Seasonal variation in abundance and size structure of phytoplankton in Baie des Chaleurs, southwestern Gulf of St. Lawrence, in relation to physical oceanographic conditions

Hydrobiologia ◽  
1995 ◽  
Vol 306 (2) ◽  
pp. 147-157 ◽  
Author(s):  
Michel R. Claereboudt ◽  
Jean C�t� ◽  
John C. Bonardelli ◽  
John H. Himmelman
Keyword(s):  
Seasonal Variation ◽  
Size Structure ◽  
Oceanographic Conditions

Mysid Life History and Seasonal Variation in Predation Pressure on Zooplankton

1983 ◽  
Vol 40 (11) ◽  
pp. 1968-1974 ◽  
Author(s):  
Paul A. Murtaugh
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Feeding Rate ◽  
Size Structure ◽  
Seasonal Fluctuations ◽  
Predation Intensity ◽  
Lake Washington ◽  
History Of ◽  
Relative Vulnerability

The bivoltine life history of Neomysis mercedis in Lake Washington, Seattle, results in seasonal variation in population size structure that influences the amount and quality of predation suffered by its zooplankton prey. Population densities and size–frequency data for Neomysis are combined with information on the influence of body size on feeding rate and composition of the diet to predict relative predation intensity on five size classes of Daphnia over a 27-mo period. An imperfect relationship between mysid numbers and expected predation intensity and seasonal fluctuations in the relative vulnerability of different-sized prey are two consequences of the mysid's pattern of life history.

Structure en taille des crustacés planctoniques d'un lac dimictique du Bouclier canadien

1988 ◽  
Vol 66 (7) ◽  
pp. 1570-1577
Author(s):  
Lucie Martin ◽  
Bernadette Pinel-Alloul
Keyword(s):  
Seasonal Variation ◽  
Annual Cycle ◽  
Size Structure ◽  
Principal Coordinate Analysis ◽  
Size Spectra ◽  
Fall Season ◽  
Planktonic Crustaceans ◽  
Bouclier Canadien ◽  
Intermediate Linkage ◽  
Chronological Clustering

From May 1981 to July 1982, 28 zooplankton samples were taken from the pelagic zone of Lake Cromwell, Quebec. Seasonal variation in the size structure of the planktonic crustacean community was studied using three different multidimensional analyses: intermediate linkage clustering, principal coordinate analysis, and chronological clustering. The results of these analyses showed the existence of distinct patterns in the size distribution of planktonic crustaceans during the annual cycle. During winter, the community was dominated by intermediate-sized organisms (0.51–0.60 mm), and by a few of larger size (0.96 mm). In springtime, nauplii appeared, and the larger size classes were reduced, giving the size spectra a characteristic shape. Small organisms (0.06–0.22 mm) dominated the population throughout the summer. The fall season was characterized by the opposite observation: small organisms slowly decreased in number while the intermediate classes (0.51–0.60 mm) increased in number to reach their peak in winter. These size–frequency patterns may be related to varying food levels and composition throughout the year.

Ontogenetic and seasonal variation in the diets of a Costa Rican leaf-litter herpetofauna

2006 ◽  
Vol 22 (4) ◽  
pp. 409-417 ◽  
Author(s):  
Steven M. Whitfield ◽  
Maureen A. Donnelly
Keyword(s):  
Seasonal Variation ◽  
Size Structure ◽  
Prey Size ◽  
Prey Selection ◽  
Large Prey ◽  
Wet Season ◽  
Ontogenetic Shifts ◽  
Prey Preferences ◽  
Lowland Wet Forest ◽  
Stomach Volume

Ontogenetic and seasonal variation in diet was examined for 11 species of insectivorous forest-floor frogs and lizards from a lowland wet forest in north-eastern Costa Rica. Specimens were collected systematically over an entire seasonal cycle and represented individuals of all sizes. Individual prey items were removed from stomachs of preserved specimens, measured and identified. Ontogenetic shifts in prey size were pervasive. Ontogenetic shifts in prey composition were limited to four species; these were not the species with greatest range in body size, nor the species with the broadest diets. Small prey types (ants, mites, collembolans) decreased in representation and large prey types (roaches, orthopterans, millipedes) increased in importance over ontogeny; this could be because prey selection is based primarily on prey size or because of different prey preferences among age classes. There is little evidence for size-structure in this assemblage. There is no evidence that total availability of arthropod prey varies among seasons, but some evidence that preferred prey are less common in the wet season. Diet was similar between lizards and frogs. Lizards were more likely to have empty stomachs, but also greater stomach volume, than frogs; this indicates a difference in food-gathering strategies. Our study indicates strong similarity between frogs and lizards in diet despite enormous differences in physiology and behaviour.

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