395 research outputs found
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
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
Heidi
No full textThe Thorndike Library edition of Heidi by Johanna Spyri, edited by Edward L. Thorndike, and illustrated by Hildegarde Woodward. The cover of the book is made of a warm yellow fabric with details in bright blue and black ink. Below the title and author's name is the logo for the publisher's collection, The Thorndike Library. The spine of the book features more detailing in blue like that of the cover and the logo as well as the title of the book. Painted on is a black stripe with its library classification. On the title page are the names of the author, editor, illustrator, and publisher as well as the title. In the center of the page is the logo for the collection. Surrounding all of this is a box with illustrations of diamonds and at the top, children reading books. On the opposite page is a black and white illustration from chapter seven is of Heidi and another boy running through a town. The same box and illustration from the title page surround this illustration. Below the illustration is a caption stating, "He ran straight off with Heidi after him." On page 41 is another black and white illustration of Heidi and a boy named Peter having a picnic in a field in the mountains surrounded by goats and plants. At the bottom is the caption, "Peter made a more splendid meal than he had ever known." Page 229 has another illustration in black and white, this one showing Heidi using a cloth to clean a table. Leaning against the table is a broom and next to the table is a ladder. Behind Heidi is a window illuminating the room. Below the illustration is the caption, "She rubbed the table until it shone again.
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Heidi
No full textThe Thorndike Library edition of Heidi by Johanna Spyri, edited by Edward L. Thorndike, and illustrated by Hildegarde Woodward. The cover of the book is made of a warm yellow fabric with details in bright blue and black ink. Below the title and author's name is the logo for the publisher's collection, The Thorndike Library. The spine of the book features more detailing in blue like that of the cover and the logo as well as the title of the book. Painted on is a black stripe with its library classification. On the title page are the names of the author, editor, illustrator, and publisher as well as the title. In the center of the page is the logo for the collection. Surrounding all of this is a box with illustrations of diamonds and at the top, children reading books. On the opposite page is a black and white illustration from chapter seven is of Heidi and another boy running through a town. The same box and illustration from the title page surround this illustration. Below the illustration is a caption stating, "He ran straight off with Heidi after him." On page 41 is another black and white illustration of Heidi and a boy named Peter having a picnic in a field in the mountains surrounded by goats and plants. At the bottom is the caption, "Peter made a more splendid meal than he had ever known." Page 229 has another illustration in black and white, this one showing Heidi using a cloth to clean a table. Leaning against the table is a broom and next to the table is a ladder. Behind Heidi is a window illuminating the room. Below the illustration is the caption, "She rubbed the table until it shone again.
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Heidi
No full textEarly edition of Heidi by Johanna Spyri. The cover of the book is red with white and black printed illustrations on it. The title and author's name are in gold. The illustration is over Heidi sitting across from a boy with her arm wrapped around a goat. In the background is a mountain with some trees and the sun peeking over the edge. On the inner cover is a illustrated print in bright green. In the illustration is Heidi standing in a forest with her arms held out above her head. On the cover page is a box which has some decorative motifs and contains the title and the names of the author, translator, author of the introduction, and the illustrator. Below that is a seal for the publishing company and then the locations and name of the publishing company. On the opposite page is an illustration of Heidi having a picnic with an older boy. They are sitting in a field holding bread and cheese. Behind them are several goats grazing on the mountainside. In the background is a forest of evergreens and more mountains
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Heidi: From the German of Johanna Spyri
No full textEnglish translated version of Heidi. The front cover on the book is a light warm blue color with five white and green flowers, one white bud, and eight dark green leaves connected to each other by vines making a crisscross pattern of green and across the cover. All of the illustrations are line with gold. Wedged in between the two flowers at the top is a side profile of Heidi's face. On the center of the cover is the title and author in gold leafing. On the spine of the book are lines of dark green and gold at the top and bottom. Also at the top of the spine is the title of the book written in gold with a flourish underneath. Below the title is the last name of the author and a white flower lined in gold. At the bottom is a red and orange stripped stripe with "GCW" written in cursive above the name of the publishing company and stands for Gustine Courson Weaver. The interior of the book contains both black and white and colored illustrations of various scenes from the book. Some of the scenes are of Heidi with her grandfather, Heide, her grandfather, and Peter, and Heidi and Clara
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
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
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Heidi: Gift Edition
No full textEarly edition of Heidi by Johanna Spyri. The front cover is is white with blue outlines of the cover, title, and an illustration. There are four sets of small illustrations of yellow flowers, blue leaves, and butterflies. In the center, in an oval, is an illustration of Heidi in a yellow standing on the side of a mountain waving to something in the distance. Behind her are more mountains covered in evergreen trees and fields of grass. The spine of the book has the title and author's name as well as a flower illustration, the edition, and the publisher's name. The interior cover pages have illustrations done in yellow ink. The title page has the title in yellow and in black ink are the names of the author, translator, author of the introduction, and the illustrator. At the bottom is the seal, location, and name of the publisher. Surrounding the title box on one side is a print of mountain goats and a boy sitting on a rock. On the page left of the title page is the same illustration from the cover. Other pages are also accompanied by yellow print illustrations that go along with the passage they accompany. Sandwiched in the novel are full color illustrations, some of which are Heidi and another child sledding down a snowy hill and a child doing a handstand at the bottom of a mountain path
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Heidi: Translated from the German of Johanna Spyri
No full textEarly edition of Heidi by Johanna Spyri, translated by H. A. Melcon. Except for a green and white boarder around the edge of the front cover, is a full page illustration of Heidi standing barefoot on a mountain clearing with her arms around two goats. On the ground around her feet are rocks, grass, and flowers. In the background are tall evergreen trees and mountain tops. The spine of the book is cream colored with the title and names of the author, series; Famous Books for Young Americans, and publishing company. Also on the spine is a small illustration of a girl in a long dress holding an umbrella with the word "illustrated" underneath it. On the inside of the cover is the flap of the dust jacket with text about the series. Behind the dust jacket flap is a bookplate for Gustine Courson Weaver. The paper attached to the interior cover and as part of the first page is a pale orange-peach color with a repeating pattern of squares with flowers in the shape of a C inside. The title page has a rectangle motif where inside has the title, name of the author, translator, and publishing company. On the center of the page is the logo for the publishers. On the opposite page is a full color illustration of Heidi and a girl named Clara sitting on stools on the ground outside while Heidi's grandfather offers them mugs of milk. Behind the girls are tall evergreen trees. In the background are the tips of mountains. The illustrated is captioned "Grandfather brought out two mugs of milk, one for Clara and the other for Heidi." On page 115 is another full color illustration. In the illustration are two girls, Clara and Heidi playing with kittens. Clara is sitting in a rolling wicker chair with a black kitten in her lap. Heidi is kneeling on the ground with a tan kitten on her shoulders and in front of her is a wicker basket with more kittens playing around and climbing out of. Behind the two is an older woman watching them in alarm. Behind them is a tall, multisided piece of furniture resting on a ledge. Behind the woman is a window with its curtains pulled to the side. The illustration is captioned, " Suddenly there jumped out of the basket one, two, three, and then some more kittens.
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