Changes in cladoceran and diatom community and its relationship with NAO index and temperature during the last 150 years

<p><strong>S08-P-03 Changes in cladoceran and diatom community and its relationship with NAO index and temperature during the last 150 years</strong></p> <p>Pérez-Martínez, C., Jiménez, L.</p> <p>Institute of Water Research. University of Granada. Spain</p> <p>We explore whether changes in cladoceran and diatom community can be linked to changes in mean temperature and in the NAO index. A high NAO index is associated to drier conditions over southern Europe and yields dust transport from Sahara desert over the western Mediterranean basin during summer. <em>Daphnia pulicaria </em>relative abundance shows an important increase in the lake during the last decades, mainly from 1970, whereas <em>Alona quadrangularis </em>increase occurs from late 80s simultaneously with the decrease of <em>Chydorus sphaericus</em>. <em>Daphnia </em>relative abundance through the core is positively correlated to the NAO index but no with temperature values. The opposite is found for <em>A. quadrangularis </em>and <em>C. sphaericus</em>. The most abundant diatom species and the factor 1 of the principal component analysis performed on diatom assemblage are correlated to temperature values and do not show any relationship with NAO index. A positive correlation between <em>Daphnia </em>and the NAO index is also found for 10 years of <em>Daphnia </em>sampling in Río Seco Lake (1996-98 and 2005- 2011).</p> <p>We hypothesized that <em>D. pulicaria </em>is probably benefited by Saharan dust calcium, because this species is likely limited by Ca in Río Seco Lake and Saharan dust is rich in Ca, whereas other cladoceran and the diatom species are more affected by temperature changes in the lake region.