Biodiversity gradient of rocky shore assemblages along the Argentinean coast.

PALOMO, MARIA GABRIELA; BIGATTI, GREGORIO; BAGUR, MARIA; GUTIÉRREZ, JORGE LUIS CEFERINO; CRUZ MOTTA, JUAN JOSÉ

Aberdeen

Congreso; World Conference on Marine Biodiversity; 2011

Identifying latitudinal patterns in species richness can be useful to predictbiodiversity changes due to climate change. As part of the activities of NaGISA(Census of Marine Life) and the South American Research Group on CoastalEcosystems, we sampled the biodiversity of Argentinean rocky intertidal shoresalong 4700 km of coast. A hierarchical nested design was used to sample sevenlocations separated by hundreds of kilometers. In each location, two sitesseparated 1 to 5 km were selected. At each site, abundance of animals andplants was determined in 10 quadrats of 0.25 m2 demarcated at each of threeshore levels (high, mid and low). Contrary to the general postulate that thenumber of species decreases from pics to poles, our data shows a positive,significant linear relationship between species richness and latitude. Biodiversitywas impressively low, with only 104 species detected along the entire region.Species richness increased from 17 species in the northernmost sites (37º S) to42 species in the southernmost ones (54º S). Future research on the factors thatinfluence this inverse biodiversity gradient and the underlying mechanisms willhelp elucidate whether rising temperatures could lead to changes in speciesdistributional ranges and biodiversity losses.