scholarly journals Intraspecific competition for food within and between year classes in the deposit-feeding amphipod Monoporeia affinis-the cause of population fluctuations?

2002 ◽  
Vol 240 ◽  
pp. 205-213 ◽  
Author(s):  
J Wenngren ◽  
E Ólafsson
Keyword(s):  
Intraspecific Competition ◽  
Population Fluctuations ◽  
Competition For Food ◽  
Deposit Feeding

The Food and the Food Supply of Sockeye Salmon (Oncorhynchus nerka Walbaum) in Cultus lake, British Columbia.

1937 ◽  
Vol 3 (5) ◽  
pp. 450-468 ◽  
Author(s):  
William E. Ricker
Keyword(s):  
Low Temperature ◽  
Intraspecific Competition ◽  
Sockeye Salmon ◽  
Abundant Species ◽  
Minor Importance ◽  
Important Food ◽  
Total Food ◽  
Competition For Food ◽  
Summer Feeding ◽  
Food Consumed

The analysis of several hundred stomachs of sockeye salmon taken from Cultus lake at all seasons shows that pelagic plankton crustaceans are practically the only food of the fingerlings, and are the most important food of the older fish. The total food consumed by fingerlings, per unit bulk, is greatest in July and August, least in winter. The entomostracan food available in the lake, as determined from plankton samples, varies seasonally in a similar manner. The percentage utilization of each of the four species of Entomostraca by a fingerling sockeye population is related directly to the plankter's abundance, and inversely to its size. Individual sockeye, however, occasionally exhibit preference for smaller or less abundant species. The summer feeding of fingerlings appears to be chiefly confined to the region between 5 and 15 metres depth, which includes the thermocline and adjacent narrow strips of the epilimnion and hypolimnion. Foraging is limited upward by scarcity of food, and downward by poor illumination or low temperature. Other fish in the lake are known to compete with sockeye for plankton, but such interspecific competition is believed to be quantitatively of minor importance, in summer at least. Intraspecific competition for food in years of large sockeye populations is sufficient to reduce their rate of growth, and is probably responsible for an unusually early decline, in those years, of the summer's supply of Entomostraca.

scholarly journals Marsupial population dynamics in a tropical rainforest: intraspecific competition and nonlinear effect of rainfall

2015 ◽  
Vol 97 (1) ◽  
pp. 121-127 ◽  
Author(s):  
Mariana Silva Ferreira ◽  
Maja Kajin ◽  
Rui Cerqueira ◽  
Marcus Vinícius Vieira
Keyword(s):  
El Niño ◽  
Intraspecific Competition ◽  
El Nino ◽  
Southern Oscillation ◽  
Population Fluctuations ◽  
Feedback Structure ◽  
Combined Action ◽  
Exogenous Factors ◽  
Perturbation Effect ◽  
Metachirus Nudicaudatus

Abstract Population fluctuations are the result of the combined action of endogenous (feedback structure) and exogenous factors (large- and local-scale climate variables). In this paper, we used a 13-year time series to identify the feedback structure in a population of the brown 4-eyed opossum Metachirus nudicaudatus and to test a hypothesis on the effects of El Niño Southern Oscillation and rainfall using Royama’s theoretical framework. Metachirus nudicaudatus was regulated by a strong 1st-order negative feedback, with intraspecific competition for food resources as the probable factor governing the endogenous system. Contrary to our expectations, El Niño did not explain the marsupial dynamics better than 1-year lagged rainfall, that may operate in 2 different manners: as a nonlinear perturbation effect influencing the strength of density dependence (intraspecific competition and intraguild predation) or as a lateral perturbation effect influencing the carrying capacity of the environment. As flutuações populacionais são resultado da ação conjunta de fatores endógenos (estrutura de retroalimentação) e exógenos (variáveis climáticas locais e de larga escala). A partir de uma série temporal de 13 anos, nós identificamos a estrutura de retroalimentação da população da cuíca marrom de quatro olhos Metachirus nudicaudatus , e testamos hipóteses a respeito dos efeitos do El Niño Oscilação Sul e chuva utilizando a abordagem teórica de Royama. Metachirus nudicaudatus é regulado por uma forte retroalimentação negativa de primeira ordem, com a competição intraespecífica por recursos alimentares como o provável fator que rege o sistema endógeno. Ao contrário do que esperávamos, o El Niño não explicou a dinâmica populacional deste marsupial melhor do que a chuva com a defasagem de 1 ano, que pode atuar em duas formas: como um efeito de perturbação não-linear, influenciando a força da dependência densidade (competição intraespecífica e predação intraguilda), ou como um efeito de perturbação lateral, influenciando a capacidade de suporte do ambiente.

Habitat and Food Segregation of Dwarf and Normal Arctic Charr (Salvelinus alpinus) from Vangsvatnet Lake, Western Norway

1982 ◽  
Vol 39 (7) ◽  
pp. 1030-1045 ◽  
Author(s):  
Kjetil Hindar ◽  
Bror Jonsson
Keyword(s):  
Environmental Conditions ◽  
Intraspecific Competition ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Habitat Segregation ◽  
Growth Season ◽  
Western Norway ◽  
Lake Morphology ◽  
Food Segregation ◽  
Competition For Food

The aim of the present study was to test possible habitat and food segregation between two charr morphs in Vangsvatnet Lake. The charr population of Vangsvatnet consists of one pale phenotype with parr marks along the flanks and poorly developed spawning coloration (dwarf charr), and another phenotype with silvery flanks in nonbreeding condition and bright red spawning colors (normal charr). The habitus of the two morphs indicated that they were adapted to different niches during the growth season. The analyses of distribution and food showed that there was marked habitat and food segregation between the two morphs during summer, when dwarf charr dwelled deep-benthic and normal charr roamed in the limnetic zone. The segregation broke down in periods of food abundance, indicating that the habitat segregation was due to intraspecific competition for food. A comparison of charr morphs of Vangsvatnet with the nearby Lønavatnet Lake suggested that the number of charr morphs is adapted to local environmental conditions, among which lake morphology, food availability, and other fish species are important. We hypothesize that the number of charr morphs within a locality depends on the number of available niches during the growth season.Key words: polymorphism, camouflage, distribution, ontogeny, intra- and inter-specific competition

Primeros datos sobre la población de lagarto negro (Gallotia simonyi simonyi STEIND.) de la Isla de Hierro1

1981 ◽  
Vol 2 (4) ◽  
pp. 369-380 ◽  
Author(s):  
Juan Pablo Martinez Rica
Keyword(s):  
Canary Islands ◽  
Intraspecific Competition ◽  
Daily Activity ◽  
Plant Cover ◽  
The Sun ◽  
Protective Measures ◽  
Industrial Facilities ◽  
Vertebrate Fauna ◽  
The Status ◽  
Competition For Food

AbstractThis paper presents the first data on the ecology of the Giant Hierro Lizard (Gallotia simonyi simonyi) from Canary Islands; this animal was believed to be extinct until its recent finding, in 1975. The biotope, a very steep rocky cliff, almost inaccessible in many places, is described; the climate of the area is subdesertic and the plant cover, very sparse, is xerophytic; the vertebrate fauna is poor, but insects are abundant and diverse. The colour of this lizard is almost black, with large dull grey patches at the sides in the adults, while in the youngs the colour is earthly brown with whitish dorsal stripes. The largest specimen we measured was near 70 cm from snout to tail's end. Daily activity begins in young specimens when the sun reaches the area, while in the adult ones activity begins somewhat later, even at noon for the oldest animals. The diet consists entirely of plants, and includes lignified stems and other non-nourishing parts from several species (Kleinia neriifolia, Lavandula abrotanoides, etc.). Obviously there exists a strong intraspecific competition for food. The number of animals was very low in September 1975, about 200 specimens, half of them or more being young. This number might have been increased by now through protective measures recently adopted. Nevertheless, the status of the population is still critical and the danger of its extinction is strong. Some recent plans to modify the area, building industrial facilities nearby, may have, of course, very bad effects on this lizard.

Effects of dispersion, travel, and environmental heterogeneity on populations of the earwig Forficula auricularia L.

1975 ◽  
Vol 53 (12) ◽  
pp. 1855-1867 ◽  
Author(s):  
R. J. Lamb
Keyword(s):  
Social Interaction ◽  
Intraspecific Competition ◽  
Environmental Heterogeneity ◽  
Early Initiation ◽  
Intraspecific Aggression ◽  
Forficula Auricularia ◽  
Feeding Sites ◽  
Competition For Food

Local earwig populations were increased by the addition of artificial shelters which protected them against an inhospitable microclimate and predation by birds. The spacing of shelters and the availability of nearby food limited the use of shelters and thus the size of populations, through intraspecific competition for food. This competition was increased by the active aggregation of earwigs in shelters. Aggregation probably assists in the location of suitable shelter and provides a focus for social interaction. Enhanced growth and early initiation of foraging were observed for earwigs reared in groups.Foraging earwigs showed intraspecific aggression, especially at feeding sites. Earwigs that had not fed during the current foraging period were less likely to join aggregations early in the night. Foraging earwigs showed no ability to home to shelters or locate aggregations from a distance of more than a few centimetres, but were capable of travelling many metres in one night. These factors resulted in the exclusion of new occupants when shelter use reached a maximum.

A comparative study of Silurian and recent deposit-feeding bivalve communities

Paleobiology ◽  
1975 ◽  
Vol 1 (1) ◽  
pp. 97-124 ◽  
Author(s):  
Jeffrey S. Levinton ◽  
Richard K. Bambach
Keyword(s):  
Water Content ◽  
Fecal Pellet ◽  
High Water ◽  
The Other ◽  
High Water Content ◽  
Physical Factors ◽  
Species Competition ◽  
Evolutionary Changes ◽  
Competition For Food ◽  
Deposit Feeding

Two communities dominated by deposit-feeding bivalves are recognized in Quisset Harbor, Massachusetts. Interference with life position and sediment preconditioning restrict the distribution of some species. The Eel Grass Community, dominated by Nucula proxima, comprises primarily non-siphonate forms which live in fecal-pellet rich, high-water-content, oxygenated sediment. The sediment texture results from active burrowing. This soft, mobile sediment readily clogs the siphons of siphonate bivalves. The Channel Community, dominated by Yoldia limatula, comprises primarily siphonate forms which live in partly compacted, low-water-content muds. Each community is characterized by abundant surface, shallow, and deep feeding species. Competition for food has generated this distinct stratification in feeding depth of the dominant species with each community.Similar competitive relationships, affecting both species occurrence and trophic stratification, are apparent in three Silurian age deposit-feeding bivalve communities from the McAdam Brook Formation of Nova Scotia. A community dominated by four non-siphonate species inhabited soupy, high-water-content muds. A community dominated by three siphonate species lived in cohesive muds. A mixed community, dominated by four species, two non-siphonate and two siphonate species (the most abundant of which are present, but not as the most abundant forms, in the other communities), characterized the mid-way point of the ecotone between the other two communities.These deposit-feeding bivalve dominated communities have similar structural patterns although separated by 400 million years and despite environmental differences and evolutionary changes. Both response to physical factors, such as sediment character, and interspecific competition impose and maintain this type of community structure.

Determining the availability of sediment-bound trace metals to aquatic deposit-feeding animals

1980 ◽  
Author(s):  
Samuel N. Luoma ◽  
D.J. Cain ◽  
E.A. Thomson ◽  
C. Johansson ◽  
E.A. Jenne ◽  
...  
Keyword(s):  
Trace Metals ◽  
Deposit Feeding
Sign in / Sign up

Export Citation Format

Share Document