Abstract

CHURA-CRUZ, René et al. Relationship between lake water level and rainfall on the landings of argentinian silverside Odontesthes bonariensis (Valenciennes, 1835) in the peruvian sector of the titicaca lake from 1981 to 2010. Ecol. apl. [online]. 2013, vol.12, n.1, pp.19-28. ISSN 1726-2216.

The Lake Titicaca is the second bigger and navigable lake in South, with a surface of 8.400 km² and located at an altitude of 3810 m.a.s.l. The objective of this work was to determine the relationship between fluctuations in the lake level and rainfall on the landings of the argentine silverside Odontesthes bonariensis in the Peruvian sector of the lake, between 1981 and 2010, considering the following hypothesis: the temporal changes of the water level of Lake Titicaca and rainfall are related to the abundance and availability of argentine silverside, with consequences in landings in the Peruvian sector of the lake. It is assumed that landings are an index of abundance. The annual catch records of argentine silverside covered the period 1981 - 2010 and monthly catch data covered from January 1990 to December 2010. To the annual time series, the linear trend was removed and residuals were calculated; while the monthly time series were decomposed. All the relationships between variables were based on residuals by using regression techniques, autocorrelation and crosscorrelation functions. It was determined that the landings of argentine silverside presented a significant relationship with the lake level after three years. . The monthly landings residuals were correlated with precipitation residuals at 18 months lag. From the lagged relationship at three years lagged in the period 1981-2004, a significant linear relationship was found, but this relationship was deteriorated when the most recent period (2005 - 2010) was included. It is established that this change in the relationship would be due to the reduced abundance and/or productivity of argentine silverside. The expansion of the coastal zone by processes associated with lake level rise would be favoring the recruitment success of argentine silverside through two main mechanisms: natural food availability and refuge against predators.

Keywords : argentine silverside; Lake Titicaca; level; precipitation; regression; correlation.

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