Dominance Of Single Species Research Articles

Mowing increased community stability in semiarid grasslands more than either fencing or grazing.

A substantial body of empirical evidence suggests that anthropogenic disturbance can affect the structure and function of grassland ecosystems. Despite this, few studies have elucidated the mechanisms through which grazing and mowing, the two most widespread land management practices, affect the stability of natural grassland communities. In this study, we draw upon 9 years of field data from natural grasslands in northern China to investigate the effects of gazing and mowing on community stability, specifically focusing on community aboveground net primary productivity (ANPP) and dominance, which are two major biodiversity mechanisms known to characterize community fluctuations. We found that both grazing and mowing reduced ANPP in comparison to areas enclosed by fencing. Grazing reduced community stability by increasing the likelihood of single-species dominance and decreasing the relative proportion of nondominant species. In contrast, mowing reduced the productivity of the dominant species but increased the productivity of nondominant species. As a consequence, mowing improved the overall community stability by increasing the stability of nondominant species. Our study provides novel insight into understanding of the relationship between community species fluctuation-stability, with implications for ecological research and ecosystem management in natural grasslands.

Glebowy bank nasion zbiorowisk leśnych Wielkopolskiego Parku Narodowego – badania wstępne

The aim of this study is to examine the soil seed banks of the following plant communities: the complex of lakeside plant communities (Carici elongate-Alnetum, Fraxino-Alnetum); the Central European oak-hornbeam forest (Galio sylvatici-Carpinetum); the thermophilous oak forest (Potentillo albae-Quercetum), in the course of transformation into the oak-hornbeam forest; the fresh coniferous mixed forest (Querco roboris-Pinetum) and the subcontinental pine forest (Leucobryo-Pinetum). All of these plant communities are located in protected areas of the Wielkopolska National Park. The soil seed banks of an individual communities are compared according to the species richness and species diversity as well as species similarity between the herb-layer and the seed bank. The soil seed banks are mainly composed of autochthonous species. The studied communities differ in size and species richness of the soil seed bank as well as in its species diversity. The indicated parameters decrease along with the decrease in the fertility and humidity of the communities. A statistically significant, moderate, positive correlation of species richness between the herb layer and the soil seed bank is observed. Nevertheless, the species similarity between the herb layer and the seed bank is relatively low, which can be attributed to the following: 1) the dominance of single species is greater in soil seed banks than in herb layer; 2) woody species whose seedlings were not recorded in the herb layer or were recorded very rarely, have a large share in seed banks; 3) seeds of some clonal plants were not recorded in seed banks as these species invest only small resources in generative reproduction.

Moss inhabiting diatoms of Galindez Island, Argentine Islands (the maritime Antarctica) exhibit low diversity and pronounced differentiation

The moss-inhabiting diatom flora has been surveyed for the first time on the Galindez Island, Argentine Islands, the maritime Antarctica. Altogether, 23 diatom taxa belonging to 9 genera were identified. Diatom taxa distribution exhibited considerable variability across the samples and lower species richness compared to the communities surveyed in other Antarctic regions studied earlier - South Shetland Islands and James Ross Island. A pronounced single-species dominance was revealed by the analysis of moss-inhabiting diatom communities’ structure at the majority of moss substrates. The allocation of certain diatom species to the particular moss substrates was detected alongside their complete absence in some samples. The reasons for such moss-inhabiting diatom communities’ variability should be further investigated in follow-up studies.

The spatial configuration of biotic interactions shapes coexistence-area relationships in an annual plant community

The increase of species richness with area is a universal phenomenon on Earth. However, this observation contrasts with our poor understanding of how these species-area relationships (SARs) emerge from the collective effects of area, spatial heterogeneity, and local interactions. By combining a structuralist approach with five years of empirical observations in a highly-diverse Mediterranean grassland, we show that spatial heterogeneity plays a little role in the accumulation of species richness with area in our system. Instead, as we increase the sampled area more species combinations are realized, and they coexist mainly due to direct pairwise interactions rather than by changes in single-species dominance or by indirect interactions. We also identify a small set of transient species with small population sizes that are consistently found across spatial scales. These findings empirically support the importance of the architecture of species interactions together with stochastic events for driving coexistence- and species-area relationships.

Effect of allelopathy on plant performance: a meta-analysis.

Allelopathy (i.e. chemical interactions between plants) is known to affect individual performance, community structure and plant invasions. Yet, a quantitative synthesis is lacking. Here, we performed a meta-analysis of 384 studies that measured allelopathic effects of one species (allelopathy plant) on another species or itself (test plant). Overall, allelopathy reduced plant performance by 25%, but the variation in allelopathy was high. The type of method affected the allelopathic effect: compared to leachates, allelopathy was more negative when residues of allelopathy plants were applied, and less negative when soil conditioned by allelopathy plants was applied. The negative effects of allelopathy diminished with study duration, and increased with concentrations of leachates or residues. Although allelopathy was not significantly related to lifespan, life form or domestication of the interacting plants, it became more negative with increasing phylogenetic distance. Moreover, native plants suffered more from leachates of naturalised alien plants than from leachates of other native plants. Our synthesis reveals that allelopathy could contribute to success of alien plants. The negative relationship between phylogenetic distance and allelopathy indicates that allelopathy might contribute to coexistence of closely related species (i.e. convergence) or dominance of single species.

Increasing signs of degradation of shallow water coral reefs due to repeated bleaching and spatial competition among benthic substrates

Summer bleaching of corals has been prevalent in the coastal waters of India in recent years before the onset of monsoon. Repeated bleaching of shallow water corals has changed the benthic dynamics of reef ecosystems. In the present study two locations, Wandoor and Burmanullah in South Andaman, were identified where such changes have occurred. After 3 years of study, the shift from coral domination to macroalgae and sponge is evident. In Wandoor, fleshy macroalgae (28.80%) have become a dominated benthic substrate and in Burmanullah, sponges (19.50%) have taken over much of reef space. Observation of multispecies domination of macroalgae in Wandoor and single species domination of sponges in Burmanullah has been established through this study of shallow reefs.

Babassu palm (Attalea speciosa Mart.) super-dominance shapes its surroundings via multiple biotic, soil chemical, and physical interactions and accumulates soil carbon: a case study in eastern Amazonia

Aggressive ruderal plant species pose an increasing problem in anthropically degraded lands. They both affect and are affected by other vegetation and by soil fertility in their surroundings. This study explores the case of the babassu palm (Attalea speciosa Mart., Arecaceae), which attains high dominance especially in frequently burned degraded lands throughout former Amazonia. We sought to understand the extent to which babassu palms affect their surroundings. We investigated the interrelationships between different components within the plant-soil continuum, from aboveground vegetation and litter-layer to topsoil (0–5 and 5–15 cm) soil organic matter fractions, and soil physical (texture, porosity, density) and chemical (pH, nutrient contents and topsoil carbon stocks) characteristics. We developed a case-study in two secondary forests in different stages (3 year.-old and 20 year.-old) and sampled 12 plots in each, covering a wide range of babassu biomass proportions (0.3–98.7% of total aboveground biomass). Babassu sequesters soil carbon, as indicated by the significantly higher C:N-ratio in the litter-layer, higher concentration of low-density (labile) organic matter, higher C-concentrations in labile SOM, and an overall increase in belowground C-stocks. The babassu palm decreases aboveground-belowground complexity by building stronger interactions via changes in the litter layer and in SOM-fractions. Our results indicate that single-species dominance can centralize ecosystem interactions to favor the dominant species and that guaranteeing high species diversity and sequestering carbon may constitute mutually exclusive management objectives.

Priority Effects and Nonhierarchical Competition Shape Species Composition in a Complex Grassland Community.

Niche and fitness differences control the outcome of competition, but determining their relative importance in invaded communities—which may be far from equilibrium—remains a pressing concern. Moreover, it is unclear whether classic approaches for studying competition, which were developed predominantly for pairs of interacting species, will fully capture dynamics in complex species assemblages. We parameterized a population-dynamic model using competition experiments of two native and three exotic species from a grassland community. We found evidence for minimal fitness differences or niche differences between the native species, leading to slow replacement dynamics and priority effects, but large fitness advantages allowed exotics to unconditionally invade natives. Priority effects driven by strong interspecific competition between exotic species drove single-species dominance by one of two exotic species in 80% of model outcomes, while a complex mixture of nonhierarchical competition and coexistence between native and exotic species occurred in the remaining 20%. Fungal infection, a commonly hypothesized coexistence mechanism, had weak fitness effects and is unlikely to substantially affect coexistence. In contrast to previous work on pairwise outcomes in largely native-dominated communities, our work supports a role for nearly neutral dynamics and priority effects as drivers of species composition in invaded communities.

Quantitative ethnomedicinal survey of medicinal plants given for cardiometabolic diseases by the non-institutionally trained siddha practitioners of Tiruvallur district, Tamil Nadu, India

Ethnobotanical relevanceThe burden of cardiometabolic diseases such as dyslipidemia, hyperglycemia, hypertension, visceral obesity and atherosclerotic cardiovascular diseases and the use of traditional medicine for the management of such diseases are high in India; hence there is a need to document and analyze such therapies. Aim of the studyThis study documented and analyzed the medicinal plants prescribed for cardiometabolic diseases by the non-institutionally trained siddha practitioners of Tiruvallur district of Tamil Nadu, India. MethodologyThe field survey was conducted between December 2014 to November 2015. Successive free listing assisted with field-walks was used to interview the informants. After assessing the sampling sufficiency using rarefaction curve analysis, indices such as Informant Consensus Factor (Fic) and Index of Agreement on Remedies (IAR) were calculated for the data. The indicators of informant's medicinal plant knowledge such as Shannon's index, equitability index, etc., were regressed with the demographic profile of the informants. ResultsFor this study 70 non-institutionally trained Siddha medical practitioners were approached; the data from 36 practitioners who were treating cardiometabolic diseases were documented. This study recorded the use of 188 species which were used to prepare 368 formulations to treat illnesses categorized under cardiometabolic diseases. In this, 53.04% claims were singletons. Regression analysis showed that single species dominance was reduced and the diversity of medicinal plants was increased with the increase in the age and experience. Increase in the years of formal education increased the equitability in the uses. The plants such as Nelumbo nucifera Gaertn. (cardiovascular diseases), Allium sativum L. (dyslipidemia), Cuminum cyminum L. (hypertension), Macrotyloma uniflorum Verdc. (obesity) and Azadirachta indica A. Juss. (type 2 diabetes) were the highly cited medicinal plants. ConclusionThis survey has identified the plants most commonly used by Siddha practitioners of Tiruvallur district, Tamil Nadu, India for cardiometabolic diseases. The prevalence of chronic, non-communicable metabolic illnesses such as type 2 diabetes, hypertension and obesity are increasing worldwide due to the rapid changes in the lifestyle. These ailments require a life-long care and in such instances, people tend to use complementary therapies in most cases, alongside with conventional therapies. In view of the high use of traditional therapies for treating cardiometabolic illnesses, this study supports the need for more research to evaluate the potential benefits of the treatments and to identify any safety concern.

Impact of fire on the macrofungal diversity in scrub jungles of south-west India

ABSTRACTFortnightly survey in control and fire-impacted regions of scrub jungle of south-west coast of India during south-west monsoon (50 m2 quadrats up to 10 weeks) yielded 34 and 25 species of macrofungi, respectively. The species as well as sporocarp richness were the highest during the fourth week, while the diversity attained the highest during the second week in control region. In fire-impacted region, the species and sporocarp richness and diversity peaked at sixth week. Seven species common to both regions were Chlorophyllum molybdites, Lepiota sp., Leucocoprinus birnbaumii, Marasmius sp. 3, Polyporus sp., Schizophyllum commune and Tetrapyrgos nigripes. The overall sporocarp richness was higher in fire-impacted than in control region. The Jaccard’s similarity between regions was 13.5%, while fortnights of regions ranged from 0% (10th week) to 11.7% (eighth week). Control region showed single-species dominance by Xylaria hypoxylon, while multispecies dominance by Cyathus striatus and Lentinus squarrosulus in fire-impacted region. Except for air temperature, nine abiotic factors significantly differed between control and fire-impacted regions. The Pearson correlation was positive between species richness and phosphorus content in fire-impacted region (r = 0.696), while sporocarp richness was negatively correlated with pH in control region (r = −0.640). Economically viable species were 12 and 10 without overlap in control and fire-impacted regions, respectively.

Diversity and composition of the copepod communities associated with megafauna around a cold seep in the Gulf of Mexico with remarks on species biogeography

In order to characterize the copepod communities associated with tubeworm and mussel aggregations around a hydrocarbon seep in the Green Canyon of the Gulf of Mexico, diversity, abundance, and community composition were analyzed. Also analyzed were species biogeography and the potential connectivity to other chemosynthesis-based habitats. Copepod abundance and biomass were very low among tubeworms and mussels, with 0.22 to 6.08 individuals per 10 cm2 sampled area and 9.02 to 42.43 μg wet weight 10 cm2 sampled area, respectively; but, abundance was significantly higher among the mussels. Fifty-five copepod species were identified, of which most were newly discovered and primarily belonging to the Harpacticoida order. Four copepod species were previously recorded from other food-rich and hard-substrata environments, such as hydrothermal vents or wood falls. Another four species showed close morphological proximity to species described from cold seeps, hydrothermal vents, and wood falls. Copepod diversity and community composition showed no significant differences between the foundation species. However, differences in the relative abundance and dominance of single species indicate a rather homogeneous community in mussel beds and a more heterogeneous community among tubeworms, indicating that foundation species may shape the abundance and community composition of associated copepods at cold seeps.

Ecological observations on the phytoplankton of Nethravati - Gurupura estuary, south west coast of India

The species composition, abundance and diversity of phytoplankton including diatoms, cyanobacteria, dinoflagellates and planktonic green algae, were studied in the NetravathiGurupura estuarine waters near Mangalore, west coast of India. Water samples were collected from three different sampling sites during three different seasons over a period of one year from June 2010 to May 2011 and physico-chemical parameters of water were recorded. A total of 80 species of phytoplankton were identified out of which 54 were diatoms (67.5%), 15 were cyanobacteria (18.75 %), 6 were planktonic green algae (7.5%) and 5 belonged to dinoflagellates (6.25 %). The density of total phytoplankton ranged between 16.94x103 cells/l-1 and 28.64 x103cells/l-1. The maximum density of phytoplankton was observed during post monsoon season coinciding with most stable hydrological conditions. Phytoplankton species diversity was also detected in different sampling stations. ShannonWiener’s (H’) diversity index of phytoplankton population ranged from 1.52 to 2.69. In addition, the species richness index (d’) ranged between 0.42 and 1.98 and evenness index between 0.67 and 0.95 (J’). The diversity indices show the instability of the system particularly during monsoon because of dominance of single species. The diatoms were found to be dominant in these waters.

FLORISTIC DIVERSITY OF WOODY PERENNIALS IN THE HAKGALA STRICT NATURE RESERVE

Sampling by the "gradsect " method found that there were 88 Woody plant species belonging to 65 genera and 36families. The trees were of six fantilics:Lauraceae, Theaceae. Symplocaceae, Myrtaceae, Elaeocarpaceae andRubiaceae. There was no evidence (!l single species dominance in trees. No major tree communities were observed at the lower elevations. but near the peak there is a community at canopy level ol Syzygium umbrosum. Eugeniamabaeoides, and Callophyllum walkeri. There are four dominant species (?lsaplings: Psychotria zevlanica, P. nigra. Maesa perrottetiana, and Lasianthcsoliganthes. of which P. zeylanica appears sometimes to be a dominant singlespecies. The dominant [antilles among the saplings are the Rubiaceae andMyrsinaccae, while the seedlings are dominated by Rubiaceae. Biologicaldiversify is high. and endemism was put at -1-/% ol the total species enumerated.It is an ecologically critical area, which includes 2 endangered species, 2vulnerable, 7 rare, and'; intermediate. This nature reserve, therefore, has ahigh conservation value. Its small size and isolation may jeopardize its longtermviability ifmeasures are not takenfor its complete protection.

Living on the edge: single-species dominance at the Pakistan oxygen minimum zone boundary

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 470:79-99 (2012) - DOI: https://doi.org/10.3354/meps10019 Living on the edge: single-species dominance at the Pakistan oxygen minimum zone boundary Rachel M. Jeffreys1,*, Lisa A. Levin2, Peter A. Lamont3, Clare Woulds4,5, Christine R. Whitcraft2,6, Guillermo F. Mendoza2, George A. Wolff1, Gregory L. Cowie4 1School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, Liverpool L69 3GP, UK 2Center for Marine Biodiversity and Conservation and Integrative Oceanography Division, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California 92093-0218, USA 3Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, UK 4School of GeoSciences, University of Edinburgh, Edinburgh EH9 3JW, UK 5Present address: School of Geography, University of Leeds, University Road, Leeds, West Yorkshire LS2 9JT, UK 6Present address: Biological Sciences, California State University Long Beach, 1250 Beltflower Blvd, Long Beach, California 90840-3702, USA *Email: rachel.jeffreys@liverpool.ac.uk ABSTRACT: Oxygen minimum zones (OMZs) are naturally occurring, low-oxygen water masses that create hypoxic conditions where they impinge on the seafloor. Their lower boundaries are characterised by elevated densities of hypoxia-tolerant fauna and an abundant food supply. The polychaete Linopherus sp. nov. (Amphinomidae) is the dominant taxon at the Pakistan margin (PM) lower OMZ, at near suboxic dissolved oxygen (DO) concentrations of 5 to 8 µM. We explored the response of Linopherus sp. nov. to gradients in oxygen and organic matter (OM) availability from depths of 700 to 1100 m during the inter- and late monsoon periods. Linopherus sp. nov. was present from 800 to 1000 m, and highest densities were found at 850 m. Population size structuring was evident and smaller individuals were present at depths of lowest DO concentrations. Linopherus sp. nov. showed morphological adaptation to low DO, and respiratory surface areas were significantly larger in worms at sites of lowest DO concentrations. Stable carbon isotopes (δ13C) revealed that Linopherus sp. nov. feeds mainly on sedimentary OM while enriched δ15N values suggest that Linopherus sp. nov. also utilises predation as a foraging strategy. Lipid biomarkers indicate an omnivorous lifestyle, in which Linopherus sp. nov. uses phytodetrital, bacterial and invertebrate/carrion food sources. Pulse-chase experiments demonstrated that Linopherus sp. nov. consumes phytodetritus and contributes significantly to OM processing, potentially altering OM quality and thus the availability of food resources to the benthic community. Severe oxygen stress leads to single-species dominance, which in turn simplifies macrofaunal ecosystems and thus reduces trophic complexity. KEY WORDS: Oxygen minimum zone · Hypoxia · Single-species dominance · Organic matter processing · Linopherus · Stable isotopes · Lipid biomarkers Full text in pdf format Supplementary material PreviousNextCite this article as: Jeffreys RM, Levin LA, Lamont PA, Woulds C and others (2012) Living on the edge: single-species dominance at the Pakistan oxygen minimum zone boundary. Mar Ecol Prog Ser 470:79-99. https://doi.org/10.3354/meps10019 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 470. Online publication date: December 06, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Simulations of Long-Term Community Dynamics in Coral Reefs - How Perturbations Shape Trajectories

Tropical coral reefs feature extraordinary biodiversity and high productivity rates in oligotrophic waters. Due to increasing frequencies of perturbations – anthropogenic and natural – many reefs are under threat. Such perturbations often have devastating effects on these unique ecosystems and especially if they occur simultaneously and amplify each other's impact, they might trigger a phase shift and create irreversible conditions.We developed a generic, spatially explicit, individual-based model in which competition drives the dynamics of a virtual benthic reef community – comprised of scleractinian corals and algae – under different environmental settings. Higher system properties, like population dynamics or community composition arise through self-organization as emergent properties. The model was parameterized for a typical coral reef site at Zanzibar, Tanzania and features coral bleaching and physical disturbance regimes as major sources of perturbations. Our results show that various types and modes (intensities and frequencies) of perturbations create diverse outcomes and that the switch from high diversity to single species dominance can be evoked by small changes in a key parameter.Here we extend the understanding of coral reef resilience and the identification of key processes, drivers and respective thresholds, responsible for changes in local situations. One future goal is to provide a tool which may aid decision making processes in management of coral reefs.

Copepodid and adult Argestidae Por, 1986 (Copepoda: Harpacticoida) in the southeastern Atlantic deep sea: diversity and community structure at the species level

Drawing on the example of Argestidae Por, 1986b, community structure and large-scale distribution patterns of harpacticoid copepods at species level were examined in the three southeastern Atlantic deep-sea basins. The study was based on 30 multicorer deployments at depths from 5,035 to 5,655 m during the DIVA-2 expedition. The 1,176 adult and copepodid Argestidae from CIII onwards belong to 114 species. Some species occurred at all five stations; others appeared to be exclusive for single stations. Inclusion of copepodids revealed a higher similarity in species composition among the five stations than consideration of just adults and caused a slight shift toward dominance of single species in the sediments at most locations.

Problems and Needs for Restorationists of Longleaf Pine Ecosystems: A Survey

ABSTRACT: In the southeastern United States, private landowners manage a majority of the forests, and despite their widespread pursuit of longleaf pine (Pinus palustris) restoration, little is known about their motivation, the challenges they face, and their expected outcomes. In 2009, in order to increase understanding of how landowners perceive, practice, and afford longleaf pine restoration, we conducted a written survey of managers in nine southeastern states. Motivations for longleaf pine restoration included both profit, as at least 50% of the respondents emphasized longleaf pine's economic value, and non-profit (wildlife habitat, natural heritage, biological diversity) goals. Our results also show that time and effort are not limiting factors, while availability of financial support and the cost of restoration are. Over 80% of respondents relied on some form of financial support for their restoration projects. The vast majority (78%) of restoration practitioners identified single-species dominance ...

Temperature mediates competitive exclusion and diversity in benthic microalgae under different N:P stoichiometry

AbstractThe dependence of competitive interactions on abiotic conditions is attracting increasing interest in the face of globally rising temperatures and altered biogeochemical cycles of major nutrients. In a microcosm experiment involving a natural inoculum of benthic microalgae, temperature and nutrient supply ratios were manipulated in order to test three main hypotheses: (1) temperature and nutrient supply ratios determine species composition and diversity of the assemblage, (2) the identity of the dominating species depends on nutrient supply and temperature, and (3) higher temperature leads to faster competitive exclusion and thus more rapid decline in species richness. Over a period of 7 weeks, algal biomass reached an equilibrium carrying capacity, with was higher at colder temperatures and intermediate N:P supply ratios (N:P = 16). Initial growth rate increased with temperature and under high P‐supply. Species richness in the stationary phase of the experiment decreased with increasing temperature, reflecting a higher extinction rate in the warmer treatments, which were also characterized by higher dominance of single species. Thus, increasing temperature both altered the identity of the dominating species and accelerated competitive displacement. This experiment thus indicates that warming might influence outcome and temporal dynamics in species interactions, and thereby eventually local diversity.

Effect of tree plantation on composition, standing biomass and diversity of ground vegetation on sodic land of North-East region of Uttar Pradesh

The structure,composition, yield and diversity of ground vegetation under eight tree plantations on sodic wasteland were compared among each other and with an adjacent open stand. The communities were floristically distinct from each other on different stands. However, the community on open stand was relatively more similar with the communities under Eucalyptus tereticornis and Acacia catechu plantation stands than with other stands. The herbage yield was lowest on open stand and it was higher under Acacia auriculiformis and Casuarina equisetifolia plantation stands. The contribution of grasses to the total herbage yield was maximum (98%) on open stand and minimum (27%) under C. equisetifolia plantation stand. Herbage yield in the present study also indicated an inverse relationship with soil ESP and pH, thus suggesting that on improving the sodic level of the soil, the herbage yield also increased. Shannon – Wiener diversity was lower, while concentration of dominance was higher for ground vegetation on open stand than any of the plantation stand. Among the plantation stands, diversity was higher under A. catechu, E. tereticornis and Terminalia arjuna plantation stands than under other plantation stands. Diversity tended to show a positive relation with the herbage yield, whereas the relationships between diversity and soil ESP and pH were negative. Dominance-diversity curves for all the herbaceous communities fit the geometric series. Single species dominance is more pronounced in the community on open stand than the communities under tree plantation stands.

Ecology and Biogeography of Free-Living Nematodes Associated with Chemosynthetic Environments in the Deep Sea: A Review

BackgroundHere, insight is provided into the present knowledge on free-living nematodes associated with chemosynthetic environments in the deep sea. It was investigated if the same trends of high standing stock, low diversity, and the dominance of a specialized fauna, as observed for macro-invertebrates, are also present in the nematodes in both vents and seeps.MethodologyThis review is based on existing literature, in combination with integrated analysis of datasets, obtained through the Census of Marine Life program on Biogeography of Deep-Water Chemosynthetic Ecosystems (ChEss).FindingsNematodes are often thriving in the sulphidic sediments of deep cold seeps, with standing stock values ocassionaly exceeding largely the numbers at background sites. Vents seem not characterized by elevated densities. Both chemosynthetic driven ecosystems are showing low nematode diversity, and high dominance of single species. Genera richness seems inversely correlated to vent and seep fluid emissions, associated with distinct habitat types. Deep-sea cold seeps and hydrothermal vents are, however, highly dissimilar in terms of community composition and dominant taxa. There is no unique affinity of particular nematode taxa with seeps or vents.ConclusionsIt seems that shallow water relatives, rather than typical deep-sea taxa, have successfully colonized the reduced sediments of seeps at large water depth. For vents, the taxonomic similarity with adjacent regular sediments is much higher, supporting rather the importance of local adaptation, than that of long distance distribution. Likely the ephemeral nature of vents, its long distance offshore and the absence of pelagic transport mechanisms, have prevented so far the establishment of a successful and typical vent nematode fauna. Some future perspectives in meiofauna research are provided in order to get a more integrated picture of vent and seep biological processes, including all components of the marine ecosystem.