Two new species of <i>Rhynchonema</i> Cobb, 1920 from a Brazilian sandy beach

Rhynchonema Cobb, 1920 is a genus with worldwide distribution. It is found in diverse coastal environments ranging from brackish water to exposed beaches in intertidal and low subtidal zones, from clay to coarse sand and in sediments under seagrass beds. In this study we describe two new tropical species from Northeast South America: Rhynchonema cemae sp.n. and R. veronicae sp. n. from Olinda’s Isthmus, Pernambuco, Brazil. These two species are mainly characterized by the shapes of the spicules and gubernaculum, which are described here for the first time. The two species can be differentiated primarily on the basis of the spicules, which in R. cemae are symmetrical, fine and long, while in R. veronicae they are asymmetrical, more robust and shorter. We describe for the first time the presence of Rhynchonema species on the east side of South America and provide a review of the genus and a polytomous identification key. Our review of the literature and construction of a polytomous key demonstrated that most of the species descriptions are incomplete

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

Alongside a primary productivity gradient between the Galicia Bank region in the Northeast Atlantic and the more oligotrophic eastern Mediterranean Basin, we investigated the bathymetric (1200–3000 m) and longitudinal variation in several measures for nematode taxon (Shannon–Wiener genus diversity, expected genus richness and generic evenness) and functional diversity (trophic diversity, diversity of life history strategies, biomass diversity and phylogenetic diversity). Our goals were to establish the form of the relation between diversity and productivity (measured as seafloor particulate organic carbon or POC flux), and to verify the positive and negative effect of sediment particle size diversity (SED) and the seasonality in POC flux (SVI), respectively, on diversity, as observed for other oceanographic regions and taxa. In addition, we hypothesised that higher taxon diversity is associated with higher functional diversity, which in turn stimulates nematode carbon mineralisation rates (determined from biomass-dependent respiration estimates). Taxon diversity related positively to seafloor POC flux. Phylogenetic diversity (measured as average taxonomic distinctness) was affected negatively by the magnitude and variability in POC flux, and positively by SED. The latter also showed an inverse relation with trophic diversity. Accounting for differences in total biomass between samples, we observed a positive linear relation between taxon diversity and carbon mineralisation in nematode communities. We could, however, not identify the potential mechanism through which taxon diversity may promote this ecosystem function since none of the functional diversity indices related to both diversity and nematode respiration. The present results suggest potential effects of climate change on deep-sea ecosystem functioning, but further also emphasise the need for a better understanding of nematode functions and their response to evolutionary processes

Diversity and structure of nematode communities across mangrove and seagrass vegetations at Gazi Bay, Kenya

Mangrove benthos has long been assumed to rely primarily on mangrove litter fall, but in recent years, several studies have shown that bacteria, macrobenthos and meiobenthos may preferentially utilize more labile sources such as microphytobenthos and inwelled phytoplankton and seagrass detritus from adjacent shallow waters. The relative importance of these different carbon sources for different consumer taxa, however, remains unclear. We have studied the meiofauna at Gazi Bay, Kenya, based upon samples of a dozen stations from the supralittoral down to the shallow subtidal, covering different mangrove and seagrass vegetations. Nematoda were by far the most abundant taxon throughout the area, followed by Oligochaeta and, depending on the station investigated, Harpacticoida, Polychaeta, Kinorhyncha, and Ostracoda. We identified 135 nematoda genera, with a range of 19 – 60 per station. We hypothesized that densities and genus diversity of nematodes could be linked to sediment organic matter (OM) quantity and quality. For both nematodes and oligochaetes, total densities were indeed positively correlated with OM content, but not with C:N ratio as a measure of OM quality. Nematode genus diversity did not show any clear trend with OM quantity or quality. The most common genus overall was Daptonema , followed by Microlaimus, Desmodora, Metachromadora and Spilophorella.We will present data from a nematode community analysis highlighting shifts in community composition and in ‘dominant’ genera across different vegetation types. Finally, we will present results from a short-term field experiment in which the colonization of fresh mangrove litter fall by nematodes was followed using in situ litter bag incubations

The MANUELA database: an integrated database on meiobenthos from European marine waters

An integrated database on meiofauna was developed with the funding of the European Union Network of Excellence on Marine Biodiversity and Ecosystem Functioning (MarBEF). The general aim of the project was to integrate the available information on the structure, dynamics and functional role of marine meiofauna, and in particular nematodes and harpacticoid copepods, into a single database to perform joint analyses. Data collection started in December 2005 and lasted for fifteen months. 83 datasets have been captured. The collected data ranged from the deep-sea to the coastal zone and from the Arctic to the Antarctic, with a focus on the North-East Atlantic region and the North Sea. Meiofaunal data were available for almost 1300 stations, representing some 140 000 distribution records. After a thorough quality control and standardisation, all the received data were uploaded into a value added database using relational database management technology. The integrated database has built-in functionalities, such as sub-selection of datasets based on spatial and/or temporal boundaries, exclusion of rare taxa and combination of data on user defined taxonomic levels. The database also allows the calculation of a variety of diversity indices. Finally, data can be exported to a commonly used data format in statistical analysis software. The advantages of an integrated database include standardisation of species lists, data quality control and bringing together large amounts of information varying over space and time. This allows the users to test hypotheses using data that could never have been collected by the individual scientists involved, thereby greatly increasing the strength of the obtained results and interpretation. Crucial to the success of compiling an integrated database is the data sharing attitude of the contributing scientists and a firm, underpinning data policy