Diet, feeding behaviour and habitat utilisation of the blue stingray Dasyatis chrysonota (Smith, 1828) in South African waters

2003 ◽  
Vol 54 (8) ◽  
pp. 957 ◽  
Author(s):  
David A. Ebert ◽  
Paul D. Cowley
Keyword(s):  
Surf Zone ◽  
Stomach Contents ◽  
Size Class ◽  
Behaviour Pattern ◽  
Medium Size ◽  
Secondary Importance ◽  
Size Classes ◽  
Important Prey ◽  
Large Size ◽  
Large Size Class

Analysis of stomach contents for Dasyatis chrysonota revealed that diet varied with size and habitat. The diet of all size classes in the surf zone was comprised primarily of Callianassa spp., Donax spp. and unidentified polychaete species. The medium and large size classes fed primarily on Donax spp., whereas the very large size class fed mainly on Callianassa spp. Polychaetes were of secondary importance as prey for the medium size class. The diet of D. chrysonota in the nearshore zone consisted mainly of Balanoglossus capensis and Callianassa spp. Balanoglossus capensis decreased from an index of relative importance (IRI) of 75.3% for the medium size class to 59.9% for the very large size class, whereas Callianassa spp. increased from 22.8% to 39.4% between the medium and the very large size classes. The offshore zone was the only area in which small size class D. chrysonota were caught. The diet of these small D. chrysonota was primarily polychaetes and amphipods. Polychaetes increased in importance in the medium size class, but declined in each successively larger size class. Conversely, Pterygosquilla armata capensis became the single most important prey item for the very large size class, comprising an IRI of 50.9%. The behaviour pattern used by D. chrysonota to locate and extract prey is described.

Screening of F1 progeny for selection of superior hybrids in mulberry (Morus spp.) - A simple approach PART I: Screening of seedlings in relation to seed size

2017 ◽  
Vol 6 (2) ◽  
pp. 5256
Author(s):  
Daryoush Shafiei ◽  
Prof. Basavaiah*
Keyword(s):  
Seed Size ◽  
Seedling Survival ◽  
Size Class ◽  
Medium Size ◽  
Screening Process ◽  
Size Classes ◽  
Morus Spp ◽  
In The Beginning ◽  
Selection Of ◽  
Size Grading

In mulberry (Morus spp.), the process of selection of promising hybrids from F1 population requires the screening of a large number of progenies and a long period. To develop a simple and faster approach for screening, studies were conducted using F1 seeds of two crosses. The details of screening studies conducted in relation to seed-size and seedling-size are reported separately in two parts. In this part, the F1 seeds were size-graded as small, medium and large seeds; their progenies were raised separately and screened in nursery. There was a considerable degree of variation in size of seeds and medium-size class seeds were in high percentage in both the crosses. The length, width and weight of seeds were also varied between the seed size classes significantly in both the crosses. The seed size classes differ with high significance in shoot length and Root collar diameter and also differ significantly in root length and weight of seedlings. The positive correlation between the seed size and growth of seedlings, seed size and germination, seed size and seedling survival in nursery indicated that size-grading of seeds and rejection of small seeds in the beginning of screening process may help to increase the efficiency of screening by increasing the chances of getting superior hybrids from limited progenies. However, confirmation on the performance of large seedlings from small seed size class may help to draw conclusion. Hence, the studies are continued with size- grading of seedlings in the next part of screening study.

scholarly journals Large Size Class Teaching Strategies: An Overview

2017 ◽  
Vol 4 (1) ◽  
pp. 39-44
Author(s):  
Kawather M. Elsayed
Keyword(s):  
Teaching Strategies ◽  
Size Class ◽  
Large Size ◽  
Large Size Class

Feeding ecology of little tunny Euthynnus alletteratus in the central Mediterranean Sea

2007 ◽  
Vol 87 (4) ◽  
pp. 999-1005 ◽  
Author(s):  
Manuela Falautano ◽  
Luca Castriota ◽  
Maria Grazia Finoia ◽  
Franco Andaloro
Keyword(s):  
Mediterranean Sea ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Prey Abundance ◽  
Central Mediterranean ◽  
Size Classes ◽  
Larval Stages ◽  
Important Prey ◽  
Predator Size ◽  
Central Mediterranean Sea

The feeding habits of Euthynnus alletteratus and its variations compared to predator size in the central Mediterranean Sea were investigated. The stomach contents of 187 specimens were analysed, ranging from 26.8 to 50.3 cm total length, caught by authorized experimental drift-nets. The difference in food items found in the stomachs was evaluated by occurrence of prey frequency, prey weight, and prey abundance; these criteria were used to calculate an index of relative importance. Fish were the dominant food detected according to all numerical indicators examined and were mainly represented by Maurolicus muelleri and larval stages of teleosts. Hyperiid amphipods, dominated by Anchylomera blossevillei and Phrosina semilunata, were well represented in terms of frequency of occurrence. Variations in the diet composition compared to fish size were observed. Comparative analysis performed on prey abundance highlighted a trend of increasing predator size-classes among prey items. The specimens of the smallest sizes ate mainly adult clupeiforms and larvae or other juvenile teleosts. As fish grew, there were increased amounts of adult teleosts, crustaceans (hyperiids and isopods) and cephalopods. Maurolicus muelleri was the most important prey for the largest specimens analysed. Significant differences among size-classes, both in prey abundance and in prey weight, were confirmed by non-parametric multivariate analysis of variance (NP-MANOVA).

scholarly journals Estudio del polen de Phaseolus chiapasanus Piper (Leguminosae: Phaseolinae)

2017 ◽  
pp. 25
Author(s):  
Alfonso Delgado-Salinas ◽  
Enrique Martínez-Hernández ◽  
Pilar Fernández-Ortuño
Keyword(s):  
Pollen Grains ◽  
Size Class ◽  
Important Research ◽  
Large Size ◽  
Large Size Class ◽  
The Creation ◽  
Taxonomical Revision ◽  
Document Relationships ◽  
Genus Vigna

In the course of a taxonomical revision of the genus Phaseolus and considering the recently important research realized in the Phaseolus-Vigna complex, where the palynological attributes for the genus were precised, the present paper describes the pollen of Phaseolus chiapasanus Piper. The large-size class pollen grains of Ph. chiapasanus are tricolporate, brevicolpate, pseudo-operculate; semitectate, and widely reticulate. The structure of the infratectum could be considered of the granular-collumelar type. Some of the attributes found in the polen of Ph. Chiapasanus were not known for the genus, though such attributes are commonly found in the subgenus Sigmoidotropis of the genus Vigna. Ph. chiapasanus shows a series of morphological and palynological differences that open the possibility for the creation of a new section within the genus. More detailed studies will definitely by needed to better document relationships to other species of the genus.

scholarly journals CRECIMIENTO Y ASPECTOS TROFICOS DEL PEZ LEON ROJO PTEROIS VOLITANS (SCORPAENIFORMES: SCORPAENIDAE) EN EL PARQUE NACIONAL SISTEMA ARRECIFAL VERACRUZANO (PNSAV), VERACRUZ, MÉXICO

2020 ◽  
Vol 13 ◽  
Author(s):  
Mariajosé Xhail Amador-Núñez ◽  
Angel Morán-Silva
Keyword(s):  
Stomach Contents ◽  
Structure Type ◽  
Size Class ◽  
Trophic Dynamics ◽  
Small Fish ◽  
Pterois Volitans ◽  
Important Prey ◽  
Class 1 ◽  
Xiphopenaeus Kroyeri ◽  
And Control

<p>The lionfish <em>Pterois volitans</em>, is an predator in coral system, whose diet is composed of small fish and crustaceans, impacting species of ecological and commercial importance. <em>P. volitans</em> is an exotic species in the Gulf of Mexico with high colonization capacity. The present study describes its population structure, type of growth and trophic dynamics. 97 organisms of the PNSAV were obtained, 64 females (185±6,7 mm LP; 257,6±27,8 g) and 22 males (183±15,8 mm of LP; 273,5±62,6 g). Whit the Battacharya model, four size classes were obtained for females (15,3; 25,3; 28,2, and 31,8 cm) and six for males (9,87; 17,95; 22,95; 26,95; 30,95 and 33,95), being the size class 1 for both sexes the most abundant. The length-weight relationship was of the potential type (r<sup>2</sup>=0,9643, b=3,1574 females, and r<sup>2</sup>=0,9843 and b=3,1089 males), and growth of allometric type for both sexes. The growth model that best adjusted to the data was that of Gompertz, (L<sub>∞</sub>=324 mm, k=0,99, t<sub>0</sub>=0,694 females and L<sub>00</sub>=379,4, k=0,468, t<sub>0</sub>=0,719 males). The families of fish identified in the stomach contents were Ophididae, Serranidae, Haemulidae, Pomacentridae, Beloniidae, Achiridae, and crustaceans Portunidae, Penaeidae, Squillida<em>e</em> and Diogenidae. Being <em>Haemulon aurolineatum</em> (Haemulidae) and <em>Xiphopenaeus kroyeri</em> (Penaeidae) the most important prey. The presence of lionfish in the PNSAV is recent, so the information presented in this research will allow us to understand its population dynamics and its adaptation to the PNSAV, contributing to its management and control.</p>

scholarly journals Quantification of Tremolite in Friable Material Coming from Calabrian Ophiolitic Deposits by Infrared Spectroscopy

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Antonella Campopiano ◽  
Angelo Olori ◽  
Annapaola Cannizzaro ◽  
Antonino Iannò ◽  
Pietro Paolo Capone
Keyword(s):  
Infrared Spectroscopy ◽  
Quantitative Analysis ◽  
Absorption Band ◽  
Size Class ◽  
Medium Size ◽  
Friable Material ◽  
Large Size ◽  
Mineral Silicates ◽  
Ir Bands ◽  
Absorbance Band

The aim of this study is to identify the infrared absorption band suitable for quantifying tremolite in three powdered samples (fine, medium, and large size classes) coming from a quarry of ophiolitic friable rocks in the western part of the Calabria region of Italy. Three IR bands were considered: OH stretching band between 3700 and 3650 cm−1, the stretching bands of the Si-O-Si linkage between 1200 and 900 cm−1, and the absorbance band at 756 cm−1attributable to tremolite. The amount of tremolite in the test samples was quantified by using the curve parameters of the three analytical bands. The quantitative analysis of tremolite using the band due to OH stretchings (3700–3650 cm−1) and the bands attributed to the Si-O-Si stretchings (1200–900 cm−1) showed high values for all test samples. Their use overestimated the tremolite amount because both bands were affected at the interfering mineral silicates such as talc, kaolinite, chlorite, and serpentinites. The abundant presence of antigorite in studied samples mainly in medium size class sample had a key role in our findings. The band at 756 cm−1was not affected at the interfering minerals and can be used for quantitative analysis of tremolite in sample coming from ophiolitic deposits.

scholarly journals Feeding ecology of invasive Perccottus glenii (Perciformes, Odontobutidae) in Slovakia

2008 ◽  
Vol 53 (No. 11) ◽  
pp. 479-486 ◽  
Author(s):  
J. Koščo ◽  
P. Manko ◽  
D. Miklisová ◽  
L. Košuthová
Keyword(s):  
Feeding Ecology ◽  
Diet Composition ◽  
Stomach Contents ◽  
Size Class ◽  
Perccottus Glenii ◽  
Class Groups ◽  
Size Classes ◽  
Lower Size

Stomach contents of 331 specimens of <I>Perccottus glenii (Perciformes: Odontobutidae</I>) were analysed. Chironomids and ephemeropterans dominated the diet of all size classes of fish; however, the frequency of crustaceans was also high. Micro-crustaceans (ostracods, copepods and cladocerans) dominated in lower size classes (20–39 mm); macro-crustaceans <I>(Isopoda, Amphipoda</I>) dominated in higher size classes (up to 79 mm). The proportion of crustaceans decreased from the size class 80–89 mm. With the increasing size of fish the frequency of molluscs (<I>Gastropoda</I>) increased, the maximum was in size class 70–79 mm. Cannibalism occurred from 60 mm, and it was significant from 80 mm. The highly mobile invertebrates (<I>Coleoptera, Heteroptera</I>) were found in the largest size classes. In middle size classes (40–59 mm), the widest spectrum of prey units was documented; the food variability of small (90 mm) individuals was poor. Differences in the diet composition of small individuals were negligible; the diet of the largest ones differed significantly. According to diet, two feeding size class groups were recognised: the first

scholarly journals An external tag for fish: tagging effects in different fish size classes and its influence on growth performance and hematology of Lophiosilurus alexandri (Siluriformes: Pseudopimelodidae)

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Túlio P. Boaventura ◽  
Viviane S. B. Gil ◽  
Camila S. B. Gil ◽  
Anderson M. Peres ◽  
Ronald K. Luz
Keyword(s):  
Growth Performance ◽  
Retention Rate ◽  
Hematological Parameters ◽  
Size Classes ◽  
Tag Retention ◽  
Large Size ◽  
Large Size Class ◽  
Survival And Growth ◽  
Hematology Parameters ◽  
Animal Size

ABSTRACT This study tested an external tag for juveniles of Lophiosilurus alexandri and measured the effects of tagging in different size classes of fishes. Experiment 1 evaluated the retention rate and influence of the tag on survival and growth of three hundred fishes divided Small, Medium and Large size classes. After 90 days of experiment the fishes had 100% survival and the tag had a higher retention rate for animals of the Large size class. Experiment 2 evaluated the tag’s influence on hematology parameters of forty-two fishes at 5, 10 and 30 days post-tagging. In this experiment both tagged and untagged animals experienced 9.4% mortality. The hematocrit was higher on the 30th day for tagged animals than for untagged animals. No difference was observed for leukocytes, plasma protein, erythrocytes and mean corpuscular volume. It was concluded from Experiment 1 that the tag reduced growth performance when applied to small sized juvenile L. alexandri, and that the tag retention rate increased with increasing animal size. Among the hematological parameters studied for juveniles on the Experiment 2 the tag only influenced the hematocrit parameters, which shows that the tag can be used without considerable influence on the hematological parameters of juvenile L. alexandri.

Size dominance regulates tree spacing more than competition within height classes in tropical Cameroon

2010 ◽  
Vol 27 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Stephan Getzin ◽  
Martin Worbes ◽  
Thorsten Wiegand ◽  
Kerstin Wiegand
Keyword(s):  
Plant Growth ◽  
Secondary Forest ◽  
Random Pattern ◽  
Minor Importance ◽  
Competitive Effects ◽  
Size Classes ◽  
Large Size ◽  
Weak Evidence ◽  
Large Size Class ◽  
And Performance

Abstract:Does competition prevail in large size classes of trees in tropical forests? This question is fundamental to our understanding of the demography and dynamics occurring in rain forests. We investigated this question based on an undisturbed late-secondary forest on a 1-ha plot in central Cameroon. Trees were stem-mapped and classified into three size classes: understorey, midstorey and overstorey. The diameter at breast height and yearly biomass increment were determined as measures of plant growth and performance. Spatial statistics such as pair- and mark-correlation functions were used to detect scale-dependent patterns that could be caused by competition within and between the three size classes. The results revealed a random pattern and spatially uncorrelated measures of plant growth of overstorey trees. This suggests that competitive effects are of minor importance in the large size class of overstorey trees. Likewise, only weak evidence for competition between trees was found within the two lower size classes. However, negative distance correlations were found between the different size classes. We suggest that competition within height classes was relatively low due to the diversity of species with their variable niche differentiations and phenotypic plasticity that may compensate for competitive effects.

scholarly journals SPATIAL VARIATION IN POPULATION CHARACTERISTICS OF VENUS CLAM GAFRARIUM TUMIDUM RÖDING, 1798 (BIVALVIA: VENERIDAE) IN AMBON BAY, MALUKU

2018 ◽  
Vol 43 (2) ◽  
pp. 63-70
Author(s):  
Muhammad Masrur Islami ◽  
Dietriech Geoffrey Bengen ◽  
Safar Dody
Keyword(s):  
Spatial Distribution ◽  
Spatial Variation ◽  
Size Class ◽  
Population Characteristics ◽  
Medium Size ◽  
Shell Width ◽  
Discriminating Power ◽  
Large Size ◽  
Different Populations ◽  
Potential Factors

Ambon Bay consists of two regions i.e. Inner and Outer Ambon Bay that was separated by Galala-Poka sill. Consequently these waters have different local environmental conditions that leads to the bivalve populations differences, one of them is venus clam Gafrarium tumidum. In this study, the distribution and spatial variation in population characteristics of of venus clam was quantified based on the analysis of their twelve shell dimensions from different populations. Fieldwork and analyses were conducted on April – Juni 2013. Total of 585 individuals of venus clam were found and could be divided into ten size-classes and three size categories i.e. small (< 23.11 mm), medium (23.12–32.05 mm) and large size (> 32.06 mm). The highest size-class density was found at medium size. Spatial distribution was related to the characteristics of sediment and other potential factors. Result of discriminant analysis showed that shell-width (SW) was the variable with the highest discriminating power and distinguishing between Inner and Outer Ambon Bay populations.

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