scholarly journals Species–specific crab predation on the hydrozoan clinging jellyfish Gonionemus sp. (Cnidaria, Hydrozoa), subsequent crab mortality, and possible ecological consequences

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3966 ◽  
Author(s):  
Mary R. Carman ◽  
David W. Grunden ◽  
Annette F. Govindarajan
Keyword(s):  
Resource Use ◽  
Callinectes Sapidus ◽  
Trophic Interaction ◽  
Green Crab ◽  
Spider Crab ◽  
Crab Species ◽  
Negative Effect ◽  
Species Specific ◽  
Crab Predation ◽  
Density Treatment

Here we report a unique trophic interaction between the cryptogenic and sometimes highly toxic hydrozoan clinging jellyfish Gonionemus sp. and the spider crab Libinia dubia. We assessed species–specific predation on the Gonionemus medusae by crabs found in eelgrass meadows in Massachusetts, USA. The native spider crab species L. dubia consumed Gonionemus medusae, often enthusiastically, but the invasive green crab Carcinus maenus avoided consumption in all trials. One out of two blue crabs (Callinectes sapidus) also consumed Gonionemus, but this species was too rare in our study system to evaluate further. Libinia crabs could consume up to 30 jellyfish, which was the maximum jellyfish density treatment in our experiments, over a 24-hour period. Gonionemus consumption was associated with Libinia mortality. Spider crab mortality increased with Gonionemus consumption, and 100% of spider crabs tested died within 24 h of consuming jellyfish in our maximum jellyfish density containers. As the numbers of Gonionemus medusae used in our experiments likely underestimate the number of medusae that could be encountered by spider crabs over a 24-hour period in the field, we expect that Gonionemus may be having a negative effect on natural Libinia populations. Furthermore, given that Libinia overlaps in habitat and resource use with Carcinus, which avoids Gonionemus consumption, Carcinus populations could be indirectly benefiting from this unusual crab–jellyfish trophic relationship.

Population dynamics of three brachyuran crab species (Decapoda) in Icelandic waters: impact of recent colonization of the Atlantic rock crab (Cancer irroratus)

2020 ◽  
Author(s):  
Sindri Gíslason ◽  
Snæbjörn Pálsson ◽  
Jónas P Jónasson ◽  
Hermann Dreki Guls ◽  
Jörundur Svavarsson ◽  
...  
Keyword(s):  
Native Species ◽  
Carcinus Maenas ◽  
Green Crab ◽  
Spider Crab ◽  
Crab Species ◽  
Brachyuran Crab ◽  
Cancer Irroratus ◽  
Rock Crab ◽  
Average Size ◽  
Icelandic Waters

Abstract The Atlantic rock crab (Cancer irroratus) was first found in Icelandic waters in 2006. Since then, the species has dispersed rapidly and is currently found clockwise from the southwest coast of Iceland to the east, corresponding to >70% of the coastline. Here, we present a monitoring study on this non-indigenous crab species in Iceland from 2007 to 2019. The study shows that the rock crab is now the most abundant brachyuran crab species on soft substrate bottoms in Southwest Iceland, both as adults and planktonic larvae, indicating that it is outcompeting its rival native species, the European green crab (Carcinus maenas) and the spider crab (Hyas araneus). The average size of the rock crab was similar over time (2007–2019), although it fluctuated between years in a pattern similar to that for the green crab, while significant reduction in size was observed for male spider crabs. The rock crab population is still in a growth phase in Icelandic waters, as seen in increasing distributional range, and can be found in densities comparable to the highest reported for the species in its native range in North America.

scholarly journals Enhancing the Quality of Two Species of Baby Leaves Sprayed with Moringa Leaf Extract as Biostimulant

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1399
Author(s):  
Stefania Toscano ◽  
Antonio Ferrante ◽  
Ferdinando Branca ◽  
Daniela Romano
Keyword(s):  
Leaf Extract ◽  
Foliar Application ◽  
Sugar Content ◽  
Nitrate Content ◽  
Specific Response ◽  
Yield And Quality ◽  
Negative Effect ◽  
Species Specific ◽  
Moringa Oleifera Lam

Natural biostimulants obtained by plants are intensively used nowadays to improve crop yield and quality. The current study aimed to evaluate the effects of leaf extract of moringa (Moringa oleifera Lam.) (MLE) in modifying baby leaf characteristics of two genotypes of Brassica. The trial was started in October 2020 in a greenhouse; a cultivar of kale ‘Cavolo Laciniato Nero di Toscana’ (CL) and a Sicilian landrace of sprouting broccoli ‘Broccoli Nero’ (BN) were used. The plants, after 15, 30 and 40 days from sowing, were treated with MLE, while the control plants (C) with distilled water. Treatment with MLE modified morphological and nutritional value, but with different behavior in the two genotypes. In fact, in BN the treatment reduced the antioxidant activity (2.2-diphenyl-1-picrylhydrazyl (DPPH)) by 54%, while in CL the treatment increased this parameter by 40%. For the phenolic concentration and the sugar content the values recorded were significantly increased by MLE compared to control plants in CL, where in BN a significant reduction was registered. The CL plants treated with MLE showed a significant reduction (−70%) in nitrate content compared to the control plants; a negative effect was, instead, observed in BN, where the plants treated with moringa showed an increase of 60%. Results of this study showed how the foliar application of MLE was effective in improving various nutraceutical parameters, in particular in kale, because it appears to be a species-specific response.

scholarly journals Species-Specific Traits Rather Than Resource Partitioning Mediate Diversity Effects on Resource Use

PLoS ONE ◽  
2009 ◽  
Vol 4 (10) ◽  
pp. e7423 ◽  
Author(s):  
Jasmin A. Godbold ◽  
Rutger Rosenberg ◽  
Martin Solan
Keyword(s):  
Resource Use ◽  
Resource Partitioning ◽  
Species Specific ◽  
Diversity Effects

A comparison of the gill physiology of two euryhaline crab species, Callinectes sapidus and Callinectes similis: energy production, transport-related enzymes and osmoregulation as a function of acclimation salinity

1995 ◽  
Vol 198 (2) ◽  
pp. 349-358 ◽  
Author(s):  
S Piller ◽  
R Henry ◽  
J Doeller ◽  
D Kraus
Keyword(s):  
Oxygen Consumption ◽  
Energy Production ◽  
Consumption Rate ◽  
Callinectes Sapidus ◽  
Crab Species ◽  
Ion Concentrations ◽  
Low Salinity ◽  
Consumption Rates ◽  
Cytochrome Content ◽  
Mitochondrial Cytochromes

Callinectes sapidus and C. similis co-occur in estuarine waters above 15 salinity. Callinectes sapidus also inhabits more dilute waters, but C. similis is rarely found below 15 . Previous work suggests that C. sapidus may be a better hyperosmoregulator than C. similis. In this study, energy metabolism and the levels of transport-related enzymes in excised gills were used as indicators of adaptation to low salinity. Oxygen consumption rates and mitochondrial cytochrome content of excised gills increased in both species as acclimation salinity decreased, but to a significantly greater extent in C. similis gills. In addition, C. similis gills showed the same levels of carbonic anhydrase and Na+/K+-ATPase activities and the same degree of enzyme induction during low-salinity adaptation as has been reported for C. sapidus gills. However, hemolymph osmolality and ion concentrations were consistently lower in C. similis at low salinity than in C. sapidus. Therefore, although gills from low-salinity-acclimated C. similis have a higher oxygen consumption rate and more mitochondrial cytochromes than C. sapidus gills and the same level of transport-related enzymes, C. similis cannot homeostatically regulate their hemolymph to the same extent as C. sapidus.

Effects of weed and erosion control on communities of soil mites (Oribatida and Gamasina) in short-rotation willow plantings in central New York

2008 ◽  
Vol 38 (5) ◽  
pp. 1061-1070 ◽  
Author(s):  
Maria A. Minor ◽  
Roy A. Norton
Keyword(s):  
New York ◽  
Species Richness ◽  
Community Structure ◽  
Cover Crop ◽  
Soil Microflora ◽  
Winter Rye ◽  
Soil Mites ◽  
Short Rotation ◽  
Negative Effect ◽  
Species Specific

Several pre-emergent herbicides (azafenidin, oxyfluorfen, and imazaquin–pendimethalin mixture), used for weed control during the establishment of short-rotation willow plantings, were tested for their impact on population density, species richness, and community structure of predaceous (Gamasina) and saprophagous and (or) mycophagous (Oribatida) soil mites. The experimental control was hand-weeded (no herbicide). Two site preparation treatments were used: conventional (disked) and erosion controlled (no-till with cover crop of winter rye). The influence of herbicide application on non-target organisms (soil mites) cannot be generalized, with groups being differentially affected. Overall, Oribatida were most affected by herbicides. Among specific herbicides, azafenidin and oxyfluorfen had a negative effect on density and species richness of soil mites. The response of Oribatida and Gamasina to herbicides was species-specific. Two species of Oribatida ( Sellnickochthonius immaculatus (Forsslund) and Liochthonius lapponicus (Trägårdh)) declined significantly in all herbicide-treated plots. The cover crop residue had positive effect on both Oribatida and Gamasina; the negative effect of herbicides on Oribatida was greatly mitigated by cover crop. Herbicides appear to reduce mite diversity and alter community structure, but they do not always affect abundance. We speculate that the sensitivity of Oribatida to herbicides can reflect the indirect impacts of herbicides on soil microflora.

scholarly journals Single and Multiple Visual Systems in Arthropods

1968 ◽  
Vol 51 (2) ◽  
pp. 125-156 ◽  
Author(s):  
George Wald
Keyword(s):  
Spectral Sensitivity ◽  
Visual Pigment ◽  
Light Adaptation ◽  
Procambarus Clarkii ◽  
Color Discrimination ◽  
Visual Pigments ◽  
Green Crab ◽  
Spider Crab ◽  
Color Adaptation ◽  
Visual Systems

Extraction of two visual pigments from crayfish eyes prompted an electrophysiological examination of the role of visual pigments in the compound eyes of six arthropods. The intact animals were used; in crayfishes isolated eyestalks also. Thresholds were measured in terms of the absolute or relative numbers of photons per flash at various wavelengths needed to evoke a constant amplitude of electroretinogram, usually 50 µv. Two species of crayfish, as well as the green crab, possess blue- and red-sensitive receptors apparently arranged for color discrimination. In the northern crayfish, Orconectes virilis, the spectral sensitivity of the dark-adapted eye is maximal at about 550 mµ, and on adaptation to bright red or blue lights breaks into two functions with λmax respectively at about 435 and 565 mµ, apparently emanating from different receptors. The swamp crayfish, Procambarus clarkii, displays a maximum sensitivity when dark-adapted at about 570 mµ, that breaks on color adaptation into blue- and red-sensitive functions with λmax about 450 and 575 mµ, again involving different receptors. Similarly the green crab, Carcinides maenas, presents a dark-adapted sensitivity maximal at about 510 mµ that divides on color adaptation into sensitivity curves maximal near 425 and 565 mµ. Each of these organisms thus possesses an apparatus adequate for at least two-color vision, resembling that of human green-blinds (deuteranopes). The visual pigments of the red-sensitive systems have been extracted from the crayfish eyes. The horse-shoe crab, Limulus, and the lobster each possesses a single visual system, with λmax respectively at 520 and 525 mµ. Each of these is invariant with color adaptation. In each case the visual pigment had already been identified in extracts. The spider crab, Libinia emarginata, presents another variation. It possesses two visual systems apparently differentiated, not for color discrimination but for use in dim and bright light, like vertebrate rods and cones. The spectral sensitivity of the dark-adapted eye is maximal at about 490 mµ and on light adaptation, whether to blue, red, or white light, is displaced toward shorter wavelengths in what is essentially a reverse Purkinje shift. In all these animals dark adaptation appears to involve two phases: a rapid, hyperbolic fall of log threshold associated probably with visual pigment regeneration, followed by a slow, almost linear fall of log threshold that may be associated with pigment migration.

scholarly journals Improved Pre-miRNA Classification by Reducing the Effect of Class Imbalance

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yingli Zhong ◽  
Ping Xuan ◽  
Ke Han ◽  
Weiping Zhang ◽  
Jianzhong Li
Keyword(s):  
Cross Validation ◽  
State Of The Art ◽  
Class Imbalance ◽  
Superior Performance ◽  
Biological Processes ◽  
Classification Models ◽  
New Classification ◽  
Negative Effect ◽  
Human Animal ◽  
Species Specific

MicroRNAs (miRNAs) play important roles in the diverse biological processes of animals and plants. Although the prediction methods based on machine learning can identify nonhomologous and species-specific miRNAs, they suffered from severe class imbalance on real and pseudo pre-miRNAs. We propose a pre-miRNA classification method based on cost-sensitive ensemble learning and refer to it as MiRNAClassify. Through a series of iterations, the information of all the positive and negative samples is completely exploited. In each iteration, a new classification instance is trained by the equal number of positive and negative samples. In this way, the negative effect of class imbalance is efficiently relieved. The new instance primarily focuses on those samples that are easy to be misclassified. In addition, the positive samples are assigned higher cost weight than the negative samples. MiRNAClassify is compared with several state-of-the-art methods and some well-known classification models by testing the datasets about human, animal, and plant. The result of cross validation indicates that MiRNAClassify significantly outperforms other methods and models. In addition, the newly added pre-miRNAs are used to further evaluate the ability of these methods to discover novel pre-miRNAs. MiRNAClassify still achieves consistently superior performance and can discover more pre-miRNAs.

scholarly journals Application of a Model of Animals’ Growth to Study Slowly Growing Pigs

2020 ◽  
Vol 12 (9) ◽  
pp. 259
Author(s):  
V. L. Stass
Keyword(s):  
Growing Pigs ◽  
Main Theme ◽  
Finishing Pigs ◽  
Breeding Scheme ◽  
Growth Performances ◽  
Negative Effect ◽  
Commercial Farms ◽  
Growth Phenotype ◽  
Species Specific ◽  
On Farm

The aim of this study was to investigate a problem in pig farming by applying results of pigs’ growth modelling. The problem this study deals with is a large amount of variation in weight between animals within groups with growing-finishing pigs with strongly negative effect of slowly growing pigs on farm efficiency. The target is to find out a breeding scheme, which can eliminate the slowly growing phenotype from commercial farms. This study was carried out by applying a mathematical model. The model is species-specific; it was built to analyse growth of pigs. In the study, the model has not been developed, it was published elsewhere. The model’s results are used to clarify some aspects of pigs’ growth under industrial conditions. The model implies that in the pig, there are three growth phenotypes that have distinct growth performances. In the study, a main theme is variation in weight between growth phenotypes in pigs. The results of the study suggest that the slowly growing pigs have a certain growth phenotype. A method to identify the phenotype, and a breading scheme to eliminate the slowly growing phenotype from commercial farms are suggested.

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