scholarly journals Network connectivity of Minnesota waterbodies and implications for aquatic invasive species prevention

Author(s):  
Szu-Yu Zoe Kao ◽  
Eva A. Enns ◽  
Megan Tomamichel ◽  
Adam Doll ◽  
Luis E. Escobar ◽  
...  

AbstractConnectivity between waterbodies influences the risk of aquatic invasive species (AIS) invasion. Understanding and characterizing the connectivity between waterbodies through high-risk pathways, such as recreational boats, is essential to develop economical and effective prevention intervention to control the spread of AIS. Fortunately, state and local watercraft inspection programs are collecting significant data that can be used to quantify boater connectivity. We created a series of predictive models to capture the patterns of boater movements across all lakes in Minnesota, USA. Informed by more than 1.3 million watercraft inspection surveys from 2014–2017, we simulated boater movements connecting 9182 lakes with a high degree of accuracy. Our predictive model accurately predicted 97.36% of the lake pairs known to be connected and predicted 91.01% of the lake pairs known not to be connected. Lakes with high degree and betweenness centrality were more likely to be infested with an AIS than lakes with low degree (p < 0.001) and centrality (p < 0.001). On average, infested lakes were connected to 1200 more lakes than uninfested lakes. In addition, boaters that visited infested lakes were more likely to visit other lakes, increasing the risk of AIS spread to uninfested lakes. The use of the simulated boater networks can be helpful for determining the risk of AIS invasion for each lake and for developing management tools to assist decision makers to develop intervention strategies.

2021 ◽  
Vol 24 (2) ◽  
pp. 76-85
Author(s):  
C. Raghunathan ◽  
T. Mondal ◽  
K. Chandra

Abstract India is endowed with a wide range of ecosystems, of which oceanic island ecosystems viz. Andaman and Nicobar and Lakshadweep are unique and ecologically fragile because of the high degree of endemism in species composition. Altogether 25 species under different faunal groups such as cnidarians, polychaetes, cirripedes, mollusks, and ascidians are reported as invasive species in Indian islands, of which 24 species are found in Andaman and Nicobar Islands, while 4 species are available in Lakshadweep. Ship-mediated invasions, especially ballast water discharge and ship-hull fouling, are the major source of invasions as these islands are located in the vicinity of the international sea route. In the present paper, we have represented these non-native species of fauna and flora to discriminate and identify them as non-native or invasive. This study deals with the diversity and distribution of aquatic invasive species in islands and their detrimental impact on the island ecosystem.


Author(s):  
D Yanuarita ◽  
D F Inaku ◽  
N Nurdin ◽  
S W Rahim ◽  
H Kudsiah ◽  
...  

1972 ◽  
Vol 18 (10) ◽  
pp. 1543-1550 ◽  
Author(s):  
Robert G. Brown

A strain of Penicillium lilacinum, isolated from soil, produced pustulanase, β-(1 → 3)-glucanase, (EC. 3.2.1.6) and cellulase (EC.3.2.1.4) when cultivated on a medium containing pustulan as the sole source of carbon. If pustulan was replaced by ketopustulan, the production of pustulanase was stimulated about 10-fold although the amount of stimulation was dependent on the degree of oxidation of pustulan. β-(1 → 3)-Glucanase production was stimulated slightly by ketopustulan; however, the degree of oxidation did not affect significantly the yield of this enzyme. Cellulase production was either unaffected by the oxidized polymer, or at higher degrees of oxidation, decreased. Tween 80 stimulated the production of the three enzymes in media containing ketopustulan with a low degree of oxidation but was inhibitory to pustulanase and cellulase production in media containing ketopustulan with a high degree of oxidation. A combination of gel filtration and isoelectric focusing revealed that each enzyme activity was attributable to at least two proteins.


Fisheries ◽  
2010 ◽  
Vol 35 (3) ◽  
pp. 121-132 ◽  
Author(s):  
John D. Rothlisberger ◽  
W. Lindsay Chadderton ◽  
Joanna McNulty ◽  
David M. Lodge

2001 ◽  
Vol 91 (1) ◽  
pp. 77-83 ◽  
Author(s):  
H. Scherm ◽  
A. T. Savelle ◽  
P. L. Pusey

The relationship of cumulative chill-hours (hours with a mean temperature <7.2°C) and heating degree-days (base 7.2°C) to carpogenic germination of pseudosclerotia of Monilinia vaccinii-corymbosi, which causes mummy berry disease of blueberry, was investigated. In two laboratory experiments, pseudosclerotia collected from rabbiteye blueberry in Georgia were conditioned at 5 to 6°C for 26 to 1,378 h prior to placement in conditions favorable for germination and apothecium development. The number of chill-hours accumulated during the conditioning period affected the subsequent proportion of pseudosclerotia that germinated and produced apothecia, with the greatest incidence of carpogenic germination occurring after intermediate levels of chilling (≈700 chill-hours). The minimum chilling requirement for germination and apothecium production was considerably lower than that reported previously for pseudo-sclerotia from highbush blueberry in northern production regions. The rate of carpogenic germination was strongly affected by interactions between the accumulation of chill-hours and degree-days during the conditioning and germination periods; pseudosclerotia exposed to prolonged chilling periods, once transferred to suitable conditions, germinated and produced apothecia more rapidly (after fewer degree-days had accumulated) than those exposed to shorter chilling periods. Thus, pseudosclerotia of M. vaccinii-corymbosi are adapted to germinate carpogenically following cold winters (high chill-hours, low degree-days) as well as warm winters (low chill-hours, high degree-days). Results were validated in a combined field-laboratory experiment in which pseudosclerotia that had received various levels of natural chilling were allowed to germinate in controlled conditions in the laboratory, and in two field experiments in which pseudosclerotia were exposed to natural chilling and germination conditions. A simple model describing the timing of apothecium emergence in relation to cumulative chill-hours and degree-days was developed based on the experiments. The model should be useful for better timing of field scouting programs for apothecia to aid in management of primary infection by M. vaccinii-corymbosi.


Author(s):  
Fahad Husain Alshammari Fahad Husain Alshammari

    This study aimed to: Identify the leadership style prevailing among public school principals in Hail from the teachers ’point of view, and to reveal the statistical significance of the differences in the estimates of the study sample individuals of the leadership style prevailing among school principals, which may due to variables of (educational stage, number of years of experience, and specialization). The researcher used the descriptive method, and prepared a questionnaire consisting of (24) statements distributed to (3) dimensions, which are: Democratic style, authoritarian style and chaotic style. The current study population included all the teachers of public education schools in Hail, who numbered (9390) teachers. The questionnaire was applied to a random sample of (296) teachers. The study found a set of results, the most important of which are: The prevailing leadership style among school principals is the democratic style, followed by the authoritarian style, and then the chaotic style. Where the democratic style obtained a mean (4.18) and a high degree of approval from the study sample, while the domineering style obtained a mean (1.83) and a low degree of approval from the study sample, and the chaotic style obtained an average (1.73) and a low degree of approval. Very members of the study sample. The results also showed that there are statistically significant differences in the degree of the study sample’s estimates of the leadership style prevailing among school principals due to the variable of years of experience, while there are no statistically significant differences in the degree of the study sample’s estimates of the leadership style prevailing among school principals due to the variables of the educational stage or specialization. In light of these results, the researcher recommended organizing training courses for school principals to enlighten them about the modern trends in educational leadership, and urged school principals to follow the democratic style of administration.


2003 ◽  
Vol 28 (1) ◽  
pp. 5-10 ◽  
Author(s):  
Amaury S. Santos ◽  
Ricardo E. Bressan-Smith ◽  
Messias G. Pereira ◽  
Rosana Rodrigues ◽  
Claudia F. Ferreira

Common bean (Phaseolus vulgaris) cultivars with a high degree of resistance to Xanthomonas axonopodis pv. phaseoli (Xap) are not available in Brazil. Despite many studies, a low degree of resistance to Xap continues to exist due to its complex genetic inheritance, which is not well known. The objectives of this research were to complement a common bean genetic map based on the cross between a susceptible genotype 'HAB-52' and a resistant genotype 'BAC-6', and to map and analyze genomic regions (quantitative trait loci – QTLs) related to Xap resistance. Eleven linkage groups were determined using 143 RAPD markers, covering 1,234.5 cM of the genome. This map was used to detect QTLs associated with Xap resistance on leaves and pods. The averages of disease severity on leaves (represented by the transformed disease index – TDI) and pods (represented by the diameter of lesion on pods – DLP) were added to the data of the linkage map. Five TDI QTLs and only one LDP QTL were detected. The TDI QTLs were placed in the A, B, G and J linkage groups, with phenotypic variations ranging from 12.7 to 71.6%. The DLP QTL explained 12.9% of the phenotypic variation and was mapped in a distinct linkage group. These results indicate that there are different genes involved in the control of resistance on leaves and pods.


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