Meeting Abstract
For two species of barnacle cyprids, Balanus glandula and B. crenatus, potential differences in their distribution in the water column have been hypothesized to be caused by a difference in their specific gravity, swimming behavior, or a combination of both. This study sought to test these proposed explanations by measuring the sinking rates of the two species and by quantifying their location in a stable water column. To measure sinking rates, cyprids were placed in a stable water column, housed in a water jacket, and falling rates were calculated using the amount of time it took to fall two centimeters. Using a modified force-balance equation, specific gravity was calculated for the two species. To quantify the water column location, cyprids were dark-adapted for 20 seconds before being exposed to white light for a minute. After a minute, a score of 0-3 was given to each cyprid depending on where the cyprid was in a tank 24.5 cm tall. A score of 0 signified the floor, and a 3 signified the upper third of the water column. Cyprids of the two species did not differ in their specific gravity or sinking speed. Cyprids of B. glandula overwhelmingly preferred the top third of the water column, where as those of B. crenatus preferred to be in the bottom third. These results imply that cyprid distribution may be driven by behavior rather than inherent physical properties.
