Use of 2,4-D as an Inhibitor of Germination in Routine Examinations of Beans for Seed-Borne Infection

Ewing, Gifford C.

doi:10.1126/science.111.2874.91-a

Cited by 26 publications

(13 citation statements)

References 1 publication

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“…Surface slicks were often observed, and there was some concentration of surface material on those slicks. Those slicks most likely corresponded to the trailing side of the crest of the highfrequency internal motions, as found by Ewing (1950). The slicks were superimposed on the onshore surface flow (Fig.…”

Section: Larval Vertical and Horizontal Distribution-previousmentioning

confidence: 58%

Circulation and larval distribution in internal tidal bore warm fronts

Pineda¹

1999

Limnology & Oceanography

228

238

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Internal tidal bore warm fronts were observed during the summer of 1996 off the coast of Southern California. Warm bore fronts had concentrating currents resulting from high-frequency internal motions and from a larger twoway flow; the two-way flow featured surface currents onshore and bottom currents offshore. A sharp thermocline depression and high-frequency, large-amplitude internal motions followed the leading edge of the bore, with downwelling currents on the trailing side of the crest of the nonlinear internal waves and upwelling currents in front of the crest. Warm bores propagated onshore with a propagation speed, c, that ranged from 10.6 to 19.6 cm s Ϫ1 , while time-averaged frontal currents, ū, varied from 11.2 to 17.6 cm s Ϫ1 in the shallowest bin. In one out of three cases ū Ͼ c, which implied that there were faster currents than the rate of advance of the front and which implied that the origin of surface frontal material is behind the front, not in front of it. Three invertebrate larval taxa were found at all sites across fronts, but only two intertidal barnacles, Pollicipes polymerus and Chthamalus spp., were concentrated at the front's surface, while the subtidal bryozoan Membranipora spp. was not. Frontal Pollicipes were more concentrated than were Chthamalus. The frontal downwelling currents observed suggested that concentrated larvae would have to swim upward in order to maintain depth. Pollicipes were abundant on the offshore warm side of the fronts but were absent or rare on the onshore colder side, suggesting that the origin of frontal Pollicipes was behind the front, although an alternative cannot be ruled out conclusively. Chthamalus were more abundant at depth than at the surface at all sites except at the front, where this pattern was reversed. The origin of frontal Chthamalus is uncertain. Membranipora were more abundant on the onshore colder side of the fronts, and abundances were usually higher at depth than at surface. Lack of accumulation in this species may be due to its limited swimming capability.Benthic communities are often composed of open populations in which recruitment is effectively uncoupled from local fecundity (e.g., Eckman 1996; Stoner et al. 1996). Because larvae of shallow-water invertebrates are generally small and cannot swim long distances, they depend on external transport mechanisms to reach adult habitats (Thorson 1950). To the extent that larval settlement and recruitment depend on external transport, these physical processes must be critically important to population dynamics. The phenomenology associated with larval transport involves larval behavior and physical transport mechanisms. Specific larval behaviors are required to exploit specific transporting or concentrating mechanisms (e.g., Scheltema 1986;Rothlisberg et al. 1995). Physical transport for nearshore species is complicated because it involves characterizing the mechanism of transport as well as its temporal and spatial variability, including the secondary flows responsible for the accumu...

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Section: Larval Vertical and Horizontal Distribution-previousmentioning

confidence: 58%

Circulation and larval distribution in internal tidal bore warm fronts

Pineda¹

1999

Limnology & Oceanography

228

238

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“…Likewise, the strong positive SSTA coincided with the lowest sea surface temperature and air temperature of the year, suggesting a seasonal stratification pattern of the water column. We hypothesize that such stratification could affect the energy of the sill processes and internal waves along the Refugio Channel (Ewing 1950), as well as plankton abundance and distribution in this area. This hypothesis requires further study.…”

Section: Discussionmentioning

confidence: 99%

“…The transport of planktonic larvae may be affected by a combination of biological characteristics in terms of larval development and oceanographic features (Ewing 1950, Le Fèvre 1986, Scheltema 1986, Fairweather 1991, Levin & Bridges 1995, Shanks 1995, Wing et al 1995, Young 1995, Pineda 1999. Through their behaviour, larvae can control their horizontal distribution (Shanks 1995, Young 1995, Poulin et al 2002a) and thereby influence their dispersal and local abundance (Shanks 1995, Natunewicz & Epifanio 2001.…”

Section: Introductionmentioning

confidence: 99%

Effects of sill processes on the distribution of epineustonic competent larvae in a stratified system of Southern Chile

Molinet¹,

Valle‐Levinson²,

Moreno³

et al. 2006

Mar. Ecol. Prog. Ser.

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The inlets of southern Chile are characterized by a well-defined pycnocline which, acting in concert with the biological characteristics of larvae, is believed to influence planktonic larval distribution. Here, we assessed the effects of stratified flow over a sill on the spatial abundance and distribution of epineustonic competent larvae of Concholepas concholepas. We used measurements of velocity profiles using an Acoustic Doppler Current Profiler (ADCP), intensive plankton collections combined with simultaneous conductivity, temperature and depth (CTD) profiles, monitoring of the pycnocline depth, and temperature records from moored thermistors. Evidence of Bernoulli aspiration and an intratidal transient front was observed over the sill from CTD data and an echosounder trace. ADCP measurements showed intensified recirculation in the residual flow over the sill. This oceanographic feature coincided with high abundances of epineustonic competent larvae of C. concholepas over the sill area. We found evidence indicating that physical mechanisms related to sill processes can influence epineustonic competent larval distribution in a stratified system. We also propose a conceptual model that brings together larval behaviour and stratified flow patterns to explain the rise of epineustonic larvae to the surface and larval aggregation over a sill.KEY WORDS: Bernoulli aspiration · Sill · Epineustonic larvae · Stratified system · Southern ChileResale or republication not permitted without written consent of the publisher

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“…Surface current dynamics encompass a complex mixture of forcing terms including wind, tides, pressure gradients, and internal waves (Ewing 1950;Munk and Cartwright 1966;Essen et al 1983;Alpers 1985;Prandle 1987;Ng 1993a,b). Generally, the wind is a dominant driving source of energy for currents, which have been considered to have an isotropic response in the open ocean (Ekman 1905;Gonella 1972;Weller 1981;Price et al 1987;Rio and Hernandez 2003) and the coastal region (Pidgeon and Winant 2005).…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Response of Surface Currents to the Wind in a Coastal Region

Kim

Cornuelle

Terrill

2009

Journal of Physical Oceanography

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Analysis of coastal surface currents measured off the coast of San Diego for two years suggests an anisotropic and asymmetric response to the wind, probably as a result of bottom/coastline boundary effects, including pressure gradients. In a linear regression, the statistically estimated anisotropic response explains approximately 20% more surface current variance than an isotropic wind-ocean response model. After steady wind forcing for three days, the isotropic surface current response veers 428 6 28 to the right of the wind regardless of wind direction, whereas the anisotropic analysis suggests that the upcoast (onshore) wind stress generates surface currents with 108 6 48 (718 6 38) to the right of the wind direction. The anisotropic response thus reflects the dominance of alongshore currents in this coastal region. Both analyses yield winddriven currents with 3%-5% of the wind speed, as expected. In addition, nonlinear isotropic and anisotropic response functions are considered, and the asymmetric current responses to the wind are examined. These results provide a comprehensive statistical model of the wind-driven currents in the coastal region, which has not been well identified in previous field studies, but is qualitatively consistent with descriptions of the current response in coastal ocean models.

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Use of 2,4-D as an Inhibitor of Germination in Routine Examinations of Beans for Seed-Borne Infection

Cited by 26 publications

References 1 publication

Circulation and larval distribution in internal tidal bore warm fronts

Circulation and larval distribution in internal tidal bore warm fronts

Effects of sill processes on the distribution of epineustonic competent larvae in a stratified system of Southern Chile

Anisotropic Response of Surface Currents to the Wind in a Coastal Region

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