scholarly journals Population dynamics of the brine shrimp Artemia persimilis Piccinelli & Prosdocimi, 1968 (Crustacea, Anostraca) in a hypersaline lake of the Central Pampa (Argentina)

2017 ◽  
Vol 17 (3) ◽  
Author(s):  
Alicia M. Vignatti ◽  
Gabriela C. Cabrera ◽  
Santiago A. Echaniz
Keyword(s):  
Brine Shrimp ◽  
High Salinity ◽  
Hypersaline Lake ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Present Information ◽  
Biological Aspects ◽  
The Mean ◽  
Density And Biomass ◽  
Artemia Persimilis

Abstract The anostracan Artemia is one of the few organisms that can inhabit hypersaline lakes. In Argentina, this genus is represented by two species: the invasive A. franciscana Kellogg, 1906 and the autochthonous A. persimilis Piccinelli & Prosdocimi, 1968, the latter being the only one recorded in the province of La Pampa. Some of the biological aspects of A. persimilis are known based on laboratory studies, and data on its ecology in natural conditions are scarce. The aim of this work is to present information on the density, biomass, and population structure of A. persimilis in relation to environmental variables in Utracán, a hypersaline lake of the semiarid Central Pampa of Argentina. Water and zooplankton samples were taken monthly from May 2009 until August 2010. The mean density and biomass were 56.98 ind.L-1 (± 106.64) and 1.23 mg.L-1 (± 1.35), respectively. The species was negatively affected by salinity, and it was absent between November and February, when salinity exceeded 320 g.L-1. However, when it was present, even during the months of higher salinity, a high proportion of naupliar stages was found, which could indicate that, in nature, A. persimilis can reproduce with high salinity. Although it has been indicated that A. persimilis could be displaced by A. franciscana, the highest tolerance of the former at low temperatures, which allowed the population to continue reproducing at values close to 3°C, would limit its displacement. However, an increase in the temperature of lakes as a result of global warming could modify this situation and allow the advance of the introduced species to the south.

scholarly journals The differential transmissibility of myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale)

1975 ◽  
Vol 75 (2) ◽  
pp. 237-247 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan
Keyword(s):  
Host Resistance ◽  
Oryctolagus Cuniculus ◽  
Selective Advantage ◽  
Myxoma Virus ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Male And Female ◽  
The Mean ◽  
Virus Strains ◽  
Sampling Times

SUMMARYLaboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

Infrapopulations ofSclerocollum saudiiAl-Jahdali, 2010 (Acanthocephala: Cavisomidae) in the rabbitfishSiganus rivulatus(Teleostei, Siganidae) from the Saudi coast of the Red Sea

2011 ◽  
Vol 86 (1) ◽  
pp. 85-94 ◽  
Author(s):  
M.O. Al-Jahdali ◽  
R.M. El-Said Hassanine
Keyword(s):  
Self Regulation ◽  
Longitudinal Distribution ◽  
Differential Mortality ◽  
Helminth Parasites ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Density Dependent ◽  
Males And Females ◽  
The Mean ◽  
Siganus Rivulatus

AbstractIn infrapopulations of helminth parasites, density-dependent effects, through some form of intra- and interspecific competition, play an important role in shaping and regulating the infrapopulations. The mechanisms responsible for these processes have often been observed in laboratory studies and rarely studied under natural conditions. Here, 24 natural infrapopulations (77–447 individuals) of the acanthocephalanSclerocollum saudiiAl-Jahdali, 2010 from the fishSiganus rivulatusconsisted of cystacanths, newly excysted juveniles, immature and mature worms, distributed in a well-defined fundamental niche (anterior 60% of the intestine). Each of these stages exhibited a significantly different longitudinal distribution within this niche. In small infrapopulations, cystacanths and newly excysted juveniles were found in the sixth 10% of the intestine, immature worms in the fifth 10% and mature worms in the anterior 40% of the intestine. However, their proportions followed a clear ascending order in each infrapopulation, and the female–male ratios of both immature and mature worms were distinctly female-biased. In large infrapopulations, mature worms existed partially in the site of immature ones, where a differential mortality among immature females was constantly observed. However, the proportions of immature worms increased significantly and those of mature worms decreased significantly, the mean lengths of immature and mature females decreased dramatically and the female–male ratios were distinctly male-biased. The mean sizes of immature and mature males seemed stable through all infrapopulations. The distribution of mature males and females suggests intense male–male competition for access to females, and reveals that larger females are copulated prior to the smaller ones. The results are statistically significant and suggest that infrapopulation self-regulation is through density-dependent mechanisms, in which immature females may play a key role.

Suppression of Weed Occurrence in a Five-year Corn-earthworm Coculture System

Weed Science ◽  
2020 ◽  
pp. 1-23
Author(s):  
Tao Li ◽  
Jiequn Fan ◽  
Zhenguan Qian ◽  
Guohui Yuan ◽  
Dandan Meng ◽  
...  
Keyword(s):  
Weed Species ◽  
Ecological Benefits ◽  
Economic Output ◽  
Green Foxtail ◽  
Weed Diversity ◽  
The Mean ◽  
Common Purslane ◽  
Species Specific ◽  
Density And Biomass ◽  
Successive Experiment

Abstract The use of a corn-earthworm coculture (CE) system is an eco-agricultural technology that has been gradually extended due to its high economic output and diverse ecological benefits for urban agriculture in China. However, the effect of CE on weed occurrence has received little attention. A five-year successive experiment (2015 to 2019) was conducted to compare weed occurrence in CE and a corn (Zea mays L.) monoculture (CM). The results show that CE significantly decreased weed diversity, the dominance index, total weed density and biomass, but increased the weed evenness index. The five-year mean number of weed species per plot was 8.4 in CE and 10.7 in CM. Compared to those in CM, the five-year mean density and biomass of total weeds in CE decreased by 59.2% and 66.6%, respectively. The effect of CE on weed occurrence was species specific. The mean density of large crabgrass [Digitaria sanguinalis (L.) Scop.], green foxtail [Setaria viridis (L.) Beauv.], goosegrass [Eleusine indica (L.) Gaertn.], and common purslane (Portulaca oleracea L.) in CE decreased by 94.5, 78.1, 75.0, and 45.8%, whereas the mean biomass decreased by 96.2, 80.8, 76.9, and 41.4%, respectively. Our study suggests that the use of CE could suppress weed occurrence and reduce herbicide inputs in agriculture.

Seasonal Changes in the Water Relations of Eucalyptus behriana F. Muell. And E. microcarpa (Maiden) Maiden in the Field

1984 ◽  
Vol 32 (5) ◽  
pp. 495 ◽  
Author(s):  
BA Myers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Water Relations ◽  
Rainfall Intensity ◽  
Field Measurements ◽  
Canopy Conductance ◽  
Laboratory Studies ◽  
Short Term ◽  
The Mean ◽  
Type Response ◽  
Vapour Pressure Difference

Field observations of some parameters of the water relations of the two eucalypt species E. behriana and E. microcarpa in dry sclerophyll, mallee and woodland vegetation were made at three sites from 1980 to 1983. The mean ( n = 519) water potential measured at dawn (Ψdawn) was -3.07± 0.01 MPa and fluctuated seasonally with rainfall intensity over the range -2.0 ± 0, 1 to -4.4 ± 0.1 MPa ( n = 30). Both species behaved similarly and some osmotic adjustment took place. Mean leaf conductance (gs) varied between 0.151 ± 0.006 and 0.003 ± 0.001 mol m-2 s-1 . Maximum daily values of gs were linearly related to Ψdawn as it fluctuated seasonally. The slope of this linear regression was not significantly different from that relating these values of gs and Ψ, when both were measured concurrently. There were thus no indications of a distinction between the responses of gs to long- and short-term fluctuations of Ψ or of a threshold-type response of gs to Ψ. Field measurements indicated that gs was decreased at high values of vapour pressure difference (Δe). In laboratory studies with seedlings of the two species gs decreased from 0.5 to 0.1 mol m-2 s-I as Δe increased from 0.5 to 3.0 kPa. Leaf and canopy conductance were the predominant plant determinants of transpiration rate (Er) in this type of vegetation which has the capacity to restrict Et via the effect of water potential (Ψ) on gs and also by the response of gs to Δe. Some of the water relations parameters of E. behriana indicated that this species was better able to withstand drought than was E microcarpa.

Biological Aspects of a High Socio-Economic Group

1970 ◽  
Vol 2 (1) ◽  
pp. 1-16 ◽  
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.

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

2011 ◽  
Vol 101 (1-2) ◽  
pp. 5-14 ◽  
Author(s):  
Douglas F Peiró ◽  
Fernando L Mantelatto
Keyword(s):  
Population Dynamics ◽  
Sandy Beach ◽  
Southwestern Atlantic ◽  
Recruitment Pattern ◽  
Size Frequency Distribution ◽  
Ghost Shrimp ◽  
Density Values ◽  
Pea Crab ◽  
Biological Aspects ◽  
The Mean

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.

scholarly journals COMMUNITY STRUCTURE AND TROPHIC STATUS OF REEF FISH IN NATUNA WATERS

2020 ◽  
Vol 26 (2) ◽  
pp. 69
Author(s):  
Isa Nagib Edrus ◽  
Pratiwi Lestari
Keyword(s):  
Reef Fish ◽  
Fish Community ◽  
Field Research ◽  
Reef Fishes ◽  
Species Number ◽  
Community Structures ◽  
Underwater Visual Census ◽  
The Mean ◽  
Coral Health ◽  
Density And Biomass

A field research on reef fish-community structures in Natuna waters was carried out in November 2015. This research aimed to obtain the trophic composition of reef fishes and its correlation to diversity, density, and biomass. Underwater visual census on several transect areas was used to collect data. Results show that the identified reef fishes were about 100 species of target-reef fish belonging to 18 families and 23 species of indicator-reef fish of the Chaetodontidae family. The mean species number of target reef fish and indicator reef fish were 42 and 7 species, respectively. The  mean density of the target reef fish and indicator reef fish were 0.4 and 0.05 individual per m2, respectively. The mean of the reef fish relative stock was 0.6 ton/ha. The composition of the herbivores mostly found in the resilient coral reefs r was 46.45 % and the omnivores and planktivores as marketable targeted fishes were 18.64 % and 14.28 %, respectively. The most predominant or major families were from herbivorous, carnivorous, planktivorous, and corallivorous fishes, including Scaridae (i.e. Scarus spp), Lutjanidae (i.e. Lutjanus spp.), Caesionidae (i,e. Caesio cuning and Pterocaesio caerulaurea), and Chaetodontidae (i.e. Chaetodon baronessa and Chaetodon octofasciatus). The results suggested that the community structures were quite prospectively implemented for fisheries; however, it may not be promising for coral resilience. Furthermore, the coral health status was at moderate level in regard to the high numbers of corallivorous butterflyfishes.

scholarly journals Some Biological Aspects of Cultured Ompok Pabda (Hamilton, 1822) Collected from A Local Fish Farm in Mymensingh, Bangladesh

2021 ◽  
Vol 21 (4) ◽  
pp. 149-159
Author(s):  
Dulon Roy ◽  
Ashish Kumer Sarker ◽  
Abu Musa Mohammad Khairul Abedin ◽  
Smita Sarker ◽  
Kazi Nahida Begum ◽  
...  
Keyword(s):  
Larval Development ◽  
Fertilization Rate ◽  
Female Dominance ◽  
Hatching Rate ◽  
Gonad Weight ◽  
Female Ratio ◽  
Gonadal Maturity ◽  
Biological Aspects ◽  
The Mean ◽  
First Maturity

An experiment was conducted to observe some biological aspects including growth, sex ratio, gonadal maturity, artificial insemination, fecundity, fertilization, hatching and larval development of O. pabda in a private hatchery. Total weight of the sampled fish varied from 1.60±0.43 to 111.12±6.83 g and length varied from 3.57±0.65 to 21.22±1.84 cm with the SGR 2.85±0.18 and ADG 0.73±0.05. The length and weight of the fish had a strong correlation (r²=0.966). Female dominance over male has been observed in the species. The male to female ratio was 1:1.48. Females were 16.8 cm in length at first maturity, while males were 16.6 cm in length. The GSI of female were ranged from 2.93 to 4.77 with the mean of 3.77±0.60 during the study period. The fecundity of O. pabda was ranged from 5675 to 19626 with the mean of 12503±4192 for the corresponding length 21.23±1.71, body weight 111.12±7.6 and gonad weight 4.19±0.87. Fertilization rate, hatching rate and larval development observed during the experiment. Scattered diagram for length-weight, fecundity-length, fecunditybody weight and fecundity-gonad weight relationship shows a perfect correlation both arithmetically and logarithmically.

scholarly journals ASPEK BIOLOGI DAN PARAMETER POPULASI UDANG JINGA (Metapenaeus affinis H. Milne Edwards, 1837) DI PERAIRAN KOTABARU, KALIMANTAN SELATAN

2017 ◽  
Vol 9 (1) ◽  
pp. 11
Author(s):  
Tirtadanu Tirtadanu ◽  
Suprapto Suprapto ◽  
Ali Suman
Keyword(s):  
Growth Parameters ◽  
Growth Function ◽  
Fishing Effort ◽  
Population Parameters ◽  
Male And Female ◽  
Management Measures ◽  
Exploitation Rate ◽  
Mean Size ◽  
Biological Aspects ◽  
The Mean

Udang jinga (Metapenaeus affinis H. Milne Edwards, 1837) merupakan salah satu jenis udang ekonomis penting yang diusahakan di perairan Kotabaru dan saat ini produksinya cenderung mengalami penurunan. Salah satu data dan informasi yang diperlukan dalam mengkaji tingkat pemanfaatan dan dasar pengelolaannya adalah aspek biologi dan parameter populasi. Penelitian ini bertujuan mengkaji aspek biologi dan parameter populasi udang jinga sebagai bahan kebijakan pengelolaan perikanan udang di perairan Kotabaru, Kalimantan Selatan. Penelitian dilakukan pada bulan Januari – November 2016 di perairan Kotabaru. Parameter pertumbuhan diestimasi berdasarkan pergeseran modus struktur ukuran panjang dengan metode ELEFAN I. Hasil penelitian menunjukkan rata-rata ukuran udang jinga (M. affinis) betina yang tertangkap adalah 23,6 ± 3,45 mmCL dengan modus ukuran 24 mmCL dan rata-rata ukuran udang jantan adalah 20,7 ± 2,9 mm dengan modus ukuran 18 mmCL. Nisbah kelamin udang jinga jantan dan betina adalah 1 : 2,5. Musim pemijahan udang jinga diduga berlangsung sepanjang tahun dan puncak pada bulan Maret. Ukuran rata-rata pertama kali tertangkap (Lc) udang lebih kecil dari ukuran rata-rata pertama kali matang gonad (Lm) (21,7 < 28,5 mm CL) sehingga sebagian besar udang tertangkap berukuran kecil dan belum memijah. Persamaan pertumbuhan udang jinga jantan  CL(t)=35,95(1-e-2.02(t+0,31) dan udang jinga betina CL(t)= 38,3(1-e-1,92(t+0,29)). Tingkat pemanfaatan udang (E) menunjukkan lebih tangkap (overfishing) yakni 0,70/tahun pada jantan dan 0,73/tahun pada betina. Dengan demikian disarankan untuk melakukan pengurangan upaya penangkapan sebesar 40% dan penutupan musim penangkapan di bulan Maret.The jinga shrimp (Metapenaeus affinis H. Milne Edwards, 1837) was one of important commodity that was exploited in Kotabaru Waters, yet the production tend to be declined recently. The data and information on biological aspects and population parameters are needed to investigate the exploitation level and the basis of management measures. This research aims to investigate the biological aspects and population parameters of jinga shrimp Kotabaru waters, South of Kalimantan. This research was conducted on January – November 2016. The growth parameters were estimated as movement of length frequency mode by ELEFAN I method. The results showed that the mean size of female jinga shrimp (M. affinis) was 23,6 ± 3,45 mm CL and the mode was 24 mmCL. While, the mean size of male jinga shrimp was 20,7 ± 2.9 mm CL and the mode was 18 mmCL. The sex ratio of male and female shrimp was 1 : 2,5 . Spawning season of jinga shrimp was estimated throughout the year and the peak was in March. The length at first captured (Lc) was shorter than length at first matured (Lm) (21,7 < 28,5 mm CL). That means most of the catches was immature. The growth function of male and female jinga shrimp were and, CL(t)=35,95(1-e-2.02(t+0,31) respectively and CL(t)= 38,3(1-e-1,92(t+0,29)). The exploitation rate (E) of male and female shrimp fishing were  0,70/year 0,73/year, respectively. The reduction of fishing effort needed by 40% of the actual combined with the temporal fishing closure March.

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