MACROINFAUNA AND HUMAN DISTURBANCE IN A SANDY BEACH OF SOUTH-CENTRAL CHILE

The effect of recreational bench users on the abundance of the interti dal macroinfauna was studied on a sandy beach of southcentral Chile (c a. 39 degrees S) during the summer of 1992. A field experiment was con ducted over a period of about two months. A fence was installed in the middle of the beach the early morning of January 22; thus, the beach was divided into a north side to which beach users were denied access and an accessible south side. The statistical analyses (BACI design wi th non-parametric Mann-Whitney U-test) was based upon the differences in macroinfaunal abundances on both sides of the fence, before and aft er it was installed. The results did not show any significant effect o f human exclusion on the macroinfaunal abundances. In the majority of cases, no significant differences in physical characteristics of sands occupied by the species on either side of the fence were detected. We conclude that presence of recreational beach users did not produce si gnificant effect on the macroinfauna during the summer of 1992. We arg ue that this kind of experimental approach is a useful tool in the des ign of management plans for sandy beaches affected by recreational pre ssures.