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dc.contributor.authorCranford, Peter James.en_US
dc.date.accessioned2014-10-21T12:38:40Z
dc.date.available1998
dc.date.issued1998en_US
dc.identifier.otherAAINQ36576en_US
dc.identifier.urihttp://hdl.handle.net/10222/55588
dc.descriptionThe primary hypothesis addressed is that food acquisition by bivalve filter feeders is driven not only by physical and morphological constraints on feeding, but also by a complex interplay between different time-scales of variation in oceanographic variables, the time-dependence of compensation capabilities and temporal variations in nutritional demands. A novel approach for monitoring food utilization by bivalve filter feeders was developed that permits time-series measurements to be obtained autonomously under natural conditions. Measurements obtained with this method are shown to exhibit high precision and accuracy. To provide empirical data to help understand and predict fluctuations in feeding/digestion behaviour, food utilization by sea scallop (Placopecten magellanicus) and blue mussel (Mytilus edulis) cohorts was measured in several coastal regions of Nova Scotia in conjunction with extensive environmental monitoring. Studies were conducted to document responses of scallops to tide- and storm-induced and seasonal changes in oceanographic conditions. The potential for interspecific differences in feeding strategy was addressed by comparing seasonal responses of sea scallop and mussel cohorts. A laboratory study was also conducted to document the time-course and magnitude of digestive compensation responses to changes in food supplies.en_US
dc.descriptionThe previous hypothesis that food utilization by bivalve filter feeders is a highly automated and unregulated process is not supported by the observations. Scallop and mussel ingestion rates varied over different time-scales in a manner that cannot be explained by assuming continuous feeding. Average clearance rate estimates for scallops and mussels in nature were between 3.2 and 6.6 times lower than predicted assuming maximal clearance rate. Periodic feeding activity was shown to account for a high proportion of daily and seasonal food intake rates. These observations dictate a re-evaluation of current theories on the role of bivalve filter-feeders in controlling seston dynamics, phytoplankton biomass, and trophic structure in many shallow coastal regions.en_US
dc.descriptionShort- and long-term ingestion rates were not closely coupled to temperature, the quantity and composition of the seston, or to horizontal and vertical particle flux, but sea scallop clearance rates were directly related to current speed. Observed seasonal variations in feeding behaviour by both species appear to have resulted from the combination of relatively low food availability at the study site and the high energy demands of reproduction. An important mechanism for controlling food intake in both species is the regulation of absorption efficiency (AE). AE was found to be closely related to the quality of the food supply and was shown to be dependent on past feeding history. Absorptive compensation was confirmed for both species in laboratory and field studies and appears to be optimized in a time-averaged manner that minimizes the need for continuous adjustments.en_US
dc.descriptionThesis (Ph.D.)--Dalhousie University (Canada), 1998.en_US
dc.languageengen_US
dc.publisherDalhousie Universityen_US
dc.publisheren_US
dc.subjectBiology, Oceanography.en_US
dc.subjectBiology, Zoology.en_US
dc.titleTemporal perspectives on food acquisition by suspension-feeding bivalves: Placopecten magellanicus and Mytilus edulis.en_US
dc.typetexten_US
dc.contributor.degreePh.D.en_US
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