scholarly journals Back-Calculation of Fish Size in Diet Analysis of Piscivorous Predators: A New Index for the Alien Silurus glanis

2021 ◽  
Vol 13 (8) ◽  
pp. 4322
Author(s):  
Renato Bacchetta ◽  
Andrea Marotta ◽  
Alessandro Nessi ◽  
Paolo Tremolada
Keyword(s):  
Diet Analysis ◽  
Native Range ◽  
Top Predator ◽  
Silurus Glanis ◽  
K Index ◽  
Caudal Vertebrae ◽  
Back Calculation ◽  
Control Capability ◽  
The Mean ◽  
Bone Remains

The wels catfish Silurus glanis has been constantly spreading in many European basins, outside its native range. Being a voracious predator, it is considered to have a severe impact on local fish communities. In the Ticino River (Northern Italy), bones of S. glanis were found in feces from the top predator Lutra lutra. To estimate the control capability of L. lutra for this species and to back-calculate S. glanis’ size from its bone remains, whole skeletons from 27 differently sized S. glanis specimens were analyzed. A double pharyngeal element and all caudal vertebrae emerged as significant items for species identification. The mean length of the pharyngeal element was directly related to fish mass, while for vertebrae, a K-index was proposed to identify the position of each vertebra along the spine and, from this, to calculate the original fish mass. This methodology allowed us to establish that the length of the preyed S. glanis was 85–435 mm, and the ages were between 0+ and 2+ years. The proposed methodology opens new perspectives for more detailed studies on the efficiency of predation by piscivorous species on allochthonous ones.

scholarly journals First data on habitat preference, diet and length-weight relationship of Gobius incognitus Kovačić & Šanda, 2016 (Pisces: Gobiidae)

2020 ◽  
Vol 61 (1) ◽  
pp. 67-78
Author(s):  
Francesco Tiralongo ◽  
Giuseppina Messina ◽  
Bianca Maria Lombardo
Keyword(s):  
Habitat Preference ◽  
Diet Analysis ◽  
Ionian Sea ◽  
Central Mediterranean ◽  
Species Identity ◽  
Weight Relationship ◽  
Important Prey ◽  
Ecological Aspects ◽  
The Mean ◽  
Relationship Of

In this work, we present first data on biological and ecological aspects of Gobius incognitus from specimens from the Ionian Sea (central Mediterranean Sea). In particular, we provided first data on habitat preference, diet and length-weight relationship of G. incognitus on material with confirmed species identity. The species preferred “mixed bottom” (sand and rocks), where it reached relatively high abundances. The diet analysis showed that G. incognitus is a generalist and opportunistic feeder. However, small benthic crustaceans were the most important prey group. The mean total length of specimens was 6.72 ± 1.85 cm and the growth was positive allometric.

Study on Correction Method of Subgrade Modulus Based on FWD

2013 ◽  
Vol 579-580 ◽  
pp. 862-865
Author(s):  
Xiao Hua Luo ◽  
Qing Yang ◽  
Xin Qiu
Keyword(s):  
Resilient Modulus ◽  
Implementation Process ◽  
Correction Method ◽  
Deformation Analysis ◽  
Test Results ◽  
Moisture Condition ◽  
Back Calculation ◽  
The Mean ◽  
Subgrade Modulus ◽  
New Perspective

In order to calibrate subgrade back calculation modulus, the correction method of subgrade back calculation modulus was put forward based on theoretical analysis and indoor/outdoor experiments, and the detailed implementation process was analyzed combined the latest results of subgrade dynamic modulus and subgrade moisture forecast. The results show that the equivalent resilient modulus of subgrade simultaneously consider subgrade material moisture condition and stress dependency and the forecast equation has higher correlation. The ratio of the loading plate test results to the predicted results ranges from 0.25 to 0.4 and the mean is 0.32, which conforms to the requirements of AASHTO normal value. Utilizing the scale factor 0.65 to calibrate subgrade back calculation modulus is viable and validated. The results provides a new perspective and approach for deformation analysis of subgrade structure. As well, the established method makes up the defect that can't reflect the effect of moisture and stress on equivalent resilient modulus of subgrade.

Elemental Composition of Bone from White Sucker (Catostomus commersoni) in Relation to Lake Acidification

1982 ◽  
Vol 39 (9) ◽  
pp. 1289-1296 ◽  
Author(s):  
Grant A. Fraser ◽  
Harold H. Harvey
Keyword(s):  
Elemental Composition ◽  
Calcium Content ◽  
Lake Acidification ◽  
White Sucker ◽  
Catostomus Commersoni ◽  
Bone Demineralization ◽  
Acid Lakes ◽  
South Central ◽  
Caudal Vertebrae ◽  
The Mean

Bone was decalcified in fish from three acid lakes and manganese was increased greatly in bone of fish from the most acid lake. The mean centrum calcium content of white suckers (Catostomus commersoni) captured in George Lake (pH 4.65) was 16% lower than in white suckers from three lakes with near-neutral pH levels. In two other acid lakes, King (pH 5.08) and Crosson (pH 5.36), centrum calcium was reduced significantly in white suckers. Centrum manganese was elevated fivefold in white sucker from recently acidified George Lake, and tended to be elevated in this species from King Lake. White suckers from George Lake exhibited shorter caudal vertebrae and some of these fish had deformed caudal fins. These anomalies may be indicative of bone demineralization. All of the study lakes were located in south-central Ontario, including the La Cloche Mountains, North Bay, Algonquin, Haliburton, and Muskoka.Key words: lake acidification, bone composition, calcium, manganese, white sucker

How Reliable are Growth Back-Calculations Based on Otoliths?

1990 ◽  
Vol 47 (11) ◽  
pp. 2219-2227 ◽  
Author(s):  
Steven E. Campana
Keyword(s):  
Somatic Growth ◽  
Growth Effect ◽  
Fish Otolith ◽  
Stochastic Error ◽  
Individual Fish ◽  
Back Calculation ◽  
The Mean ◽  
The Individual ◽  
The Relationship ◽  
Slow Growing

Growth back-calculations from otoliths assume that the relationship between fish and otolith length is linear through time. The final (or observed) individual fish-otolith ratios are then combined to prepare a fish-otolith regression for the population, upon which the subsequent back-calculations are based. However, recent studies have demonstrated that the fish:otolith size ratio varies systematically with somatic growth rate, resulting in relatively large otoliths in slow-growing fish. Such a growth effect will result in a fitted fish-otolith regression which differs significantly from that of the mean of the individual fish-otolith slopes. Fraser–Lee growth back-calculations made from such a regression consistently underestimate previous lengths at age. The bias may explain the apparent ubiquity of Lee's phenomenon. Back-calculation bias was eliminated through use of an algorithm defining individual fish-otolith trajectories and a biologically determined, rather than a statistically estimated, intercept. Adaptations of the biological intercept back-calculations procedure accurately predicted previous lengths in the presence of both stochastic error and time-varying growth rates. When used to reevaluate some published back-calculations, the biological intercept procedure resulted in more accurate values than those previously estimated, and reduced or eliminated the presence of Lee's phenomenon.

scholarly journals Incipient resistance to an effective pesticide results from genetic adaptation and the canalization of gene expression

2019 ◽  
Author(s):  
Xiaoshen Yin ◽  
Alexander S. Martinez ◽  
Abigail Perkins ◽  
Morgan M. Sparks ◽  
Avril M. Harder ◽  
...  
Keyword(s):  
Gene Expression ◽  
Oxidative Phosphorylation ◽  
Large Scale ◽  
Pest Species ◽  
Native Range ◽  
Societal Costs ◽  
History Of ◽  
Uncoupling Of Oxidative Phosphorylation ◽  
The Mean ◽  
Subunit B

AbstractThe resistance of bacteria, disease vectors, and pest species to chemical controls has vast ecological, economic, and societal costs. In most cases, resistance is only detected after spreading throughout an entire population. Detecting resistance in its incipient stages, by comparison, provides time to implement preventative strategies. Incipient resistance can be detected by coupling standard toxicology assays with large-scale gene expression experiments. We apply this approach to a system where an invasive parasite, sea lamprey (Petromyzon marinus), has been treated with the highly-effective pesticide 3-trifluoromethyl-4-nitrophenol (TFM) for 60 years. Toxicological experiments revealed that lamprey from treated populations did not have higher survival to TFM exposure than lamprey from their native range, demonstrating that full-fledged resistance has not yet evolved. In contrast, we find hundreds of genes differentially expressed in response to TFM in the population with the longest history of exposure, many of which relate to TFM’s primary mode of action, the uncoupling of oxidative phosphorylation and subsequent depletion of ATP. Three genes critical to oxidative phosphorylation, ATP5PB, PLCB1, and NDUFA9, were nearly fixed for alternative alleles in comparisons of SNPs between native and treated populations (FST > 5 SD from the mean). ATP5PB encodes subunit b of ATP synthase and an additional subunit, ATP5F1B, was canalized for high expression in treated populations, but remained plastic in response to TFM treatment in individuals from the native range. These combined genomic and transcriptomic results demonstrate that an adaptive, genetic response to TFM is driving incipient resistance in a damaging pest species.

scholarly journals Diet of European Catfish in a Newly Invaded Region

Fishes ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 58
Author(s):  
Marco Ferreira ◽  
João Gago ◽  
Filipe Ribeiro
Keyword(s):  
Dietary Habits ◽  
Stomach Contents ◽  
Biodiversity Loss ◽  
Freshwater Ecosystems ◽  
Top Predator ◽  
Silurus Glanis ◽  
Lotic Environment ◽  
European Catfish ◽  
Prey Items ◽  
Lentic Systems

Biological invasions are considered to be one of the leading causes of biodiversity loss worldwide. Freshwater ecosystems are amongst the most biodiverse, containing about 50% of the world’s known fish species but, ironically, are the most invaded ecosystems. In Portuguese freshwaters, there are currently 20 identified non-native fishes, arriving at an unprecedented rate of a new species every two years. A recent non-native is the European catfish Silurus glanis, a top predator native to Central and Eastern Europe, that arrived at the Lower Tagus (Portugal) circa 2006. This study compares the dietary habits of this top predator in two different habitats of the Lower Tagus in order to evaluate its potential impact. The stomach contents of 96 individuals were analyzed, 61 from the lotic environment and 35 from the lentic systems. A total of 66 stomachs contained prey items, 38 from the lotic and 28 from the lentic. Diet varied considerably between habitats, with shrimp and crayfish being the most abundant prey items in the lentic systems and shrimp and fish the most abundant prey items in the lotic section. Tendency to piscivory was observed in large-sized individuals. Overall, the findings in this study provide the first evidence of the potential impacts of European catfish through predation on the fish communities.

Survival feeding of pregnant and lactating ewes with combinations of wheat and lucerne hay

1979 ◽  
Vol 19 (99) ◽  
pp. 419
Author(s):  
BW Clements ◽  
AR Gleeson ◽  
PJ Nicholls
Keyword(s):  
Milk Yield ◽  
Energy Levels ◽  
Diet Analysis ◽  
Net Energy ◽  
Growth And Survival ◽  
Drought Conditions ◽  
The Mean ◽  
Net Energy Intake ◽  
Dietary Treatments ◽  
Lamb Growth

An experiment was performed to determine the proportion of roughage required by pregnant and lactating ewes fed wheat-based diets under drought conditions. Five dietary treatments ranging from wheat alone to lucerne hay alone were fed to pregnant and lactating Merino ewes, at levels estimated to give a similar net energy intake per ewe per day. The energy levels fed were altered during the experiment in an attempt to maintain ewe liveweight at a constant level. Wheat alone was unsuitable for lactating ewes, while a diet of 54% hay and 46% wheat (54:46) gave the best milk yields, lamb growth and lamb survival. The mean milk yields of the ewes ranged from 26.5 � (SD) 2.5 ml hour-1 for wheat alone to 38.1 � 2.2 ml hour-1 for the 54:46 diet. Lamb liveweight gains between birth and weaning (at seven weeks) were related to ewe milk yields, with lambs on the wheat alone diet gaining 3.17 kg and those on the 54:46 diet gaining 5.10 kg. Only half of the lambs born to ewes fed wheat alone survived to weaning, compared with 89% of lambs on the 54:46 diet. Analysis of the responses indicated that, for milk yield, the 54:46 diet was near optimum and that lamb growth and survival would be maximized at 60-67% hay.

scholarly journals Thirty-Year-Old Paradigm about Unpalatable Perch Egg Strands Disclaimed by the Freshwater Top-Predator, the European Catfish (Silurus glanis)

PLoS ONE ◽  
2017 ◽  
Vol 12 (1) ◽  
pp. e0169000 ◽  
Author(s):  
Lukáš Vejřík ◽  
Ivana Vejříková ◽  
Luboš Kočvara ◽  
Zuzana Sajdlová ◽  
Son Chung Hoang The ◽  
...  
Keyword(s):  
Top Predator ◽  
Silurus Glanis ◽  
European Catfish

Morphology of the brown tree snake, Boiga irregularis, with a comparison of native and extralimital populations

2000 ◽  
Vol 48 (4) ◽  
pp. 357 ◽  
Author(s):  
Joan Whittier ◽  
Conrad Macrokanis ◽  
Robert T. Mason
Keyword(s):  
Solomon Islands ◽  
Natural Populations ◽  
Single Species ◽  
Morphological Characters ◽  
Nonparametric Analysis ◽  
Native Range ◽  
Boiga Irregularis ◽  
Brown Tree Snake ◽  
The Mean ◽  
Brown Tree Snakes

We conducted an analysis of the morphology of specimens of the brown tree snake, Boiga irregularis, from the native range of eastern and northern Australia, Papua New Guinea and the Solomon Islands. First, a cluster analysis was conducted to determine natural groupings in the data; however, no groupings based on morphological characters were found. Then the importance of additional factors such as geographical groupings and coloration was analysed in a nonparametric analysis of variance. Significant differences were found in the mean rankings of key characters such as dorsal mid-body, ventral and subcaudal scale counts. However, the amount of variation and the degree of overlap among populations and groupings precluded separating animals on the basis of these features. Our data support the recognition of a single species with two subspecies based on colour variation. We also compared the morphology of a sample of brown tree snakes from an extralimital population on Guam to that of this species in the areas of the native range. Our data supported suggestions of alliances of the Guam population with northern Papuan populations. However, the Guam population of the brown tree snake was found to be less variable than were localised natural populations. Morphologically, the Guam population is distinctive, suggesting that it has undergone significant morphological change since its introduction.

INCREASE IN SEED PRODUCTION FROM NITROGEN FERTILIZATION OF NATIVE BEARDLESS WHEATGRASS

1962 ◽  
Vol 42 (2) ◽  
pp. 359-364
Author(s):  
J. E. Miltimore ◽  
J. L. Mason ◽  
C. B. W. Rogers
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Nitrogen Fertilization ◽  
Mean Annual Precipitation ◽  
Native Range ◽  
Maximum Increase ◽  
Acre Yield ◽  
The Mean ◽  
Preferred Species ◽  
Nitrogen Treatments

Nitrogen fertilization greatly increased pure seed yield of native beardless wheatgrass, Agropyron inerme, where the mean annual precipitation was 11 inches in the South Okanagan area of British Columbia. In one experiment in 1959, ammonium nitrate broadcast at 450 pounds of actual nitrogen per acre increased seed yield from 3.5 pounds per acre for the unfertilized plots to 17.5 pounds, a maximum increase of 400 per cent. One hundred and fifty pounds of actual nitrogen per acre increased seed yield 330 per cent and the 50-pound rate increased the yield of seed 140 per cent. At two other locations in 1961, unfertilized plots yielded 18.8 pounds of seed per acre; 150 pounds of actual nitrogen per acre increased seed yield to 59.2 pounds and the 50-pound treatment produced 46.5 pounds of seed per acre. Yield increases resulted from increases in spike production because weight of seed per spike was not increased by fertilization. Germination was not affected and per cent pure seed was slightly increased by the nitrogen treatments. This increase in seed production is considered favorable for the restoration of preferred species on depleted native range.

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