Population dynamics and morphometries of Gammarus pulex L.: evidence of seasonal food limitation in a freshwater detritivore

1988 ◽  
Vol 19 (3) ◽  
pp. 333-343 ◽  
Author(s):  
JOHN H. R. GEE
Keyword(s):  
Population Dynamics ◽  
Food Limitation ◽  
Gammarus Pulex

Life cycle of Calanus finmarchicus in the lower St. Lawrence Estuary: the imprint of circulation and late timing of the spring phytoplankton bloom

2001 ◽  
Vol 58 (4) ◽  
pp. 647-658 ◽  
Author(s):  
Stéphane Plourde ◽  
Pierre Joly ◽  
Jeffrey A Runge ◽  
Bruno Zakardjian ◽  
Julian J Dodson
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Production Rate ◽  
Egg Production ◽  
Phytoplankton Bloom ◽  
Food Limitation ◽  
Calanus Finmarchicus ◽  
Lawrence Estuary ◽  
Egg Production Rate ◽  
St Lawrence Estuary

The life cycle of Calanus finmarchicus in the lower St. Lawrence estuary is described based on observations of female egg production rate, population stage abundance, and chlorophyll a biomass collected over 7 years (1991–1997) at a centrally located monitoring station. The mean seasonal pattern shows maximum abundance of females in May, but peak population egg production rate and naupliar (N3–N6) abundance occur in early July just after onset of the late spring – early summer phytoplankton bloom. The population stage structure is characterized by low summer abundance of early copepodite stages C1–C3 and high stage C5 abundance in autumn. Between 1994 and 1997, there was important interannual variation in both timing (up to 1 month) and amplitude (five- to eight-fold) of population reproduction. Patterns of seasonal increase of C5 abundance in autumn suggest interannual variations of both timing and magnitude of deep upstream advection of this overwintering stage. Thus, the main features of C. finmarchicus population dynamics in the central lower St. Lawrence Estuary are (i) late reproduction resulting from food limitation prior to the onset of the summer phytoplankton bloom, (ii) probable export of early developmental stages during summer, and (iii) advection into the central lower St. Lawrence Estuary of overwintering stage C5 in autumn from downstream regions. These results support the hypothesis that circulation, mainly driven by discharge from the St. Lawrence River and its tributaries, is a key factor governing population dynamics of C. finmarchicus in this region.

scholarly journals The role of predation and food limitation on claims for compensation, reindeer demography and population dynamics

2014 ◽  
Vol 51 (5) ◽  
pp. 1264-1272 ◽  
Author(s):  
Torkild Tveraa ◽  
Audun Stien ◽  
Henrik Brøseth ◽  
Nigel G. Yoccoz
Keyword(s):  
Population Dynamics ◽  
Food Limitation

scholarly journals Introduction: Carnivorous marsupials

2001 ◽  
Vol 28 (5) ◽  
pp. I
Author(s):  
Menna Jones ◽  
Chris Dickman
Keyword(s):  
Population Dynamics ◽  
Food Supply ◽  
Large Range ◽  
Arid Zone ◽  
Food Limitation ◽  
Life Time ◽  
Minimum Convex Polygon ◽  
Rocky Habitat ◽  
Rocky Habitats

Population dynamics and movements were investigated in a population of Pseudantechinus macdonnellensis, a dasyurid marsupial occupying rocky habitats in the Australian arid zone. Intra-annual cycling in abundance, activity and numbers of resident and transient individuals was not regular from year to year, although the number of residents was high compared with the number of transients. Juvenile recruitment varied between years and was as low as 18%. Densities were low (0.05–0.2 ha–1 for females and 0.05–0.3 ha–1 for males), and individuals exhibited large stable long-term ranges – mean Minimum Convex Polygon (MCP) area for males was 427 m2 and for females 171 m2. The constraints of the monoestrous, synchronised reproductive strategy of P. macdonnellensis, together with the ameliorating effect of its rocky habitat, which may decrease food limitation and increase survival, seem to have produced a different pattern of population dynamics to that seen in arid-zone dasyurids that are polyoestrous plains-dwellers. The patterns of movement in P. macdonnellensis also differ from plains-dwelling species, in which individuals display high life-time mobility. The existence of large but non-drifting ranges in P. macdonnellensis may be seen as a consequence of a low but relatively predictable food supply, which precludes the necessity for individuals to shift their activity to temporary patches of high food supply, but requires them to occupy a large range to obtain enough food to meet energy requirements.

An ecological study of a population of Pseudantechinus macdonnellensis (Marsupialia : Dasyuridae) in central Australia. II. Population dynamics and movements

2001 ◽  
Vol 28 (5) ◽  
pp. 481 ◽  
Author(s):  
Sandra L. Gilfillan
Keyword(s):  
Population Dynamics ◽  
Food Supply ◽  
Ecological Study ◽  
Arid Zone ◽  
Food Limitation ◽  
Life Time ◽  
Minimum Convex Polygon ◽  
Rocky Habitat ◽  
Rocky Habitats

Population dynamics and movements were investigated in a population of Pseudantechinus macdonnellensis, a dasyurid marsupial occupying rocky habitats in the Australian arid zone. Intra-annual cycling in abundance, activity and numbers of resident and transient individuals was not regular from year to year, although the number of residents was high compared with the number of transients. Juvenile recruitment varied between years and was as low as 18%. Densities were low (0.05–0.2 ha–1 for females and 0.05–0.3 ha–1 for males), and individuals exhibited large stable long-term ranges – mean Minimum Convex Polygon (MCP) area for males was 427 m2 and for females 171 m2. The constraints of the monoestrous, synchronised reproductive strategy of P. macdonnellensis, together with the ameliorating effect of its rocky habitat, which may decrease food limitation and increase survival, seem to have produced a different pattern of population dynamics to that seen in arid-zone dasyurids that are polyoestrous plains-dwellers. The patterns of movement in P. macdonnellensis also differ from plains-dwelling species, in which individuals display high life-time mobility. The existence of large but non-drifting ranges in P. macdonnellensis may be seen as a consequence of a low but relatively predictable food supply, which precludes the necessity for individuals to shift their activity to temporary patches of high food supply, but requires them to occupy a large range to obtain enough food to meet energy requirements.

scholarly journals Population regulation of African buffalo in the Mara–Serengeti ecosystem

2015 ◽  
Vol 42 (5) ◽  
pp. 382 ◽  
Author(s):  
Holly T. Dublin ◽  
Joseph O. Ogutu
Keyword(s):  
Land Use ◽  
Population Dynamics ◽  
Population Growth ◽  
Density Dependence ◽  
Food Limitation ◽  
Land Use Changes ◽  
African Buffalo ◽  
Regulatory Factor ◽  
Density Dependent ◽  
Serengeti Ecosystem

Context The processes regulating ungulate populations have been the focus of numerous studies. For the African buffalo (Syncerus caffer Sparrman) population inhabiting the Mara–Serengeti ecosystem, rinderpest was the primary regulatory factor up to the mid-1960s. Following reduction of rinderpest and buffalo population increase, interspecific competition for food, notably with cattle and wildebeest (Connochaetes taurinus Burchell), was thought to be the primary regulatory factor in the ecosystem. Aims We analysed buffalo population trends and the relationship between buffalo population growth and rainfall and density dependence in the Mara–Serengeti ecosystem and discuss the findings in the context of the key ecosystem processes governing buffalo population dynamics in African savannas, namely, food limitation, competition, predation, disease and land use changes. Methods We analysed buffalo population dynamics in the Mara–Serengeti ecosystem in relation to rainfall and density dependence feedback between 1984 and 2010. Key results Buffalo population growth was both significantly density-dependent and positively correlated with the dry season rainfall after, but not before, a severe drought in 1993. Buffalo numbers crashed by 48.6% in 1984–85 and by 76.1% in 1993–94 during severe droughts when food availability was lowest and competition with the more numerous cattle and wildebeest was highest. Conclusions Recovery of buffalo numbers to pre-drought levels took 8–9 years after the 1984–85 drought but was much slower, with buffaloes numbering merely 36% of their 1993 population (12 895 animals) 18 years after the 1993–94 drought despite intermittent periods of high rainfall, probably due to demographic and/or reproductive factors, heightened competition with livestock, land use changes in the adjoining pastoral ranches, lion predation and recurrent severe droughts. Implications Our findings demonstrate how food limitation caused by droughts associated with the hemispheric El Niño–Southern Oscillation can cause severe declines in and threaten the persistence of large ungulate populations. The findings also portray how density-dependent food limitation, competition, predation, land use changes and other factors can accentuate the effect of droughts and greatly prolong population recovery.

scholarly journals Population Dynamics of Three Gammarid Species (Crustacea, Amphipoda) in a French Chalk Stream.

1981 ◽  
Vol 51 (1) ◽  
pp. 31-69 ◽  
Author(s):  
Annemarie Goedmakers
Keyword(s):  
Population Dynamics ◽  
Standing Crop ◽  
Gammarus Pulex ◽  
Amphipod Species ◽  
Life Stages ◽  
Chalk Stream

The standing crop of Gammarus pulex pulex (Linnaeus, 1758), G. fossarum Koch in Panzer, 1836 and Echinogammarus berilloni (Catta, 1878) has been studied in a small French chalk stream, the Slack. A brief description of all amphipod species encountered in this river is given, with a key to different life stages.

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