Selection of foraging sites and invertebrate prey by migrant Semipalmated Sandpipers, Calidris pusilla (Pallas), in Minas Basin, Bay of Fundy

1984 ◽  
Vol 62 (11) ◽  
pp. 2201-2210 ◽  
Author(s):  
Peter W. Hicklin ◽  
P. C. Smith
Keyword(s):  
Visual Cues ◽  
Size Composition ◽  
Fine Sand ◽  
Bay Of Fundy ◽  
Particle Sizes ◽  
Corophium Volutator ◽  
Prey Behavior ◽  
Coarse To Fine ◽  
Selection Of ◽  
Semipalmated Sandpipers

We determined the particle size composition of substrates, the species composition and abundances of mud-dwelling invertebrates, and the distribution, densities, and diets of Semipalmated Sandpipers foraging on different mud flats in Minas Basin, Bay of Fundy, during the birds' southward migration. Substrate types varied between the mud flats used by shorebirds; particle sizes ranged from sandy (coarse to fine sands) to muddy (mainly silt and clay). Of 34 species of invertebrates identified, the polychaetes Spiophanes bombyx (Clarapede) and Heteromastus filiformis (Clarapede) and the amphipod Corophium volutator (Pallas) were the most numerous and widely distributed. Spiophanes and the "bamboo" worm Clymenella torquata (Leidy) were more abundant in coarse sandy substrates whereas numbers of Heteromastus were negatively correlated with grain size. The densities of Corophium were positively correlated with the amount of very fine sand in the substrate. The sandpipers foraged in larger numbers on mud flats where densities of Corophium were greatest and it was the main prey taken at those sites. The birds' diet was more diverse in areas of low Corophium density. It appears that the birds use visual cues for foraging and that prey behavior is particularly important in their choice of prey items.

Variation in diet of Semipalmated Sandpipers (Calidris pusilla) during stopover in the upper Bay of Fundy, Canada

2012 ◽  
Vol 90 (9) ◽  
pp. 1181-1190 ◽  
Author(s):  
J.T. Quinn ◽  
D.J. Hamilton
Keyword(s):  
Diet Composition ◽  
Prey Availability ◽  
Prey Selection ◽  
Bay Of Fundy ◽  
Corophium Volutator ◽  
Stopover Site ◽  
Semipalmated Sandpiper ◽  
Calidris Pusilla ◽  
Isotope Analyses ◽  
Semipalmated Sandpipers

Semipalmated Sandpipers ( Calidris pusilla (L., 1766)) use the upper Bay of Fundy, Canada, as a critical stopover site during their annual fall migration to wintering grounds in South America. While in the area, they feed extensively on mudflat invertebrates. Historically the amphipod Corophium volutator (Pallas, 1766) has been thought to make up the majority of their diet. However, we have recently observed flexibility in foraging behaviour and prey selection by sandpipers. The extent of this flexibility and the current diet composition is unknown. To address these knowledge gaps, we assessed Semipalmated Sandpiper diets using stable isotope analyses of blood plasma and available prey items. Data were collected in two arms of the Bay of Fundy during summer 2009 and 2010. Diets fluctuated between years and sites, but in all cases the diet was much more diverse than previously thought. Polychaetes and biofilm made substantial contributions, and C. volutator was still present in the diet, but at much reduced levels than previously noted. This previously unrecognized inclusion of biofilm in the diet is consistent with recent observations of other calidrid shorebirds. Based on measures of prey availability, there is little evidence of preference for C. volutator.

Some aspects of the foraging ecology of migrant juvenile sandpipers in the outer Bay of Fundy

1984 ◽  
Vol 62 (9) ◽  
pp. 1889-1892 ◽  
Author(s):  
G. W. Gratto ◽  
M. L. H. Thomas ◽  
C. L. Gratto
Keyword(s):  
Benthic Invertebrates ◽  
Foraging Ecology ◽  
Bay Of Fundy ◽  
Large Prey ◽  
Intertidal Flat ◽  
Corophium Volutator ◽  
Semipalmated Sandpipers ◽  
Size Refuge

Thirty-seven sandpipers (29 semipalmated and 8 least) were collected in early September 1983 on an intertidal flat on the outer Bay of Fundy. Analysis of esophagus and gizzard contents revealed a variety of benthic invertebrates but the diets of both species were dominated by the amphipod Corophium volutator (Pallas). Females of both species ate larger Corophium than did males of the same species. Both least and semipalmated sandpipers were underutilizing a cohort of large (7–10 mm) Corophium. It is possible that the large amphipods have reached a size refuge from predation such that the energy required to handle and ingest these large prey offsets too great a portion of the energy obtained.

Effect of Sedimentation on Infaunal Invertebrate Populations of Cobequid Bay, Bay of Fundy

1981 ◽  
Vol 38 (6) ◽  
pp. 642-648 ◽  
Author(s):  
Ted R. Turk ◽  
Michael J. Risk
Keyword(s):  
Grain Size ◽  
Macoma Balthica ◽  
Fine Sand ◽  
Coarse Sand ◽  
Sediment Deposition ◽  
Mya Arenaria ◽  
Bay Of Fundy ◽  
Corophium Volutator ◽  
Tidal Power ◽  
Order Of Magnitude

Construction of a tidal dam in the upper reaches of the Bay of Fundy is expected to result in deposition of sediment. We investigated the effect of sediment deposition on populations of three major benthic species of the upper reaches: Corophium volutator, Macoma balthica, and Mya arenaria. In fences and boxes that induced deposition on intertidal mudflats, accumulation of 1.0–3.5 cm of sediment at rates of 1.9–10.2 cm/mo caused Corophium density to decrease sharply, usually by an order of magnitude. Macoma density was generally unaffected. In fishing weirs, mud that accumulated at 1.5 cm/mo to a mean depth of 5.2 cm supported normal Corophium densities. The effect of sedimentation on Mya depends strongly on grain size: LD50 was 24 cm for coarse sand, 6 cm for fine sand, and 3 cm for mud. Mya is able to burrow upward in accumulating coarse sand. Even moderate rates and depths of sediment deposition, particularly of fine sediment, could have a major adverse effect on existing Corophium and Mya populations.Key words: Bay of Fundy, tidal power, sedimentation, grain size, water content, Corophium volutator, Macoma balthica, Mya arenaria

scholarly journals Fatty acid composition and concentration of alternative food of Semipalmated Sandpipers (Calidris pusilla) in the upper Bay of Fundy, Canada

2017 ◽  
Vol 95 (8) ◽  
pp. 565-573 ◽  
Author(s):  
J.T. Quinn ◽  
D.J. Hamilton ◽  
C.E. Hebert
Keyword(s):  
Fatty Acid ◽  
Substantial Part ◽  
Bay Of Fundy ◽  
Corophium Volutator ◽  
Fa Composition ◽  
Quality Of Food ◽  
Calidris Pusilla ◽  
Migrating Birds ◽  
Semipalmated Sandpipers

Semipalmated Sandpipers (Calidris pusilla (L., 1766)) that migrate through the upper Bay of Fundy, Canada, depend on a rich food supply to fuel their continued migration. Although past studies have reported a diet dominated by the amphipod Corophium volutator (Pallas, 1766), an animal rich in n–3 polyunsaturated fatty acids (PUFAs), recent evidence suggests that sandpiper diets are broad. This is beneficial in that it allows Semipalmated Sandpipers to respond to a changing food base, but quality of food is also important. PUFAs are important in providing the energy required by migrating birds and may play a role in migratory preparation. We assessed fatty acid (FA) concentrations and proportions in three common food items. We found that polychaetes should adequately meet the needs of migrating sandpipers in terms of FA composition. Concentrations of FAs in biofilm were low, but proportionally, n–3 PUFAs were well represented, particularly in biofilm collected in Shepody Bay, where it forms a substantial part of the sandpiper diet. Therefore, provided that birds can consume a sufficient volume of biofilm, it is also probably a suitable source of essential FAs. Our results suggest that Semipalmated Sandpipers in the Bay of Fundy can meet their FA needs with a variety of dietary options.

Biochemistry instructors’ use of intentions for student learning to evaluate and select external representations of protein translation

2019 ◽  
Vol 20 (4) ◽  
pp. 787-803
Author(s):  
Thomas J. Bussey ◽  
MaryKay Orgill
Keyword(s):  
Student Learning ◽  
Visual Cues ◽  
Bond Formation ◽  
Protein Translation ◽  
Peptide Bond ◽  
External Representation ◽  
External Representations ◽  
Peptide Bond Formation ◽  
Scientific Phenomena ◽  
Selection Of

Instructors draw on their intentions for student learning in the enactment of curriculum, particularly in the selection and presentation of external representation of scientific phenomena. These representations both create opportunities for students to experience non-experiential biochemical phenomena, such as protein translation, and constrain the possibilities for student learning based on the limited number of features depicted and the visual cues used to draw viewers attention to those features. In this study, we explore biochemistry instructors’ intentions for student learning about protein translation and how those intentions influence their selection of external representations for instruction. A series of instructor interviews were used to identify information that students need to know in order to develop a biochemically accurate understanding of protein translation. We refer to this information as the “critical features” of protein translation. Two dominant themes of critical features were identified: (1) components/structures of protein translation and (2) interactions/chemistry of protein translation. Three general components (the ribosome, the mRNA, and the tRNA) and two primary interactions (base pairing and peptide bond formation) were described by all instructors. Instructors tended to favor simpler, stylized representations that closely aligned with their stated critical features of translation for instructional purposes.

scholarly journals Modelling of Metallic Particle Binders for Increased Part Density in Binder Jet Printed Components

2019 ◽  
Author(s):  
Joseph Roberts ◽  
Peter Green ◽  
Kate Black ◽  
Christopher Sutcliffe
Keyword(s):  
Particle Size ◽  
Critical Radius ◽  
Detailed Knowledge ◽  
Particle Sizes ◽  
Powder Bed ◽  
Beneficial Effects ◽  
Drop Tests ◽  
Maximum Particle ◽  
Packing Efficiency ◽  
Selection Of

Binder jet printed components typically have low overall density in the green state and high shrinkage and deformation after heat treatment. It has previously been demonstrated that, by including nanoparticles of the same material in the binder, these properties can be improved as the nanoparticles can fill the interstices and pore throats between the bed particles. The beneficial effects from using these additive binder particles can be improved by maximising the binder particle size, enabling the space within the powder bed to be filled with a higher packing efficiency. The selection of maximum particle size for a binder requires detailed knowledge of the pores and pore throats between the powder bed particles. In this paper, a raindrop model is developed to determine the critical radius at which binder particles can pass between pores and penetrate the bed. The model is validated against helium pycnometry measurements and binder particle drop tests. It is found that the critical radius can be predicted, with acceptable accuracy, using a linear function of the mean and standard deviation of the particle radii. Percolation theory concepts have been employed in order to generalise the results for powder beds that have different mean particle sizes and size distributions. The results of this work can be employed to inform the selection of particle sizes required for binder formulations, to optimise density and reduce shrinkage in printed binder jet components.

Spatial distribution of the intertidal snail Ilyanassa obsoleta in relation to parasitism by two species of trematodes

2000 ◽  
Vol 78 (7) ◽  
pp. 1137-1143 ◽  
Author(s):  
Dean G McCurdy ◽  
J Sherman Boates ◽  
Mark R Forbes
Keyword(s):  
Spatial Distribution ◽  
Intertidal Zone ◽  
Bay Of Fundy ◽  
Spatial Distributions ◽  
Ilyanassa Obsoleta ◽  
Intermediate Hosts ◽  
Corophium Volutator ◽  
Vertical Distributions ◽  
Second Intermediate Host ◽  
Intertidal Snail

We studied the spatial distributions of mud snails (Ilyanassa obsoleta) infected by two trematodes, Lepocreadium setiferoides and Gynaecotyla adunca, on a macrotidal mudflat in the Minas Basin, Bay of Fundy. Snails, as first intermediate hosts, were castrated by both parasites, and we found no evidence of sex differences in parasitism. Similar to previous work, prevalence of L. setiferoides in I. obsoleta increased exponentially with host size (and age). Unexpectedly, prevalence of G. adunca decreased over the largest size classes of snails, a result that may be due to several causes. Distributions of both parasites across the intertidal zone differed from previous accounts in that snails infected with L. setiferoides were found only in the middle of the intertidal zone, whereas prevalence of G. adunca increased exponentially moving seaward. Several species of polychaetes could be infected by L. setiferoides in the laboratory and may act as appropriate second intermediate hosts, whereas only the amphipod Corophium volutator served as a second intermediate host for G. adunca. Finally, the vertical distributions of I. obsoleta infected by either species of trematode overlap with distributions of apparent or known second intermediate hosts.

Crawling behaviour of the amphipod Corophium volutator and foraging by Semipalmated Sandpipers, Calidris pusilla

1989 ◽  
Vol 67 (2) ◽  
pp. 457-462 ◽  
Author(s):  
J. Sherman Boates ◽  
Peter C. Smith
Keyword(s):  
Nova Scotia ◽  
Food Intake ◽  
Lunar Cycle ◽  
Intertidal Mudflat ◽  
Sharp Reduction ◽  
Corophium Volutator ◽  
Quantitative Evidence ◽  
Qualitative And Quantitative ◽  
Calidris Pusilla ◽  
Semipalmated Sandpipers

During late spring and summer, the crawling behaviour of the amphipod Corophium volutator was studied on an intertidal mudflat in the Minas Basin, Nova Scotia. On average, less than 1% of the population crawled on any tide and these individuals tended to be large adults that were predominantly males. Animals emerged as the tide receded but most had crawled into burrows after 25 min. The crawling behaviour did not seem to be related to the lunar cycle as was expected; however, there was a sharp reduction in crawling activity (from 36.3 to 1.2 amphipods/m2) in July that coincided with the arrival of Semipalmated Sandpipers, Calidris pusilla, an abundant seasonal predator. The proportion of males in the amphipod population declined during the period when sandpipers were present. It appears that both a change in amphipod behaviour and depletion of the animals most prone to crawling may contribute to the observed reduction in crawling activity. Qualitative and quantitative evidence show that sandpipers were attracted to the tide edge where crawling amphipods were relatively abundant and that they increased their food intake by doing so.

Essai d'interpretation du mecanisme des courants de turbidite

1962 ◽  
Vol S7-IV (6) ◽  
pp. 849-856
Author(s):  
Wladimir D. Nesteroff
Keyword(s):  
Fine Sand ◽  
Turbidity Current ◽  
Abyssal Plain ◽  
Upper Ocean ◽  
Turbidity Currents ◽  
Current Pulses ◽  
Coarse To Fine

Abstract When the mechanism of turbidity currents was first proposed, it was thought that ooze deposits, which alternated with coarse to fine sand, were deposited on abyssal plains by pelagic sedimentation between turbidity current pulses. Later it was thought that concentrations of calcareous bioclastic material in the upper part of the ooze pointed to turbidity current deposition of the sand and lower part of the ooze, with only the upper ooze a result of pelagic sedimentation. Because CaCO <sub>3</sub> tests dissolve in sinking, no calcareous tests of upper ocean origin are found below 5500 to 5600 m. However, a study of terrigenous turbidites from abyssal plain samples taken at depths exceeding 5900 m which follow the sand to ooze sequence with foraminiferal concentrations in the upper ooze demonstrate that the beds are turbidite alone. It is hypothesized that any pelagic deposits forming between turbidity currents would be eroded away at the beginning of each pulse and that the fossil concentrations in the upper ooze result from delayed settling of the gas or protoplasm filled tests.

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