Seasonal changes in the biochemical composition and nutritional state of the immigrant triclad Dugesia polychroa (Platyhelminthes: Turbellaria) in Toronto Harbour, Canada

1975 ◽  
Vol 53 (11) ◽  
pp. 1723-1734 ◽  
Author(s):  
M. J. Boddington ◽  
D. F. Mettrick
Keyword(s):  
Biochemical Composition ◽  
Energy Content ◽  
Nutritional State ◽  
Caloric Content ◽  
Time Period ◽  
Competition For Food ◽  
Highly Correlated ◽  
Food Reserves ◽  
Second Peak ◽  
Dugesia Polychroa

The biochemical components of a population of Dugesia polychroa from Toronto Harbour showed, with the exception of total nitrogen, statistically significant variations over the time period studied (May 1971 through January 1972). The variation in biochemical composition was not totally correlated to changes in percentage biomass (mean individual weight), although the latter was itself indicative of events occurring in the population.Fluctuations in carbohydrate, lipid, and caloric content were highly correlated to changes occurring in percentage biomass during the period of reproduction and subsequent recruitment to the population. During this period a maximum in stored food reserves and energy content was observed. Before the winter these fractions increased to a second peak but at a disproportionately higher rate than that for percentage biomass. In both cases the caloric values were lower than the maximum physiological energy values.The changing nutritional state of Dugesia polychroa strongly supports the thesis that triclad population numbers are controlled by intraspecific competition for food, and, specifically shows that Dugesia polychroa exists, at least in Canada, in a state of relative starvation over the whole year.

scholarly journals Comparación de la composición química proximal de la carne de Anadara Tuberculosa y A. Similis (Bivalvia: Arcidae) de Chomes, Puntarenas, Costa Rica

2012 ◽  
Vol 3 ◽  
pp. 95
Author(s):  
Rafael A. Cruz ◽  
Cristian Fonseca Rodríguez ◽  
Fabián Chavarría-Solera
Keyword(s):  
Seasonal Variation ◽  
Costa Rica ◽  
Proximate Composition ◽  
Biochemical Composition ◽  
Nutritional Value ◽  
Energy Content ◽  
Human Consumption ◽  
Caloric Content ◽  
Monthly Basis ◽  
Average Value

Se estudiaron la variación estacional de la composición química proximal y el contenido energético de la carne de las pianguas Anadara tuberculosa y A. similis. Mensualmente, entre marzo de 2010 y febrero de 2011, se recolectaron de 15 a 20 ejemplares de cada especie. La composición proximal se determinó siguiendo la metodología recomendada por la Asociación Oficial de Químicos Analíticos (AOAC). El valor promedio de las proteínas de la carne de A. similis fue de 57.9 ± 7.2%, carbohidratos 25.6 ± 4.4%, cenizas 6.87 ± 0.23% y lípidos 9.2 ± 0.2%. El contenido calórico promedio fue de 5.3 ± 0.2 kcal/g. Para A. tuberculosa se calculó 61.6% de proteínas, 21.6% de carbohidratos, 8.8% de cenizas, 7.9% de lípidos; el valor calórico fue de 5.2 kcal/g. Se puede concluir que tanto A. tuberculosa como A. similis presentan valores nutricionales óptimos para el consumo humano, por su bajo contenido de grasa y su aceptable contenido proteico. Abstract The seasonal variation in proximate biochemical composition and energy content of Anadara tuberculosa and A. similis were studied between March 2010 and February 2011 on a monthly basis. Fifteen to twenty individuals of each species were collected monthly. The proximate composition was determined following the methodology recommended by the Association of Official Analytical Chemists (AOAC). The average value of meat protein in A. similis was 57.9 ± 7.2%, carbohydrate 25.6 ± 4.4%, ash 6.87 ± 0.23%, and lipids 9.2 ± 0.2%. The average caloric content was 5.3 ± 0.2 kcal/g. For A. tuberculosa the values were protein 61.6%, carbohydrate 21.6%, ash 8.8%, and lipids 7.9%. The caloric value was 5.2 kcal/g. It can be concluded that both A. tuberculosa and A. similis have optimal nutritional value for human consumption, due to their low lipid and high protein contents.

Biochemical composition, energy content and chemical antifeedant and antifoulant defenses of the colonial Antarctic ascidian Distaplia cylindrica

2004 ◽  
Vol 145 (5) ◽  
pp. 885-894 ◽  
Author(s):  
J. B. McClintock ◽  
M. O. Amsler ◽  
C. D. Amsler ◽  
K. J. Southworth ◽  
C. Petrie ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Energy Content

scholarly journals MODELLING AND SIMULATION OF VOLUMETRIC RAINFALL FOR A CATCHMENT IN THE MURRAY–DARLING BASIN

2016 ◽  
Vol 58 (2) ◽  
pp. 119-142 ◽  
Author(s):  
J. BOLAND ◽  
P. HOWLETT ◽  
J. PIANTADOSI ◽  
R. ZAKARIA
Keyword(s):  
Food Production ◽  
Joint Probability ◽  
Fixed Time ◽  
Modelling And Simulation ◽  
Joint Probability Distribution ◽  
Production Region ◽  
Time Period ◽  
Murray Darling Basin ◽  
Management Policies ◽  
Highly Correlated

We discuss modelling and simulation of volumetric rainfall in a catchment of the Murray–Darling Basin – an important food production region in Australia that was seriously affected by a recent prolonged drought. Consequently, there has been sustained interest in development of improved water management policies. In order to model accumulated volumetric catchment rainfall over a fixed time period, it is necessary to sum weighted rainfall depths at representative sites within each sub-catchment. Since sub-catchment rainfall may be highly correlated, the use of a Gamma distribution to model rainfall at each site means that catchment rainfall is expressed as a sum of correlated Gamma random variables. We compare four different models and conclude that a joint probability distribution for catchment rainfall constructed by using a copula of maximum entropy is the most effective.

Piscivory, Growth, and Size-Selective Mortality of Age 0 Pikeperch (Stizostedion lucioperca)

1992 ◽  
Vol 49 (5) ◽  
pp. 894-902 ◽  
Author(s):  
Anthonie D. Buijse ◽  
Rob P. Houthuijzen
Keyword(s):  
Frequency Distribution ◽  
Energy Content ◽  
Stomach Contents ◽  
Proximate Analysis ◽  
Skewed Distribution ◽  
Fish Length ◽  
Growth And Survival ◽  
Class Strength ◽  
Highly Correlated ◽  
Stizostedion Lucioperca

Year-class strength of pikeperch (Stizostedion lucioperca), indexed as the age 0 abundance in trawl surveys, varied 300-fold in the northern part of Lake IJssel, The Netherlands, over the period 1966–89. Both mean length and year-class strength of age 0 pikeperch in November were highly correlated with mean summer temperature. Depending on the environmental conditions, especially water temperature and availability of food, the initially unimodal length frequency distribution of age 0 pikeperch developed into a positively skewed, bimodal or negatively skewed distribution towards the end of the summer. Strong year-classes were characterised by larger mean lengths and a negatively skewed frequency distribution, while weak year-classes were smaller and positively skewed. Stomach contents consisted of zooplankton and macrofauna for the smaller specimens and of age 0 smelt (Osmerus eperlanus) for the larger pikeperch (> 10 cm). Body energy content increased with fish length, and differences in proximate analysis were more pronounced later in the season. The condition of nonpiscivorous age 0 pikeperch was low and decreased over time, while that of piscivorous pikeperch increased. The onset of piscivory, favoured by high temperatures during summer, has a direct positive effect on the growth and survival of age 0 pikeperch.

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