Tuesday, June 5, 2007 - 11:00 AM
131

Analyzing a modification of the swirl and decant method of collecting meiofauna from core samples

Garrett Tyler Clark1, Arthur V. Brown1, Andrea J. Radwell1, and Julia K. Eichman2. (1) Biological Sciences, University of Arkansas, Fayetteville, AR 72701, (2) EcoAnalysts, Moscow, ID 83843

Studies of stream meiofauna require efficient, accurate methods of quantitatively collecting them.  The swirl and decant method typically involves adding 250 ml of water to a 250 ml core sample, swirling it in a 1-liter container, then promptly pouring the liquid through a Wisconsin bucket with appropriate mesh.  This procedure is usually repeated three times.  We decided to try using saturated CaCl2 solution for the second rinse to detach and float organisms out of the substrate, and follow with a distilled water rinse to counteract shrinkage of soft-bodied organisms by the salt.  This study compared the original method with the CaCl2 and distilled water treatment.  We collected ten pairs of core samples from an area of stream (ca. 2 m2) with uniform flow, depth, and substrate composition.  After analyzing seven of the ten pairs of samples, results indicate that we did not obtain significantly more total meiofauna (p=0.097) using the CaCl2 treatment (1729 vs. 1121 n/l).  The treatment did produce more bivalve juveniles (745 vs. 430 n/l, p=0.024), but not most other taxa.  Although it appears that we collected more organisms using the flotation technique, the meiofauna are quite patchy in distribution resulting in high variances.