Investigation of the Relationship Between Tidal Height and Body Volume of Abarenicola pacifica in False Bay, Washington

Abstract

This study aimed to determine whether nourishment of Abarenicola pacifica varied at different tidal heights in False Bay, Washington. We hypothesized that the higher concentration of sediment organic matter at the head of the bay would lead to a negative correlation between body volume and distance from shore, as well as a relationship between fecal to body volume ratio and distance from shore. We tested this by measuring the volume of the fecal castings and the body of 120 individuals of A. pacifica on two 100-meter transects placed on the north and south sides of False Bay. Our linear regression showed a positive correlation between body volume and distance from shore. This correlation was weak but significant on the northern transect, but was not significant on the southern transect. When the data from both transects were combined, the correlation was signfiicant. This disparity was likely due to the amount of variability within the data, resulting in low R-squared values on both transects. There was no evidence of a significant relationship between fecal volume to body volume ratio and tidal height, likely because fecal volume is not a good indicator of body size. This indicates that although sediment organic concentration may be higher at the head of the bay, multiple factors influence growth of A. pacifica, some of which include selective feeding behavior, temperature, salinity, and exposure to pollutants.