. Sophia Stone Dr. Hal Whitehead Dr. Ramon Filgueira Dr. Paul Bentzen Dr. Neil Ross Not Applicable Yes 2019-08-29T17:15:36Z http://hdl.handle.net/10222/76352 en eng http://hdl.handle.net/10222/76352 Crassostrea virginica Eastern oyster MSX Haplosporidium nelsoni parasite 2019 ftdalhouse 2022-03-06T00:10:46Z In the late 1950s, oyster populations in the Chesapeake and Delaware Bays suffered mortality from the parasite, Haplosporidium nelsoni that is now present from Florida to Maine. In 2001 and 2002, H. nelsoni caused oyster mortality in the Bras d’Or Lake, Cape Breton, N.S. Temperature and food availability are two factors thought to influence the development of H. nelsoni based on field observations from the U.S. and mathematical models developed for the parasite. This research investigated the role of environmental parameters that influence the progression of H. nelsoni. Field studies showed that (i) H. nelsoni prevalence differed among oysters within tens of metres, (ii) high prevalence does not always result in high mortality, (iii) detailed field studies could provide more valuable information than laboratory experiments, and (iv) current models for infection and disease progression could be tested and modified at a small scale in Cape Breton. To examine the role of temperature in the progression of the parasite, oysters were maintained at 5oC, 10oC, 15oC, 20oC, and 24oC. Surprisingly, the parasite prevalence was reduced under controlled conditions. Food availability treatments showed there was a reduction in the parasite burden of treated oysters compared to the field samples, but there was no clear pattern with respect to parasite progression or reduction and the amount of food available. These studies suggest that temperature and food availability may have been influencing some factor(s) outside of the host-parasite direct interaction such as the abundance of intermediate and/or reservoir host(s). Alternatively, it is possible that laboratory conditions had an effect on the results. Eighteen years after the initial oyster mortality in the Bras d’Or Lake, oysters from several locations within the Bras d’Or Lake having different histories of exposure to H. nelsoni were placed in an area known to have high H. nelsoni activity. Following 16 months exposure, high mortalities were observed from all originating oyster populations, providing evidence of a lack of resistance to mortality in any of the originating locations. The lack of mortality in some originating locations was likely due to low level or absent H. nelsoni in those areas. A potential model that includes the parasite, intermediate/reservoir hosts, and oyster mortality is proposed to explain some of these observations across Cape Breton. Other/Unknown Material Breton Island Dalhousie University: DalSpace Institutional Repository Breton Island ENVELOPE(141.383,141.383,-66.800,-66.800) Canada |
institution |
Open Polar |
collection |
Dalhousie University: DalSpace Institutional Repository |
op_collection_id |
ftdalhouse |
language |
English |
topic |
Crassostrea virginica Eastern oyster MSX Haplosporidium nelsoni parasite |
spellingShingle |
Crassostrea virginica Eastern oyster MSX Haplosporidium nelsoni parasite Beresford, Roderick THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA |
topic_facet |
Crassostrea virginica Eastern oyster MSX Haplosporidium nelsoni parasite |
description |
In the late 1950s, oyster populations in the Chesapeake and Delaware Bays suffered mortality from the parasite, Haplosporidium nelsoni that is now present from Florida to Maine. In 2001 and 2002, H. nelsoni caused oyster mortality in the Bras d’Or Lake, Cape Breton, N.S. Temperature and food availability are two factors thought to influence the development of H. nelsoni based on field observations from the U.S. and mathematical models developed for the parasite. This research investigated the role of environmental parameters that influence the progression of H. nelsoni. Field studies showed that (i) H. nelsoni prevalence differed among oysters within tens of metres, (ii) high prevalence does not always result in high mortality, (iii) detailed field studies could provide more valuable information than laboratory experiments, and (iv) current models for infection and disease progression could be tested and modified at a small scale in Cape Breton. To examine the role of temperature in the progression of the parasite, oysters were maintained at 5oC, 10oC, 15oC, 20oC, and 24oC. Surprisingly, the parasite prevalence was reduced under controlled conditions. Food availability treatments showed there was a reduction in the parasite burden of treated oysters compared to the field samples, but there was no clear pattern with respect to parasite progression or reduction and the amount of food available. These studies suggest that temperature and food availability may have been influencing some factor(s) outside of the host-parasite direct interaction such as the abundance of intermediate and/or reservoir host(s). Alternatively, it is possible that laboratory conditions had an effect on the results. Eighteen years after the initial oyster mortality in the Bras d’Or Lake, oysters from several locations within the Bras d’Or Lake having different histories of exposure to H. nelsoni were placed in an area known to have high H. nelsoni activity. Following 16 months exposure, high mortalities were observed from all originating oyster populations, providing evidence of a lack of resistance to mortality in any of the originating locations. The lack of mortality in some originating locations was likely due to low level or absent H. nelsoni in those areas. A potential model that includes the parasite, intermediate/reservoir hosts, and oyster mortality is proposed to explain some of these observations across Cape Breton. |
author2 |
Department of Biology Doctor of Philosophy Dr. Jeff Davidson Dr. Sophia Stone Dr. Hal Whitehead Dr. Ramon Filgueira Dr. Paul Bentzen Dr. Neil Ross Not Applicable Yes |
author |
Beresford, Roderick |
author_facet |
Beresford, Roderick |
author_sort |
Beresford, Roderick |
title |
THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA |
title_short |
THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA |
title_full |
THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA |
title_fullStr |
THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA |
title_full_unstemmed |
THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE PROGRESSION OF HAPLOSPORIDIUM NELSONI (MSX) IN CRASSOSTREA VIRGINICA (AMERICAN OYSTER) ON CAPE BRETON ISLAND, NOVA SCOTIA, CANADA |
title_sort |
influence of environmental factors on the progression of haplosporidium nelsoni (msx) in crassostrea virginica (american oyster) on cape breton island, nova scotia, canada |
publishDate |
2019 |
url |
http://hdl.handle.net/10222/76352 |
long_lat |
ENVELOPE(141.383,141.383,-66.800,-66.800) |
geographic |
Breton Island Canada |
geographic_facet |
Breton Island Canada |
genre |
Breton Island |
genre_facet |
Breton Island |
op_relation |
http://hdl.handle.net/10222/76352 |
_version_ |
1766381535570690048 |