scholarly journals Testing the Improvement of Coral Reef Associated Fish Distribution Models Based on Multibeam Bathymetry by Adding Seafloor Backscatter Data

2021 ◽  
Vol 8 ◽  
Author(s):  
Marcela Montserrat Landero Figueroa ◽  
Miles J. G. Parsons ◽  
Benjamin J. Saunders ◽  
Ben Radford ◽  
Iain M. Parnum
Keyword(s):  
Strong Relationship ◽  
Demersal Fish ◽  
Important Variable ◽  
Acoustic Energy ◽  
Fish Distribution ◽  
Distribution Models ◽  
Seafloor Morphology ◽  
Seafloor Backscatter ◽  
Using Data ◽  
Lagocephalus Sceleratus

Demersal fishes constitute an essential component of the continental shelf ecosystem, and a significant element of fisheries catch around the world. However, collecting distribution and abundance data of demersal fish, necessary for their conservation and management, is usually expensive and logistically complex. The increasing availability of seafloor mapping technologies has led to the opportunity to exploit the strong relationship demersal fish exhibit with seafloor morphology to model their distribution. Multibeam echo-sounder (MBES) systems are a standard method to map seafloor morphology. The amount of acoustic energy reflected by the seafloor (backscatter) is used to estimate specific characteristics of the seafloor, including acoustic hardness and roughness. MBES data including bathymetry and depth derivatives were used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Lethrinus miniatus, Loxodon macrorhinus, Lutjanus sebae, and Scomberomorus queenslandicus. The possible improvement of model accuracy by adding the seafloor backscatter was tested in three different areas of the Ningaloo Marine Park off the west coast of Australia. For the majority of species, depth was a primary variable explaining their distribution in the three study sites. Backscatter was identified to be an important variable in the models, but did not necessarily lead to a significant improvement in the demersal fish distribution models’ accuracy. Possible reasons for this include: the depth and derivatives were capturing the significant changes in the habitat, or the acoustic data collected with a high-frequency MBES were not capturing accurately relevant seafloor characteristics associated with the species distribution. The improvement in the accuracy of the models for certain species using data already available is an encouraging result, which can have a direct impact in our ability to monitor these species.

scholarly journals The use of singlebeam echo-sounder depth data to produce demersal fish distribution models that are comparable to models produced using multibeam echo-sounder depth

2021 ◽  
Author(s):  
Marcela Montserrat Landero Figueroa ◽  
Miles Parsons ◽  
Benjamin Saunders ◽  
Ben Radford ◽  
Chandra Salgado-Kent ◽  
...  
Keyword(s):  
High Resolution ◽  
Demersal Fish ◽  
Important Variable ◽  
Fish Distribution ◽  
Slope Aspect ◽  
Distribution Models ◽  
Explanatory Variables ◽  
Continuous Map ◽  
Spatial Coverage ◽  
Echo Sounder

Seafloor characteristics can help in the prediction of fish distribution, which is required for fisheries and conservation management. Despite this, only 5-10% of the world’s seafloor has been mapped at high resolution as it is a time-consuming and expensive process. Multibeam echo-sounders (MBES) can produce high-resolution bathymetry and a broad swath coverage of the seafloor, but require greater financial and technical resources for operation and data analysis than singlebeam echo-sounders (SBES). In contrast, SBES provide comparatively limited spatial coverage, as only a single measurement is made from directly under the vessel. Thus, producing a continuous map requires interpolation to fill gaps between transects. This study assesses the performance of demersal fish species distribution models by comparing those derived from interpolated SBES data with full-coverage MBES distribution models. A Random Forest classifier was used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Loxodon macrorhinus, Pristipomoides multidens and Pristipomoides typus, with depth and depth derivatives (slope, aspect, standard deviation of depth, terrain ruggedness index, mean curvature and topographic position index) as explanatory variables. The results indicated that distribution models for A. stellatus, G. grandoculis, L. sceleratus, and L. macrorhinus performed poorly for MBES and SBES data with Area Under the Receiver Operator Curves (AUC) below 0.7. Consequently, the distribution of these species could not be predicted by seafloor characteristics produced from either echo-sounder type. Distribution models for P. multidens and P. typus performed well for MBES and the SBES data with an AUC above 0.8. Depth was the most important variable explaining the distribution of P. multidens and P. typus in both MBES and SBES models. While further research is needed, this study shows that in resource-limited scenarios, SBES can produce comparable results to MBES for use in demersal fish management and conservation.

scholarly journals The use of singlebeam echo‐sounder depth data to produce demersal fish distribution models that are comparable to models produced using multibeam echo‐sounder depth

2021 ◽  
Author(s):  
Marcela Montserrat Landero Figueroa ◽  
Miles J. G. Parsons ◽  
Benjamin J. Saunders ◽  
Ben Radford ◽  
Chandra Salgado‐Kent ◽  
...  
Keyword(s):  
Demersal Fish ◽  
Fish Distribution ◽  
Distribution Models ◽  
Depth Data ◽  
Echo Sounder

Explaining variability in parasite aggregation levels among host samples

Parasitology ◽  
2013 ◽  
Vol 140 (4) ◽  
pp. 541-546 ◽  
Author(s):  
ROBERT POULIN
Keyword(s):  
Body Size ◽  
Strong Relationship ◽  
Host Susceptibility ◽  
Helminth Parasites ◽  
Susceptibility To Infection ◽  
Host Body ◽  
Parasite Aggregation ◽  
Using Data ◽  
Species Specific ◽  
Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

Distribution of moss-inhabiting diatoms along an altitudinal gradient at sub-Antarctic Îles Kerguelen

2007 ◽  
Vol 19 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Niek J.M. Gremmen ◽  
Bart van de Vijver ◽  
Yves Frenot ◽  
Marc Lebouvier
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Altitudinal Gradient ◽  
Cross Validation ◽  
Strong Relationship ◽  
Distribution Patterns ◽  
Common Species ◽  
Important Variable ◽  
Diatom Species ◽  
Expected Species Richness

Altitudinal gradients provide excellent opportunities to study relationships between species distribution and climatic variables. We studied the species composition of 39 samples of moss-inhabiting diatoms, collected at 50 m intervals from 100–650 m above sea level. The samples contained a total of 130 diatom species, of which 51 occurred in 10 or more samples. Altitude appeared to be the most important variable explaining variation in species composition. Of the 51 common species, 33 showed a significant relationship with altitude. Although the majority of the latter declined with increasing altitude, for nine species the probability of occurrence first increased with increasing elevation, but decreased again at higher altitudes, and four species increased systematically with elevation. As a result, expected species richness per sample decreased from an estimated 43 at 100 m to 25 species per sample at 650 m. Diatom distribution patterns proved to be suitable predictors of the altitudinal position of sample sites. Cross-validation yielded a strong relationship between predicted and observed altitudes.

scholarly journals New findings on protected and strictly protected species confirm the value of the prime hoverfly area network

2018 ◽  
pp. 63-71
Author(s):  
Marina Jankovic ◽  
Marija Milicic ◽  
Dimitrije Radisic ◽  
Dubravka Milic ◽  
Ante Vujic
Keyword(s):  
Protected Areas ◽  
Species Distribution ◽  
Species Distribution Models ◽  
Small Sample Size ◽  
Small Sample ◽  
Area Network ◽  
Distribution Models ◽  
Environmental Pressures ◽  
New Findings ◽  
Using Data

With environmental pressures on the rise, the establishment of pro?tected areas is a key strategy for preserving biodiversity. The fact that many species are losing their battle against extinction despite being within protected areas raises the question of their effectiveness. The aim of this study was to evaluate established Priority Hoverfly Areas (PHAs) and areas that are not yet but could potentially be included in the PHA network, using data from new field surveys. Additionally, species distribution models have been created for two new species recognized as important and added to the list of key hoverfly species. Maps of potential distribution of these species were superimposed on maps of protected areas and PHAs to quantify percentages of overlap. The results of this study are not statisti?cally significant, which could be influenced by a small sample size. However, the results of species distribution models and the extent of overlap with PHAs confirm the utility of these expert-generated designations.

scholarly journals BUSINESS STRATEGY AND INNOVATIVE PRACTICES ON SERVICES INDUSTRY IN INDONESIA SETTING

2010 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Achmad Hidayat Sutawidjaya
Keyword(s):  
Business Strategy ◽  
Theoretical Perspective ◽  
Organizational Factors ◽  
Strong Relationship ◽  
Strategic Orientation ◽  
Strategy Type ◽  
Strategic Orientations ◽  
Management Of Innovation ◽  
Services Industry ◽  
Using Data

This study explores how firms on services industry (cellular company) in indonesia setting with different strategic orientations manage innovative practices. Specifically, we examine differences in how firms with contrasting strategic orientations view the environmental and organizational factors that influence their management of innovation. This study contributes to the integration of the strategic management and innovation perspective by empirical examining how innovative practices vary among firms on services industry in indonesia setting with different strategic orientation, thereby achieving tighter integration between these two important theoretical perspective. In doing this research, we begin to address some important questions which are likely to be crucial interest to both scholars and practicing managers. This study proceeds as follows, we first established a foundation for our study by examining the literatures on strategy and innovation. We then develop hypotheses on relationship between a firm’s strategy type and its management of innovation (innovative practice, product innovation), external advantage, internal advantage. We the test hypotheses using data from 3 firms of cellular company (XL, Satelindo, Telkomsel) with sample 87 Manager randomly. A discussion of the empirical results and conclusion there is strong relationship between a firm’s strategy type and its management of innovation on services industry (cellular company) in indonesia setting

Newspaper Readership as a Determinant of Political Knowledge and Activity

1986 ◽  
Vol 7 (2) ◽  
pp. 47-54 ◽  
Author(s):  
Hampden H. Smith
Keyword(s):  
Social Class ◽  
Political Participation ◽  
Strong Relationship ◽  
Political Knowledge ◽  
National Election ◽  
Political News ◽  
Using Data ◽  
Different Levels

Using data from 1972, 1976 and 1980 national election surveys, the study supports previous research showing newspaper readership relates strongly to both political knowledge and activity. Although there is a strong relationship for newspaper readership, there is none for viewing political news on television. Finally, the strong relationship between newspaper readership and political participation remains at different levels of social class and education.

The Influence Of Facebook Marketing On Consumer Buying Intention Of Clothing: Evidence From Young Adults

2020 ◽  
Vol 8 (9) ◽  
pp. 37-51
Author(s):  
D. T. Kingsley Bernard ◽  
A. A. S. N. Munasinghe ◽  
I. K. R. J. Premarathne ◽  
S. Wijayarathne
Keyword(s):  
Social Media ◽  
Young Adults ◽  
Purchase Intention ◽  
Strong Relationship ◽  
Important Variable ◽  
Consumer Purchase Intention ◽  
Social Media Platforms ◽  
Comprehensive Survey ◽  
The Impact ◽  
Facebook Marketing

As a result of the rapid improvements paved through global advertising pathways, marketers have started to promote their products through social media platforms and among that; Facebook had become the most popular mode of communicating out of all. The study was conducted with the objective of comprehensively investigating the influence of Facebook marketing on consumer buying intention of clothing using evidence of young adults. Predominantly, the research focused upon identifying the superiority of Facebook as a social media communication platform and its relevant impact upon advertising. Majority of the businesses aims toward increasing the  reach, whereas Facebook users expect clear experience through Facebook rather than watching typical pop ups, web banners and adds. However,         Facebook marketing was identified to be positively and negatively influencing the companies and users. Therefore, focus was to analyze the impact to consumer’s buying intention from Facebook marketing. The companies can identify the effectiveness of the advertising and the improvement to be done. The study has undertaken a comprehensive survey to achieve the objectives of the research and those data was analyzed through component factor analysis, regression analysis and correlation coefficient. As per the results of the analysis, researchers have accomplished the stated objectives of the study. In conclusion, it was identified that there was a strong relationship between independent and dependent variables except E-WOM. Among that, Likes and sharing are the most important variables in Facebook marketing. According to outcomes, E- WOM was not an important variable, nonetheless researchers recommend focusing on E-WOM in order to convert this variable in to positive way to make better results, as previous researches stated that E-WOM can make massive impact to consumer purchase intention.  

Distribution, biomass and community structure of demersal fishes of the Gulf of Carpentaria, Australia

1994 ◽  
Vol 45 (3) ◽  
pp. 375 ◽  
Author(s):  
SJM Blaber ◽  
DT Brewer ◽  
AN Harris
Keyword(s):  
Community Structure ◽  
Abiotic Factors ◽  
Fish Fauna ◽  
Distribution Patterns ◽  
Demersal Fish ◽  
Fish Distribution ◽  
Sediment Type ◽  
Principal Coordinates Analysis ◽  
Main Site ◽  
Principal Coordinates

The demersal fish fauna of the Gulf of Carpentaria was surveyed during November and December 1990. Over 300 species from 85 families were caught by trawling a systematic grid of 107 stations. The absolute mean biomass was 124.8 kg ha-1 (s.e. =44.1) for day trawls and 53.7 kg ha-1 (s.e. =6.0) for night trawls. The overall mean catch rates were 421.3 kg h-1 (s.e. = 128.5) for day trawls and 198.6 kg h-1 (s.e. =21.5) for night trawls. Biomasses were twice as high in the prawn-trawling grounds of Albatross Bay, the south-eastern gulf and Groote Eylandt as they were elsewhere in the gulf. Twenty-five species made up 75% of the biomass; the dominant families were Haemulidae, Carangidae, Leiognathidae and Nemipteridae. Community-structure and distribution patterns were analysed by numerical classification techniques and principal-coordinates analysis. These indicated six main site groups and 15 fish community groups, based on fish species occurrences and biomasses. There was a relationship between fish distribution patterns and depth of water but not other abiotic factors recorded (sediment type, salinity, temperature and turbidity).

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