The vertical profiles of dominant metazoan meiohenthic taxa were studied at four contrastingsites in the Adriatic Sea in relation to macrofaunal activity and oxyg-en penetration depth in the sediment. Vertical profiles of copepods were related to the oxygen penetration depth and showed peak densities in the upper cm or deeper in sediments with a broader oxic zone. In contrast, nematodes penetrated much deeper into the sediment and no direct relationship with oxyg-en penetration depth was evident. Nematode penetration depths were related to or reflected the diflerences in macrofaunal activity or mixing at the four sites which appears to he an important factor g-overning the subsurface activity of nematodes.

SUMMARY: Meiofauna from 20 stations (ranging between 8 and 550 m) in the Magellan Straits and the Beagle Channel revealed 28 small sized taxa of higher categories including the temporary meiofauna. Nematoda, Copepoda Harpacticoidea and Polychaeta occurred in all samples; Turbellaria, Bivalvia, Kinorhyncha and Ostracoda were regularly present. Nematodes represented between 68% and 94% of the meiofauna at each station, followed by the copepods (2.3% to 14.5%) and polychaetes (1.1% to 11.5%). Maximal total density, 9700 individuals 10 cm -2 , was found in the surroundings of Picton Island, while the mean abundance per station was 3374 individuals 10 cm -2 . The vertical pattern within the sediment showed that 87% of meiofauna components concentrated in the upper 0-5 cm sediment layers and 13% in the lower (> 5cm) layers. More than 95% of copepods, as well as the temporary meiofauna occurred in the top 5 cm layers. The proportion of nematodes and copepods shows opposite trends in the vertical distribution. Multivariate analysis using the total density and the 10 'true' meiofauna taxa densities discriminates between communities in the Straits of Magellan and the Beagle Channel area. Meiofaunal density was much higher in the Beagle Channel, but the diversity was lower than that in the Straits of Magellan. The Southern Magellan meiofauna communities are compared with those found at the Antarctic Peninsula and in the Weddell Sea (high Antarctic). It is considered that hydrodynamic features (tidal currents with strong winds), geographical characteristics, together with sediment composition are the key parameters structuring the meiofauna community in the Straits of Magellan and in the Beagle Channel.Key words: Meiofauna, Density, Community, Straits of Magellan, Beagle Channel, Antarctic. RESUMEN: COMUNIDADES DE MEIOFAUNA DEL ESTRECHO DE MAGALLANES Y DEL CANAL DEL BEAGLE. -La meiofauna de 20 estaciones (extendiéndose entre 8 y 550 m) en el Estrecho de Magallanes y el Canal del Beagle reveló 28 taxones de tamaños pequeños de categorías más altas incluyendo la meiofauna temporal. Nematoda, Copepoda Harpacticoidea y Polychaeta estuvieron presentes en todas las muestras; Turbellaria, Bivalvia, Kinorhyncha y Ostracoda estuvieron regularmente presentes. Los nemátodos representaron entre 68% y 94% de la meiofauna en cada estación, seguidos por los copépodos (2,3% a 14,5%) y los poliquetos (1,1% a 11,5%). La densidad total máxima, 9700 individuos/10 cm 2 , fue encontrada en los alrededores de la Isla de Picton, mientras que la abundancia promedio por estación fue de 3374 individuos/10 cm 2 , incluyendo la meiofauna temporal. El modelo vertical dentro del sedimento mostró que 87% de las componentes de la meiofauna se concentraron en las capas superiores del sedimento de 0-5 centímetros y 13% en las más bajas (> capas de los 5 cm). Más del 95% es de los copépodos así como la meiofauna temporal aparecieron en las capas superiores de 5 centímetros. La proporción de nemátodos y de copépods muestra una tendencia opuesta en la distri...

A large-scale database concerning benthic copepods from the Arctic, Baltic Sea, North Sea, British Isles, Adriatic Sea and Crete was compiled to assess species richness, biodiversity, communities, ecological range size and biogeographical patterns. The Adriatic showed the highest evenness and the most species-rich communities. Assemblages from the North Sea, British Isles, Baltic and Crete had a lower evenness. The British Isles were characterised by impoverished communities. The ecological specificity of copepod species showed two diverging trends: higher specificity of species in more diverse assemblages was observed in the Adriatic, North Sea and Baltic. A uniformly high species specificity disregarding sample diversity was found on Crete and in the British Isles. Benthic copepod communities showed distinct 123Mar Biol DOI 10.1007/s00227-010-1454 patterns that clearly fit the predefined geographical regions. Communities were distinguishable and b-diversity was found to be high around Europe, indicating a high species turnover on the scale of this investigation. The British Isles and the North Sea were found to be faunistic links to the Baltic and the Arctic.

No abstract

No abstract