Type
Text
Type
Dissertation
Advisor
Cerrato, Robert | Allam, Bassem | Levinton, Jeffery | Meliker, Jaymie | Bushek, David.
Date
2015-12-01
Keywords
Clam, Disease, Mercenaria, QPX, Salinity, Temperature | Biology
Department
Department of Marine and Atmospheric Science.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/77794
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
There is increasing recognition of the role of suspension-feeding bivalves in providing important ecosystem services (e.g. | water clarity, benthic-pelagic coupling, and habitat structure) within estuarine systems. Mercenaria mercenaria (aka hard clams, quahogs) are frequently the dominant suspension-feeder in estuarine systems across the US east coast and have had significant commercial fishery importance and a steadily growing mariculture industry. M. mercenaria have generally not had disease problems which contrasts the microbial infections that have plagued oyster fisheries. Quahog Parasite Unknown (QPX) is the first substantial infectious microbial pathogen affecting hard clams across both wild populations and cultured stocks. QPX is identified as a Thraustochytrid, a group of saprophytic protists that are considered to play an important role in detrital organic matter recycling in coastal ecosystems, yet there are some reports of their association with molluscan disease and mortalities. QPX infections can be present in hard clams but without causing overt disease problems. Controlled laboratory experiments and applied field experiments were utilized in an approach to understand the factors that control infection dynamics. Results revealed a significant role of the primary environmental factors of temperature and salinity influencing the balance between the hard clam host and opportunistic pathogen QPX, regulating the resultant disease progression. Counter to most microbial pathogens affecting bivalves, warm temperatures (≥21°C) deter infection progression and promote disease remission. High estuarine salinity (e.g. | 30ppt) promotes infection and increases the risk of QPX-related hard clam mortalities. Applied field experiments showed the potential to mitigate disease risk. Areas subject to low salinities and high summer temperatures within an enzootic estuary were utilized to deter infection progression. Reductions of hard clam density also helped reduce disease risk. Clam seed raised from locally sourced wild populations displayed good growth and disease resistance during grow out challenges. The investigations provide fundamental insights for developing management strategies. | There is increasing recognition of the role of suspension-feeding bivalves in providing important ecosystem services (e.g. | water clarity, benthic-pelagic coupling, and habitat structure) within estuarine systems. Mercenaria mercenaria (aka hard clams, quahogs) are frequently the dominant suspension-feeder in estuarine systems across the US east coast and have had significant commercial fishery importance and a steadily growing mariculture industry. M. mercenaria have generally not had disease problems which contrasts the microbial infections that have plagued oyster fisheries. Quahog Parasite Unknown (QPX) is the first substantial infectious microbial pathogen affecting hard clams across both wild populations and cultured stocks. QPX is identified as a Thraustochytrid, a group of saprophytic protists that are considered to play an important role in detrital organic matter recycling in coastal ecosystems, yet there are some reports of their association with molluscan disease and mortalities. QPX infections can be present in hard clams but without causing overt disease problems. Controlled laboratory experiments and applied field experiments were utilized in an approach to understand the factors that control infection dynamics. Results revealed a significant role of the primary environmental factors of temperature and salinity influencing the balance between the hard clam host and opportunistic pathogen QPX, regulating the resultant disease progression. Counter to most microbial pathogens affecting bivalves, warm temperatures (≥21°C) deter infection progression and promote disease remission. High estuarine salinity (e.g. | 30ppt) promotes infection and increases the risk of QPX-related hard clam mortalities. Applied field experiments showed the potential to mitigate disease risk. Areas subject to low salinities and high summer temperatures within an enzootic estuary were utilized to deter infection progression. Reductions of hard clam density also helped reduce disease risk. Clam seed raised from locally sourced wild populations displayed good growth and disease resistance during grow out challenges. The investigations provide fundamental insights for developing management strategies. | 77 pages
Recommended Citation
Dahl, Soren, "Ecology of QPX disease in the hard clam Mercenaria mercenaria" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 3572.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/3572