The effect of physical and chemical parameters on the macroinfaunal community structure of San Vicente bay, Chile

2001 Revista Chilena de Historia Natural  
Efectos de pa metros ffsicos y qufmicos en la estructura comunitaria de la macroinfauna en la bahfa de San Vicente, Chile ABSTRACT San Vicente bay is a heavily industrialised bay located in central Chile, which has a sand beach extending from an area of recreational use in the south to an area of industrial use and discharge in the north. A survey of the macrofauna in the intertidal zone revealed a non-homogeneous distribution; a maximum of five invertebrate species were found with all five
more » ... occurring in one of six transects down the beach. The density ranged from 0 to 188 individuals m , with the highest density at the recreational end. The most common species, Emerita analog a (Stimpson), was chosen to study the macrofauna! response to beach morphodynamics, physicochemical parameters and metal concentrations. The E. analog a distribution was not significantly correlated with the results of the physicochemical analyses of interstitial water (pH, temperature, salinity and oxygen concentrations). However, oxygen concentrations decreased to 3 ml O 1 in the lower intertidal closest to the recreational area where the highest numbers of intertidal macrofauna were observed. Analyses of 12 metals in the sediments showed three distinct distribution patterns across the beach in which the metals could be classified: a representative metal was chosen for each distribution. The concentration oftin ranged from 3.4 to 11.58 mg g DW sediment, representing the 'wave' pattern. The concentration of cadmium ranged from 0 to 0.23 mg g DW sediment, representing the 'banded' pattern. The concentration of chromium ranged from 1.97 to 3.18 mg g DW sediment, representing the 'intermediate' pattern of metal distribution. The E. analog a distribution was not significantly correlated with the concentrations of any single metal, although multivariate statistical analysis indicated that Sn and Fe had the largest negative effect and Mn had the largest positive one. The distribution of E. analog a across the sandy beach of San Vicente bay was significantly correlated with the relative tidal range (RTR) beach morphodynamic parameter. There was also a significant linear relationship between E. analog a and 1/slope parameter. Although there was a significant correlation between the physical parameters of the beach and E. analog a distribution, these results should not be taken as conclusive for we must not exclude other possible factors, including chemical ones, which were not measured in this study. Absence of the amphipod Orchestoidea tuberculata Nicolet at the high water mark in the industrial zone can be explained by destruction of habitat due to direct human disturbance.
doi:10.4067/s0716-078x2001000200017 fatcat:cwj5otohxfehdkxpyyqranyh2y