Population dynamics of the pea crab Austinixa aidae (Brachyura, Pinnotheridae): a symbiotic of the ghost shrimp Callichirus major (Thalassinidea, Callianassidae) from the southwestern Atlantic

The Pinnotheridae family is one of the most diverse and complex groups of brachyuran crabs, many of them symbionts of a wide variety of invertebrates. The present study describes the population dynamics of the pea crab Austinixa aidae (Righi, 1967), a symbiont associated with the burrows of the ghost shrimp Callichirus major (Say, 1818). Individuals (n = 588) were collected bimonthly from May, 2005 to September, 2006 along a sandy beach in the southwestern Atlantic, state of São Paulo, Brazil. Our data indicated that the population demography of A. aidae was characterized by a bimodal size-frequency distribution (between 2.0 and 4.0 mm and between 8.0 and 9.0 mm CW) that remained similar throughout the study period. Sex ratio does not differ significantly from 1:1 (p > 0.05), which confirms the pattern observed in other symbiontic pinnotherids. Density values (1.72 ± 1.34 ind. • ap.-1) are in agreement with those found for other species of the genus. The mean symbiosis incidence (75.6%) was one of the highest among species of the Pinnotheridae family, but it was the lowest among the three studied species of the genus. Recruitment pattern was annual, beginning in May and peaking in July, in both years, after the peak of ovigerous females in the population (from March to May). Our findings describe ecological and biological aspects of A. aidae similar to those of other species of this genus, even from different geographic localities.

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Long-term and multilevel impact assessment of the 2015–2016 El Niño on a sandy beach of the southwestern Atlantic

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.145689 ◽

2021 ◽

Vol 775 ◽

pp. 145689

Author(s):

Gabriela Jorge-Romero ◽

Eleonora Celentano ◽

Diego Lercari ◽

Leonardo Ortega ◽

Juan A. Licandro ◽

...

Keyword(s):

Impact Assessment ◽

El Niño ◽

Sandy Beach ◽

El Nino ◽

Southwestern Atlantic

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Coverage Increases of Porites astreoides in Grenada Determined by Shifts in Size-Frequency Distribution

Diversity ◽

10.3390/d13070288 ◽

2021 ◽

Vol 13 (7) ◽

pp. 288

Author(s):

Ryan G. Eagleson ◽

John S. Lumsden ◽

Lorenzo Álvarez-Filip ◽

Christophe M. Herbinger ◽

Ryan A. Horricks

Keyword(s):

Coral Community ◽

Scleractinian Corals ◽

Area Measurement ◽

Coralline Algae ◽

Measurement Tool ◽

Size Frequency Distribution ◽

Point Count ◽

Porites Astreoides ◽

The Mean ◽

The Caribbean

Despite coral community collapse, the mustard hill coral (Porites astreoides) is a species currently experiencing success throughout the Caribbean. The inshore reefs of Grenada were selected to study the influence of benthic factors on the abundance, size, and coverage of P. astreoides colonies. Surveys of reef communities along established 30 m transects were conducted at eight sites in 2014 and 2017 using a 0.5 m² quadrat. Coral Point Count was used to annotate the images, estimating the coverage of scleractinian corals, sponges, algae, and benthic substrates. Coverage, size, and abundance of P. astreoides colonies were quantified using the area measurement tool in ImageJ standardized against the quadrats. There were significant differences in benthic community assemblages between islands, selected sites, and between years. From 2014 to 2017 there was a significant decrease in the mean abundance of P. astreoides colonies and significant increases in mean colony size and coverage. The presence of P. astreoides colonies was significantly correlated with: rubble (−), sand (−); pavement (+); macroalgae (−); coralline algae (+); sponges (varying response); gorgonians (−); massive corals (+); and branching corals (−). P. astreoides follows similar recruitment patterns as other scleractinian corals. Observed changes in P. astreoides populations appear to indicate a recovery event following a disturbance, potentially tropical storm Chantal in 2013.

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PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

The Canadian Entomologist ◽

10.4039/ent1041197-8 ◽

1972 ◽

Vol 104 (8) ◽

pp. 1197-1207 ◽

Cited By ~ 18

Author(s):

R. F. Morris

Keyword(s):

Population Dynamics ◽

Nova Scotia ◽

North America ◽

Population Density ◽

New Brunswick ◽

Numerical Response ◽

Initial Number ◽

Hyphantria Cunea ◽

The North ◽

The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

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Larval density, temperature and biological aspects of Chrysomya megacephala (Diptera: Calliphoridae)

Arquivo Brasileiro de Medicina Veterinária e Zootecnia ◽

10.1590/s0102-09352006000400018 ◽

2006 ◽

Vol 58 (4) ◽

pp. 562-566 ◽

Cited By ~ 7

Author(s):

C. Reigada ◽

W.A.C. Godoy

Keyword(s):

Population Dynamics ◽

Life History ◽

Body Size ◽

Larval Density ◽

Chrysomya Megacephala ◽

Life History Characteristics ◽

Two Temperatures ◽

Biological Aspects ◽

Experimental Populations ◽

Simultaneous Influence

The effect of larval density on the survival, fecundity and body size at two temperatures in experimental populations of C. megacephala was studied. No effect from simultaneous influence of density and temperature on life history characteristics of C. megacephala was found. Significant effects of density and temperature on survival, fecundity and body size were observed. The importance of these results for the population dynamics of C. megacephala is discussed.

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The population dynamics of metacercariae of Apatemon gracilis (Trematoda: Digenea) in three species of lake-dwelling leeches

Parasitology ◽

10.1017/s0031182000081221 ◽

1986 ◽

Vol 93 (3) ◽

pp. 517-530 ◽

Cited By ~ 8

Author(s):

S. M. Spelling ◽

J. O. Young

Keyword(s):

Population Dynamics ◽

Relative Density ◽

Sexual Maturity ◽

Egg Production ◽

Seasonal Pattern ◽

Distinct Pattern ◽

The Other ◽

Mean Intensity ◽

Density Values ◽

Host Mortality

SUMMARYMonthly samples of the leeches Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis were taken over a two-year period from an eutrophic, English lake to detect metacercariae of the trematode, Apatemon gracilis. In each cohort of each of the three leeches, prevalence was low in young individuals, rose to a peak in autumn/winter, and then declined until the cohort had almost died out; in E. octoculata and H. stagnalis a final brief increase occurred. Mean intensity and relative density values followed a similar seasonal pattern of change to that of prevalence in these last two species, but in G. complanata values fluctuated irregularly with no distinct pattern. The frequency distribution of the parasite in G. complanata was highly over-dispersed, but less so in the other two species. Infected E. octoculata reached sexual maturity. The parasite reduced egg production in G. complanata and H. stagnalis, but only by maximum values of 2·5 and 9% respectively. This reduction in fecundity is low compared to the subsequent high mortality, at 95% or more, of newly recruited young from as yet unidentified causes. Parasite-related host mortality was difficult to assess in young leeches, but there was some evidence for its occurrence in older leeches of E. octoculata and H. stagnalis. However, this is unlikely to play a prominent role in the control and regulation of lacustrine leech populations.

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Biological Aspects of a High Socio-Economic Group

Journal of Biosocial Science ◽

10.1017/s0021932000007434 ◽

1970 ◽

Vol 2 (1) ◽

pp. 1-16 ◽

Cited By ~ 13

Author(s):

John B. Gibson

Keyword(s):

Social Class ◽

Social Stratification ◽

Educational Opportunity ◽

Population Sample ◽

Stabilizing Selection ◽

Class Differences ◽

Social Scale ◽

The Social ◽

Biological Aspects ◽

The Mean

Data are presented on the social backgrounds and IQs of a sample of scientists, their male sibs and their fathers. The range of IQ in the scientists is similar to the range of scores expected of the higher 25% of a representative general population sample.The IQs of the scientists showed a positive correlation with social class. Differences in IQ between the scientists and their fathers in each social class are related to the distance the scientists have moved up the social scale. In the twenty-two families in which the IQs of the father and two male sibs are known the upwardly mobile sibs tend to have higher IQs than the non-mobile or downwardly mobile sibs.In Class II there is evidence that stabilizing selection operates on IQ to maintain the mean IQ level. The effect on social stratification of such selection, together with increased educational opportunity, is discussed.

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Procedural Revision to the AOAC Germicidal Spray Products as Disinfectants Test Method: Establishment of Minimum and Maximum Log Density Values for Test Microbes on Inoculated Carriers

Journal of AOAC International ◽

10.5740/jaoacint.12-406 ◽

2013 ◽

Vol 96 (3) ◽

pp. 567-572 ◽

Cited By ~ 1

Author(s):

Rebecca M Pines ◽

Stephen F Tomasino ◽

Michele P Cottrill ◽

Gordon C Hamilton ◽

Albert E Parker

Keyword(s):

Count Data ◽

Geometric Mean ◽

Test Method ◽

Official Method ◽

Data Set ◽

Label Claim ◽

Density Values ◽

Good Repeatability ◽

The Mean ◽

Test Microbe

Abstract The AOAC Germicidal Spray Products as Disinfectants test method (AOAC Official Method 961.02) is used to measure the efficacy of spray products on hard inanimate surfaces; however, the method does not provide procedures to determine the population of the test microbe on inoculated glass slide carriers (e.g., carrier counts reported as CFU/carrier). Without a method to measure and monitor carrier counts, the associated efficacy data may not be reliable and repeatable. This report provides a standardized procedure to address this issue and, based on carrier count data collected by four laboratories from 2000 to 2010, proposes a specific range for the mean log density per carrier as a requirement. Laboratory-based carrier count data were collected concurrently with 116 Method 961.02 efficacy tests conducted on spray products bearing claims against Pseudomonas aeruginosa and Staphylococcus aureus. For many of the tests a soil load (SL) was added to the inoculum (as specified on the product label claim). Six carriers were assayed per test for a total of 696 carriers. All but two of the 116 mean log densities were at least 5.0 (a geometric mean of 1.0 × 105 CFU/carrier). Across the four combinations of microbes and SL treatments, the mean TestLD (mean log density across all enumerated carriers in a test) ranged from approximately 6.0 (a geometric mean of 0.9 × 106 CFU/carrier) to 6.3 (a geometric mean of 2.0 × 106 CFU/carrier). Across all microbes and SL treatments, the mean log density (±SEM) was 6.2 (±0.07) per carrier (a geometric mean of 1.5 × 106 CFU/carrier). The mean log density for six carriers per test showed good repeatability (0.32) and reproducibility (0.34). The proposed requirement for S. aureus tests and P. aeruginosa tests is a mean log density (across six carriers) between 5.0 and 6.5. A separate 2009 study at three laboratories was conducted to evaluate the persistence of P. aeruginosa, S. aureus, and Salmonella enterica on glass carriers. Based on the persistence data, a 2 h use period is proposed for using the inoculated carriers post drying. The persistence data set was also used to assess the carrier counts for S. enterica. The carrier counts were approximately one log lower for S. enterica compared to S. aureus and P. aeruginosa; a range of 4.0 to 5.5 logs is proposed as a requirement for S. enterica tests.

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Paleolimnology of Lake Yamanaka as reflected on particle-size distribution

Bulletin of the Department of Geology ◽

10.3126/bdg.v14i0.5437 ◽

1970 ◽

Vol 14 ◽

pp. 35-42 ◽

Cited By ~ 1

Author(s):

Danda Pani Adhikari

Keyword(s):

Particle Size ◽

Grain Size ◽

Size Distribution ◽

Central Japan ◽

Size Frequency Distribution ◽

Factors Affecting ◽

Mean Grain Size ◽

The Mean ◽

Main Factors ◽

Lake Size

A 17.63 m long bore-hole core extracted from the deepest part of Lake Yamanaka, one of the Fuji-five Lakes at the northeasternfoot of Mount Fuji, central Japan, composed of sediment with intercalations of scoria fallout deposits. The sediment of the upper11.4 m was investigated for grain-size distribution by using a laser diffraction particle size analyser. The mean grain-size profileshowed various degrees of fluctuations, both short-and long-terms, and the size-frequency distribution revealed unimodal-trimodalmixing of sediments. Changes in lake size and water depth appear to be the main factors affecting the variability in the grain-sizedistribution and properties. The lake level appears low during 7000–5000 cal BP and 2800–1150 cal BP and relatively high during5000–2800 cal BP and 1150 cal BP– present.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5437Bulletin of the Department of Geology Vol.14 2011, pp.35-42

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Population dynamics with spatial structure and an Allee effect

10.1101/2020.06.26.173153 ◽

2020 ◽

Author(s):

Anudeep Surendran ◽

Michael Plank ◽

Matthew Simpson

Keyword(s):

Population Dynamics ◽

Spatial Structure ◽

Short Range ◽

Allee Effect ◽

Mean Field ◽

Mean Field Approximation ◽

Continuum Approximation ◽

Spatial Moment ◽

Mean Field Models ◽

The Mean

AbstractAllee effects describe populations in which long-term survival is only possible if the population density is above some threshold level. A simple mathematical model of an Allee effect is one where initial densities below the threshold lead to population extinction, whereas initial densities above the threshold eventually asymptote to some positive carrying capacity density. Mean field models of population dynamics neglect spatial structure that can arise through short-range interactions, such as short-range competition and dispersal. The influence of such non mean-field effects has not been studied in the presence of an Allee effect. To address this we develop an individual-based model (IBM) that incorporates both short-range interactions and an Allee effect. To explore the role of spatial structure we derive a mathematically tractable continuum approximation of the IBM in terms of the dynamics of spatial moments. In the limit of long-range interactions where the mean-field approximation holds, our modelling framework accurately recovers the mean-field Allee threshold. We show that the Allee threshold is sensitive to spatial structure that mean-field models neglect. For example, we show that there are cases where the mean-field model predicts extinction but the population actually survives and vice versa. Through simulations we show that our new spatial moment dynamics model accurately captures the modified Allee threshold in the presence of spatial structure.

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Linking lineage and population observables in biological branching processes

10.1101/527291 ◽

2019 ◽

Author(s):

Reinaldo García-García ◽

Arthur Genthon ◽

David Lacoste

Keyword(s):

Population Dynamics ◽

Generation Time ◽

Doubling Time ◽

Branching Processes ◽

Underlying Mechanism ◽

Population Doubling ◽

Population Doubling Time ◽

Division Rate ◽

Fluctuation Theorems ◽

The Mean

Using a population dynamics inspired by an ensemble of growing cells, a set of fluctuation theorems linking observables measured at the lineage and population levels are derived. One of these relations implies inequalities comparing the population doubling time with the mean generation time at the lineage or population levels. We argue that testing these inequalities provides useful insights into the underlying mechanism controlling the division rate in such branching processes.

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