versión On-line ISSN 0717-6538
LEPEZ, Irene; FURET, Luis y ARACENA, Olga. POPULATION OF EMERITA ANALOGA (STIMPSON 1857) IN AMARILLA AND RINCONADA BEACH, ANTOFAGASTA: ABIOTICS AND BIOTIC ASPECTS AND COPPER CONCENTRATION. Gayana (Concepc.) [online]. 2001, vol.65, n.1, pp. 55-76. ISSN 0717-6538. doi: 10.4067/S0717-65382001000100008.
Species of the genus Emerita are decapoda anomura in the Crustacea class, very commons in sandy beach. The distribution of Emerita analoga (Stimpson 1857) is from Alaska to Argentina, it is not found in tropical zones with temperature over 20°C, and inhabit the intertide zone between lower and middle level, mainly in exposed beach. E. analoga is common in the coastal zone of Antofagasta, where shipment of copper is carried out by the enterprise "Minera Escondida Ltda". This activity tolerate the possibility of leaking, that can altered the marine environment. Considering the species as a good indicator of polluted areas, Minera Escondida funded this study with the following objectives: 1) Describe the population parameters of E. analoga in Amarilla beach and compare those with a population from Rinconada beach, 33 km north, and not subjected directly to possible disturbance. 2) Relationship between the amount of copper in E. analoga and the sediments in both beach. This study are the basic data to be compared in the future, taking in account the possible increments of copper in the sediments. Abiotic conditions in Amarilla and Rinconada Beach were studied. The percentage of organic mater and copper was measured in both beaches, from samples obtained through transects in the intertidal zone from July 1993 to May 1994. The amount of copper was determined in individuals of E. analoga, too. The abiotic conditions in Amarilla and Rinconada Beach are similar in relation to granulometry, degree and the contents of organic matter. Not significant differences are found when the amount of copper are compared. The amount of copper in E. analoga shows a relationship with the sediments of Rinconada Beach. The populations of E. analoga shows differences in the fluctuations of abundance and density; in Amarilla Beach the number of individuals and biomass per square meter is higher than Rinconada Beach. Two reproductive peaks are present in the species: in winter and summer. In Amarilla Beach reproductive peak in winter is the most important, on the other hand, in Rinconada Beach the spawning period occur in summer. The main conclusions are: the parameters in both populations are not a consequence of different contents of copper in the tissues; on the contrary, these differences explains the distinct behavior in relation with the amount of copper in the sediments in boths beaches. Finally, E. analoga is not a good indicator of antropic disturbance, considering the differences found in populations and the examination of bibliography
Palabras clave : Population; Emerita analoga; copper; Antofagasta.