Meiobenthos of the Deep Northeast Atlantic

Article · December 1994with7 Reads
DOI: 10.1016/S0065-2881(08)60061-9
    • he relationship between nematode communities and environmental factors, BIOENV analysis revealed that water depth was an important factor to determine nematode community structure. The previous studies also indicated that the community structure and distribution of marine nematodes were related to water depth (Liu et al., 2007; Vincx et al., 1990). Vincx et al. (1994) pointed out that poor food resources were the most important environmental factor causing decreasing densities of meiofauna with increasing water depth. However, Danovaro et al. (1999) reported that organic matter quality surprisingly increased with water depth. In our study, organic matter increased with increasing water depth (Table 1
    [Show abstract] [Hide abstract] ABSTRACT: A quantitative study on the community structure and biodiversity of free-living marine nematodes and their relationship with environmental factors in the northern South China Sea were carried out based on the samples collected at five stations in the deep sea (from 313 to 1 600 m) and one station in shallow waters (87 m) during the cruise in September, 2010. Results showed that the abundance of marine nematodes ranged from 224 to 1 996 ind./(10 cm2). A total of 69 free-living marine nematode genera, belonging to 26 families and three orders, were identified. The most dominant genera were Sabatieria, Linhystera, Aegialoalaimus and Daptonema according to SIMPER analysis. Results of CLUSTER analysis revealed four types of marine nematode community (or station groups) in the sampling area. In terms of trophic structure, non-selective deposit feeders (1B) and selective deposit feeders (1A) were the dominant trophic types with highest genera numbers and abundances, which implied that organic detritus was the main food source of marine nematodes in the northern South China Sea. The percentage of male nematode was low, ranging from 2.22% to 17.81%, while those of juvenile individuals ranged from 36.99% to 82.09%. For genera level diversity of marine nematodes, Shannon-Wiener diversity indices (H’) ranged from 3.76 to 4.57 and had highly significant negative correlation with water depth. In general, diversity indices H’ at the five stations in deep sea (over 200 m) were lower than that at the station in shallow waters (87 m). BIOENV analysis showed that the most important environmental factor controlling marine nematode communities was water depth.
    Full-text · Article · Jun 2015
    • Nematodes are usually the dominant meiobenthic 30 metazoans in the deep sea, and their numerical dominance increases with water depth with up to more than 90% in some cases (Heip et al. 1985; Vincx et al. 1994). Despite this dominance, the distribution and composition of deep-sea nematode assemblages 35 is still scarcely studied (particularly at species level), and the Indian Ocean is one of the least-studied regions.
    [Show abstract] [Hide abstract] ABSTRACT: The Central Indian Ocean Basin (CIOB) is an important area for prospective mining for polymetallic nodules. However, little is known about the biodiversity or community structure of abyssal benthic assemblages in the area. The aim of this study was to investigate nematode assemblages inhabiting nodule fields in the CIOB in terms of species composition, diversity, density, biomass, size spectra and sex ratio. Samples were collected by box corer from a depth of 5000–5100 m during the 39th cruise of RV Akademik Boris Petrov in 2009. In total, 1066 individuals were examined from 4 stations and 16 samples. The total average density of nematodes recorded in the CIOB was considerably lower than reported from other deep-sea regions (27.17 ± 2.7 inds/10 cm2). Nematode diversity was comparable with that of other deep-sea regions and the composition of the dominant taxa was typical for oceanic basins. A total of 284 morphotypes belonging to 113 genera and 30 families were identified. Chromadoridae (29.6%), Xyalidae (19.3%), Oxystominidae (6.6%) and Desmoscolecidae (5.0%) were the dominant families. Among the genera, Acantholaimus (23.2%), Halalaimus (5.7%), Desmoscolex (4.8%), Theristus (3.5%) and Daptonema (3.4%) were the most numerous. The majority of specimens had a body length in the range of 1000–1500 µm, which is also in accordance with other deep-sea studies. Females were three times more abundant than males at all CIOB stations. Average total nematode biomass (52.39 ± 10.0 mg/m2) was comparable with macrofauna biomass from the same area.
    Full-text · Article · May 2014
    • The richness of the meiofauna was overall comparable to the data available on similar types of habitats and in tropical regions (Gourbault & Renaud-Mornant 1990; Guo et al., 2008; Semprucci et al., 2013). The lowest abundances recorded in the Huvadhoo lagoon could be explained by the wellknown inverse trend between meiofaunal abundance and depth (Alongi & Pichon, 1988; de Bovée et al., 1990; Tietjen, 1992; Vincx et al., 1994; Sommer & Pfannkuche, 2000; Rex et al., 2006). Accordingly, Danovaro et al. (2000) documented a decline in meiofaunal abundance in the continental shelf of the Mediterranean Sea between 40 and 700 m depth.
    [Show abstract] [Hide abstract] ABSTRACT: Huvadhoo Atoll is a little-known and generally uncontaminated atoll of the southern Maldives, although the human pressure is increasing. This study represents the first attempt to characterize the meiofaunal and nematode assemblages of its lagoon both from a taxonomic and functional point of view. The nematode assemblage was made up of a total of 131 genera in 33 families. Desmodoridae, Chromadoridae and Xyalidae represented the richest and most abundant families, followed in terms of abundance by Selachinematidae and Comesomatidae. The nematode richness was overall higher than that reported in the previous studies carried out in the Central part of the archipelago. The diversity patterns revealed higher values than those reported for the back-reefs platforms, so confirming the positive influence of the water depth on the biodiversity of the nematode assemblage. The statistical analysis highlighted a significant taxonomic difference of the assemblages between the stations characterized by fine and medium-coarse sands, respectively, in line with the auto-ecological preferences of the taxa detected. The use of some nematode descriptors for assessing the ecological quality status (EQS) of the lagoon has revealed a slight disturbance in the station close to Viligili, one of the most urbanized islands. However, the summarization of all the descriptors used allows the highlighting of the good EQS of the Huvadhoo lagoon. Thus, the results of this study may be taken as the starting point for the future monitoring of the potential and real impact of the anthropogenic activity on the area over time.
    Full-text · Article · May 2014
    • It is generally accepted that metazoan meiobenthos densities are much more variable on a small scale in the deep sea than in shallow waters. However, there is little information on the scale of this spatial variation and only a few studies consider possible causes' (Vincx et al., 1994). Biogenic structures such as burrows, depressions and mounds produced by the larger macrobenthos clearly influence the distribution of the meiobenthos on small scales, for example within box cores (Thistle and Eckman, 1988).
    [Show abstract] [Hide abstract] ABSTRACT: Meiofaunal density distribution was studied from 400 m to 1500 m depth inside Blanes submarine canyon (NW Mediterranean), and on the eastern open slope in autumn 2003 and spring 2004. Our multidisciplinary approach allowed to study the hydrodynamics and sedimentary processes in the Blanes Canyon that characterize it as highly heterogeneous environment. Inside the canyon area, particle fluxes were higher than on the slope area, increased from autumn to spring and mostly consisted of lithogenic material. Moreover the canyon’s locations experienced more intense bottoms’ currents and sediment disturbance, being reflected in a greater variability of meiobenthic densities, both between stations and sampling times than on the open slope. No clear trends (e.g. declining densities) associated with increasing depths were observed. Contrary in the open slope, current velocities were relatively lower compared with the canyon area and showed lower temporal variability. At the same time, the nutritional quality of the particle fluxes at deeper grounds were higher, probably allowing the meiofaunal densities not to change over time. In conclusion, the meiobenthos in our system apparently showed a higher temporal variability, inside the canyon area, strongly affected by particle fluxes or erosive and sediment-mixing processes linked to current modifications induced by the canyon topography.
    Full-text · Article · Nov 2013
    • In deep-sea sediments, the meiobenthos (typically, individual organism between 32 and 1000 lm in size, but definitions vary between authors) is omnipresent, inhabiting the interstitial spaces between the sediment grains in vast numbers. Nematodes are usually the most abundant metazoan component of deep-sea meiobenthos and, compared to larger size classes, their numerical dominance frequently increases with depth (Thiel, 1975; Vincx et al., 1994; Mokievsky et al., 2007). Nematode communities can be characterized based on abundance and biomass (Standing Stock, SS), feeding types, gender/life stage ratios, and size class distributions which can be used to infer spatial and temporal dynamics of infaunal communities.
    [Show abstract] [Hide abstract] ABSTRACT: Despite recent advances in the knowledge of submarine canyons ecosystems, our understanding of the faunal patterns and processes in these environments is still marginal. In this study, meiobenthic nematode communities (from 300 m to 1600 m depth) obtained in November 2003 and May 2004 at eight stations inside and outside Blanes submarine canyon were analysed for nematode standing stocks (SSs), feeding types and gender-life stage distributions. Environmental data were obtained by sediment traps and current meters, attached to moorings (April 2003–May 2004), and sediments samples analysed for biogeochemistry and grain size (May 2004). In November 2003, nematode SSs decreased with increasing depth (367.2 individuals and 7.31 μg C per 10 cm2 at 388 m water depth to 7.7 individuals and 0.18 μg C per 10 cm2 at 1677 m water depth), showing a significant negative relation (abundance: R2 = 0.620, p = 0.020; biomass: R2 = 0.512, p = 0.046). This was not the case in May 2004 (283.5 individuals and 3.53 μg C per 10 cm2 at 388 m water depth to 490.8 individuals and 4.93 μg C per 10 cm2 at 1677 m water depth; abundance: R2 = 0.003, p = 0.902; biomass: R2 = 0.052, p = 0.587), suggesting a temporal effect that overrides the traditional decrease of SSs with increasing water depth. Both water depth and sampling time played a significant role in explaining nematode SSs, but with differences between stations. No overall differences were observed between canyon and open slope stations. Nematode standing stock (SS) patterns can be explained by taking into account the interplay of phytodetrital input and disturbance events, with station differences such as topography playing an important role. Individual nematode size decreased from November 2003 to May 2004 and was explained by a food-induced genera shift and/or a food-induced transition from a ‘latent’ to a ‘reproductive’ nematode community. Our results suggest that size patterns in nematode communities are not solely governed by trophic conditions over longer periods of time in relatively food-rich environments such as canyons. We hypothesize that food pulses in a dynamic and topographical heterogeneous environment such as canyons regulate nematode size distributions, rather than long-term food availability. Feeding type distributions in the Blanes Canyon did not clearly resemble those from other canyon systems, apart from the spring assemblage at one station in the head of the canyon.
    Full-text · Article · Nov 2013
    • This allowed Romano et al. (this volume-a) to check to which extent meiofaunal communities from the hydrodynamically disturbed canyon floor sediments differ from those of the more stable adjacent western open slope, and whether the deep-sea meiofaunal density varies with time and/or depth (Ingels et al., this volume). Nematodes usually are the most abundant metazoans of deep-sea meio-infauna, with their dominance generally increasing and their standing stocks decreasing with depth, respectively (Mokievsky et al., 2007; Vincx et al., 1994). Nematodes allow examining the trophic status of the deep-sea meiobenthos and investigating community dynamics (Soetaert and Heip, 1995).
    [Show abstract] [Hide abstract] ABSTRACT: This volume compiles a number of scientific papers resulting from a sustained multidisciplinary research effort of the deep-sea ecosystem in the Mediterranean Sea. This started 20 years ago and peaked over the last few years thanks to a number of Spanish and European projects such as PROMETEO, DOS MARES, REDECO, GRACCIE, HERMES, HERMIONE and PERSEUS, amongst others. The geographic focus of most papers is on the NW Mediterranean Sea including the Western Gulf of Lion and the North Catalan margin, with a special attention to submarine canyons, in particular the Blanes and Cap de Creus canyons.
    Full-text · Article · Sep 2013
Show more