caa a22 4500 445891106 CHVBK 20180317145616.0 cr unu---uuuuu 170323e20110901xx s 000 0 eng 10.1007/s10750-011-0780-7 doi (NATIONALLICENCE)springer-10.1007/s10750-011-0780-7 Latitudinal gradients in macroalgal biodiversity in the Southwest Atlantic between 36 and 55°S [Elektronische Daten] [María Liuzzi, Juan López Gappa, María Piriz] Different groups of marine benthic organisms show contrasting latitudinal patterns of biodiversity. The widely accepted paradigm of increasing biodiversity towards the tropics does not seem to be valid for macroalgal floras of the Southern Hemisphere. We compiled a database summarizing the distributional ranges of macroalgae along the coast of Argentina to test whether biodiversity decreases towards lower latitudes, as in the Pacific coast of South America, and whether breaking points in the geographical distribution can be recognized in one or more areas of the Southwest Atlantic south of 36°S. We found a clear trend of decreasing biodiversity with decreasing latitude. The interpretation of some biodiversity declines is confounded by changes in the intensity of the sampling effort. A 51% reduction in algal species richness between 42 and 41°S coincides with the boundary between the Argentine and Magellanic Zoogeographic Provinces. This sharp breaking point is related to a thermal anomaly caused by long residence times of water masses within San Matías Gulf, suggesting an upper thermal tolerance limit for most Antarctic/sub-Antarctic seaweeds. A further reduction occurs at 38-37°S. This breaking point can be explained by the disappearance of suitable hard substrata, since rocky outcrops give place to wide extensions of sandy beaches. The impoverished algal assemblage inhabiting the northern coast of Argentina is mainly related to the reduction or disappearance of the Antarctic/sub-Antarctic floristic component. This area is characterised by a predominance of widely distributed species, Chlorophytes and opportunistic filamentous or foliose algae. Springer Science+Business Media B.V., 2011 Biogeography nationallicence Species richness nationallicence Sampling effort nationallicence Algal functional groups nationallicence Breaking points nationallicence Argentina nationallicence Liuzzi María Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina aut López Gappa Juan Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina aut Piriz María Morgan 2455, U9120AFM, Puerto Madryn, Chubut, Argentina aut Hydrobiologia Springer Netherlands 673/1(2011-09-01), 205-214 0018-8158 673:1<205 2011 673 10750 https://doi.org/10.1007/s10750-011-0780-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-011-0780-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Liuzzi María Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina aut NATIONALLICENCE 700 1- López Gappa Juan Museo Argentino de Ciencias Naturales, Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina aut NATIONALLICENCE 700 1- Piriz María Morgan 2455, U9120AFM, Puerto Madryn, Chubut, Argentina aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 673/1(2011-09-01), 205-214 0018-8158 673:1<205 2011 673 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer