The population density, growth rate and production of roach Rutilus mtilus (L.) in Tjeukemeer, The Netherlands

1979 ◽  
Vol 15 (4) ◽  
pp. 473-498 ◽  
Author(s):  
C. R. Goldspink
Keyword(s):  
Growth Rate ◽  
Population Density ◽  
The Netherlands ◽  
Density Growth

scholarly journals Growth performance and nutritional quality enrichment of Phronima pacifica by Chlorella vulgaris and Chaetoceros calcitrans as natural feed

2020 ◽  
Vol 21 (9) ◽  
Author(s):  
Vivi Endar Herawati ◽  
Zumalallail Nailulmuna ◽  
Nurmanita Rismaningsih ◽  
Johannes Hutabarat ◽  
Pinandoyo Pinandoyo ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Density ◽  
Growth Performance ◽  
Chlorella Vulgaris ◽  
Nutritional Quality ◽  
Stocking Density ◽  
Nutrient Content ◽  
Nutritional Content ◽  
Density Growth ◽  
Chaetoceros Calcitrans

Abstract. Herawati VE, Nailulmuna Z, Rismaningsih N, Hutabarat J, Pinandoyo, Elfitasari T, Riyadi PH, Radjasa OK. 2020. Growth performance and nutritional quality enrichment of Phronima pacifica by Chlorella vulgaris and Chaetoceros calcitrans as natural feed. Biodiversitas 21: 4253-4259. Phronima pacifica as a natural feed has the potential to replace Artemia sp. because of its high nutritional content. The purpose of this study was to determine the effects of different types of feed for P. pacifica during its culture on its population density, growth rate, and nutritional content because of its potential use as a natural feed for fish. The test animals in this study consisted of P. pacifica at a stocking density of 3 ind/L, which were cultured for 18 d. Then, Chlorella vulgaris and Chaetoceros calcitrans were introduced as enrichment feed for P. pacifica. This study used a completely randomized design with three treatments and three replications. The treatments were as follows: A (100% Chlorella vulgaris), B (100% Chaetoceros calcitrans), and C (50% Chlorella vulgaris and 50% Chaetoceros calcitrans). The results showed that treatment increased the population density of P. pacifica by up to 54.67 ± 0.0038 ind/L by the 12th day. Based on the results of proximate analysis for amino acid and fatty acid profiles, the highest values for proteins and fats were in P. pacifica enriched with Chlorella vulgaris (A) and consisted of 45.45% protein, 7.57% fat, 5.95% eicosapentaenoic acid, and 39.23% lysine. Based on an ANOVA, feeding of P. pacifica with Chlorella vulgaris and Chaetoceros calcitrans had a significant effect on population density, relative growth rate, biomass production, and nutrient value of proteins and fats of P. pacifica (P < 0.05). The best results, including population density, growth rate, weight of biomass, and nutrient content of P. pacifica, occurred after feeding with Chlorella vulgaris.

Prediction Vulnerability Level of Dengue Fever Using KNN and Random Forest

2020 ◽  
Vol 4 (3) ◽  
pp. 531-536 ◽  
Author(s):  
Abduh Salam ◽  
Sri Suryani Prasetiyowati ◽  
Yuliant Sibaroni
Keyword(s):  
Growth Rate ◽  
Wind Speed ◽  
Random Forest ◽  
Population Density ◽  
Dengue Virus ◽  
Dengue Fever ◽  
Population Mobility ◽  
Density Growth ◽  
The Government ◽  
Over Time

Indonesia is a country that is prone to Dengue Fever, this happens because Indonesia is a country with a tropical climate. More than 50 years after Indonesia contracted the dengue virus, dengue fever cases have not been resolved, currently the cases that occur are greatly increased over time this happens because of factors that cause dengue fever. By considering this serious problem, the authors created a system that can predict the vulnerability level in Bandung and looks for the factors that most influence from all factors of Dengue Fever using the KNN Algorithm and Random Forest. The results of the system show the results of the best model is KNN algorithm with RMSE 29,26, and from the model shows the most influencing factors are population density, growth rate population mobility, rainfall, wind speed. by utilizing the results of the study, the government can adjust actions to each level of sub-district vulnerability and pay more attention to the factors that most influence dengue fever according to the results of the study.

Population Densities Allowed Around Dutch SEVESO Establishments

2000 ◽  
Author(s):  
G. M. H. Laheij ◽  
B. J. M. Ale ◽  
J. G. Post
Keyword(s):  
Population Density ◽  
The Netherlands ◽  
Individual Risk ◽  
Population Densities ◽  
Planning Policy ◽  
Relative Contribution ◽  
Societal Risk ◽  
Dangerous Substances ◽  
The Individual ◽  
Uniform Population

Abstract In the Netherlands, the individual risk and societal risk are used in efforts to reduce the number of people exposed to the effect of an accident at an establishment with dangerous substances. To facilitate the societal risk planning policy an investigation was carried out for the Dutch SEVESO establishments to investigate the possibility of determining a generic uniform population density for the zone between the individual risk contours of 10−5 and 10−6 per year. The indicative limit for the societal risk at this density was not to be exceeded. Also there was to be enough space left for a significantly higher population density outside the individual risk contour of 10−6 per year. The RORISC methodology and the actual data for the 124 Dutch SEVESO establishments were used to determine the generic uniform population density. Based on the data available it can be concluded that the maximum allowed uniform population density in the zone between the individual risk contours of 10−5 and 10−6 per year is lower than one person per hectare. At this density there is no space left for a higher population density outside the individual risk contour of 10−6 per year. For uniform population densities the relative contribution to the societal risk has been found significant up to the individual risk contour of 10−7 per year.

Paddlefish Management, Propagation, and Conservation in the 21st Century

2009 ◽  
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Mortality Rate ◽  
Population Density ◽  
21St Century ◽  
High Growth ◽  
High Growth Rate ◽  
Demographic Groups ◽  
Annual Mortality ◽  
Remnant Population

<em>Abstract</em>.—Paddlefish <em>Polyodon spathula </em>vanished from areas of the upper Tombigbee River basin in Mississippi and Alabama during the 1950s, long before channelization and damming associated with construction of the Tennessee-Tombigbee Waterway (TTW) were completed in 1984. This study was undertaken to assess distribution and population dynamics of any remaining stock. Paddlefish were not captured in upstream impoundments, but an unexploited remnant population was located in the downstream impoundment: Demopolis Lake, Alabama. Paddlefish in Demopolis Lake were characterized by a population density of 2.6 fish/ha, high growth rate relative to more northern populations, and natural annual mortality rate (<em>A </em>= 0.406) similar to other southern populations. Two wintering habitats (cutoff bendways) were heavily utilized by paddlefish. Large males primarily inhabited the more lotic bendway while females and small males were more common in the more lentic bendway, indicating differential importance of habitats among demographic groups. The restricted distribution of TTW paddlefish and demographic differences between habitats suggest that areas heavily utilized by paddlefish should be protected from further degradation. Sedimentation has resulted in reductions of bendway depth and reduced connectivity of backwaters, reducing availability of suitable paddlefish habitat. Restoring connectivity of bendways through dredging could reverse this trend and provide other benefits to fisheries.

Effect of environmental factors on survival and population growth of ciliated parasite, Mesanophrys sp. (Ciliophora: Scuticociliatia) infecting Portunus trituberculatus

Parasitology ◽  
2020 ◽  
pp. 1-9
Author(s):  
Summia Perveen ◽  
Yuhua Lei ◽  
Fei Yin ◽  
Chunlin Wang
Keyword(s):  
Growth Rate ◽  
Population Density ◽  
Effect Of Temperature ◽  
Portunus Trituberculatus ◽  
Parasite Development ◽  
Control Group ◽  
Infection Dynamics ◽  
Lower Temperature ◽  
Increasing Temperature

Abstract Mesanophrys sp. is a newly identified parasitic ciliate infecting farmed swimming crab. To demonstrate the correlation between parasite development and environmental conditions, this study aimed to investigate the effect of temperature, salinity, pH and frequency of passage of parasite on survival, growth and body size of Mesanophrys sp. in vitro. The results revealed that survival, population density and growth rate of the parasite were highest at 12°C and decreased with increasing temperature from 16 to 26°C. In addition, the survival, population density and growth rate of Mesanophrys sp. were high at 20‰. When salinity was adjusted to levels lower (0–10‰) and higher (40–60‰) than 20‰, the parasite's survival and growth rate gradually declined. The optimal pH for parasite survival was 8.0, whereas its survival was inhibited at <4.5 or >9.5. Our result also showed that parasite body proportions (length:width) were significantly smaller at the highest temperature compared to the lower temperature, whereas different salinities had no significant effect. Furthermore, we introduced dynamic parasite culture systems in vitro where Mesanophrys sp. was cultured in medium-containing culture plates through continually reducing and halving the old medium into fresh. Application of this optimized dilution timing technique with fresh medium and sub-cultured enabled a continuous culture of parasites. Under this optimized condition, the highest population density and exponential growth rate of the parasite were achieved than that of a control group. This study will help to understand the ciliated parasite infection dynamics and provides new possibilities for in vitro parasite-associated studies.

Positive density-dependent growth supports costs sharing hypothesis and population density sensing in a manipulative parasite

Parasitology ◽  
2017 ◽  
Vol 144 (11) ◽  
pp. 1511-1518 ◽  
Author(s):  
MIKHAIL GOPKO ◽  
VICTOR N. MIKHEEV ◽  
JOUNI TASKINEN
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Population Density ◽  
Cost Sharing ◽  
Positive Density ◽  
Diplostomum Pseudospathaceum ◽  
Instance Theory ◽  
Positive Density Dependence ◽  
Study Support ◽  
Dependent Growth

SUMMARYParasites manipulate their hosts’ phenotype to increase their own fitness. Like any evolutionary adaptation, parasitic manipulations should be costly. Though it is difficult to measure costs of the manipulation directly, they can be evaluated using an indirect approach. For instance, theory suggests that as the parasite infrapopulation grows, the investment of individual parasites in host manipulation decreases, because of cost sharing. Another assumption is that in environments where manipulation does not pay off for the parasite, it can decrease its investment in the manipulation to save resources. We experimentally infected rainbow trout Oncorhynchus mykiss with the immature larvae of the trematode Diplostomum pseudospathaceum, to test these assumptions. Immature D. pseudospathaceum metacercariae are known for their ability to manipulate the behaviour of their host enhancing its anti-predator defenses to avoid concomitant predation. We found that the growth rate of individual parasites in rainbow trout increased with the infrapopulation size (positive density-dependence) suggesting cost sharing. Moreover, parasites adjusted their growth to the intensity of infection within the eye lens where they were localized suggesting population density sensing. Results of this study support the hypothesis that macroparasites can adjust their growth rate and manipulation investment according to cost sharing level and infrapopulation size.

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