Oneirophanta Mutabilis Research Articles

Response of deep-sea deposit-feeders to detrital inputs: A comparison of two abyssal time-series sites

Biological communities on the abyssal plain are largely dependent on detritus from the surface ocean as their main source of energy. Seasonal fluctuations in the deposition of that detritus cause temporal variations in the quantity and quality of food available to these communities, altering their structure and the activity of the taxa present. However, direct observations of energy acquisition in relation to detritus availability across megafaunal taxa in abyssal communities are few. We used time-lapse photography and coincident measurement of organic matter flux from water column sediment traps to examine the impact of seasonal detrital inputs on resource acquisition by the deposit feeding megafauna assemblages at two sites: Station M (Northeast Pacific, 4000 m water depth) and the Porcupine Abyssal Plain Sustained Observatory (PAP-SO, Northeast Atlantic 4850 m water depth). At Station M, studied over 18-months, the seasonal particle flux was followed by a salp deposition event. At that site, diversity in types of deposit feeding was related to seabed cover by detritus. At PAP-SO, studied over 30 months, the seasonal particle flux consisted of two peaks annually. While the two study sites were similar in mean flux (~8.0 mgC m−2 d−1), the seasonality in the flux was greater at PAP-SO. The mean overall tracking at PAP-SO was five times that of Station M (1.9 and 0.4 cm2 h−1, respectively); both are likely underestimated because tracking by some common taxa at both sites could not be quantified. At both sites, responses of deposit-feeding megafauna to the input of detritus were not consistent across the taxa studied. The numerically-dominant megafauna (e.g. echinoids, large holothurians and asteroids) did not alter their deposit feeding in relation to the seasonality in detrital supply. Taxa for which deposit feeding occurrence or rate were correlated to seasonality in particle flux were relatively uncommon (e.g. enteropneusta), known to cache food (e.g. echiurans), or to be highly selective for fresh detritus (e.g. the holothurian Oneirophanta mutabilis). Thus, the degree of seasonality in deposit feeding appeared to be taxon-specific and related to natural history characteristics such as feeding and foraging modes.

Phytopigments as biomarkers of selectivity in abyssal holothurians; interspecific differences in response to a changing food supply

Holothurians dominate the abyssal megabenthos. They are key consumers and bioturbators of surficial sediment. Compounds essential for holothurian reproduction, such as carotenoids, are in short supply in the deep ocean. Holothurians cannot synthesise carotenoids de novo; the compounds are supplied with the flux of phytodetritus. Therefore, the supply of these compounds may play an important role in regulating processes on the seafloor. This study examines the link between the diet of abyssal holothurians and their ovarian carotenoid biochemistry. Phytodetritus, surficial sediment, holothurian gut content and ovaries were sampled in June 2004 and in July 2005 at the Porcupine Abyssal Plain (PAP), NE Atlantic. Gut content chlorophyll a concentration showed that Amperima rosea, Peniagone diaphana and Oneirophanta mutabilis fed selectively on fresh organic matter, although when this was scarce, O. mutabilis was outcompeted and fed on more refractory material. All three species display consistent ovarian carotenoid profiles and have relatively high carotenoid concentrations in their ovaries. Psychropotes longicauda, Paroriza prouhoi, Pseudostichopus aemulatus, P. villosus and Molpadia blakei fed less selectively and exhibited low ovarian carotenoid concentrations with inconsistent profiles. The results suggest that abyssal holothurian ovarian biochemistry is a complex function of OM supply, holothurian feeding guild and reproductive adaptation. Changes in upper ocean biogeochemistry, altering the composition of organic matter reaching the deep-sea floor, may favour certain holothurian species, as suggested by the interspecific differences in holothurian ovarian biochemistry. This may lead to large community changes as seen at the PAP, which can alter the reworking rates of sediment, probably affecting carbon burial. The study also demonstrated that using the presence of biomarkers in gut contents to infer feeding selectivity should be used with caution. Only biomarkers in gut contents that are not present in the tissues of the holothurians (e.g., chlorophyll a) should be used to determine their feeding selectivity.

Lipid, sterols and fatty acid composition of abyssal holothurians and ophiuroids from the North-East Pacific Ocean: Food web implications

The lipid, fatty acid (FA), and sterol composition of two ophiuroids and four holothurians from the abyssal eastern North Pacific were analysed to assess their feeding habits and to ascertain their composition for use in a larger study to examine food web dynamics and trophic ecology. Holothurians were rich in phytosterols and algal derived FA such as docosahexaenoic acid and eicosapentaenoic suggesting tight trophic coupling to phytodetritus. Large proportions of stanols were found, probably a result of enteric bacteria but they may come from sterol metabolism in the holothurians themselves. Oneirophanta mutabilis was distinct with much higher levels of stanols and bacterially derived FA suggesting specific selection of bacteria rich detrital particles or the activity of enteric and integumental bacteria. The ophiuroids sterol and FA compositions differed greatly from the holothurians and reflected consumption of animal material in addition to phytodetritus. Large proportions of energy storage lipids suggested a sporadic food supply. Several unusual fatty acids were found in these abyssal echinoderms. Tetracosahexaenoic acid, 24:6ω3, in ophiuroids and 23:1 in holothurians may be good biomarkers for food web studies. We report the first occurrence of αOH 24:1 in holothurians with none detected in ophiuroids. Its function is presently unknown.

The influence of changing food supply on the lipid biochemistry of deep-sea holothurians

The biochemical response of three species of deep-sea holothurian ( Oneirophanta mutabilis, Pseudostichopus villosus, and Psychropotes longicauda) to temporal variation in food supply at the Porcupine Abyssal Plain (PAP; ∼4850 m water depth in the NE Atlantic) was studied over a period of 22 months. Lipid contents of P. longicauda showed a strong positive correlation with the contents of lipids in the surficial sediments (0–5 mm; Spearman rank correlation, R s=1.0, P<0.001). O. mutabilis did not show the same trend in total lipid, but there was an apparent enrichment of sterol in both particulate organic matter (POM) arriving at the sea floor in September–October 1997 and the tissues of O. mutabilis, suggesting that this species can respond to changing availability of food resources. Lipid contents of P. villosus did not vary temporally, probably because this species feeds on deeper layers of sediment, which show little or no temporal variation in lipid composition or concentration. The biochemical response of holothurians to variations in food supply appears to depend on their feeding mode. Changes in the quantity and quality of organic matter have the potential to change deep-sea benthic community structure.

Evidence for matrotrophy in the viviparous sea cucumber Leptosynapta clarki: A role for the genital haemal sinus?

Summary Viviparity, where the embryos develop in the female reproductive system, is a rare form of reproduction in marine invertebrates, being described in only 14 species of echinoderm. In the intraovarian brooding sea cucumber, Leptosynapta clarki Heding 1928 (cf., Sewell et al. 1995), we used direct evidence (changes in energetic content) to show that significant additional nutrients are provided to the embryos during viviparous development (matrotrophy). In the transition from a structure used to produce gametes to a long-term brooding structure there are visual, histological and transmission electron microscopy (TEM) changes in the structure of the ovarian wall. Changes occur primarily in the cells of the visceral peritoneum and involve an increase in size of the connective tissue/genital haemal sinus (CT/GHS). In the latter part of the brooding period the visceral peritoneum returns to a flattened form, and new oocytes develop along the tubule wall. Similar changes in the intraovarian brooding sea cucumber Oneirophanta mutabilis affinis lead us to suggest that there is a role for the genital haemal sinus in providing nutrition during the brooding period in viviparous echinoderms. Future research is suggested to focus on changes in the ovarian wall structure during the different phases of reproduction (gamete production/brooding) in these species.

Long-term changes in reproductive patterns of the holothurian Oneirophanta mutabilis from the Porcupine Abyssal Plain

Time-series studies (1989–2002) in the NE Atlantic have shown large-scale changes in the composition and structure of the benthic community on the Porcupine Abyssal Plain. Radical changes in the abundance of some species in 1996 led to a significant shift in the way in which organic matter was reprocessed at the seabed. This article examines the reproductive processes of the holothurian Oneirophanta mutabilis collected during the time series. The reproductive biology of O. mutabilis is reviewed. No males were evident in any of the samples. The sex ratio (females: ‘no gender’) was biased significantly towards no-gender individuals. The maximum egg size was 650 μm and there was no evidence of synchrony in reproduction. Significant changes in the oocyte-size distribution and the fecundity of O. mutabilis were noted through time, coinciding with the time of greatest faunal change in the benthic community. There was an increase in the proportion of previtellogenic oocytes and a decrease in the proportion of mature vitellogenic oocytes in 1997 and 1998, in parallel with a significant decrease in fecundity of the post-1996 samples. Samples from 2002 showed a reversal in the reproductive trends, with an increase in the proportion of mature vitellogenic oocytes and fecundity. The results are discussed in relation to large changes in abundance of the epibenthos on the Porcupine Abyssal Plain. It is suggested that the superabundance of certain megafaunal species on the abyssal seafloor affected the availability of trophic resources for O. mutabilis, leading to the changes in its reproductive effort.

Temporal variations in fatty acid composition of deep-sea holothurians: evidence of bentho-pelagic coupling

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 281:109-120 (2004) - doi:10.3354/meps281109 Temporal variations in fatty acid composition of deep-sea holothurians: evidence of bentho-pelagic coupling Ian R. Hudson1,*, David W. Pond2, David S. M. Billett1, Paul A. Tyler1, Richard S. Lampitt1, George A. Wolff3 1Southampton Oceanography Centre, George Deacon Division and University of Southampton, School of Ocean and Earth Science, Empress Dock, Southampton SO14 3ZH, UK 2British Antarctic Survey, Madingley Road, Cambridge CB3 0ET, UK 3Environmental Organic Chemistry and Geochemistry Group, Oceanography Laboratories, Department of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 3BX, UK *Email: irh@soc.soton.ac.uk ABSTRACT: Fatty acid biomarkers were used to examine the diet of deep-sea holothurians. We collected 3 species from the Porcupine Seabight and Porcupine Abyssal Plain, NE Atlantic, between 800 and 4850 m in August 2001 (summer), March 2002 (pre-spring bloom), and October 2002 (autumn). Of these, 2 species, the abyssal Amperima rosea and the bathyal Bathyplotes natans, showed significant variations in fatty acid compositions. These are likely to be seasonal. Polyunsaturated fatty acids (PUFAs) were dominant within muscle tissue of both species during August 2001 and October 2002, in particular 20:4 (n-6), 20:5 (n-3) and 22:6 (n-3). During March 2002, prior to the spring bloom, there were substantially lower proportions of PUFAs in both species, and increased amounts of mono-unsaturated fatty acids (monoenes), particularly the bacterially-derived biomarkers 18:1 (n-7) and non-methyl uninterrupted dienes (NMIDs). In contrast, the fatty acid composition of the third species, the abyssal Deima validum, remained relatively stable, with muscle tissue containing a high proportion of PUFAs during pre- and post-spring-bloom periods. A further 6 species were sampled in March 2002 and October 2002. Across all these species, 3 patterns of fatty composition were evident: (1) Laetmogone violacea had higher proportions of PUFAs in October than in March; (2) Psychropotes longicauda and Benthogone rosea had lower proportions of PUFAs in October than in March; (3) Deima validum, Oneirophanta mutabilis, Paroriza pallens and P. prouhoi had unchanged fatty acid compositions during these contrasting periods. These differences may be related to the varying reproductive strategies of the species. The implications of changes in fatty acids for reproductive processes, and how these could be factors determining allocation of lipid resources in gonads, is discussed. KEY WORDS: Holothurian · Deep sea · Bentho-pelagic coupling · Seasonal flux · NE Atlantic · Lipids Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 281. Online publication date: November 01, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

1-O-Alkylglyceryl Ether Lipids of the Gut Walls and Contents of an Abyssal Holothurian (Oneirophanta mutabilis)

A study of the glyceryl ether composition of free lipids of gut walls and contents of an abyssal holothurian species, Oneirophanta mutabilis has been carried out. A series of saturated and unsaturated 1-O-alkylglyceryl ethers with alkyl side chains ranging from C15 to C21 were detected inthe gut walls and contents of O. mutabilis. Glyceryl ethers accounted for 5-12% of the total free lipids contents. Foregut, midgut and hindgut walls and contents have identical 1-O-alkylglyceryl ether compositions. The C16:0, C16:1, C17:0, C18:0 and C18:1 are the main glyceryl ethers with C18:0 being dominant. The total organic carbon (TOC) and nitrogen (N) contents were also evaluated in gut contents of the digestive tract of O. mutabalis and these decreased from foregut to hindgut. The average assimilation efficiencies were estimated to be 40 and 55% for TOC and N respectively.

A preliminary investigation of the lipids of abyssal holothurians from the north-east Atlantic Ocean

The dominant lipids of seven species of abyssal holothurians (Oneirophanta mutabilis, Pseudostichopus villosus, Psychropotes longicauda, Deima validium, Parariza prouhoi, Amperima rosea and Molpadia blakei) have been examined in detail. Fatty acid compositions are qualitatively similar to those of shallow-water holothurians, but relatively higher amounts of unsaturated compounds in the deep sea animals are ascribed to an adaptation of the latter to maintain membrane fluidity at high pressure and low temperature. The sterol distributions of abyssal holothurians are complex, with mixtures of C26–C30 sterols being present in all of the animals. These are most likely to be dietary in origin; the holothurians substitute Δ5 with Δ7 unsaturation, via Δ5,7 or Δ0 intermediates. 14α-methylcholest-9(11)-enol, which is a common product of de novo biosynthesis in shallow-water holothurians is absent in all of the deep-water species. Furthermore, cholest-7-enol, the dominant product of de novo biosynthesis in shallow water animals, is a relatively minor component in all of the species, except A. rosea. This holothurian is also the only one that appears to assimilate 4α-methylsterols directly and contains high amounts of steryl sulphates. There are significant interspecies differences in the free sterol distributions which may reflect their different feeding strategies or niches.

234Th and 21Pb evidence for rapid ingestion of settling particles by mobile epibenthic megafauna in the abyssal NE Pacific

Particle-scavenged 234Th and 210Pb can be used to trace the fate of particulate matter reaching the deep-sea floor. We used this technique to demonstrate rapid ingestion of particles arriving at the sea floor (at a depth of 4,100 m) by mobile epibenthic holothuroids (Abyssocucumis abyssorum and Oneirophanta mutabilis). Excess 234Th and 210Pb activities of sediment trap material, detrital aggregates from the sea floor, and animal gut contents all were similar while activities of surface sediments (top 0–5 mm) were considerably lower. A simple calculation using the excess 210Pb concentration of two potential food sources, sediment trap material and surface sediments, shows that ∼91% of gut content material of A. abyssorum must have come from material similar to that found in the sediment trap cups. By setting the sediment trap material as age 0, apparent ages of <0–20 d, >100 d, and 12–13 d were estimated for the aggregates, surface sediments, and A. abyssorum guts, respectively. The population of A. abyssorum at this site could potentially process 0.2–4% of the vertical mass flux (m−2 d−1) during the high particle flux period between June and October 1994. The percentage of vertical flux processed could be substantially greater when all of the mobile epibenthic megafauna species are considered.

Areal coverage of the ocean floor by the deep-sea elasipodid holothurian Oneirophanta mutabilis: estimates using systematic, random and directional search strategy simulations

Deep-sea sediment can be markedly modified by the activities of the mobile epibenthic megafauna. Among other factors, the scale and rate of such bioturbations will be influenced by the population density, as well as by the pattern and speed of movement of members of such a faunal group. Any attempt to obtain an estimate of the effects of the activity of such groups on the sediment is accompanied by a number of assumptions about their individual mode of movement. We examined the degree to which these estimates depend on the assumed mode of motion. Speed and behaviour data were recovered from a free-vehicle camera for the elasipodid holothurian Oneirophanta mutabilis, a dominant component of the mobile invertebrate megafauna on the Porcupine Abyssal Plain (PAP), northeast Atlantic. Using these data, we developed a number of simulations to determine the time taken by the PAP population of O. mutabilis to cover 50% of the sediment area ( t 50%) by differing ranging strategies. At a hypothetical population density of 27.78 indiv. × 10 −3 m −2 using a systematic search, t 50% is 12 days whereas for a random ranging strategy, t 50% is 17 years. A simulation incorporating observed distributions of speed and angles of turn, hence approximating the actual behaviour of the holothurian, issued a t 50% of 9.6 years. The behaviour of the animal is shown to have a profound effect on areal coverage times and consequent rates of bioturbation. Simply multiplying mean speed by swath width is shown to be too simplistic an approach.

Tentacular diversity in deep-sea deposit-feeding holothurians: implications for biodiversity in the deep sea

The tentacles of deep-sea holothurians show a wide range of morphological diversity. The present paper examines gross tentacle morphology in surface deposit feeding holothurians from a range of bathymetric depths. Species studied included the elasipods: Oneirophanta mutabilis, Psychropotes longicauda and Benthogone rosea and the aspidochirotids: Paroriza prouhoi, Pseudostichopus sp., Bathyplotes natans and Paroriza pallens. The sympatric abyssal species Oneirophanta mutabilis, Psychropotes longicauda and Pseudostichopus sp. show subtle differences in diet and the structure and filling patterns of the gut that suggest differences in feeding strategies which may represent one mechanism to overcome competition for food resources in an environment where nutrient resources are considered to be, at least periodically, limiting. Interspecific differences in tentacle functional morphology and digestive strategies, which reflects taxonomic diversity could be explained in terms of Sanders'; Stability–Time Hypothesis. Since different tentacle types will turn over sediments to different extents, their impact on sedimentary communities will be enormous so that high diversity in meiofaunal communities may be explained most simply by Dayton and Hessler's Biological Disturbance Hypothesis.

Extraction of Prokaryotic Genomic DNA from Marine Microbial Communities Suitable for Amplification Using the Polymerase Chain Reaction

AbstractWe present a method for extraction of DNA from marine microbial communities and amplification of the small subunit ribosomal RNA gene from the prokaryotic organisms contained therein. Results of cloning, sequencing and phylogenetic analyses are also presented. This DNA extraction technique is specifically designed to be used in conjunction with the Polymerase Chain Reaction (PCR). Emphasis was placed on producing a technique which results in total cell lysis yielding DNA of sufficient purity to facilitate amplification using PCR. Minimisation of surface contamination and procedure suitability for a multi‐sample study were considered to be of prime importance throughout this investigation. As a demonstration of the suitability of the technique, a preliminary analysis of the small subunit ribosomal RNA (SSU rRNA) gene from marine microbial communities was investigated. The amplification reactions are designed to specifically target the SSU rRNA gene from the two primary prokaryotic domains: Bacteria and Archaea sensu Woese (Woese et al., 1990). The primers were designed to amplify a sequence exceeding 1 Kb in length which is sufficient for use in taxonomic and phylogenetic analyses of marine communities (Murray and Schleifer, 1994). The samples used represent spatially and temporally distinct regimes, from the North East Atlantic. These include water samples from open ocean sites and gut contents from a deep sea deposit feeder, Oneirophanta mutabilis (Holothuria: Elasipodida). The analysis shows the identification of a group of unusual Archaea. as‐yet uncultured, in the samples analysed.

Organic and calorific content of the body tissues of deep-sea elasipodid holothurians in the northeast Atlantic Ocean

Data are presented on the biochemical analysis of protein, lipid, carbohydrate and ash for the ovary, testis, gut and body wall of six species of elasipodid holothurians at a variety of stations in the Porcupine Seabight and Abyssal Plain (northeast Atlantic Ocean). Samples were collected between 1980 and 1982. The species investigated were Benthogone rosea, Laetmogone violacea, Oneirophanta mutabilis, Deima validum, Benthodytes sordida and Psychropotes longicauda. Lipid was the dominant soluble constituent of the ovary and protein was dominant in the testis. Tissue calorific content was determined from the biochemical data and by microbomb calorimetry. The ovaries had higher calorific values than the other body tissues when determined by both methods. Comparison of the two methods suggests that the calorific values for testis, gut and body wall are significantly different, and this may be a function of the calcium-carbonate content of these tissues. Total-body calorific value varied from 24.26 J mg-1 ash-free dry weight (AFDW) (5 799 cal g-1 AFDW) to 25.43 J mg-1 AFDW (6 078 cal g-1 AFDW). Total holothurian-body calorific biomass at depths of 1 010, 2 000 and 4 000 m is 0.49, 3.69, and 0.25 kJ m-2 (118, 882, 59.4 cal m-2), respectively. Holothurians form a significant store of energy in the deep sea.