Population Dynamics of an Estuarine-Dependent Fish, the Spot (Leiostomus xanthurus), ASong a Tidal Creek–Seagrass Meadow Coenocline

1983 ◽  
Vol 40 (10) ◽  
pp. 1633-1638 ◽  
Author(s):  
Michael P. Weinstein
Keyword(s):  
Population Dynamics ◽  
Decay Rate ◽  
Turnover Rate ◽  
Total Population ◽  
Seagrass Meadow ◽  
Tidal Creek ◽  
Leiostomus Xanthurus ◽  
Population Turnover ◽  
Young Of The Year ◽  
Average Individual

To study the population dynamics of young-of-the-year spot (Leiostomus xanthurus) I released 6981 marked fish midway up the tidal creek portion of a small (<20 ha) marsh creek–seagrass meadow coenocline. Holding mortality experiments (96 h) indicated that 61.5%, or 4300 individuals, survived the marking process to constitute the population available for recapture. Over a 90-d study period, 212 marked fishes were recaptured. From plots of the ratio of marked to unmarked individuals in subsequent samples, I concluded that the population was resident in the creek for up to 182 d with the average individual present for 91 d. When this population turnover rate was compared to the total population decay rate (marked plus unmarked fish), the exchange between habitats (immigration/emigration) accounted for about 26% of the total decay rate, with the remainder attributed to natural mortality. By correcting the overall disappearance rate for population turnover due to immigration/emigration, and using this adjusted value as a measure of instantaneous mortality (Z), the estimated production in this population was 21.8 kcal (91342 J)∙m−2∙d−1. This figure is over six times greater than previously reported values for this species for all size classes over the entire growing season.

QUALITATIVE PROPERTIES OF A POPULATION DYNAMICS SYSTEM DESCRIBING PREGNANCY

2005 ◽  
Vol 15 (04) ◽  
pp. 507-554 ◽  
Author(s):  
G. FRAGNELLI ◽  
P. MARTINEZ ◽  
J. VANCOSTENOBLE
Keyword(s):  
Population Dynamics ◽  
Asymptotic Behavior ◽  
Linear Model ◽  
Nonlinear Model ◽  
Total Population ◽  
Type A ◽  
Qualitative Properties

We study a model of population dynamics describing pregnancy: our model is composed by an equation describing the evolution of the total population, and an equation describing the evolution of pregnant individuals. These equations are of course coupled: one coupling expresses that the total population varies with the number of born people, and another coupling says that the number of fecundated individuals depends on the total population. We study three models of that type: a linear model without diffusion, a nonlinear model without diffusion and a linear model with diffusion. For these three models, we study precisely the qualitative properties and the asymptotic behavior of the solutions.

scholarly journals Intra and inter annual variation in a seagrass meadow on the Caribbean coast of Costa Rica: 2009-2015

2018 ◽  
Vol 66 (3) ◽  
pp. 1149 ◽  
Author(s):  
Margarita Loría-Naranjo ◽  
Jimena Samper-Villarreal ◽  
Marylaura Sandoval-Siles ◽  
Jorge Cortés
Keyword(s):  
Costa Rica ◽  
Leaf Area ◽  
Turnover Rate ◽  
Seagrass Meadow ◽  
Seagrass Beds ◽  
Seagrass Bed ◽  
Monitoring Methods ◽  
Caribbean Coast ◽  
Area Index ◽  
The Caribbean

Seagrass beds are an important ecosystem on the Caribbean coast of Costa Rica. At Cahuita National Park (CNP) a seagrass bed at Perezoso has been monitored continually since 1999 within the CARICOMP program. Thalassia testudinum is the dominant seagrass species, in some cases mixed with Syringodium filiforme. The results from the 2009 to 2015 monitoring period are presented here, and contrasted with data before 2009. Total (above and below ground tissue) mean biomass of T. testudinum was higher (1 255.4 ± 146.0 gm-2) than biomass before 2009, with an increasing tendency. However, productivity (1.5±0.59 gm-2d-1) and turnover rate (4.3 ± 1.22 %d-1) were lower than previous monitoring periods. In this period, mean leaf area diminished considerably (4.9 ± 2.30 m2), but leaf area index (LAI) increased (1.9 ± 0.80 m2leafm-2) in comparison to prior monitoring. Productivity, density, turnover rate, LAI and biomass showed intra-annual variations; while mean biomass of T. testudinum did not vary significantly among years. No correlations were found between water salinity, temperature and clarity with seagrass measurements. However, most seagrass parameters were strongly correlated with precipitation. These results highlight the effect of external environmental agents acting on the ecosystem. CNP presents a long-term stable seagrass meadow. However, there are indirect signals, such as high biomass and above-ground biomass proportion, along with low productivity and LAI, which point to a nutrient increment in Perezoso’s seagrass bed. To continue protecting this seagrass bed, it is necessary to improve monitoring methods, and seagrass beds should be included in national conservation policies and monitoring programs.

scholarly journals Estimating Population Turnover Rates by Relative Quantification Methods Reveals Microbial Dynamics in Marine Sediment

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Richard Kevorkian ◽  
Jordan T. Bird ◽  
Alexander Shumaker ◽  
Karen G. Lloyd
Keyword(s):  
Population Dynamics ◽  
Microbial Community ◽  
16S Rrna ◽  
Sulfate Reduction ◽  
Relative Quantification ◽  
Turnover Rates ◽  
Content Type ◽  
Sulfate Reducing ◽  
Population Turnover ◽  
Read Abundance

ABSTRACT The difficulty involved in quantifying biogeochemically significant microbes in marine sediments limits our ability to assess interspecific interactions, population turnover times, and niches of uncultured taxa. We incubated surface sediments from Cape Lookout Bight, North Carolina, USA, anoxically at 21°C for 122 days. Sulfate decreased until day 68, after which methane increased, with hydrogen concentrations consistent with the predicted values of an electron donor exerting thermodynamic control. We measured turnover times using two relative quantification methods, quantitative PCR (qPCR) and the product of 16S gene read abundance and total cell abundance (FRAxC, which stands for “fraction of read abundance times cells”), to estimate the population turnover rates of uncultured clades. Most 16S rRNA reads were from deeply branching uncultured groups, and ∼98% of 16S rRNA genes did not abruptly shift in relative abundance when sulfate reduction gave way to methanogenesis. Uncultured Methanomicrobiales and Methanosarcinales increased at the onset of methanogenesis with population turnover times estimated from qPCR at 9.7 ± 3.9 and 12.6 ± 4.1 days, respectively. These were consistent with FRAxC turnover times of 9.4 ± 5.8 and 9.2 ± 3.5 days, respectively. Uncultured Syntrophaceae, which are possibly fermentative syntrophs of methanogens, and uncultured Kazan-3A-21 archaea also increased at the onset of methanogenesis, with FRAxC turnover times of 14.7 ± 6.9 and 10.6 ± 3.6 days. Kazan-3A-21 may therefore either perform methanogenesis or form a fermentative syntrophy with methanogens. Three genera of sulfate-reducing bacteria, Desulfovibrio, Desulfobacter, and Desulfobacterium, increased in the first 19 days before declining rapidly during sulfate reduction. We conclude that population turnover times on the order of days can be measured robustly in organic-rich marine sediment, and the transition from sulfate-reducing to methanogenic conditions stimulates growth only in a few clades directly involved in methanogenesis, rather than in the whole microbial community. IMPORTANCE Many microbes cannot be isolated in pure culture to determine their preferential growth conditions and predict their response to changing environmental conditions. We created a microcosm of marine sediments that allowed us to simulate a diagenetic profile using a temporal analog for depth. This allowed for the observation of the microbial community population dynamics caused by the natural shift from sulfate reduction to methanogenesis. Our research provides evidence for the population dynamics of uncultured microbes as well as the application of a novel method of turnover rate analysis for individual taxa within a mixed incubation, FRAxC, which stands for “fraction of read abundance times cells,” which was verified by quantitative PCR. This allows for the calculation of population turnover times for microbes in a natural setting and the identification of uncultured clades involved in geochemical processes.

scholarly journals Municipalities in Vojvodina with the highest share of refugees: Influence on dynamics and structural characteristics of the population

2006 ◽  
pp. 103-110 ◽  
Author(s):  
Vesna Lukic ◽  
Dragana Matijevic
Keyword(s):  
Population Dynamics ◽  
20Th Century ◽  
Economic Activity ◽  
Total Population ◽  
Structural Characteristics ◽  
Natural Increase ◽  
Refugee Population ◽  
Educational Structure ◽  
Structure Of Population ◽  
Migration Component

The paper treats the issue of significance of refugee migrations in the last decade of the 20th century, for the changes of total number of inhabitants in the municipalities: Indjija, Ruma, Sremski Karlovci, Stara Pazova and Sid. These municipalities have the highest share of refugees in the total population, according to the 2002 census. The trend of negative natural increase of population in Vojvodina since 1989, contributed to the increase of the significance of migration component in population dynamics, regarding the fact that it mostly represents the crucial factor of population in-crease. In that sense, contribution of refugees to the values of mechanical inflow of population is ascertained. Having in mind the differentiation of municipalities according to the socio-economic characteristics of population, the paper gives the analysis of influence of refugees on the changes of these structures. The study encompasses economic and educational structure of population. The structure of refugee population by their economic activity also shows the extent of economic adaptation of refugees, as a very important factor in the process of their integration.

scholarly journals The influence of subjective criteria USGE as official principle at nationality identification in censuses to manifestation Gypsies ethnic identity

2007 ◽  
Vol 87 (1) ◽  
pp. 79-88
Author(s):  
Aleksandar Knezevic
Keyword(s):  
Population Dynamics ◽  
Ethnic Identity ◽  
Ethnic Minorities ◽  
Total Population ◽  
Population Development ◽  
Official Statistic ◽  
Main Defect ◽  
Change Attitude

According to final results of Census in 2002, total number of declare Gypsies in Serbia (without Kosovo and Metohija) was 108.193, apropos 1.44% in total population of Serbia, conditional third position in rang of ethnic minorities (behind Hungarians and Bosnians). Though, in sense population dynamics of Gypsies, it is needs to know, that official statistic data could give only information about population which "them selves repute Gypsies", declare as Gypsies in that moment, and because of that we are probability to take on scientific observe only number of declare Gypsies. During the period 1948-2002, Gypsies was included on all census statistic classifications of nationalities. But, oscillations in number of Gypsies show population dynamics without any evenly and projected trends of population development. This fact is problem and for official statistic research. Certainly, the main defect at statistic registration of Gypsies is ability to change attitude about nationality declare in censuses.

Population dynamics of the shore crab Pachygrapsus marmoratus (Brachyura: Grapsidae) in the central Portuguese coast

2002 ◽  
Vol 82 (2) ◽  
pp. 229-241 ◽  
Author(s):  
Augusto A.V. Flores ◽  
José Paula
Keyword(s):  
Population Dynamics ◽  
Size Structure ◽  
Shore Crab ◽  
Late Winter ◽  
Rocky Shores ◽  
Study Region ◽  
Frequency Distributions ◽  
Portuguese Coast ◽  
Pachygrapsus Marmoratus ◽  
Young Of The Year

The population dynamics of the shore crab Pachygrapsus marmoratus was studied at two different rocky shores, Cabo Raso and Avencas, within the central Portuguese coast. The population structure at these shores, obtained by pooling monthly samples, revealed marked discrepancies. Unimodal, right-skewed size–frequency distributions at Avencas contrasts with the bimodal distributions obtained at Cabo Raso, corresponding to early recruits and larger adults. Recruitment timing and intensity together with habitat complexity are probable causes of the differences observed. At Cabo Raso an intense recruitment season was recorded from September to November, but very small juveniles were always present in samples. Monthly polymodal distributions are apparent but the size structure too complex to identify age groups through the sampling period. At Avencas, the influx of new juveniles is temporally restricted and year groups recognizable from main recruitment events taking place around October. Young-of-the-year crabs grow quickly to mature size and join the reproductive stock in the next breeding season from late March to early September in the study region. The growth pattern in both sexes follows a seasonal trend with minimum growth during the breeding months and maximum growth rates from late winter to early spring. Life span may reach four years, probably more in males. At Avencas, population maintenance seems to be highly dependent on favourable conditions promoting adequate settlement intensity and timing. Early recruitment is presumed to enhance the reproductive output of young-of-the-year individuals which comprise the bulk of breeding crabs. At Cabo Raso settlement rates are much higher and recruitment timing may be less critical since most breeding crabs belong to the 1-y+ class.

Population dynamics of the harvested clam Anomalocardia brasiliana (Bivalvia: Veneridae) in Cidade Beach, south-east Brazil

2015 ◽  
Vol 95 (6) ◽  
pp. 1183-1191 ◽  
Author(s):  
Guilherme Nascimento Corte ◽  
Leonardo Querobim Yokoyama ◽  
Ross A. Coleman ◽  
A. Cecília Z. Amaral
Keyword(s):  
Population Dynamics ◽  
West Indies ◽  
Turnover Rate ◽  
Sandy Beach ◽  
Limiting Factors ◽  
Fishery Resource ◽  
The Sustainable Development ◽  
Eastern Brazil ◽  
Density And Biomass

Knowledge of the population dynamics and productivity of exploited species is essential to achieve the sustainable development of fisheries, and to ensure sustainable, long-term use of these resources. The venerid clam Anomalocardia brasiliana is harvested as a fishery resource from the French West Indies to Brazil. Yet, the exploitation of this species is not backed by management or regulations based on scientific knowledge. This can result in reduced (or even depleted) A. brasiliana density and biomass. Here, we examined the population dynamics of A. brasiliana over the course of 1 year at Cidade Beach, a sheltered sandy beach located in south-eastern Brazil. Sampling was done monthly from March 2007 to February 2008. The sampled population was predominantly juvenile. Growth and recruitment were continuous, indicating no major fluctuation in limiting factors, such as temperature, salinity and food. Nevertheless, the abundance and the turnover rate (P/B ratio) of A. brasiliana at Cidade were much smaller than the values observed in other areas of occurrence. The mortality was more intense in young individuals, and the peak of individual production occurred in individuals with a 25 mm shell length, suggesting that individuals smaller than this size should not be exploited.

Population dynamics and production of Daphnia carinata (King) and Simocephalus exspinosus (Koch) in waste stabilization ponds

1982 ◽  
Vol 33 (5) ◽  
pp. 837 ◽  
Author(s):  
BD Mitchell ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Turnover Time ◽  
Time Model ◽  
Waste Stabilization Ponds ◽  
Net Production ◽  
Turnover Model ◽  
Biomass Turnover ◽  
Stabilization Ponds ◽  
Waste Stabilization ◽  
Population Turnover

The population dynamics and production of D. carinata and S. exspinosus were investigated in two adjacent maturation-type waste stabilization ponds in South Australia. Population parameters (b', r', and d') for both species were determined from population density, brood size, and egg-development time. Length-weight relationships were determined for both species. Growth of D. carinata was investigated experimentally. Net production of both species was determined using Edmondson's population turnover- time model. Production of D. carinata was also determined using Winberg's biomass turnover model. D. carinata, the numerically dominant species, was a cold water form; high water temperatures increased mortality and reduced growth rate. Both species were food-limited at high population densities. Total annual net production of D. carinata in pond 1 during 1977 (345 g dry wt m-2): calculated using the population turnover-time model, was the highest yet recorded for any planktonic cladoceran. Annual net production of D. carinata determined using the population turnover-time model exceeded annual production determined using the biomass turnover model by 100%. Overestimation of daily production rate was highest during periods of high egg mortality. Total annual net production of D. carinata and S. exspinosus (biomass turnover model) represented a nutrient store equivalent to less than 6% of total PO4-P and total nitrogen retained in the ponds annually.

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