Diet analysis indicates seasonal fluctuation in trophic overlap and separation between a native and an introduced shrimp species (Decapoda, Palaemonidae) in the tidal river Thames (U.K.)

Crustaceana ◽  
2016 ◽  
Vol 89 (6-7) ◽  
pp. 701-719 ◽  
Author(s):  
Christopher W. Ashelby ◽  
Sammy De Grave ◽  
Magnus L. Johnson
Keyword(s):  
Prey Availability ◽  
Seasonal Fluctuation ◽  
Tidal River ◽  
Diet Analysis ◽  
Chironomid Larvae ◽  
Large Numbers ◽  
Seasonal Basis ◽  
Competition For Food ◽  
Palaemon Longirostris ◽  
High Degree

The diets of Palaemon longirostris and the non-native P. macrodactylus were investigated to explore their competitive interactions. Both species are largely carnivorous with amphipods being the dominant prey. Chironomid larvae were consumed in large numbers by both species in summer. Vacuity coefficients were higher for both species in winter than summer. A high degree of dietary overlap occurs in winter, with less overlap in summer suggesting that the two species compete for food on a seasonal basis, which may be partly attributed to the absence of chironomid larvae, and generally reduced prey availability, in the winter. If summer prey also become limited then competition for food may increase and P. macrodactylus may then have an adverse effect on P. longirostris. An introduction of P. macrodactylus in the summer, when there is less competition for food, may be more likely to lead to a successful colonisation than one in the winter.

Feeding habits and diet overlap of three species of garter snakes (Thamnophis) on Vancouver Island

1978 ◽  
Vol 56 (9) ◽  
pp. 1967-1974 ◽  
Author(s):  
Patrick T. Gregory
Keyword(s):  
Prey Availability ◽  
Feeding Habits ◽  
Food Preferences ◽  
Vancouver Island ◽  
Niche Shift ◽  
Thamnophis Sirtalis ◽  
Garter Snakes ◽  
Large Numbers ◽  
Competition For Food ◽  
Thamnophis Elegans

Closely related, sympatrtc species of organisms often show resource partitioning. In this study, diet partitioning is examined in three sympalric species of garter snakes (Thamnophis) on Vancouver Island. Thamnophis sirtalis feeds mainly on amphibians and earthworms, Thamnophis ordinoides on earthworms and slugs, and Thamnophis elegans on slugs, fish, and small mammals. Thamnophis sirtalis and T. ordinoides, which are mote widely distributed on Vancouver Island than is T. elegans, have not been shown to modify their diets in the absence of T. elegans, but it is suggested that this lack of niche shift may be due to variations in prey availability. Neither innate differences in food preferences among the species nor interspecific competition for food have been shown to explain the observed differences in diet among the three species. Certain types of prey appear more likely than others to turn up in large numbers in stomach samples and it is suggested that this may be due to variations in ease of capture and (or) abundance. Possible explanations of the observed diets are discussed.

scholarly journals CYTOPLASMIC DNA SYNTHESIS IN AMOEBA PROTEUS

1962 ◽  
Vol 15 (3) ◽  
pp. 525-534 ◽  
Author(s):  
M. Rabinovitch ◽  
W. Plaut
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Living Cells ◽  
Large Numbers ◽  
Cytoplasmic Dna ◽  
Basic Dyes ◽  
Nuclease Digestion ◽  
High Degree ◽  
Very High

The incorporation of tritiated thymidine in Amoeba proteus was reinvestigated in order to see if it could be associated with microscopically detectable structures. Staining experiments with basic dyes, including the fluorochrome acridine orange, revealed the presence of large numbers of 0.3 to 0.5 µ particles in the cytoplasm of all cells studied. The effect of nuclease digestion on the dye affinity of the particles suggests that they contain DNA as well as RNA. Centrifugation of living cells at 10,000 g leads to the sedimentation of the particles in the centrifugal third of the ameba near the nucleus. Analysis of centrifuged cells which had been incubated with H3-thymidine showed a very high degree of correlation between the location of the nucleic acid-containing granules and that of acid-insoluble, deoxyribonuclease-sensitive labeled molecules and leads to the conclusion that cytoplasmic DNA synthesis in Amoeba proteus occurs in association with these particles.

scholarly journals The distribution of Cd and Cu in sediments covered with algal mat

2013 ◽  
Vol 9 (3) ◽  
pp. 243-250
Keyword(s):  
Organic Compounds ◽  
Sediment Cores ◽  
Seasonal Fluctuation ◽  
Bcr Sequential Extraction ◽  
Algal Mats ◽  
Fe Oxides ◽  
Coastal Marine ◽  
Sequential Extraction Method ◽  
Seasonal Basis ◽  
Algal Mat

In coastal marine environments, with shallow, warm and calm waters, it is sometimes possible to observe the presence of organosedimentary structures that are commonly flat and laminar in shape. These structures are called algal mats or recent stromatolites due to their remarkable similarities to fossil stromatolites. The aim of this work was the study of the distribution of the various forms of Cu and Cd in the main layers of coastal algal mats in a closed bay at Anavissos, on the coast of Saronikos Gulf. Small sediment cores were collected from one point inside the cove on a seasonal basis and the trace metals extracted according to the BCR sequential extraction method. The main results of the study were: Most of the labile Cd was associated with small inorganic grains or lime particles. The contribution of the fraction associated with Mn and Fe oxides, was similar to that adsorbed to organic compounds and sulfides. The high contribution of the labile Cd to the total element (over 85%) was a strong indication of anthropogenic origin. On the other hand, most of the Cu in the sediment was associated with the crystal lattice (74%). Cu showed increased seasonal fluctuation; most of its labile forms were associated with organic compounds and sulfides whereas the less abundant form was that associated with Mn and Fe oxides. On the whole, the sediments were slightly enriched in Cd, while the concentrations of Cu were normal for the region.

Impedance Screening for Preschool Children: State of the Art

1979 ◽  
Vol 88 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Jack L. Paradise ◽  
Clyde G. Smith
Keyword(s):  
Preschool Children ◽  
Middle Ear ◽  
Large Scale ◽  
High Sensitivity ◽  
Cutoff Point ◽  
Screening Programs ◽  
Large Numbers ◽  
Middle Ear Disease ◽  
High Degree ◽  
Large Scale Screening

As a test for detecting middle ear disease among preschool children, tympanometry — as opposed to audiometry — has three advantageous attributes: a high degree of sensitivity, minimal need for subject cooperation, and total objectivity. For these reasons interest has arisen in tympanometry as a method for screening, i.e., identifying children with previously undetected middle ear disease. However, uncertainty persists concerning the importance of detecting apparently asymptomatic middle ear effusions, and concerning optimal methods, or even the advisability, of treating them. Further, the sensitivity and specificity of tympanometry depend on how the pass-fail cutoff point is defined. Defining this cutoff point so as to achieve high sensitivity may result in excessively low specificity, with the production of large numbers of false-positives who then become overreferrals. Data are presented to show how the validity of the test may be increased to some extent by attention to the gradient of “negative-pressure” tympanograms. At the present time, given the various aforementioned uncertainties, and with adequate validation as to the presence or absence of disease often lacking in reported studies of impedance screening in preschool populations, the cumulative results of these studies do not warrant embarking on large-scale screening programs. What is needed instead is additional research to explore the issue further.

Growth and differentiation of Tubularia cells in a chemically defined physiological medium

Development ◽  
1968 ◽  
Vol 20 (1) ◽  
pp. 73-80
Author(s):  
Allison L. Burnett ◽  
Faith E. Ruffing ◽  
June Zongker ◽  
Anna Necco
Keyword(s):  
Defined Medium ◽  
Control Mechanisms ◽  
Mucous Cells ◽  
Chemically Defined Medium ◽  
Experimental Animals ◽  
Molecular Weights ◽  
Large Numbers ◽  
High Degree ◽  
I Cells

Although hydroids have proven valuable experimental animals for studies involving polarity and regeneration, they have not been extensively used by chemical embryologists studying control mechanisms in differentiation. Ideally, hydroids should be valuable tools for such a study. Their morpohology is relatively simple since they are diploblastic; their cells achieve a high degree of specialization (cnidoblasts, nerve cells, gland and mucous cells); cell differentiation (and morphogenesis) from a reserve stock of interstitial or i-cells is rapid; and many species can be cultured in large numbers under controlled environmental conditions. Probably one of the reasons for this lack of attention is that no one has succeeded in cloning cells of a particular type in a chemically defined medium. In vivo systems, mainly because of their impermeability to most exogenous materials with molecular weights over 200, have not proven to be especially reliable.

scholarly journals MACROPHAGE PLASMA MEMBRANES

1971 ◽  
Vol 133 (4) ◽  
pp. 785-806 ◽  
Author(s):  
Ralph L. Nachman ◽  
Barbara Ferris ◽  
James G. Hirsch
Keyword(s):  
Alveolar Macrophages ◽  
Plasma Membranes ◽  
Gradient Centrifugation ◽  
Protein A ◽  
Membrane Preparation ◽  
Polystyrene Spheres ◽  
Protein Patterns ◽  
Large Numbers ◽  
Structural Preservation ◽  
High Degree

Plasma membranes have been isolated from pure populations of rabbit alveolar macrophages which were swollen in water, fixed briefly with glutaraldehyde, disrupted by Dounce homogenization, and separated by sucrose gradient centrifugation. The recovered membranes exhibited good structural preservation and enzymatic activity; both morphologic and biochemical evidence indicated a high degree of purity (>90%) of the membrane preparation. Interiorized plasma membranes were also prepared without exposure to glutaraldehyde from phagocytic vacuoles recovered from alveolar macrophages which had ingested large numbers of polystyrene spheres. These membranes were contaminated with lysosomal constituents, but they were nevertheless of value for comparison to the "pure" membranes isolated by the glutaraldehyde procedure. Acrylamide gel electrophoresis of the solubilized plasma membranes and phagolysosomal membranes revealed similar protein patterns, with seven to nine individual components ranging in molecular weight from 70,000 to 140,000. The two most rapidly migrating components gave positive reactions for lipid as well as protein. A band containing carbohydrate was detected near the origin of the plasma membrane gels. Antisera were made by injecting guinea pigs with the purified rabbit alveolar macrophage plasma membranes. Gel diffusion and immunoelectrophoretic study of these antisera established the presence of rabbit immunoglobulin G and of one or two other antigenic constituents in the membrane preparation.

scholarly journals Breeding stage, not sex, affects foraging characteristics in masked boobies at Rapa Nui

2020 ◽  
Vol 74 (12) ◽  
Author(s):  
Miriam Lerma ◽  
Nina Dehnhard ◽  
Guillermo Luna-Jorquera ◽  
Christian C. Voigt ◽  
Stefan Garthe
Keyword(s):  
Prey Availability ◽  
General Pattern ◽  
Sexual Segregation ◽  
Food Distribution ◽  
Rapa Nui ◽  
Breeding Stage ◽  
Horizontal Competition ◽  
Show Evidence ◽  
Competition For Food ◽  
The Difference

Abstract Sexual segregation in foraging occurs in some species and populations of boobies (Sulidae), but it is not a general pattern. Sexual segregation in foraging may occur to avoid competition for food, and this competition may intensify during specific stages of breeding. We examined sexual segregation in foraging in relation to breeding stage in masked boobies Sula dactylatra at Rapa Nui by tracking simultaneously incubating and chick-rearing birds using GPS recorders (n = 18) and collected a total of 11 regurgitate samples. Stable isotope analyses (δ13C and δ15N) of whole blood samples were carried out in 20 birds. There were no differences in foraging trip parameters or diet between females and males. Both sexes traveled farther and for longer while incubating than while rearing chicks. Isotopic niches (δ13C and δ15N) overlapped to some degree among all groups at all times, but the lowest overlap between sexes occurred during incubation. While preying on ephemerally distributed flying fish, vertical or horizontal competition avoidance may be almost impossible, and thus females and males share their foraging grounds. Since birds were tracked simultaneously, shorter foraging trips of chick-rearing birds must be an effect of the constraints of provisioning the chick. Differences observed in δ15N and δ13C values between sexes may be caused by subtle differences in their foraging behaviors, or by differences in physiology linked to breeding. Our findings suggest that local oceanography and its inherent food distribution are determinants for sexual segregation in foraging patterns in masked boobies and possibly also other booby species. Significance statement In some animals, females and males forage on different areas or prey on different species to avoid competition for food resources. In boobies (Sula sp.), some studies show evidence of sexual segregation in foraging and others do not. Here, we tested if sexual segregation in foraging occurred in masked boobies on the Pacific island of Rapa Nui by studying simultaneously incubating and chick-rearing birds. We found no evidence of sexual segregation on foraging behavior or diet. We discuss that the difference between this and other studies in boobies may be an effect of the local prey availability. When the prey community is more diverse and heterogeneously distributed, each sex may access different resources and thus sexual foraging segregation will occur. In contrast, in areas like Rapa Nui where prey resources are distributed ephemerally, sexual segregation in foraging will not be useful and is thus less likely to occur.

scholarly journals Mid-winter temperatures, not spring temperatures, predict breeding phenology in the European starling Sturnus vulgaris

2015 ◽  
Vol 2 (1) ◽  
pp. 140301 ◽  
Author(s):  
Tony D. Williams ◽  
Sophie Bourgeon ◽  
Allison Cornell ◽  
Laramie Ferguson ◽  
Melinda Fowler ◽  
...  
Keyword(s):  
Clutch Size ◽  
Prey Availability ◽  
Sturnus Vulgaris ◽  
Winter Temperature ◽  
Laying Date ◽  
Breeding Phenology ◽  
European Starlings ◽  
Winter Temperatures ◽  
Lag Times ◽  
High Degree

In many species, empirical data suggest that temperatures less than 1 month before breeding strongly influence laying date, consistent with predictions that short lag times between cue and response are more reliable, decreasing the chance of mismatch with prey. Here we show in European starlings ( Sturnus vulgaris ) that mid-winter temperature ca 50–90 days before laying (8 January–22 February) strongly ( r 2 = 0.89) predicts annual variation in laying date. Mid-winter temperature also correlated highly with relative clutch size: birds laid later, but laid larger clutches, in years when mid-winter temperatures were lower. Despite a high degree of breeding synchrony (mean laying date 5–13 April = ±4 days; 80% of nests laid within 4.8 days within year), European starlings show strong date-dependent variation in clutch size and productivity, but this appears to be mediated by a different temporal mechanism for integration of supplemental cue (temperature) information. We suggest the relationship between mid-winter temperature and breeding phenology might be indirect with both components correlating with a third factor: temperature-dependent development of the starling's insect (tipulid) prey. Mid-winter temperatures might set the trajectory of growth and final biomass of tipulid larvae, with this temperature cue providing starlings with information on breeding season prey availability (though exactly how remains unknown).

Ecology of metazoan parasites infecting Catostomus spp. (Catostomidae) from southwestern Lake Superior

1993 ◽  
Vol 71 (8) ◽  
pp. 1646-1652 ◽  
Author(s):  
Cheryl C. Hogue ◽  
Daniel R. Sutherland ◽  
Bruce M. Christensen
Keyword(s):  
Intestinal Tract ◽  
Lake Superior ◽  
Parasitic Copepod ◽  
Parasite Fauna ◽  
White Sucker ◽  
Anterior Portion ◽  
Metazoan Parasites ◽  
Seasonal Basis ◽  
Longnose Sucker ◽  
High Degree

Ecology of the parasite fauna of two abundant nongame fish species, Catostomus catostomus (longnose sucker) and Catostomus commersoni (white sucker), from southwestern Lake Superior was examined. White sucker harbored a total of 17 parasite species compared with 8 species in longnose sucker. Echinorhynchus salmonis and Neoechinorhynchus crassus were the most abundant helminths in both sucker species. The only parasitic copepod found in this study, Ergasilus nerkae, was more prevalent in longnose sucker. In white sucker, Glaridacris catostomi, Capillaria catostomi, Ergasilus nerkae, Allocreadium lobatum, and Isoglaridacris bulbocirrus showed fluctuations in prevalence on a seasonal basis. Several helminth species showed a high degree of microhabitat overlap in the gut (e.g., A. lobatum, G. catostomi, and Echinorhynchus salmonis). Helminths that exhibited a higher mean intensity in certain sections of the intestinal tract included I. bulbocirrus in the anterior portion of the gut and Capillaria catostomi in the posterior region of the gut.

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