While a significant degree of salinity tolerance has been observed in the bivalve mollusk species Corbicula fluminea, the physiological and behavioral responses to changes in salinity by these organisms are not completely understood. It was hypothesized that Corbicula would initially avoid any salinity stress behaviorally through valve closure, but would eventually have to open to dispel anaerobic waste products and deal with the salinity. To explore this, Corbicula were collected and put through a series of experiments at salinity exposures of 0, 2.5, and 5.0ppt, with tissue water content and hemolymph osmolality being measured. After an initial 96-hour exposure period, it was observed that the tissue water content ratio of clams in 2.5ppt and 5.0ppt water dropped below that of the control groups in 0ppt. After a 24-hour time course experiment, it was observed that this change in tissue water largely occurred within the first eight hours of exposure for the 2.5ppt and 5.0ppt groups. It was also noted that the hemolymph osmolality of both the 2.5ppt and 5.0ppt groups rose to match the osmolality of the water in roughly the same time span. The osmolality of the control group did not match the osmolality of the 0ppt water, but was held at a constant level above it. In a later experiment measuring the same variables for clams in 10.0ppt, it was found that the tissue water and osmolality did not begin to change significantly until after 12 hours. The findings suggest that Corbicula osmoregulate at salinities lower than 2.5ppt, but osmoconform in salinities above that threshold. Furthermore, it seems that the clams are able and willing to tolerate conformation at 2.5ppt and 5.0ppt, but that they are reluctant to conform in 10.0ppt, behaviorally avoiding exposure for as long as possible.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:asrf-1097 |
| Date | 05 April 2018 |
| Creators | Roden, John Warren, III |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Appalachian Student Research Forum |
| Rights | http://creativecommons.org/licenses/by/4.0/ |
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