The Inverse Biodiversity Gradient of Rocky Shore Assemblages Along the Argentinean Coast.

GABRIELA PALOMO; GREGORIO BIGATTI; MARIA BAGUR; JORGE L. GUTIÉRREZ; JUAN JOSE CRUZ MOTTA

Aberdeen

Conferencia; 2nd World conference on Marine Biodiversity; 2011

St Andrew University

dentifying latitudinal patterns in species richness can be useful to predict biodiversity changes due to climate change. As part of the activities of NaGISA (Census of Marine Life) and the South American Research Group on Coastal Ecosystems, we sampled the biodiversity of Argentinean rocky intertidal shores along 4700 km of coast. A hierarchical nested design was used to sample seven locations separated by hundreds of kilometers. In each location, two sites separated 1 to 5 km were selected. At each site, abundance of animals and plants was determined in 10 quadrats of 0.25 m2 demarcated at each of three shore levels (high, mid and low). Contrary to the general postulate that the number of species decreases from tropics to poles, our data shows a positive, significant linear relationship between species richness and latitude. Biodiversity was impressively low, with only 104 species detected along the entire region. Species richness increased from 17 species in the northernmost sites (37º S) to 42 species in the southernmost ones (54º S). Future research on the factors that influence this inverse biodiversity gradient and the underlying  mechanisms will help elucidate whether rising temperatures could lead to changes in species distributional ranges and overall biodiversity losses.