Ontogenic changes in prey consumption by the stonefly Paragnetina media in relation to temporal variation in prey nutrient content

2000 ◽  
Vol 78 (5) ◽  
pp. 748-763 ◽  
Author(s):  
Catherine J. Duvall ◽  
D. Dudley Williams
Keyword(s):  
Temporal Variation ◽  
Nutrient Content ◽  
Prey Consumption ◽  
Paragnetina Media

Ontogenic changes in prey consumption by the stonefly Paragnetina media in relation to temporal variation in prey nutrient content

2000 ◽  
Vol 78 (5) ◽  
pp. 748-763 ◽  
Author(s):  
Catherine J Duvall ◽  
D Dudley Williams
Keyword(s):  
Temporal Variation ◽  
Protein Content ◽  
Lipid Level ◽  
Nutrient Content ◽  
Chironomid Larvae ◽  
Larval Recruitment ◽  
Prey Protein ◽  
Baetis Tricaudatus ◽  
Female Bodies ◽  
Paragnetina Media

In Duffin Creek, Ontario, nymphs of the predatory stonefly Paragnetina media (Perlidae) commonly feed on detritus and three prey types: hydropsychid larvae (Hydropsyche sparna and Hydropsyche slossonae), nymphs of the mayfly Baetis tricaudatus, and chironomid larvae belonging to subfamilies Tanypodinae and Orthocladiinae. This study examined temporal changes in the nutrient (lipid and protein) content of these prey to determine if the predator tracks food resources by selecting prey on the basis of nutrient requirements at different stages in its own development. All three common prey types exhibited temporal variation in lipid levels, with peaks occurring at different times: June for the hydropsychids, August for the chironomids, and October for B. tricaudatus. Prey protein levels were less variable. The proportions of the prey types that were eaten varied throughout the year and according to predator size. For example, while small P. media ate mostly detritus, they also consumed early-instar hydropsychids during the larval recruitment period of the latter; mid-sized nymphs included more animal matter in their diet, primarily chironomid larvae; and larger nymphs primarily ate B. tricaudatus. Paragnetina media nymphs in all size categories showed an increase in body lipid level in the autumn, suggesting a general accumulation of lipid reserves in readiness for the winter, although dietary adjustment to accomplish this was detectable only in small P. media. There was no evidence to suggest that P. media selected prey on the basis of the latter's protein content. Male P. media nymphs preyed predominantly on chironomid larvae and included mites in their diet, whereas female nymphs preferred B. tricaudatus and hydropsychids. On a per milligram body mass basis, male nymphs had the higher nutrient gain, since, for both lipid and protein, intake by males was between two and three times that by females. However, male and female bodies had similar lipid contents. We conclude that whereas there is temporal variation both in the nutritional (lipid and protein) content of the common prey of P. media and in this predator's diet, there is only weak evidence for nutrient-resource tracking.

Feeding variability among individual aquatic predators in experimental channels

1993 ◽  
Vol 71 (10) ◽  
pp. 2033-2037 ◽  
Author(s):  
Roger S. Wotton ◽  
Mark S. Wipfli ◽  
Luke Watson ◽  
Richard W. Merritt
Keyword(s):  
Field Experiments ◽  
Prey Consumption ◽  
Black Fly ◽  
Predator Prey ◽  
Future Studies ◽  
Size Classes ◽  
Feeding Trials ◽  
Aquatic Predators ◽  
Fly Larvae ◽  
Paragnetina Media

Experiments were conducted in experimental channels to study feeding variability through time and between conspecific individuals of four species of lotic predators. Large and small Rhyacophila dorsalis (Trichoptera: Rhyacophilidae) were given black fly larvae, mainly Simulium ornatum (Diptera: Simuliidae) of two size classes during laboratory feeding trials lasting up to 5 days. Acroneuria lycorias (Plecoptera: Perlidae) were also given black fly larvae (Prosimulium fuscum, S. venustum) during 11-day laboratory feeding trials. Paragnetina media (Perlidae) and Isoperla signata (Plecoptera: Perlodidae), were supplied with a mixed prey assemblage of black fly larvae and mayfly nymphs, Baetis flavistriga (Ephemeroptera: Baetidae), and Epeorus vitrea (Heptageniidae), for 9 days in field experiments. There was significant variability in the consumption of prey among individuals of R. dorsalis, this being true for both large and small predators. Significant among-predator and day-to-day feeding variability also occured with A. lycorias, P. media, and I. signata. Our experiments showed that there are significant differences in prey consumption among individual predators within a given species, and these differences need to be considered when planning, and interpreting, future studies on predator – prey interactions, particularly those conducted in experimental streams.

Towards a European Food Composition Data Interchange Platform

2012 ◽  
Vol 82 (3) ◽  
pp. 209-215 ◽  
Author(s):  
Simone Bell ◽  
Heikki Pakkala ◽  
Michael P. Finglas
Keyword(s):  
Nutrient Content ◽  
Food Composition ◽  
Consumer Information ◽  
Health Claims ◽  
Composition Data ◽  
European Committee ◽  
Food Properties ◽  
Data Interchange ◽  
Food Composition Data ◽  
Definition Of

Food composition data (FCD) comprises the description and identification of foods, as well as their nutrient content, other constituents, and food properties. FCD are required for a range of purposes including food labeling, supporting health claims, nutritional and clinical management, consumer information, and research. There have been differences within and beyond Europe in the way FCD are expressed with respect to food description, definition of nutrients and other food properties, and the methods used to generate data. One of the major goals of the EuroFIR NoE project (2005 - 10) was to provide tools to overcome existing differences among member states and parties with respect to documentation and interchange of FCD. The establishment of the CEN’s (European Committee for Standardisation) TC 387 project committee on Food Composition Data, led by the Swedish Standards Institute, and the preparation of the draft Food Data Standard, has addressed these deficiencies by enabling unambiguous identification and description of FCD and their quality, for dissemination and data interchange. Another major achievement of the EuroFIR NoE project was the development and dissemination of a single, authoritative source of FCD in Europe enabling the interchange and update of data between countries, and also giving access to users of FCD.

Temporal variation in food utilisation by three species of temperate demosponge

2013 ◽  
Vol 485 ◽  
pp. 91-103 ◽  
Author(s):  
A Perea-Blázquez ◽  
SK Davy ◽  
B Magana-Rodríguez ◽  
JJ Bell
Keyword(s):  
Temporal Variation ◽  
Food Utilisation

Food procurement in English-language Canadian public schools: Opportunities and challenges

2019 ◽  
Vol 6 (1) ◽  
pp. 75-99
Author(s):  
Shawna Holmes
Keyword(s):  
Public Schools ◽  
Food Environment ◽  
Nutritional Quality ◽  
English Language ◽  
Nutrient Content ◽  
Food Environments ◽  
School Food ◽  
Provincial Level ◽  
School Food Environment

This paper examines the changes to procurement for school food environments in Canada as a response to changes to nutrition regulations at the provincial level. Interviews with those working in school food environments across Canada revealed how changes to the nutrition requirements of foods and beverages sold in schools presented opportunities to not only improve the nutrient content of the items made available in school food environments, but also to include local producers and/or school gardens in procuring for the school food environment. At the same time, some schools struggle to procure nutritionally compliant foods due to increased costs associated with transporting produce to rural, remote, or northern communities as well as logistic difficulties like spoilage. Although the nutrition regulations have facilitated improvements to food environments in some schools, others require more support to improve the overall nutritional quality of the foods and beverages available to students at school.

Effect of inter-row cultivation on soil carbon dioxide emission in a peach plantation

2010 ◽  
Vol 59 (1) ◽  
pp. 157-164 ◽  
Author(s):  
E. Tóth ◽  
Cs. Farkas
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Carbon Dioxide Emission ◽  
Nutrient Content ◽  
Soil Disturbance ◽  
Biological Properties ◽  
Soil Tillage ◽  
Favourable Effect ◽  
Volumetric Soil Water Content

Soil biological properties and CO2emission were compared in undisturbed grass and regularly disked rows of a peach plantation. Higher nutrient content and biological activity were found in the undisturbed, grass-covered rows. Significantly higher CO2fluxes were measured in this treatment at almost all the measurement times, in all the soil water content ranges, except the one in which the volumetric soil water content was higher than 45%. The obtained results indicated that in addition to the favourable effect of soil tillage on soil aeration, regular soil disturbance reduces soil microbial activity and soil CO2emission.

Effect of NPK fertilization on the yield of winter wheat and maize and on the nutrient content of the soil in a long-term experiment network in Hungary

2013 ◽  
Vol 62 (2) ◽  
pp. 311-330
Author(s):  
Jakab Loch ◽  
János Lazányi
Keyword(s):  
Winter Wheat ◽  
Nutrient Content ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Npk Fertilization

Az Országos Műtrágyázási Tartamkísérletek (OMTK) tizenkét NPK kezeléskombinációjában, kilenc termőhelyen vizsgáltuk az NPK-trágyázás hatását az őszi búza és a kukorica termésére és a talajok 0,01 M CaCl2-oldható tápelemtartalmára. A termőhelyek: Bicsérd (BI), Hajdúböszörmény (HA), Iregszemcse (IR), Karcag (KA), Keszthely (KE), Kompolt (KO), Mosonmagyaróvár (MO), Nagyhörcsök (NA), Putnok (PU). Az NPK kezelések: 000, 101, 111, 121, 201, 220, 221, 222, 331, 341, 421, 441. A N- és P-kezelések a kódoknak megfelelően 50 kg N, ill. P2O5·ha−1, a K-adagok 100 kg K2O·ha−1 hatóanyag-mennyiséggel növekszenek. Az őszi búza termésadatok a 23., 24., 27., 28. és 31. évi kísérletekből, a kukoricatermések a 25., 26., 29. és 30. évből származnak.Az NPK-kezelések jelentősen növelték az őszi búza és a kukorica öt-, illetve négyéves átlagtermését, szignifikáns különbségek jöttek létre a termőhelyek átlagában. Az NPK-kezelések különböző érvényesülése az egyes termőhelyeken az eltérő ökológiai viszonyok, köztük a különböző eredeti tápelemtartalom és szolgáltató képesség következménye.Az NPK-kezelések hatására a talajok 0,01 M CaCl2-oldható tápelemtartalma is jelentősen változott. A növények tápelemigényét meghaladó kezelések tartamhatásaként tápelem-felhalmozódás igazolható mindhárom tápelem esetében. A növények szükségletét meghaladó N-adagok, a karbonátos talajokat és a nagy agyagtartalmú kompolti (KO) talajt kivéve csökkentették a talaj pH-t. A másodfokú görbék az őszi búza ötéves termésátlaga és a 0,01 M CaCl2-ban mért összes-N, P- és K-tartalom közötti összefüggéseket szemléltetik termőhelyenként.A legnagyobb kezeléshatások azokon a talajokon igazolhatók, melyeken a kontroll 0,01 M CaCl2-oldható összes-N értéke kisebb, mint 5–10 mg·kg−1. A 15,0 mg·kg−1 érték felett altalaban nem érvényesült a nitrogén termésnövelő hatása. Kivételt képez a tápanyagban gazdag, hajdúböszörményi nem karbonátos réti talaj. A foszfor termésnövelő hatása 2,0 mg P·kg−1 érték felett — a karbonátos réti talaj kivételével — általában nem érvényesül. Az összefüggéseket jellemző R2 meghatározottsági tényezők a legkisebbek az őszi búza és a talaj 0,01 M CaCl2-oldható K-tartalma között, ami az egyéb tényezők nagyobb szerepére utal.A bemutatott eredmények igazolják, hogy a 0,01 M CaCl2-oldható N-, P- és Kfrakciók alkalmasak a tápanyaghiány és -felesleg jellemzésére. Egyben igazolják, hogy az eltérő ökológiai viszonyok között nagyobb terméskülönbségek jöhetnek létre, mint a kezelések hatására. A környezetkímélő tápanyag-gazdálkodás megköveteli a tápanyagok eltérő érvényesülésének figyelembevételét.A termésadatok átengedéséért köszönet az OMTK Hálózati Tanács elnökének, titkárának, és valamennyi kísérletfelelősnek.

Sign in / Sign up

Export Citation Format

Share Document