scholarly journals Predation follows competition in depth selection behaviour of Cladocera in a deep lake (E Poland)

2009 ◽  
Vol 46 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Małgorzata Adamczuk
Keyword(s):  
Habitat Segregation ◽  
Daphnia Longispina ◽  
Deep Lake ◽  
Migration Patterns ◽  
Chydorus Sphaericus ◽  
Predation Avoidance ◽  
Small Depth ◽  
Bosmina Coregoni ◽  
Diaphanosoma Brachyurum ◽  
The Vertical Distribution

Predation follows competition in depth selection behaviour of Cladocera in a deep lake (E Poland)Observations of the vertical distribution of Cladocera in the pelagic zone of the deep Lake Piaseczno (38.8 m) focused on 6 species:Diaphanosoma brachyurum, Daphnia longispina, D. cucullata, Bosmina coregoni, B. longirostris, andChydorus sphaericus.The animals displayed clear depth preferences, and their migration patterns were limited to small depth amplitudes. The results show that vertical habitat segregation of cladocerans in the lake consists mostly in the mechanism of competition for accessible food resources, rather than in the mechanism of predation avoidance.

scholarly journals Variations de la structure trophique du lac-réservoir oligotrophe Bin El Ouidane (Maroc)

2005 ◽  
Vol 15 (1) ◽  
pp. 193-208 ◽  
Author(s):  
O. Cherifi ◽  
M. Loudiki
Keyword(s):  
Ceriodaphnia Dubia ◽  
Régime Alimentaire ◽  
Tube Digestif ◽  
Tinca Tinca ◽  
Daphnia Longispina ◽  
Tractus Digestif ◽  
Diaphanosoma Brachyurum ◽  
Bin El Ouidane ◽  
Ceriodaphnia Reticulata ◽  
Spectre Alimentaire

L'étude combinée des apports par les crues, du plancton, des contenus algaux du tractus digestif des Cladocères et du régime alimentaire de quelques espèces de poissons dans le lac de barrage oligotrophe Bin El Ouidane a permis de dégager les conclusions suivantes : - les apports particulaires et dissous par les crues durant la période d'étude 1995-1997 ont une influence marquée sur la dynamique saisonnière du zooplancton via les changements dans la dynamique du peuplement phytoplanctonique ; - durant les trois années d'étude, le maximum de biomasse zooplanctonique se situe généralement juste après les pics printanier et estival du phytoplancton mettant ainsi en évidence l'importance du zooplancton herbivore dans la chaîne alimentaire pélagique du lac ; - l'étude des contenus algaux du tractus digestif des Cladocères Daphnia longispina, Daphnia lumholtzi, Diaphanosoma brachyurum, Ceriodaphnia dubia, Ceriodaphnia reticulata et Bosmina longirostris a montré que l'essentiel des espèces sont des filtreuses herbivores qui adoptent un comportement nutritionnel variable en fonction du temps lié à la disponibilité en phytoplancton, à leur âge et aux caractéristiques biotiques et abiotiques de l'écosystème lacustre ; - l'étude préliminaire du régime alimentaire de trois espèces de poissons Tinca tinca, Eupomotis gibbosus et Cyprinus carpio montre que leur spectre alimentaire est nettement dominé par le plancton. La fraction faunistique au niveau de leur tube digestif est représentée essentiellement par les Cladocères de grande taille et les Chironomes. Ceci met en évidence l'importance de ces poissons, à régime essentiellement planctonophage, dans la régulation des peuplements planctoniques de la retenue Bin El Ouidane.

scholarly journals Interactions zooplancton-poissons dans une retenue oligotrophe de mise en eau récente (Ste-Croix, Provence, France)

2005 ◽  
Vol 2 (4) ◽  
pp. 777-792 ◽  
Author(s):  
D. Pont ◽  
R. Chappaz ◽  
G. Brun ◽  
A. Champeau
Keyword(s):  
Régime Alimentaire ◽  
Daphnia Longispina ◽  
Cette Augmentation ◽  
Diaphanosoma Brachyurum ◽  
Leuciscus Cephalus

Les peuplements zooplanctoniques et piscicoles de la retenue de Sainte-Croix (lac oligotrophe profond) ont été suivis de la mise en eau (1974) à 1986. La phase initiale de colonisation (1974-1975), caractérisée par le calanide Acanthodiaptomus denticornis et la dominance des espèces piscicoles peuplant antérieurement le Verdon lotique (Barbus fluvatilis, Leuciscus cephalus) a été de courte durée. Par la suite, les cladocères sont restés dominants avec cependant de profondes modifications dans la structure du peuplement. En 1977-78, Daphnia longispina était dominante tout au long de l'année (76 %). Plus récemment, cette espèce ne représentait plus que 34 %. des effectifs (1983-84), puis 24 % (1985-1986). La situation actuelle est caractérisée par la présence de Diaphanosoma brachyurum en été et l'abondance des petites formes (bosmines). L'ichtyofaune s'est elle aussi modifiée avec, notamment, une importante population d'ablette (Alburnus cluburnus), exploitant la zone pélagique. Son régime alimentaire est largement zooplanctonophage mais inclut mollusques et insectes lorsqu'elle est capturée en zone littorale. Cette augmentation de la pression de prédation a entraîné un net déplacement du spectre des tailles du zooplancton vers tes classes inférieures à 0,8 mm en 1986 (82 %) alors que les grandes formes ( > à 1 mm) représentaient 60 % des effectifs en 1977-78. Les densités de D. longispina et D. brachyurum décroissent rapidement entre 1983 et 1986. Les conséquences de cette prédation sélective sont discutées (évolution prévisible du système) ainsi que les causes pouvant expliquer l'absence de régulation efficace (densité-dépendance) dans un tel système prédateur-proie.

Acidification and the structure of crustacean zooplankton in mountain lakes: The Tatra Mountains (Slovakia, Poland)

Biologia ◽  
2006 ◽  
Vol 61 (18) ◽  
Author(s):  
Zuzana Hořická ◽  
Evžen Stuchlík ◽  
Igor Hudec ◽  
Martin Černý ◽  
Jan Fott
Keyword(s):  
Species Composition ◽  
Daphnia Pulex ◽  
Crustacean Zooplankton ◽  
Tatra Mountains ◽  
Daphnia Longispina ◽  
Forest Zone ◽  
Lake Ecosystems ◽  
Chydorus Sphaericus ◽  
Ceriodaphnia Quadrangula ◽  
High Concentrations

AbstractSpecies composition of planktonic Crustacea in 102 lakes in the West and High Tatra Mountains, studied during the peak of anthropogenic acidification (1978–1996), is presented in this work. Zooplankton of the Tatra lakes have been studied since the middle of the 19th century, which later enabled the recognition of lake acidification and the assessment of its effect on the plankton community of lake ecosystems. In the pre-acidification period, the distribution of zooplankton was determined namely by the lake altitude and orientation (north vs. south) and by the catchment character. Crustacean zooplankton in larger lakes consisted of a limited number of species, with Acanthodiaptomus denticornis and Daphnia longispina dominating lakes in the forest zone, and Arctodiaptomus alpinus, Cyclops abyssorum, Daphnia longispina, Daphnia pulicaria, and Holopedium gibberum dominating lakes in the alpine zone. Ceriodaphnia quadrangula, Daphnia obtusa, Daphnia pulex, and Mixodiaptomus tatricus occurred in lakes with high concentrations of dissolved organic matter and in strongly acidified waters. Anthropogenic acidification has caused drastic changes in both the chemistry and biology of the Tatra lakes. Based on their status during the acidification peak, lakes were divided into three categories: non-acidified (with no change in the species composition of crustacean zooplankton due to the acidification), acidified (planktonic Crustacea disappeared in lakes with meadow-rocky catchments), and strongly acidified lakes where original Crustacea in meadow-rocky catchment lakes disappeared and were replaced by populations of the acid-tolerant littoral species Acanthocyclops vernalis, Chydorus sphaericus, and Eucyclops serrulatus. The acidification-induced processes of oligotrophication and toxicity of aluminium played a key role in the extinction of species. Despite the first signs of biological recovery observed in the early 2000s, acidification remains the most important factor governing the structure of plankton in the Tatra lakes.

Vertical migration of postlarval penaeid prawns in two Australian estuaries: the effect of tide and day/night

2008 ◽  
Vol 59 (8) ◽  
pp. 671 ◽  
Author(s):  
D. J. Vance ◽  
R. C. Pendrey
Keyword(s):  
Water Column ◽  
Vertical Migration ◽  
Hydrodynamic Models ◽  
Water Turbidity ◽  
Spawning Grounds ◽  
Migration Patterns ◽  
Nursery Areas ◽  
Net Migration ◽  
Penaeus Semisulcatus ◽  
The Vertical Distribution

Knowledge of the vertical migration behaviour of postlarval penaeid prawns is important in understanding postlarval migration from offshore spawning grounds to estuarine nursery areas. We sampled throughout several 24-h periods in two estuaries in Australia to assess the distribution of postlarvae in the water column. We used four trawl nets: one net in the top 0.5 m of the water column and three nets one above the other, from the seabed to 0.72 m above the seabed. Penaeus plebejus was abundant in catches in the Nerang River, southern Queensland, while Penaeus semisulcatus, Penaeus esculentus and Penaeus merguiensis were caught in the Embley River, northern Queensland. For all species, the highest catches at the surface were on night flood tides. Many postlarvae in the Embley River were caught in nets above the seabed on ebb tides, suggesting that net migration patterns cannot be determined simply by sampling surface waters. The vertical distribution of penaeid postlarvae is determined primarily by tide and day/night; however, water turbidity and cloud cover, factors that reduce light at the seabed, are also likely to be important. All these aspects of postlarval behaviour should be included in hydrodynamic models of larval advection from spawning grounds to inshore nursery areas.

scholarly journals CRUSTACEA OF THE POND OF TOMASHEV KOLOK IN THE SAMARA CITY

2017 ◽  
Vol 19 (3) ◽  
pp. 154-160
Author(s):  
A.V. Kireev ◽  
Yu.L. Gerasimov
Keyword(s):  
Species Composition ◽  
Seasonal Dynamics ◽  
Daphnia Longispina ◽  
Crustacean Species ◽  
Chydorus Sphaericus ◽  
Urban Pond ◽  
Ceriodaphnia Reticulata

The species composition and seasonal dynamics of quantity of Crustacean populations in small urban pond is studied. The list of 15 Crustacean species is presented. Daphnia longispina, Ceriodaphnia reticulata and Cyclops copepodits dominate in the first half of summer to July, Chydorus sphaericus dominate in August and September.

New forms of intra-European migration, labour market dynamics and social inequality in Europe

2014 ◽  
Vol 11 (2) ◽  
pp. 125-136 ◽  
Author(s):  
Roland Verwiebe ◽  
Laura Wiesböck ◽  
Roland Teitzer
Keyword(s):  
Labour Market ◽  
Social Inequality ◽  
Social Stratification ◽  
Labour Markets ◽  
Second Step ◽  
Market Dynamics ◽  
Migration Patterns ◽  
European Continent ◽  
The Past ◽  
European Migration

This article deals mainly with new forms of Intra-European migration, processes of integration and inequality, and the dynamics of emerging transnational labour markets in Europe. We discuss these issues against the background of fundamental changes which have been taking place on the European continent over the past two decades. Drawing on available comparative European data, we examine, in a first step, whether the changes in intra-European migration patterns have been accompanied by a differentiation of the causes of migration. In a second step, we discuss the extent to which new forms of transnational labour markets have been emerging within Europe and their effects on systems of social stratification.

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