Location

Methods
      substrata
        mobility
        dimensions
 

Data Analysis
 

^ view of site area with extensive Ascophyllum nodosum

This area is characterized by a relatively level surface of jagged rock substrate with a think covering of the brown fucoid algae Ascophyllum nodosum.

Methods
    To examine any relationships between color morphology and substrate, I sampled a ten meter transect line parallel to the shore.  Although I was not interested in the density of the snails, a 25x25x25x23 cm quadrat was used to designate random areas along the transect line for sampling. 



10 meter transect line with wire quadrat and clip board

L. obtusata were searched for and then sorted according to substrate (rock or Ascophyllum nodosum) and color.  Color morphologies were designated as dark brown, red brown, light brown, olive green, greenish yellow, and yellow.  A total of 116 individual snails were sampled.

Examples:
 
dark brown     red brown          light brown  olive green      greenish yellow

yellow


To begin to assess the mobility of the snails, 45 individuals found on Ascophyllum within any of the 10 quadrats sampled were marked with bright pink nail enamel.  These marked snails were then placed back on the Ascophyullum which was also marked with yellow field tape.  The marked Ascophyllum and snails were searched for the  following day on October 5th.  Of the marked algae, 9 were recovered but only 1 marked greenish yellow L. obtusata was found.
 

To collect data pertaining to a relationship between color morphology and size, I obtained a total of 85 shell height and 82 length measurements (in mm) by shell color using a caliper.  Height was measured as the distance from the aperture of the shell to the apex, and the length was measured at the longest part of the shell. 


Data Analysis

For clarity, the color morphologies were pooled into more broad categories of dark, green, and yellow (as performed by Wilbur and Steneck, 1999) for analysis using a Chi-Square Contingency test.  Dark brown, red brown, and light brown were considered "dark" morphologies; olive green was considered as a "green" morphology; and greenish yellow and yellow were placed in the "yellow" category.  For further explanation please see the Evaluation page.
The snail mobility experiment did not yield enough data to work with and therefore, no analysis was performed.  Please see Evaluation page for further discussion.
Height and length measurements for the pooled color morphologies were analyzed using a single-factor analysis of variance (ANOVA).

snails were taken from their substrata and placed in a container for color assessment