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William E. Browne - One of the best experts on this subject based on the ideXlab platform.
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kruppel like factor gene function in the ctenophore Mnemiopsis Leidyi assessed by crispr cas9 mediated genome editing
Development, 2021Co-Authors: Jason S Presnell, William E. BrowneAbstract:The Kruppel-like factor (Klf) gene family encodes transcription factors that play an important role in the regulation of stem cell proliferation, cell differentiation and development in bilaterians. Although Klf genes have been shown to specify functionally various cell types in non-bilaterian animals, their role in early-diverging animal lineages has not been assessed. Thus, the ancestral activity of these transcription factors in animal development is not well understood. The ctenophore Mnemiopsis Leidyi has emerged as an important non-bilaterian model system for understanding early animal evolution. Here, we characterize the expression and functional role of Klf genes during M. Leidyi embryogenesis. Zygotic Klf gene function was assessed with both CRISPR/Cas9-mediated genome editing and splice-blocking morpholino oligonucleotide knockdown approaches. Abrogation of zygotic Klf expression during M. Leidyi embryogenesis resulted in abnormal development of several organs, including the pharynx, tentacle bulbs and apical organ. Our data suggest an ancient role for Klf genes in regulating endodermal patterning, possibly through regulation of cell proliferation.
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kruppel like factor gene function in the ctenophore Mnemiopsis Leidyi assessed by crispr cas9 mediated genome editing
bioRxiv, 2020Co-Authors: Jason S Presnell, William E. BrowneAbstract:The Kruppel-like factor (Klf) gene family encodes for transcription factors that play an important role in the regulation of stem cell proliferation, cell differentiation, and development in bilaterians. While Klf genes have been shown to be expressed in various cell types in non-bilaterian animals, their functional role in early diverging animal lineages has not been assessed. Thus, the ancestral activity of these transcription factors in animal development is not well understood. The ctenophore Mnemiopsis Leidyi has emerged as an important non-bilaterian model system for understanding early animal evolution. Here we characterize the expression and functional role of Klf genes during M. Leidyi embryogenesis. Zygotic Klf gene function was assessed with both CRISPR/Cas9-mediated genome editing knockout and splice-blocking morpholino oligonucleotide knockdown approaches. Abrogation of zygotic Klf expression during M. Leidyi embryogenesis results in the irregular development of several organs including the pharynx, tentacle bulbs, and apical organ. Our data suggest an ancient role for Klf genes in regulating endodermal patterning.
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Still Enigmatic: Innate Immunity in the Ctenophore Mnemiopsis Leidyi.
Integrative and comparative biology, 2019Co-Authors: Nikki Traylor-knowles, Lauren E. Vandepas, William E. BrowneAbstract:Innate immunity is an ancient physiological response critical for protecting metazoans from invading pathogens. It is the primary pathogen defense mechanism among invertebrates. While innate immunity has been studied extensively in diverse invertebrate taxa, including mollusks, crustaceans, and cnidarians, this system has not been well characterized in ctenophores. The ctenophores comprise an exclusively marine, non-bilaterian lineage that diverged early during metazoan diversification. The phylogenetic position of ctenophore lineage suggests that characterization of the ctenophore innate immune system will reveal important features associated with the early evolution of the metazoan innate immune system. Here, we review current understanding of the ctenophore immune repertoire and identify innate immunity genes recovered from three ctenophore species. We also isolate and characterize Mnemiopsis Leidyi cells that display macrophage-like behavior when challenged with bacteria. Our results indicate that ctenophores possess cells capable of phagocytosing microbes and that two distantly related ctenophores, M. Leidyi and Hormiphora californiensis, possess many candidate innate immunity proteins.
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the maternal zygotic transition and zygotic activation of the Mnemiopsis Leidyi genome occurs within the first three cleavage cycles
Molecular Reproduction and Development, 2017Co-Authors: Phillip L Davidson, Christine E Schnitzler, Bernard J Koch, Athanasios D. Baxevanis, Jonathan Q Henry, William E. BrowneAbstract:The maternal-zygotic transition (MZT) describes the developmental reprogramming of gene expression marked by the degradation of maternally supplied gene products and activation of the zygotic genome. While the timing and duration of the MZT vary among taxa, little is known about early stage transcriptional dynamics in the non-bilaterian phylum Ctenophora. We sought to better understand the extent of maternal mRNA loading and subsequent differential transcript abundance during the earliest stages of development by performing comprehensive RNA-sequencing-based analyses of mRNA abundance in single- and eight-cell-stage embryos in the lobate ctenophore Mnemiopsis Leidyi. We found 1,908 contigs with significant differential abundance between single- and eight-cell stages, of which 1,208 contigs were more abundant at the single-cell stage and 700 contigs were more abundant at the eight-cell stage. Of the differentially abundant contigs, 267 were exclusively present in the eight-cell samples, providing strong evidence that both the MZT and zygotic genome activation (ZGA) have commenced by the eight-cell stage. Many highly abundant transcripts encode genes involved in molecular mechanisms critical to the MZT, such as maternal transcript degradation, serine/threonine kinase activity, and chromatin remodeling. Our results suggest that chromosomal restructuring, which is critical to ZGA and the initiation of transcriptional regulation necessary for normal development, begins by the third cleavage within 1.5 hours post-fertilization in Mnemiopsis Leidyi. This article is protected by copyright. All rights reserved
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Establishing and maintaining primary cell cultures derived from the ctenophore Mnemiopsis Leidyi.
The Journal of Experimental Biology, 2017Co-Authors: Lauren E. Vandepas, Kaitlyn J. Warren, Chris T. Amemiya, William E. BrowneAbstract:We have developed an efficient method for the preparation and maintenance of primary cell cultures isolated from adult Mnemiopsis Leidyi, a lobate ctenophore. Our primary cell cultures are derived from tissue explants or enzymatically dissociated cells, and maintained in a complex undefined ctenophore mesogleal serum. These methods can be used to isolate, maintain and visually monitor ctenophore cells to assess proliferation, cellular morphology and cell differentiation in future studies. Exemplar cell types that can be easily isolated from primary cultures include proliferative ectodermal and endodermal cells, motile amebocyte-like cells, and giant smooth muscle cells that exhibit inducible contractile properties. We have also derived 'tissue envelopes' containing sections of endodermal canal surrounded by mesoglea and ectoderm that can be used to monitor targeted cell types in an in vivo context. Access to efficient and reliably generated primary cell cultures will facilitate the analysis of ctenophore development, physiology and morphology from a cell biological perspective.
Lindsay J. Sullivan - One of the best experts on this subject based on the ideXlab platform.
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gut evacuation of larval Mnemiopsis Leidyi a agassiz ctenophora lobata
Journal of Plankton Research, 2010Co-Authors: Lindsay J. SullivanAbstract:Despite their potential importance as predators, the early life-history stages of ctenophores are relatively understudied. Measurements of digestion times for larvae are especially limited compared with adults, even though these measurements are required to calculate feeding rates using gut content analysis. This study reports digestion times for larval Mnemiopsis Leidyi for a wide range of prey, Larval M. Leidyi consumed the copepodite and naupliar stages of copepods, polychaete larvae, bivalve larvae, rotifers, rotifer eggs, ciliates and flagellates. Digestion times varied significantly among prey taxa and ranged from ~ 1 min for aloricate ciliates to 2 h for copepodites. Although ciliates and flagellates are frequently observed in ctenophore guts, feeding on protistan microplankton cannot be quantified adequately using gut content analysis because these prey items are often digested too rapidly to be identified in ctenophore guts.
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Preservation of the larval ctenophore Mnemiopsis Leidyi A. Agassiz (Ctenophora, Lobata)
Journal of Plankton Research, 2009Co-Authors: Lindsay J. Sullivan, Dian J. GiffordAbstract:Mnemiopsis Leidyi larvae were preserved quantitatively for up to 1 year in 5―20% acid Lugol's solution. The highest preservation efficiency and least shrinkage and deformation occurred in the 5% treatment.
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growth and feeding rates of the newly hatched larval ctenophore Mnemiopsis Leidyi a agassiz ctenophora lobata
Journal of Plankton Research, 2007Co-Authors: Lindsay J. Sullivan, Dian J. GiffordAbstract:Mnemiopsis Leidyi. larvae depend on microplankton ( 0.5 mm in length and can successfully capture and consume mesozooplankton prey. Feeding and growth rates of newly hatched M. Leidyi larvae were measured in controlled laboratory experiments. When fed natural microplankton assemblages, newly hatched larvae consumed significant quantities of both autotrophic and heterotrophic prey, including diatoms, phototrophic, heterotrophic and mixotrophic dinoflagellates, euglenoid flagellates, aloricate and tintinnid ciliates, and rotifers. Average per capita clearance rates were 1.99-7.59 mL individual -1 h -1 (X = 4.01 mL individual -1 h -1 ; SD = 1.95) and total per capita ingestion was 0.01-4.70 μg C individual -1 day -1 x 10 2 (X = 0.83 μg C individual -1 day -1 × 10 2 ; SD = 1.89). Larval growth rates were -0.13 to 0.56 mm individual -1 day -1 (equivalent to -1.72 to 4.33 μgC individual -1 day -1 ) over a range of larval sizes from 0.5 ( 2 weeks, and growth rate decreased when larvae reached 4-5 mm in length, corresponding to the beginning of their morphological transition from tentaculate to lobate feeding mode. The gross growth efficiency of larvae fed natural microplankton assemblages was ∼3%.
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Feeding Efficiency of the Larval Ctenophore Mnemiopsis Leidyi A. Agassiz (Ctenophora, Lobata)
Journal of Plankton Research, 2006Co-Authors: Rebecca J. Waggett, Lindsay J. SullivanAbstract:Larval stages of the ctenophore Mnemiopsis Leidyi rely on metazoan prey, such as Acartia tonsa nauplii and copepodites, to support high growth rates. However, M. Leidyi larvae 2.0 mm, nauplii REs plateaued at a mean of 91.03 ± 1.70%. All larvae 2.5 mm reached a maximum copepodite RE of 63.75 ± 3.01%.
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diet of the larval ctenophore Mnemiopsis Leidyi a agassiz ctenophora lobata
Journal of Plankton Research, 2004Co-Authors: Lindsay J. Sullivan, Dian J. GiffordAbstract:Larvae and post-larvae of the lobate ctenophore Mnemiopsis Leidyi consumed significant quantities of microphytoplankton and microzooplankton prey in controlled experiments where they were fed in situ assemblages of microplankton prey. Prey taxa ingested included phototrophic and heterotrophic dinoflagellates, choreotrich ciliates, cyclotrich ciliates and euglenoid flagellates. Per capita clearance and ingestion rates varied with consumer size, prey taxon and prey abundance. Average per capita clearance rates for the 11 size classes of larvae and post-larvae examined ranged from 9 to 230 mL individual � 1 h � 1 . Average per capita clearance rates for tentaculate-stage, transition-stage and lobate-stage individuals were 40, 31 and 95 mL individual � 1 h � 1 , respectively. Total ingestion rate varied similarly with consumer size, prey taxon and prey abundance, ranging from 1 to 6259% body carbon day � 1 . All size classes of M. Leidyi larvae and post-larvae derived more nutrition from dinoflagellates than from ciliates. Both positive and negative selection of specific prey taxa were observed, and varied with larval size and prey taxonomic composition. The results contradict the prevailing view that all life history stages of M. Leidyi are primarily carnivorous. The measured clearance rates are sufficiently high that the larvae, when abundant, have the potential to exert a significant predation impact on their prey populations in the water column. Understanding the processes that influence survival during early developmental stages may provide one key to understanding the initiation and maintenance of the adult M. Leidyi blooms that are commonly observed in coastal waters.
Jennifer E. Purcell - One of the best experts on this subject based on the ideXlab platform.
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aggregations of the invasive ctenophore Mnemiopsis Leidyi in a hypersaline environment the mar menor lagoon nw mediterranean
Aquatic Invasions, 2013Co-Authors: Macarena Marambio, Jennifer E. Purcell, Ignacio Franco, Antonio Canepa, Elena Guerrero, Veronica FuentesAbstract:The ctenophore Mnemiopsis Leidyi, a species native to estuaries and coastal regions of the western Atlantic Ocean, was first introduced into the Black Sea in the early 1980s, where it negatively affected zooplankton biodiversity and biomass, and commercial fisheries. This invasive ctenophore was first reported along the Spanish Mediterranean coast in 2009. In 2012, new blooms of this species were reported in the hypersaline and largest coastal lagoon of the Western Mediterranean basin, the Mar Menor lagoon, Spain. Sampling in the lagoon during summer 2012 showed an average abundance of 23.4 ctenophores 100 m -3 , in early August, declining to 8.2 ctenophores 100 m -3 by early September. The population contained only adults (total length 19 to 79 mm), which increased in size through the summer. Generalized additive models suggested M. Leidyi abundance was significantly related to temperature, but not to salinity or depth. The Mar Menor lagoon is an anthropogenically-disturbed habitat that may favour this species. Blooms of M. Leidyi in the Mar Menor lagoon are of great concern given its negative impacts in previously invaded habitats.
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blooms of the invasive ctenophore Mnemiopsis Leidyi span the mediterranean sea in 2009
Hydrobiologia, 2010Co-Authors: Veronica Fuentes, Jennifer E. Purcell, Dacha Atienza, Josep Maria Gili, Dror L Angel, Keith M Bayha, Dor Edelist, Cesar BordehoreAbstract:Blooms of the invasive ctenophore, Mnemiopsis Leidyi, occurred in 2009 along the Mediterranean Sea coasts of Spain and Israel. This voracious zooplanktivore spread throughout the Black Sea basin after its introduction in the early 1980s, throughout northern European coastal waters, and now occurs throughout the Mediterranean Sea. M. Leidyi occurred throughout the summer along the entire Catalan Spanish and Israeli coasts in 2009. Those locations had high temperatures (18–26°C) and salinities (37–38) during the blooms. The patterns of abundance of large jellyfish along the Catalan coast were unusual in 2009, with low numbers during July, August, and September when ctenophores were abundant. Small populations of those potential predators and food competitors of M. Leidyi could have contributed to the ctenophore bloom. The identity of the ctenophores from Spain and Israel was confirmed as M. Leidyi by molecular analysis based on DNA sequencing of the nuclear internal transcribed spacer (ITS) regions. This is the first molecular confirmation of M. Leidyi in the Mediterranean Sea. Most ctenophores had an ITS genotype previously found in M. Leidyi from other invaded regions (the Black, Azov, and Mediterranean seas), as well as native regions in the United States, suggesting common ancestry. Based on the circulation patterns of Mediterranean surface waters and shipping activities, we conclude that the spread of M. Leidyi in the Mediterranean probably resulted from re-introductions by ballast water transport and subsequent distribution by currents. We also conclude that the near-simultaneous blooms in opposite ends of both the Mediterranean basins indicate that M. Leidyi is resident around the Mediterranean. We discuss environmental conditions, food, and predators of M. Leidyi in both regions that would influence the future effects of this voracious consumer on the pelagic food web of the Mediterranean Sea.
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First records of Mnemiopsis Leidyi A. Agassiz 1865 off the NW Mediterranean coast of Spain
Aquatic Invasions, 2009Co-Authors: Veronica Fuentes, Dacha Atienza, Josep Maria Gili, Jennifer E. PurcellAbstract:The comb jelly Mnemiopsis Leidyi was first reported in July 2009 along the Spanish coast of the NW Mediterranean Sea and occurred throughout the summer (last report 26 September 2009). Large numbers of the ctenophore were reported by many participants of the "Medusa Project". The high concentrations of M. Leidyi along the Spanish coast, together with its blooms earlier this year in Israel, suggests establishment in the Mediterranean Sea. This is of great concern because of the well-known effects of M. Leidyi on marine ecosystems and the consequences for commercial fisheries.
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invasive ctenophore Mnemiopsis Leidyi in limfjorden denmark in late summer 2007 assessment of abundance and predation effects
Aquatic Invasions, 2007Co-Authors: Hans Ulrik, Line Bottiger, Caroline V Madsen, Jennifer E. PurcellAbstract:Abstract The invasive ctenophore, Mnemiopsis Leidyi , was recently observed for the first time in Danish waters where it was widely distributed during the summer of 2007. In certain areas, including Limfjorden, it exhibited mass occurrence. In this study, we assess the abundance of M. Leidyi in Limfjorden in the late summer of 2007 and give a preliminary evaluation of the predation effects of this ctenophore. On two cruises in August and September, M. Leidyi was found in every net sample from 9 locations in Limfjorden. The population densities were high, up to more than 800 individuals m -3 in the innermost part, but body lengths were small (5 to 15 mm). The bio-volumes were very high (100 and 300 ml m -3 ) in the central parts of Limfjorden and are even greater than those from the Black Sea, where the greatest mean bio-volume was about 184 ml m -3 in the autumn of 1989 when the zooplankton and fish stocks collapsed. The possible ecological consequences of the mass occurrence of this ctenophore are discussed. Key words: Ctenophora, comb jelly, alien species, jellyfish, zooplankton,
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effects of low dissolved oxygen on zooplankton predation by the ctenophore Mnemiopsis Leidyi
Marine Ecology Progress Series, 2004Co-Authors: Mary Beth Decker, Denise L Breitburg, Jennifer E. PurcellAbstract:The occurrence of low dissolved oxygen (DO), caused by vertical stratification and excess nutrient inputs, is an important and widely occurring physical feature in aquatic systems. Because some gelatinous species, such as the lobate ctenophore Mnemiopsis Leidyi are more tolerant of low DO concentrations than their prey and competitors, hypoxia may have profound effects on trophic interactions. Predation, clearance and digestion rates of ctenophores feeding on zooplankton (primarily Acartia tonsa) were measured at 1.0, 2.0, 3.0 mg l -1 and air-saturated (approximately 7 mg l -1 ) DO. Clearance of zooplankton by large ctenophores (mean 22.5 ml, range 7 to 46 ml) was greater at low DO concentrations than under normoxic conditions. In contrast, consumption of zooplankton by small (mean 2.9 ml, range 1 to 10 ml) M. Leidyi did not differ among DO levels. Similarly, ctenophore digestion rates were unchanged at oxygen concentrations as low as 1 mg l -1 . Jumping frequency of A. tonsa copepods decreased significantly with decreasing DO concentration (1.0, 2.0, 3.0 mg l -l and air-saturated). Such changes in prey behavior in low DO could affect both encounter and capture rates, potentially making less-tolerant prey more vulnerable to predation in hypoxic waters. Gelatinous species, which are more tolerant of hypoxia than fishes, may be able to inhabit regions of low oxygen that are avoided by zooplanktivorous fishes with high oxygen requirements. This could lead to dominance of gelatinous predators in areas affected by severe hypoxia and might alter energy pathways in these systems.
J. H. Costello - One of the best experts on this subject based on the ideXlab platform.
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ambient fluid motions influence swimming and feeding by the ctenophore Mnemiopsis Leidyi
Journal of Plankton Research, 2014Co-Authors: Kelly R Sutherland, J. H. Costello, Sean P Colin, John O DabiriAbstract:Planktonic organisms are exposed to turbulent water motion that affects the fundamental activities of swimming and feeding. The goal of this study was to measure the influence of realistic turbulence levels on (i) swimming behavior and (ii) fluid interactions during feeding by the lobate ctenophore, Mnemiopsis Leidyi, a highly successful suspension-feeding predator. A laboratory turbulence generator produced turbulence (e = 0.5–1.4 × 10^(−6) W kg^(−1)) representative of a field site in Woods Hole, MA, USA. Compared with still water, M. Leidyi avoided regions in the experimental vessel where turbulence was greatest (e = 1.1–1.4 × 10^(−6) W kg^(−1)) by increasing its swimming speeds and accelerations. Both laboratory and in situ particle image velocimetry data demonstrated that feeding currents of M. Leidyi were eroded by ambient fluid motions. Despite this, the overall flux to the feeding structures remained constant due to higher swimming speeds in turbulent conditions. Instantaneous shear deformation rates produced by background turbulence were higher than those produced by ctenophore feeding currents and frequently exceeded the published escape thresholds of copepod prey. Feeding current erosion and fluid mechanical signal noise within turbulent flows affect the mechanics of predator–prey interactions during suspension feeding by the ctenophore M. Leidyi.
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Transitions of Mnemiopsis Leidyi (Ctenophora: Lobata) from a native to an exotic species: a review
Hydrobiologia, 2012Co-Authors: J. H. Costello, K. M. Bayha, H. W. Mianzan, T. A. Shiganova, J. E. PurcellAbstract:The genus Mnemiopsis is comprised of a single species, Mnemiopsis Leidyi A. Agassiz, 1865, that has recently made the transition from a distribution limited to the Atlantic coasts of North and South America to an invasive range that includes the Black, Caspian, Mediterranean, North, and Baltic seas. We review the foundations of the ctenophore’s invasive success, which include the source-sink dynamics that characterize Mnemiopsis populations in temperate coastal waters where the ctenophore achieves its highest biomass levels and ecosystem impacts. Within its native temperate range, Mnemiopsis is frequently a dominant, seasonal, colonizing species with limited dispersal capacities. Cross-oceanic transport within ballast waters of intercontinental shipping vessels has altered this dispersal limitation and initiated a rapid global spread of Mnemiopsis . Owing to continuing transport via transoceanic shipping, we anticipate continued range expansion and review the variables most likely to determine whether introduction of Mnemiopsis to a novel community results in an inconspicuous addition or a disruptive invasion.
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Life-stage dependent, in situ dietary patterns of the lobate ctenophore Mnemiopsis Leidyi Agassiz 1865
Journal of Plankton Research, 2005Co-Authors: R. Rapoza, D. Novak, J. H. CostelloAbstract:Analysis of in situ gut contents of the ctenophore Mnemiopsis Leidyi collected during summer months of 1998 at Woods Hole, MA, USA indicates that dietary changes accompanied development of this zooplankter. The transition from cydippid to lobate morphologies involved a shift from a micro-planktonic diet dominated by protists to a metazoan-based diet. Dietary diversity increased rapidly during the transition from cydippid to lobate stage but remained essentially similar through most (>3.0 cm total length) of the lobate stage. These stage-dependent dietary differences may have important implications for understanding population dynamics of M. Leidyi.
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Sampling field distributions of Mnemiopsis Leidyi (Ctenophora, Lobata): planktonic or benthic methods?
Journal of Plankton Research, 2003Co-Authors: J. H. Costello, H. W. MianzanAbstract:SCUBA observations confirm dense aggregations of the ctenophore Mnemiopsis Leidyi in surface and bottom layers of waters off southern Argentina. These observations are consistent with results from prior studies indicating directed vertical migration of M. Leidyi.
Dian J. Gifford - One of the best experts on this subject based on the ideXlab platform.
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Preservation of the larval ctenophore Mnemiopsis Leidyi A. Agassiz (Ctenophora, Lobata)
Journal of Plankton Research, 2009Co-Authors: Lindsay J. Sullivan, Dian J. GiffordAbstract:Mnemiopsis Leidyi larvae were preserved quantitatively for up to 1 year in 5―20% acid Lugol's solution. The highest preservation efficiency and least shrinkage and deformation occurred in the 5% treatment.
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growth and feeding rates of the newly hatched larval ctenophore Mnemiopsis Leidyi a agassiz ctenophora lobata
Journal of Plankton Research, 2007Co-Authors: Lindsay J. Sullivan, Dian J. GiffordAbstract:Mnemiopsis Leidyi. larvae depend on microplankton ( 0.5 mm in length and can successfully capture and consume mesozooplankton prey. Feeding and growth rates of newly hatched M. Leidyi larvae were measured in controlled laboratory experiments. When fed natural microplankton assemblages, newly hatched larvae consumed significant quantities of both autotrophic and heterotrophic prey, including diatoms, phototrophic, heterotrophic and mixotrophic dinoflagellates, euglenoid flagellates, aloricate and tintinnid ciliates, and rotifers. Average per capita clearance rates were 1.99-7.59 mL individual -1 h -1 (X = 4.01 mL individual -1 h -1 ; SD = 1.95) and total per capita ingestion was 0.01-4.70 μg C individual -1 day -1 x 10 2 (X = 0.83 μg C individual -1 day -1 × 10 2 ; SD = 1.89). Larval growth rates were -0.13 to 0.56 mm individual -1 day -1 (equivalent to -1.72 to 4.33 μgC individual -1 day -1 ) over a range of larval sizes from 0.5 ( 2 weeks, and growth rate decreased when larvae reached 4-5 mm in length, corresponding to the beginning of their morphological transition from tentaculate to lobate feeding mode. The gross growth efficiency of larvae fed natural microplankton assemblages was ∼3%.
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seasonal refugia shoreward thermal amplification and metapopulation dynamics of the ctenophore Mnemiopsis Leidyi in narragansett bay rhode island
Limnology and Oceanography, 2006Co-Authors: John H. Costello, Dian J. Gifford, Barbara K Sullivan, D Van Keuren, L J SullivanAbstract:The lobate ctenophore Mnemiopsis Leidyi occurs throughout Narragansett Bay, Rhode Island, during warm summer months but is often undetectable in the central portion of the bay during winter months. During 2 yr of weekly sampling, we found that M. Leidyi populations in a shallow embayment, Greenwich Cove, either overwintered or were only briefly absent during winter. The Greenwich Cove population reproduced weeks earlier and reached higher average and peak population concentrations than open-bay populations. Shallow embayment populations such as that in Greenwich Cove probably serve as source populations that inoculate the main region of the bay by advective transport in the spring months. We propose that earlier occurrences of M. Leidyi during recent years are due to amplification of pulsed spring warming events that permit early reproduction in the shallow embayments that serve as source regions for M. Leidyi in Narragansett Bay. We further suggest that the source-sink perspective we describe is relevant not only to Narragansett Bay but other temperate regions of the world persistently occupied by M. Leidyi.
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diet of the larval ctenophore Mnemiopsis Leidyi a agassiz ctenophora lobata
Journal of Plankton Research, 2004Co-Authors: Lindsay J. Sullivan, Dian J. GiffordAbstract:Larvae and post-larvae of the lobate ctenophore Mnemiopsis Leidyi consumed significant quantities of microphytoplankton and microzooplankton prey in controlled experiments where they were fed in situ assemblages of microplankton prey. Prey taxa ingested included phototrophic and heterotrophic dinoflagellates, choreotrich ciliates, cyclotrich ciliates and euglenoid flagellates. Per capita clearance and ingestion rates varied with consumer size, prey taxon and prey abundance. Average per capita clearance rates for the 11 size classes of larvae and post-larvae examined ranged from 9 to 230 mL individual � 1 h � 1 . Average per capita clearance rates for tentaculate-stage, transition-stage and lobate-stage individuals were 40, 31 and 95 mL individual � 1 h � 1 , respectively. Total ingestion rate varied similarly with consumer size, prey taxon and prey abundance, ranging from 1 to 6259% body carbon day � 1 . All size classes of M. Leidyi larvae and post-larvae derived more nutrition from dinoflagellates than from ciliates. Both positive and negative selection of specific prey taxa were observed, and varied with larval size and prey taxonomic composition. The results contradict the prevailing view that all life history stages of M. Leidyi are primarily carnivorous. The measured clearance rates are sufficiently high that the larvae, when abundant, have the potential to exert a significant predation impact on their prey populations in the water column. Understanding the processes that influence survival during early developmental stages may provide one key to understanding the initiation and maintenance of the adult M. Leidyi blooms that are commonly observed in coastal waters.