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Journal ArticleDOI

SHORT COMMUNICATION Determination of generation time and asexual fecundity of doliolids (Tunicata, Thaliacea)

01 Jun 1999-Journal of Plankton Research (Oxford University Press)-Vol. 21, Iss: 6, pp 1183-1189
TL;DR: In this paper, the authors provided temporal information on the generation time of Dolio letta gegenbauri and some of the life cycle's components, showing that asexual production per cubic meter by phorozooids with that of nurses should result in rapid colonization of a wide shelf by doliolids.
Abstract: The goal of this study was to provide temporal information on the generation time of Dolio- letta gegenbauri and some of the life cycle's components. At 20°C and ~90 µg C l-1 of ingestible phyto- plankton, D.gegenbauri's life cycle is completed in 20.5 days. Phorozooids ♢ 5 mm produce on average 11.0 gonozooids day-1 over a period of 8-18 days. Utilizing field data on the abundance and size distri- bution of an assemblage of phorozooids and nurses, in conjunction with experimentally obtained rates, indicates that asexual production per cubic meter by phorozooids with that of nurses should result in rapid colonization of a wide shelf by doliolids, as observed during July and August 1981 on the southeastern continental shelf of the USA.
Citations
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Journal ArticleDOI
TL;DR: An evaluation of data and published results on abundances of doliolids and salps from ocean margins reveals that a considerable degree of prediction is possible, based upon meteorological and boundary current intrusion dynamics.
Abstract: The occurrence of large patches of gelatinous zooplankton has for decades been considered to be unpredictable. An evaluation of our own data and published results on abundances of doliolids and salps from ocean margins reveals that a considerable degree of prediction is possible, based upon meteorological and boundary current intrusion dynamics.

88 citations

Journal ArticleDOI
TL;DR: Large planktonic microphages are focused on as a model of selective mucus feeding because of their important roles in the ocean food web: as bacterivores, prey for higher trophic levels, and exporters of carbon via mucous aggregates, faecal pellets and jelly-falls.
Abstract: Mucous-mesh grazers (pelagic tunicates and thecosome pteropods) are common in oceanic waters and efficiently capture, consume and repackage particles many orders of magnitude smaller than themselves. They feed using an adhesive mucous mesh to capture prey particles from ambient seawater. Historically, their grazing process has been characterized as non-selective, depending only on the size of the prey particle and the pore dimensions of the mesh. The purpose of this review is to reverse this assumption by reviewing recent evidence that shows mucous-mesh feeding can be selective. We focus on large planktonic microphages as a model of selective mucus feeding because of their important roles in the ocean food web: as bacterivores, prey for higher trophic levels, and exporters of carbon via mucous aggregates, faecal pellets and jelly-falls. We identify important functional variations in the filter mechanics and hydrodynamics of different taxa. We review evidence that shows this feeding strategy depends not only on the particle size and dimensions of the mesh pores, but also on particle shape and surface properties, filter mechanics, hydrodynamics and grazer behaviour. As many of these organisms remain critically understudied, we conclude by suggesting priorities for future research.

68 citations

BookDOI
29 Jan 2014
TL;DR: This work provides the most comprehensive overview available of the state of the art in this exciting field of evolutionary research with a focus on nervous systems.
Abstract: The growing success of molecular methods has challenged traditional views of animal evolution and a large number of alternative hypotheses are hotly debated today. For the deep metazoan phylogeny project, data sets of hitherto unmatched quality and quantity were compiled and analysed with innovative bioinformatics tools. The book begins at the base of the tree of life to discuss the origin of animals and early branches of the phylogenetic tree. The following section presents special data sets gained from mitochondrial genomes and from morphology, with a focus on nervous systems. The final section is dedicated to theoretical aspects of data analysis and new bioinformatics tools. The book closes with a unique general discussion of all hypotheses contained in previous chapters. This work provides the most comprehensive overview available of the state of the art in this exciting field of evolutionary research.

67 citations

Journal ArticleDOI
TL;DR: Using literature data on lifetime egg production and generation time of appendicularians, salps, and doliolids, rmax, the maximum rate of lifetime reproductive fitness, is calculated as a common metric of adaptation to environmental conditions.
Abstract: Phylogeny, life cycles, and life-history adaptations of pelagic tunicates to temperature and food concentration are reviewed. Using literature data on lifetime egg production and generation time of appendicularians, salps, and doliolids, rmax, the maximum rate of lifetime reproductive fitness, is calculated as a common metric of adaptation to environmental conditions. The rmax values are high for all three groups, ranging from 0.1 to 1.9 d, so population doubling times range from 8 h to 1 week. These high values of rmax are attributable primarily to short generation times, ranging from 2 to 50 d. Clearly, pelagic tunicates are adapted to event-scale (i.e. days to weeks) rather than seasonal-scale changes in environmental conditions. Although they are not closely related phylogenetically, all three groups have a unique life-history adaptation promoting high lifetime fitness. Appendicularians have late oocyte selection, salps are viviparous, and doliolids possess a polymorphic asexual phase. There has been little research on hermaphroditic appendicularians, on large oceanic salps, and on doliolids generally. Research is needed on factors regulating generation time, on the heritability of life-history traits, and on ageand size-specific rates of mortality.

66 citations

Journal ArticleDOI
TL;DR: It is proposed that acquiring new stem cell lineages in the larvae may be a preadaptation necessary for the evolution of budding, and hypotheses for changes in stem cell linesages in colonial species are reviewed.

62 citations

References
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Book
01 Jan 1998
TL;DR: The relationships and systematics of the Thaliacea, with keys for identification, and the role of appendicularia in marine food webs are discussed.
Abstract: Introduction Chapter 1 - Anatomy of Thaliacea Chapter 2 - Anatomy of Appendicularia Chapter 3 - Locomotion, locomotor muscles and buoyancy Chapter 4 - Nervous system, sense organs and excitable epithelia Chapter 5 - Feeding and energetics of Thaliaceans Chapter 6 - The Appendicularian house Chapter 7 - Salp and pyrosomid blooms and their importance in biogeochemical cycles Chapter 8 - Feeding and metabolism of appendicularians Chapter 9 - Life history of the appendicularians Chapter 10 - The role of appendicularia in marine food webs Chapter 11 - The parasites and predators of Thaliacea Chapter 12 - Bioluminescence in the Appendicularia Chapter 13 - The cladistic biogeography of salps and pyrosomas Chapter 14 - Appendicularian distribution and zoogeography Chapter 15 - Molecular phylogeny of tunicates. A preliminary study using 28 Sribosomal RNA partial sequences: implications in terms of evolution and ecology Chapter 16 - The relationships and systematics of the Thaliacea, with keys for identification Chapter 17 - The classification of Appendicularia References Taxonomic Index Subject Index

251 citations

Journal ArticleDOI
01 Jan 1985
TL;DR: In this article, a large-scale intrusion of upwelled nutrient-rich Gulf Stream water was the dominant process affecting temporal and spatial changes in phytoplankton biomass and productivity of the southeastern United States continental shelf between 29 and 32°N latitude.
Abstract: During July and August 1981 subsurface intrusion of upwelled nutrient-rich Gulf Stream water was the dominant process affecting temporal and spatial changes in phytoplankton biomass and productivity of the southeastern United States continental shelf between 29 and 32°N latitude. Intruded waters in the study area covered as much as 10 1 km including virtually all of the middle and outer shelf and approximately 50% of the inner shelf area. Within 2 weeks following a large intrusion event in late July, middle shelf primary production and Chl a reached 3 to 4 gC m − d −1 and 75 mg m − , respectively. At the peak of the bloom 80% of the water column primary production occurred below the surface mixed-layer, and new primary production (i.e., NO 3 -supported) exceeded 90% of the total. Chl a-normalized photosynthetic rates were very high as evidenced by high mean assimilation number (15.5 mg C mg Chl a −1 h −1 ), high mean α (14 mg C mg Chl a −1 Ein −1 m), and no photoinhibition. As a result of the high photosynthetic rates, mean light-utilization index (Ψ) was 2 to 3 times higher than reported for temperature sub-arctic and arctic waters. The results imply a seasonal (June to August) middle shelf production of 150 g C m −1 , about 15% higher than previous estimates of annual production on the middle shelf. Intrusions of the scale we observed in 1981 may not occur every summer. However, when such events do occur, they are by far the most important processes controlling summer phytoplankton dynamics of the middle and outer shelf and of the inner shelf in the southern half of the study area.

83 citations

Journal ArticleDOI
TL;DR: In this article, the authors observe a pullulation of a 60 km stretch of the front thermique du Gulf Stream in the North-Ouest of the United Kingdom, with temperature and salinite of 20m and 40m, respectively.
Abstract: On observe une pullulation de D.g. a 60 km au nord-ouest du front thermique du Gulf Stream. La pullulation apparait entre deux fronts, l'un de temperature et de salinite a l'isobathe 20-m, l'autre de temperature a l'isobathe 40-m. La presence de ces masses de tuniciers est une reponse biologique a des forces physiques conductrices; ce n'est pas seulement un cas de concentration par un seul mecanisme physique

76 citations