| dc.identifier.uri | http://hdl.handle.net/11401/78135 | |
| dc.description.sponsorship | This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree | en_US |
| dc.format | Monograph | |
| dc.format.medium | Electronic Resource | en_US |
| dc.language.iso | en_US | |
| dc.type | Thesis | |
| dcterms.abstract | Bottom water oxygen concentrations in coastal environments can oscillate between fully oxygenated and hypoxic conditions on a daily basis. How benthic organisms deal with such drastic changes in oxygen availability is not well understood. Specifically, we do not know the magnitude, duration, and frequency at which diel-cycling hypoxia conditions become harmful. Here we have used non-invasive infrared sensors to measure the cardiac activity of the Atlantic bay scallops, Argopecten irradians, in response to diel-cycling hypoxia in-situ over one-month periods as well as in the laboratory in controlled incubations using animals conditioned to contrasting field conditions. In the field, heartbeat rates at a well-oxygenated site were relatively stable while scallops deployed at two sites with pronounced diel-cycling hypoxia were elevated and more variable. Maximal heartbeat rates during diel-cycling hypoxia were commonly recorded around dawn when oxygen concentrations fell to 5 mg L-1 indicating a sub-lethal response to dissolved oxygen (DO) concentrations higher than what is typically defined as hypoxia. Laboratory incubations confirmed the tight link between DO and cardiac activity. An increase of heartbeat rate in response to an initial decline from fully oxygenated conditions was indicative of a regulatory response in which cardiac activity was enhanced presumably to maintain oxygen supply. At DO below 3 mg L-1 heartbeat rates declined reaching a state of acardia during anoxia, suggesting a conformer response to severe hypoxia. In-situ and laboratory data was integrated into a novel conceptual model to characterize four phases that interpret cardiac and respiratory activity in diel-cycling hypoxia. Heartbeat frequency was a suitable proxy for respiration under normoxia, but scallops were unable to compensate for reduced oxygen availability by increasing heartbeat rates below hypoxic thresholds. Pre-conditioning to diel-cycling hypoxia did not affect survival or cardiac activity in anoxic and severe hypoxic treatments. However, A. irradians pre-conditioned to diel-cycling hypoxia were less responsive to normoxia with heightened effort to maintain vital aerobic functions after long-term exposure to severe hypoxia. Survival after 12-14 hours of anoxia and mortality after 23-32 hours of anoxia convey physiological limitations unaffected by acclimation. We speculate that repetitive exposure to periods of DO oscillations with exposure below 5.0 mg L-1 in the field can cause sub-lethal effects to A. irradians affecting fitness, growth, and reproductive success. | |
| dcterms.available | 2018-03-22T22:39:04Z | |
| dcterms.contributor | Gobler, Christopher | en_US |
| dcterms.contributor | Volkenborn, Nils. | en_US |
| dcterms.contributor | Cerrato, Robert. | en_US |
| dcterms.creator | Gurr, Samuel Jonathan | |
| dcterms.dateAccepted | 2018-03-22T22:39:04Z | |
| dcterms.dateSubmitted | 2018-03-22T22:39:04Z | |
| dcterms.description | Department of Marine and Atmospheric Science. | en_US |
| dcterms.extent | 56 pg. | en_US |
| dcterms.format | Monograph | |
| dcterms.format | Application/PDF | en_US |
| dcterms.identifier | http://hdl.handle.net/11401/78135 | |
| dcterms.issued | 2017-08-01 | |
| dcterms.language | en_US | |
| dcterms.provenance | Made available in DSpace on 2018-03-22T22:39:04Z (GMT). No. of bitstreams: 1
Gurr_grad.sunysb_0771M_13386.pdf: 2834617 bytes, checksum: 8716bad4008549d2d165e2389d68ea21 (MD5)
Previous issue date: 2017-08-01 | en |
| dcterms.subject | cardiac activity | |
| dcterms.subject | Biological oceanography | |
| dcterms.subject | ecophysiology | |
| dcterms.subject | hypoxia | |
| dcterms.subject | scallops | |
| dcterms.title | Effects of Diel-Cycling Hypoxia on the Cardiac Activity and Growth of Argopecten irradians | |
| dcterms.type | Thesis | |
