Determinación de los períodos cálidos (El Niño) y fríos (La Niña), en base al comportamiento mensual de los Pterópodos y Heterópodos, como bioindicadores del ecosistema marino ecuatoriano
El propósito de esta contribución es aportar al mejor conocimiento en la determinación de los períodos cálidos y fríos observados frente a la costa de Ecuador, con la finalidad de aportar al mejor conocimiento de estos eventos oceanográficos naturales, con los que tenemos que aprender a vivir y a tratar de encontrar especies que puedan indicarnos un pronóstico temprano a El Niño o La Niña.Of the analysis of more than 200 superficial samples of zooplankton, obtained from june of 1990 to june of the 2005, in the fixed station of "La Libertad", located to 10 miles offshore the Peninsula of Santa Elena, Ecuador, 15 species of Pterópods and Heterópods have been identified, of which only nine species respond to the changes in the marine ecosystem from to Ecuador. From the nine species, have been selected four, those species have had a positive answer when warm waters appear offshore of Ecuador, while when there is conditions cold, some species are absented and others decrease significantly their abundance, size of their shells or appears in juvenile stage. The interpretation of the state of the marine ecosystem is based of the different associations that are observed, also dominance of the species, development of its shells, abundances of juveniles, season of obtaining of the sample among other more observations. From june of 1990 to july of 1991 the period can be considered cold. From august of 1991 a warm period began that was developed with more intensity on march of 1992 like "El Niño 1992", after that continued unstable conditions that finished in january of 1996. From february of 1996 a cold period of "La Niña", characterized by a low biodiversity of Pteropods and Heteropods began to march of 1997, from april of 1997 warm water species began to be observed and the beginning of "El Niño 1997-1998", that it funished on august of 1998. On september began a cold period or "La Niña" until september of 2000, on october of the 2000, an unstable period in the marine ecosystem has been observed, that it is not defined like a warm or cold period until june of the 2005, where it seems that they have been accentuated the characteristics of a cold event like "La Niña".