a-, β-, γ-, δ- and ε-diversity of deep-sea nematodes in canyons and open slopes of Northeast Atlantic and Mediterranean margins

Abstract

Meiofaunal biodiversity, with a special focus on nematodes, was investigated in 6 submarine canyons and 5 adjacent open slopes along bathymetric gradients (from ca. 200 to 5000 m depth) from 3 deep-sea regions (northeastern Atlantic, western and central Mediterranean) spanning > 2500 km and across a wide gradient of trophic and physicochemical conditions. The analysis of local (α) diversity at equal depths showed the presence of similar values in the NE Atlantic and Mediterranean deep-sea sediments. The comparison of the α diversity between different deep-sea habitats (canyons versus adjacent open slopes) revealed the lack of significant differences in species richness in most of the investigated systems. However, the analysis of nematode species composition showed the presence of major differences among different sampling depths (i.e. 500 versus 1000 versus 2000 m depth) and habitats. Turnover (β) diversity was high in all of the investigated deep-sea systems, but was higher in the NE Atlantic (87%) than in the Mediterranean margins (range 51 to 60%), resulting in higher values of regional (γ) diversity in the Atlantic margin. Turnover diversity among regions (δ diversity) was highest (~91%) between the NE Atlantic and western Mediterranean, but still extremely high between the western and central Mediterranean margins (~80%), thus leading to similar values of biogeographical diversity (ε) in the NE Atlantic and Mediterranean deep biogeographical provinces. The results suggest that biogeographic differences in deep-sea species composition are related to differences in β and δ diversity and not to differences in α diversity, and that the analysis of the factors driving β diversity are crucial to understand the spatial patterns of biodiversity in the deep sea.

Unravelling the environmental drivers of deep-sea nematode biodiversity and its relation with carbon mineralisation along a longitudinal primary productivity gradient

“…Nematode genus diversity, measured as ShannonWiener diversity and expected genus richness EG(20), did not change along the longitudinal axis between the Galicia Bank (GB) region, in the Northeast Atlantic, and the eastern Mediterranean. In contrast, similar studies based on nematode species found a significant decrease in diversity between the Northeast Atlantic and the southern Adriatic Sea (Danovaro et al, 2009a) and alongside the longitudinal axis Table 3. in the Mediterranean Basin (Danovaro et al, 2008b(Danovaro et al, , 2009b(Danovaro et al, , 2010. Even though genus richness remained relatively constant along the longitudinal axis, generic (J ) and taxonomic evenness (1/ + ), as well as the average taxonomic distinctness amongst individuals ( * , quantitative data) increased towards the east.…”

“…Unimodal diversitydepth trends are generally found in open oceans like the Atlantic and the Pacific where temperature decreases rapidly (to barely a few degrees) with depth. As opposed to Danovaro et al (2009a) and Danovaro et al (2010), bathymetric diversity patterns did not vary between the different regions that were sampled.…”

Broad-scale patterns in local diversity of marine benthic harpacticoid copepods (Crustacea)

“…This diversity component is commonly suggested to be mediated by the nature and degree of habitat heterogeneity, which increases with spatial scale due to patchiness, meta population dynamics, and/or environmental gradients (Willig et al 2003, Veech & Crist 2007. Indeed, a positive correlation between β diversity and scale has been found for birds and mammals (Koleff & Gaston 2002, Melo et al 2009), Mediterranean macrofauna (Munari & Mistri 2008), deep-sea nematodes (Danovaro et al 2009), and cladoceran zooplankton (Declerck et al 2011). Intertidal harpacticoids present a noticeable increase in β diversity when the spatial scale in creases from centimeters to tens of meters (Azovsky et al 2004, Rose & Seifried 2006.…”

“…Unfortunately, both diversity components have been rarely investigated simult aneously on the same dataset. In particular, very few β diversity measures deal with meiofauna, al though high rates of species turnover have been reported in several regional studies (Muthumbi et al 2004, 2011, Danovaro et al 2009). …”

An insight into the feeding ecology of deep-sea canyon nematodes — Results from field observations and the first in-situ 13C feeding experiment in the Nazaré Canyon

“…Rarely do studies combine structural as well as trophic diversity or investigate the intricate relationship between both (e.g. Danovaro et al, 2009). Although the use of 5…”