scholarly journals Impact of eutrophication on the life cycle, population dynamics and production of Ampithoe valida (Amphipoda) along an estuarine spatial gradient (Mondego estuary, Portugal)

2000 ◽  
Vol 196 ◽  
pp. 207-219 ◽  
Author(s):  
MA Pardal ◽  
JC Marques ◽  
I Metelo ◽  
AI Lillebø ◽  
MR Flindt
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Spatial Gradient ◽  
Mondego Estuary ◽  
Ampithoe Valida

scholarly journals Population dynamics of Pseudomonas sp. along a spatial gradient of phosphate: an experimental approach for spatial ecology

2000 ◽  
Vol 60 (4) ◽  
pp. 637-644
Author(s):  
C. T. CODEÇO ◽  
J. P. GROVER
Keyword(s):  
Population Dynamics ◽  
Culture System ◽  
Spatial Ecology ◽  
Experimental Approach ◽  
Theoretical Models ◽  
Spatial Gradient ◽  
Pseudomonas Sp ◽  
Directional Flow ◽  
Experimental Tool ◽  
Theoretical Predictions

Many theoretical models have been proposed to study the effect of space on population dynamics and interactions, but most of them are difficult to translate into experimental setups due to their abstract nature. Here we defend the gradostat as a valuable experimental tool for testing such theories. The gradostat is a culture system with bi-directional flow that forms nutrient gradients at steady state. In this study, we use a 3-vessel gradostat with a phosphate gradient to study the effect of spatial heterogeneity on the spatial distribution of Pseudomonas sp., an heterotrophic aquatic bacterium. The observed distributions partially agree with theoretical predictions, obtained from a mathematical model.

Seasonal Abundance and Population Dynamics of a Bamboo Aphid, Takecallis arundinaria (Homoptera: Aphididae)

1990 ◽  
Vol 25 (4) ◽  
pp. 526-534 ◽  
Author(s):  
Mark A. Coffelt ◽  
Peter B. Schultz
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Plant Species ◽  
Woody Plant ◽  
Early Spring ◽  
Climatic Conditions ◽  
Seasonal Abundance ◽  
Alternate Host ◽  
Woody Plant Species ◽  
Aphid Populations

The anholocyclic life cycle of the aphid Takecallis arundinaria (Essig) on golden stem bamboo, Phyllostachys aurea (Carrie're) was investigated in 1987 – 1988. Aphid populations peaked from March – May, declined from June – October, and peaked again in December. Aphid population dynamics were strongly influenced by climatic conditions. When aphid populations were at constant or rising levels, significantly more nymphs were found in the southern and eastern quadrants, than in the northern and western quadrants. This directionality may have allowed T. arundinaria populations to be exposed to increased sunlight and decreased winds during the winter and early spring periods. Alate viviparae had a mean fecundity of 147 nymphs and a longevity of 46.5 days. Predators were few and no parasites were found. An alternate host study revealed no aphids on yellow sticky traps placed on nine woody plant species.

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.

Importance of life cycle events in the population dynamics of Gonyaulax tamarensis

1983 ◽  
Vol 76 (2) ◽  
pp. 179-189 ◽  
Author(s):  
D. M. Anderson ◽  
S. W. Chisholm ◽  
C. J. Watras
Keyword(s):  
Population Dynamics ◽  
Life Cycle

Population dynamics in echinococcosis and cysticercosis: mathematical model of the life-cycles of Taenia hydatigena and T. ovis

Parasitology ◽  
1987 ◽  
Vol 94 (1) ◽  
pp. 181-197 ◽  
Author(s):  
M. G. Roberts ◽  
J. R. Lawson ◽  
M. A. Gemmell
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
New Zealand ◽  
Equation Model ◽  
Life Cycles ◽  
Control Measures ◽  
Taenia Hydatigena ◽  
Infection Pressure ◽  
Lower Infection ◽  
Compare And Contrast

SUMMARYIt is shown that under the conditions that prevailed in New Zealand in the late 1950s, Taenia hydatigena was hyperendemic, the life-cycle being regulated by a density-dependent constraint in the form of acquired immunity, and T. ovis was rare. The control measures that caused Echinococcus granulosus, which was endemic at the time, to decline towards extinction reduced T. hydatigena and T. ovis to endemic status only. A non-linear integrodifferential equation model, which was previously linearized to describe the life-cycle of E. granulosus in dogs and sheep in New Zealand, is used to describe the life-cycles of T. hydatigena and T. ovis. The model is then used to compare and contrast the population dynamics of these three species. The model is used to demonstrate that the endemic steady state is structurally unstable, and may be asymptotically unstable to small perturbations. It is also shown that despite the lower infection pressure experienced by the intermediate host in the endemic state, the numbers of larvae in sheep may be higher than in the hyperendemic state. Finally it is shown that the partial success of the control measures against T. hydatigena may have caused an increase in the numbers and prevalence of T. ovis larvae in sheep due to the reciprocal immunity between the two species.

Life cycle, population dynamics and productivity of Ventrosia maritima in the Evros Delta (northern Aegean Sea)

2005 ◽  
Vol 85 (2) ◽  
pp. 375-382 ◽  
Author(s):  
Theodoros Kevrekidis ◽  
Thomas Wilke
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Outer Part ◽  
Dry Weight ◽  
Early Summer ◽  
Late Winter ◽  
Published Data ◽  
Annual Life Cycle ◽  
Frequency Method ◽  
Innermost Part

Life cycle, population dynamics and productivity of the larviparous mudsnail species Ventrosia maritima were investigated at low salinities (0·3–6 psu) in differentiated parts of a Mediterranean lagoon (Monolimni Lagoon). Monthly samples were collected during the period from February 1998 to February 1999 in both parts of the lagoon. Ventrosia maritima displayed an annual life cycle. Recruitment occurred in summer and autumn at the outer part of the lagoon and additionally in late winter at the innermost part. A positive correlation was found between the percentages of small individuals and salinity or sediment organic matter at the outer part. Growth practically ceased in winter. The mudsnail displayed remarkable densities and an increase in growth in spring at <1 psu indicating that it is highly tolerant to extremely low salinities. Population density showed a significant seasonal variation; it increased from early summer to autumn (30,000–40,000 individuals m−2) following the summer and autumn recruitment. No significant correlation between the density of V. maritima and several examined physicochemical variables was found; a negative correlation was observed between the density of the mudsnail and that of the co-occurring polychaete Streblospio shrubsolii. Secondary production calculated by the size–frequency method gave a mean annual density (N) of 9740 ind m−2, a mean biomass (B) of 1·66 g ash-free dry weight (AFDW) m−2 y−1, a production (P) of 4·51 g m−2 y−1 and a P:B ratio of 2·72 at the outer part of the lagoon and a N of 14,570 ind m−2, a B of 3·2 g AFDW m−2 y−1, a P of 9·9 g m−2 y−1 and a P:B ratio of 3·09 at the innermost part. At the innermost part of the lagoon, where the seawater renewal rate and hydro-dynamism were lower and the sediment finer and organically richer, V. maritima displayed more recruitment pulses, a larger body size and a denser and more productive population than the one at the outer part. Our findings are compared to published data for the direct-developing congeners V. ventrosa and V. truncata.

scholarly journals A full life cycle and spatially explicit individual-based model for the giant mud crab (Scylla serrata): a case study from a marine protected area

2013 ◽  
Vol 71 (3) ◽  
pp. 484-498 ◽  
Author(s):  
J.-O. Meynecke ◽  
R. G. Richards
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Marine Protected Area ◽  
Multiple Stressors ◽  
Individual Variability ◽  
Population Increase ◽  
Scylla Serrata ◽  
Spatially Explicit ◽  
Mud Crab ◽  
Individual Based Model

Abstract The giant mud crab (Scylla serrata) is an important fisheries species throughout southeast Asia and the South Pacific. In Australia, marine protected areas (MPAs) and fish habitats have been declared specifically to protect the local populations of S. serrata. The cannibalistic behaviour of S. serrata coupled with the potential attraction of increased predators may counteract the effect of excluding fishing from these areas as a means of increasing the local crab population. The population dynamics of S. serrata could also be confounded by the spatio-temporal variability in environmental conditions (e.g. run-off and temperature). Here, we used a spatially explicit individual-based model (IBM) to explore the population dynamics of S. serrata in an MPA located in southern Moreton Bay, Queensland, Australia. This IBM simulated the life cycle dynamics of individual S. serrata and integrated the key processes affecting its population dynamics. These processes include physical transport of the planktonic life stages, movement, growth, metamorphosis, setting, reproduction, spawning, harvesting, and predation. Individual variability was built into the model to account for demographic variation. The modelled scenarios indicated that the effect of the different harvest strategies trialled on the population dynamics after 30 months and the MPA influenced the number of individuals in the creek system resulting in a partial 35% population increase. Further development and application of this model has implications for MPAs and catch limits under multiple stressors including climate change.

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