Living polycystines in the World Ocean: highlights of their distribution and diversity

BOLTOVSKOY DEMETRIO; CORREA NANCY

El Puerto de Santa Maria

Congreso; Interrad 13; 2011

Interrad

On the basis of data compiled from 91 publications and databases produced between 1958 and 2008 (Boltovskoy et al., 2010) we discuss selected aspects of the distribution and diversity of Recent polycystine species in the World Ocean. Our analyses focus on the following traits: (1) e vertical distribution of species numbers in the water-column. Contrary to expectation, deeper samples almost invariably yield higher numbers of species, which suggests strong “contamination” of the deep layers with dead individuals settling from above. (2) e relationship between species-speci(c relative abundance, occurrence and latitudinal spread. e three traits are correlated beyond the degree expected by probability alone, suggesting that abundant species are environmentally more ubiquitous than rare ones. (3) Differences in the mean water temperature of speci(c distribution ranges as derived from water-column samples and from surface sediment samples. Sedimentary records are generally associated with higher water temperatures, largest disagreements affecting the coldwater species. (4) e association between the mean water temperature of speci(c distribution ranges and the latitudinal span of the corresponding species. On average, temperate species (preferred temperature around 10–15°C) cover noticeably wider latitudinal belts than coldwater ones (up to 15°C), and warm-water species (15–30°C). (5) Species similarity decay as a function of distance. Faunal similarity between sites decreases monotonically as a function of distance up to 10.000 km (the distance from the Equator to either Pole); however, at greater distances simple matching (species presenceabsence) shows that inventories become increasingly similar, whereas comparisons based on quantitative data (e.g. Bray-Curtis) indicate further separation. is suggests that speci(c inventories differ little between hemispheres, but dominant species are different. ese features are causally analyzed, contrasted with other planktonic organisms, and discussed in the context of the use of polycystines for biogeographic and paleoecologic surveys. References Boltovskoy, D., Kling, S.A., Takahashi, K. & Bjørklund, K. 2010. World atlas of distribution of Recent Polycystina (Radiolaria). Palaeontologia Electronica, 13(3): 13.3.18A, 1–229.