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Several individuals belonging to a new species of the genus Chromadorita (Nematoda: Adenophorea) were collected in a cold-seep area in the Gulf of Guinea during two French cruises: BIOZÄIRE 2 (2001) and BIOZAÏRE 3 (2003-2004) on board the R/V L'Atalante. In this area, rich chemosynthetic benthic communities have been discovered at 3150 m depth in the large pockmark field named Regab. Chromadorita regabi sp. nov. was found among the eggs in ovigerous specimens of the shrimp Alvinocaris muricola. The combination of long size (1500-2200 µm), nine strong preanal papillae and relatively small dorsal tooth with weak musculature distinguishes this species from all known congeneric ones. An identification key to all known species of Chromadorita is provided. http://zoobank.org/urn:lsid:zoobank.org:pub:68B32253-D4B4-45EB-B4F8-4F7B015E6FCC [ABSTRACT FROM AUTHOR]

In this paper we have explored for the first time the biodiversity pattern of the meiobenthic assemblage in a Blue Hole of the Maldivian Archipelago. The cave is characterised by a marked change of the chemical water parameters below 50 m of depth, with a relevant increase in hydrogen sulfide, carbon dioxide, and sulfates (H2S, CO2 and SO42–). Thus, three stations were selected above and two below the chemo-thermocline in order to test the possible effects of the chemical variations on the meiobenthos. The difficulty of adaptation to these environmental conditions is clearly suggested by the presence of only a few dominant meiobenthic taxa in the bottom of the cave. However, meiobenthic organisms seemed more resistant than macrobenthos, which disappeared completely below this depth. The nematode assemblage was mainly represented by Xyalidae, Desmodoridae, Comesomatidae and Linhomoeidae. A high level of confinement of nematode genera at the different depths has been documented. In the upper part, their structure and biodiversity were comparable to those of the Maldivian subtidal habitats characterised by fine coralline sediments, while a notable dominance was detected in the bottom. The Blue Hole features also influenced the functional traits of the nematode assemblage with a documented increasing number of general opportunists and decrease of Maturity Index. The dominance of non-selective deposit feeders supports the hypothesis of a high amount of organic matter accumulated on the sea bottom of the cave. [ABSTRACT FROM AUTHOR]

Meiofauna assemblages of three Italian Marine Protected Areas (MPAs), Miramare (Trieste, Friuli-Venezia Giulia), Porto Cesareo (Lecce, Apulia) and Capo Caccia (Sassari, Sardinia), were investigated. Sediment samples were collected during summer 2005 in the shallow subtidal (1-4 m depth). The meiofauna was primarily represented by Nematoda and Copepoda. The results showed that significant differences in meiofauna communities abundances were found among the three Italian MPAs, and in particular between Capo Caccia and Porto Cesareo (3840 ± 422 SE individuals·10 cm-2 at Miramare, 5716 ± 857 SE ind.·10 cm-2 in Porto Cesareo, and 1063 ± 289 SE ind.·10 cm-2 in Capo Caccia). These differences were mainly due to a clear change in nematodes and copepods abundances in the two MPAs. Meiofauna diversity was not significantly different among the three MPAs. The analysis on nematode communities showed a dominance of deposit feeders in Porto Cesareo (Anoplostoma, Daptonema and Theristus), while in the marine reserves of Miramare and Capo Caccia epigrowth feeding nematodes, and predators/omnivores were dominant (Mesacanthion, Marylynnia). The results reported here represent a new contribution to the knowledge of the Mediterranean meiofauna and nematode assemblages structure and composition. [ABSTRACT FROM AUTHOR]

Ocean acidification is causing major changes in marine ecosystems, with varying levels of impact, depending both on the habitat and the studied organisms. Here, we investigated for the first time the meiobenthos and nematode fauna inhabiting the sediments around Castello Aragonese (Ischia, Italy), characterized by variable pH values due to coastal volcanic CO 2 venting. In this scenario, nematode functional diversity changed according to different pH levels and grain size: maturity index was higher at most acidic stations and trophic composition spanned from the dominance of predators in the acidic stations, to the high abundance of non-selective deposit feeders and epistrate feeders in the ambient-pH stations. Overall, the present study revealed a relatively high tolerance of meiobenthos and nematodes to lower pH conditions. However, an in-depth analysis of nematode fauna showed differences in their assemblages at different pH levels with few nematode genera rather adapted to the extreme environmental conditions at the acidic stations. • Ocean acidification modify the composition of marine communities. • Meiobenthos around Castello Aragonese is influenced by CO 2 emissions. • Nematofauna inhabiting CO 2 vents is adapted to pH variability. • Acidification influences nematode diversity and functional diversity. • Sediment type and O 2 are major factors affecting the nematofauna. [ABSTRACT FROM AUTHOR]