1,475 research outputs found
Larval responses to turbulence and temperature in a tidal inlet: Habitat selection by dispersing gastropods?
No full textAuthor Posting. © Sears Foundation for Marine Research, 2010. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 68 (2010): 153-188, doi:10.1357/002224010793079013.Marine larval dispersal is affected by hydrodynamic transport and larval behavior, but little is known about how behavior affects large-scale patterns of dispersal and recruitment. Intertidal habitats are characterized by strong and variable turbulence relative to shelf and pelagic waters, so larval responses to turbulence may affect both dispersal and habitat selection. This study combined observations and theoretical approaches to model gastropod larval responses to multiple physical variables in a well-mixed tidal inlet. Physical measurements and larvae were collected in July 2004 in Barnstable Harbor, Massachusetts (USA). Physical measurements were incorporated in an advection-diffusion model where larval vertical velocity is a function of turbulence dissipation rate, temperature, and the temperature gradient. Modeled larval distributions were fitted to observed concentration profiles by maximum likelihood to estimate larval behavioral velocity (swimming or sinking) as a function of environmental conditions. These quantitative behavior estimates were used to test hypotheses about behavioral differences among groups and to assess the relative impact of different cues on overall larval behavior. Larvae of five common gastropod species from different coastal habitats reacted most strongly to turbulence but had genus-specific responses to environmental cues. Larvae of a species from tidal inlets (the mud snail Nassarius obsoletus) had near-zero velocities under calmer conditions and sank in strong turbulence. In contrast, larvae from exposed beach habitats (Crepidula spp. and Anachis spp.) sank in weak turbulence and swam up in strong turbulence, with additional responses to temperature and temperature gradient. Larval responses also differed between small and large size classes and between flood and ebb tides. Behavior of mud snail larvae would contribute to retention inside the inlet and near adult habitats, whereas behavior of beach snail larvae would contribute to rapid export from muddy inlets lacking suitable adult habitats.This work was funded by the Woods Hole Oceanographic Institution (WHOI) Coastal Ocean
Institute, the WHOI Rinehart Coastal Research Center, the National Science Foundation (NSF OCE-
0326734), NSF and US Office of Naval Research grants to S. Elgar and B. Raubenheimer, and the
WHOI Sea Grant (National Oceanic and Atmospheric Administration, Grant No. NA16RG2273,
project no. R/O-38-PD). Analyses were completed while HLF was a postdoctoral scholar at Scripps
Institution of Oceanography (SIO), supported by the California Current Ecosystem Long-Term Ecological
Research program (NSF OCE-0417616) and by SIO funding to P. Franks
Mussel larval responses to turbulence are unaltered by larvalage or light condition
No full textLarval responses to hydromechanical cues potentially have important effects on larval dispersal and settlement. This study examined the behavior of mussel larvae (Mytilus edulis) in laboratory-generated turbulence representative of nearshore currents. We video recorded the behavior of early- and late-stage veligers in a grid-stirred tank at five turbulence levels under light and dark conditions. Water velocities and kinetic energy dissipation rates were measured using particle image velocimetry and acoustic Doppler velocimetry. We characterized the vertical velocity distributions for sinking, hovering, and swimming modes in still water and calculated the average larval behavioral velocity in turbulence. In still water, young larvae had more positive (upward) velocities than old larvae, and both stages had more positive velocities in light than in dark. In turbulence, the mean larval vertical velocity varied from positive at low dissipation rates to negative at dissipation rates above a threshold of 8.3 £ 1022 cm2 s23. At this threshold, the Kolmogorov length scale (h ¼ 590mm) was two to three times the mean larval shell lengths (171–256mm), implying that turbulence is detectable even by larvae that are smaller than the smallest eddies. Responses to turbulence were unaffected by larval age or light conditions and contributed substantial behavioral variation. By sinking in strong turbulence, mussel larvae could increase their flux to the bed in energetic coastal flows, particularly over rough substrates like mussel beds. The response to turbulence by early-stage larvae will also affect their dispersal and may help larvae remain near coastal populations.Peer reviewedOriginally published in Limnology and Oceanography: Fluids & Environments (2011) and available via this link: http://lofe.dukejournals.org/content/1/120.full.pdfCopyright 2011 by the Association for the Sciences of Limnology and Oceanography, Inc
Frieda Fuchs Collection 1907-1957
No full textThe collection contains materials representing the academic career of Frieda Fuchs, from her early school years, through her doctoral studies and research into psychology in Germany, to her career in the United States. The following material is from her earlier years in Germany: grade certificates from the Grossherzogliche Seminar für Volksschullehrerinnen in Darmstadt indicating good marks (1907-1914); her teaching contract for the Israelitische Volksschule (1916), certificates confirming satisfactory studies and a diploma granting a doctoral degree from the Universtät Frankfurt am Main, in recognition of her dissertation "Experimentelle Studien über das Bewegungsnachbild" (1927-1928). The following material is from either shortly before or after her emigration to the United States: editions of her curriculum vitae (1940-1941); letters of recommendation, job correspondence and offers (1939-1942), report entitled "Von Nachbildern und ihrer Bedeutung," undated. Also included is an offprint, signed by the author, Dr. S. Hirsch, entitled "Die letzten Millimeter der arteriellen Strombahn," and two photographs of Frieda Fuchs approximately ages 30 and 50.Frieda Fuchs was born in Dieburg in 1893. She studied at the teacher's college in Darmstadt and the University in Frankfurt, receiving her doctoral degree in in 1928. From 1914 through 1940 she taught at the Israelitische Volksschule in Frankfurt am Main. She also gave classes at the Heim des Juedischen Frauenbundes in Neu-Isenburg. She immigrated to the United States in 1940 and found employment with the congregation of Rabbi Dr. Breuer in New York. At the same time she enlisted the support of the American Psychological Association Committee on Displayed Foreign Psychologists. She died in New York in 1974.Processed for digitizationdigitized2007110
FIGURE 3 in Two new species of Spathiphyllum (Araceae) from Tabasco, Mexico with notes on their floral scent
No full textFIGURE 3. Visitors to the inflorescences of Spathiphyllum maldonadianum in the male phase. A. Euglossa sp. B. Plebeia sp. Photos by P. Díaz Jiménez.Published as part of Jiménez, Pedro Díaz, Dötterl, Stefan, Fuchs, Roman, Hentrich, Heiko, Pérez-Farrera, Miguel Ángel, Vega, José Padilla & Aguilar-Rodríguez, Pedro A., 2022, Two new species of Spathiphyllum (Araceae) from Tabasco, Mexico with notes on their floral scent, pp. 121-132 in Phytotaxa 566 (1) on page 124, DOI: 10.11646/phytotaxa.566.1.7, http://zenodo.org/record/710353
Plankton community properties determined by nutrients and size-selective feeding
No full textThe potential impacts of climate change on marine planktonic ecosystems remain difficult to predict. Climate forcing can alter nutrient availability and predator community composition, and here we show that these shifts may dramatically alter plankton trophic structure, size distributions and biomass. We modeled phytoplankton and zooplankton as a highly resolved size spectrum with size-dependent nutrient uptake and predation and analyzed the model both as a size spectrum and as a food web. Model results identified 2 distinct regimes defined by the average zooplankton feeding preferences. Regime I communities, where planktonic predators are specialists or large relative to prey, had low omnivory, many top predators, low connectance and relatively flat size spectra. Regime II communities, where predators are generalists or small relative to prey, had a high degree of omnivory, no top predators, high connectance and steep size spectra. Model ecosystems with generalist predators had lower size diversity, smaller plankton and gappier size distributions than ecosystems with specialist predators. Nutrient availability had little influence on trophic structure but strongly impacted size structure and biomass. Most surprisingly, phytoplankton biomass sometimes decreased with added nutrients if predators were small relative to prey, implying that both predators and nutrients mediate shifts between bottom-up and top-down control. Based on our synthesized estimates of size-selective feeding parameters, we infer that size and trophic structure should be strongly affected by abundances of generalist, bloom-forming taxa such as salps and jellyfish, many of which are responsive to ocean temperature. Size-selective feeding fundamentally affects community structure and is a likely mechanism of change in planktonic ecosystems where community composition varies with temperature.Article accompanied by supplement (13 p.): Plankton community properties determined by nutrients and size-selective feedingPeer reviewe
Planorbis varians Fuchs 1870
No full textPlanorbis varians Fuchs, 1870 —how to recombine? Planorbis varians Fuchs, 1870 in Fuchs 1870a: 356, pl. 14, figs 1–9. Gyraulus (Gyraulus) varians (Fuchs): Wenz 1923: 1622 (cum syn.). Muellerpalia varians (Fuchs, 1870); Bandel 2010: 104 [not pl. 8, figs 90–94, = Muellerpalia bicincta (Fuchs, 1870)]. Marinescugyra varians (Fuchs, 1870); Bandel 2010: 112, pl. 13, figs 153–158. In his revision about the valvatiform gastropods of the Paratethys realm, Bandel (2010) introduced amongst others the genera Muellerpalia (Hydrobiidae) and Marinescugyra (Planorbidae), based on characteristic protoconch features. One of the discussed species is Planorbis varians Fuchs, 1870 from Rădmăneşti in Romania. On the grounds of different protoconch properties, Bandel assigned specimens, putatively belonging to the same species, to either Muellerpalia (p. 104) or Marinescugyra (p. 112). For the latter, it even constitutes the type species. Hence, Bandel used two different combinations based on the same original combination. From a nomenclatural as well as a taxonomic view this is of course not tenable. It means that either the various specimens belong to two different species or the diagnostic features of the two genera are not meaningful. The associated problems were clear to the author as became evident from personal correspondence: Bandel (pers. comm.) stated the possibility that " Planorbis varians " is actually represented by two species, which would have to be assigned variably to Muellerpalia or Marinescugyra based on their protoconchs. Unfortunately, this discussion is wanting in the paper. However, it turned out that the two combinations indeed refer to different species. The specimens illustrated by Bandel (2010) as " Marinescugyra varians " (pl. 13, figs 153–158) undoubtedly refer to the same species as described by Fuchs (1870a). They correspond in the two strong keels, the intermediate spiral lines, the slightly concave umbilical part, and the weakly stepped funnel-like apical part. In contrast, the individuals depicted as " Muellerpalia varians " (Bandel 2010, pl. 8, figs 90–95) belong to a different species: they have both keels on the umbilical side, apparently lack additional spiral lines, have highly convex whorls, and more distinct growth lines. Direct comparison of the descriptions and illustrations of Fuchs (1870a, b) and Bandel (2010) suggest that Bandel confused several species. Firstly, " Muellerpalia varians " sensu Bandel rather corresponds to " Valvata bicincta Fuchs, 1870 " in Fuchs (1870b) [= Muellerpalia bicincta (Fuchs, 1870)]. Secondly, specimens illustrated as " Muellerpalia bicincta " by Bandel rather resemble " Valvata carinata Fuchs, 1870 " in Fuchs (1870b) [= Muellerpalia carinata (Fuchs, 1870)]. Conversely, Muellerpalia carinata (Fuchs, 1870) sensu Bandel, 2010 may represent Muellerpalia bicincta. The new combinations of both latter taxa with the new genus Muellerpalia still remain valid. The presence of a second, fainter keel on the umbilical side in " Muellerpalia varians " sensu Bandel (2010) [= Muellerpalia bicincta (Fuchs, 1870)], which is not discernible in the original material of Fuchs (1870a), is regarded as intraspecific variability herein, as all other features correspond quite well. Unfortunately, Bandel did not provide an illustration of the apical region, which would show a distinct keel if our determination as M. bicincta is correct. Nevertheless, the endpoint of keel-like structure is visible in the apertural view (Bandel 2010, pl. 8, fig. 94). Even if it might turn out that this tentative placement is wrong, it still remains well separated from Marinescugyra varians. In conclusion, the genus Marinescugyra, with Planorbis varians Fuchs, 1870 as type species, remains valid and the combination Marinescugyra varians (Fuchs, 1870) is the only accepted one. The combination Muellerpalia varians (Fuchs, 1870) is based on a misidentification of the species. We tentatively synonymize this record with Muellerpalia bicincta (Fuchs, 1870).Published as part of Neubauer, Thomas A., Harzhauser, Mathias, Georgopoulou, Elisavet, Mandic, Oleg & Kroh, Andreas, 2014, Replacement names and nomenclatural comments for problematic species-group names in Europe's Neogene freshwater Gastropoda, pp. 453-468 in Zootaxa 3785 (3) on pages 464-465, DOI: 10.11646/zootaxa.3785.3.7, http://zenodo.org/record/491336
Biophysical Constraints on Optimal Patch Lengths for Settlement of a Reef-Building Bivalve
No full textReef-building species form discrete patches atop soft sediments, and reef restoration often involves depositing solid material as a substrate for larval settlement and growth. There have been few theoretical efforts to optimize the physical characteristics of a restored reef patch to achieve high recruitment rates. The delivery of competent larvae to a reef patch is influenced by larval behavior and by physical habitat characteristics such as substrate roughness, patch length, current speed, and water depth. We used a spatial model, the ‘‘hitting-distance’’ model, to identify habitat characteristics that will jointly maximize both the settlement probability and the density of recruits on an oyster reef (Crassostrea virginica). Modeled larval behaviors were based on laboratory observations and included turbulence-induced diving, turbulenceinduced passive sinking, and neutral buoyancy. Profiles of currents and turbulence were based on velocity profiles measured in coastal Virginia over four different substrates: natural oyster reefs, mud, and deposited oyster and whelk shell. Settlement probabilities were higher on larger patches, whereas average settler densities were higher on smaller patches. Larvae settled most successfully and had the smallest optimal patch length when diving over rough substrates in shallow water. Water depth was the greatest source of variability, followed by larval behavior, substrate roughness, and tidal current speed. This result suggests that the best way to maximize settlement on restored reefs is to construct patches of optimal length for the water depth, whereas substrate type is less important than expected. Although physical patch characteristics are easy to measure, uncertainty about larval behavior remains an obstacle for predicting settlement patterns. The mechanistic approach presented here could be combined with a spatially explicit metapopulation model to optimize the arrangement of reef patches in an estuary or region for greater sustainability of restored habitats.Peer reviewe
Participation of civil society in new modes of governance: the case of the new EU member states. Part 3: Involvement at the EU level
No full text"This working paper is the third and final part of a series presenting the first results of a research team examining the impact of the 2004 EU enlargement on governance structures involving the participation of civil society organisations. The research team is part of the NEWGOV Integrated Project, led by the European University Institute. Starting from the thorough analysis of the situation at the national level, in this working paper we examine the engagement of civil society organisations from post-socialist member states in EU governance. The contributions cover the respective EU regulations as well as informal practices and focus on the capacity, impact and accountability of the civil society actors involved." (excerpt). Contents: Brigitte-Erika Krech: The integration of civil society organisations from the post-socialist member states into the EU decision-making process (7-18); Daniela Obradovic, Jose M. Alonso Vizcaino: Good governance requirements for the participation of interest groups in EU consultations (19-44); Kristýna Busková, Heiko Pleines: Case study: Czech environmental NGOs and the EU (45-53); Gesine Fuchs: Case study: Polish non-governmental women's organisations and the EU (54-65); Zdenka Mansfeldová: Case study: Czech trade unions and employers' associations on the way to multi-level dialogue (66-78); Joanna Einbock: Case study: the activities of Polish trade unions at the EU level (79-86); Heiko Pleines: Case study: the Polish agricultural lobby between Warsaw and Brussels (87-99)
Veb pristupačnost i elektronskih formati za pristup informacijama za osobe sa invaliditetom
No full textAuthor described the context of the development of technological and social relationships and how they mutually made changes on ways how people interact with information and access to knowledge.
The development of societies changed significantly the role of libraries and posed new technological and other challenges due to the development of information technologies.
Since the development of information technologies caused expansion of production capacities in societies there was additional need to standardize production of formats of access, distribution, archiving of information. Due to democratic character of many developed societies openness of information and human rights emphasized an importance of legal aspects and rights of persons with disabilities. Author mentioned articles of the UN Convention of Rights of Persons with Disabilities which required that parties which ratified convention should implement accessibility standards for persons with disabilities. Author presented standards and technical specifications that define accessibility of web interface, computer software and file formats. It is especially emphasized that those standards are important in libraries. Modern libraries should adopt and use file formats which are accessible for persons with disabilities in order to avoid risk of increased discrimination against persons with disabilities if inaccessible technologies will be used. Author believes that this would help persons with disability to use library resources and services equally as other users do.
Swimming behavior and velocities of barnacle cyprids in a downwelling flume
No full textIt has been proposed that barnacle cyprids can maintain position in shorewardpropagating fronts by swimming upward against a downwelling flow, potentially mediating onshore transport of larvae toward intertidal habitat. This study developed a novel flume to characterize swimming behavior of barnacle cyprids in a laboratory downwelling flow. Seawater was pumped through a cylindrical observation chamber fitted with diffusers to produce a homogeneous downwelling velocity field. The flume generated plug flow with mean downwelling velocities (indicated by negative sign) of 0 to –47.3 mm s–1. Behavior experiments were done with wild Semibalanus balanoides cyprids. Vertical swimming rates and behaviors were estimated from video observations, and a mixture model was used to estimate velocity distributions for distinct behavioral modes. Larvae exhibited multiple behaviors but typically swam upward in response to downwelling, with a maximum estimated vertical velocity of 72.3 mm s–1. When faced with downwelling flows, cyprids alternated between upward swimming and downward swimming to maintain their vertical position in the chamber. As downwelling velocities increased, cyprids that remained in the field of view of the cameras exhibited faster mean upward swimming velocities. It is unclear how long individual S. balanoides cyprids can maintain depth, but cyprids were able to maintain depth throughout the 2 min observation period. This study supports earlier hypotheses based on field observations by demonstrating that S. balanoides cyprids swim well enough to counter downwelling velocities characteristic of convergence zones. Swimming against downwelling flow could be an adaptive behavior that enables shoreward transport in the absence of any larval ability to swim toward shore or even to sense its direction.Peer reviewe
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