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Abstract Background Shell strength is an important trait in peanuts that impacts shell breakage and yield. Despite its significance, the genetic basis of shell strength in peanuts remains largely unknown, and the current methods for rating this trait are qualitative and subjective. This study aimed to investigate the genetics of shell strength using a segregating recombinant-inbred-line (RIL) population derived from the hard-shelled cultivar ‘Hanoch’ and the soft-shelled cultivar ‘Harari’. Results Initially, a quantitative method was developed using a texture analyzer, focusing on the proximal part of isolated shells with a P/5 punching probe. This method revealed significant differences between Hanoch and Harari. Shell strength was then measured in 235 RILs across two distinct environments, revealing a normal distribution with some RILs exhibiting shell strength values beyond those of the parental lines, indicating transgressive segregation. Analysis of variance indicated significant effects for the RILs, with no effects of block or year, and a broad-sense heritability estimate of 0.675, indicating a substantial genetic component. Using an existing genetic map, we identified three QTLs for shell strength, with one major QTL (qSSB02) explaining 18.7% of the phenotypic variation. The allelic status of qSSB02 corresponded significantly with cultivar designation for in-shell or shelled types over four decades of Israeli peanut breeding. Physical and compositional analyses revealed that Hanoch has a higher shell density than Harari, rather than any difference in shell thickness, and is associated with increased levels of lignin, cellulose, and crude fiber. Conclusions These findings provide valuable insights into the genetic and compositional factors that influence shell strength in peanut, laying a foundation for marker-assisted selection in breeding programs focused on improving pod hardness in peanuts.

This study examines the physiological response of the Atlantic surfclam (Spisula solidissima) to ocean acidification in warm summer temperatures. Working with ambient seawater, this experiment manipulated pH conditions while maintaining natural diel fluctuations and seasonal shifts in temperature. One-year-old surfclams were exposed to one of three pH conditions (ambient (control): 7.8 ± 0.07, medium: 7.51 ± 0.10, or low: 7.20 ± 0.10) in flow-through conditions for six weeks, and feeding and digestive physiology was measured after one day, two weeks, and six weeks. After six weeks of exposure to medium and low pH treatments, growth was not clearly affected, and, contrastingly, feeding and digestive physiology displayed variable responses to pH over time. Seemingly, low pH reduced feeding and absorption rates compared to both the medium treatment and ambient (control) condition; however, this response was clearer after two weeks compared to one day. At six weeks, suppressed physiological rates across both pH treatments and the ambient condition suggest thermal stress from high ambient water temperatures experienced the week prior (24–26 °C) dominated over any changes from low pH. Results from this study provide important information about reduced energy acquisition in surfclams in acidified environments and highlight the need for conducting multistressor experiments that consider the combined effects of temperature and pH stress. [ABSTRACT FROM AUTHOR]

This study examines the physiological response of the Atlantic surfclam (Spisula solidissima) to ocean acidification in warm summer temperatures. Working with ambient seawater, this experiment manipulated pH conditions while maintaining natural diel fluctuations and seasonal shifts in temperature. One-year-old surfclams were exposed to one of three pH conditions (ambient (control): 7.8 ± 0.07, medium: 7.51 ± 0.10, or low: 7.20 ± 0.10) in flow-through conditions for six weeks, and feeding and digestive physiology was measured after one day, two weeks, and six weeks. After six weeks of exposure to medium and low pH treatments, growth was not clearly affected, and, contrastingly, feeding and digestive physiology displayed variable responses to pH over time. Seemingly, low pH reduced feeding and absorption rates compared to both the medium treatment and ambient (control) condition; however, this response was clearer after two weeks compared to one day. At six weeks, suppressed physiological rates across both pH treatments and the ambient condition suggest thermal stress from high ambient water temperatures experienced the week prior (24–26 °C) dominated over any changes from low pH. Results from this study provide important information about reduced energy acquisition in surfclams in acidified environments and highlight the need for conducting multistressor experiments that consider the combined effects of temperature and pH stress.

The establishment of non-indigenous species in the Antarctic, an ecosystem isolated for millions of years, could dramatically alter its unique and endemic biota. In coastal waters, calcified species (e.g., echinoderms, gastropods, bivalves) of benthic communities will be particularly vulnerable to shell-crushing (i.e., durophagous) predators such as crabs. The magnitude of changes in the community structure of shallow Antarctic waters potentially produced by such non-indigenous predators will depend on the innate vulnerability of these species (e.g., shell characteristics) and their potential to respond to novel threats (e.g., behavior, shell thickening). This study aims to evaluate the potential interaction between shell-crushing predators and the limpet Nacella concinna, an endemic Antarctic species and one of the most abundant and conspicuous gastropods in intertidal and shallow subtidal zones of the Antarctic. First, we showed that the king crab Lithodes santolla, a representative species of a group of crabs likely to invade Antarctic waters, was able to break the shell of N. concinna and consume it in the laboratory. We then assessed the shell-breaking force of N. concinna living in four Antarctic habitats (two intertidal and two subtidal) and found wide variation in this trait. Finally, we examined shell-breaking force of a subantarctic congener, N. deurata, which naturally coexists with shell-crushing predators in its native range, and found its shell-breaking force to be similar to the strongest populations of the Antarctic species. Taking into account the crushing claw force of crabs and their high consumption rate of limpets, N. concinna will be highly vulnerable to this kind of durophagous predators and may have limited reaction norms for increasing any inducible defenses such as the thickening and hardening of the shell or changes in their behavior in the face of the almost inevitable invasion of shell-crushing predators into the Antarctic marine ecosystem. [ABSTRACT FROM AUTHOR]

A total of 240 white Shaver laying hens from 22 to 34 weeks of age were assigned to 3 treatments and 5 replications. The treatments included: i) Conventional (hens were kept in experimental building without access to outdoor area and fed with the conventional diet), ii) Semi-organic (hens were kept in experimental building with access to outdoor area and fed with the organic diet plus amino acids and vitamin-minerals supplement), and iii) Organic (hens were kept in experimental building with access to outdoor and fed with the organic diet). The results showed statistically significant differences in the feed intake, egg production, egg mass, egg weight, and change body weight(g) means among the treatments (p < 0.05). The hens kept in the organic treatment had fecal highest contain of oocytes coccidia (p < 0.05). The yolk color index and shell strength in the organic treatment significantly increased in comparison with that of other treatments (p < 0.05). The highest HDL was in the semi-organic and organic treatments (p < 0.05). The lowest egg yolk cholesterol concentration was found in hens kept in the semi-organic and organic treatments (p < 0.05). It is concluded that organic production system is useful for improving egg quality.

Shell strength of the modern freshwater molluscs Heleobia parchappii, Biomphalaria peregrina, Uncancylus concentricus, Musculium argentinum, Physa acuta, Succinea meridionalis and Pomacea canaliculata was quantified through load measurements and analysed using Weibull distribution, a statistical method used for brittle materials. In this study, we defined shell strength as the maximum compressive force required to break a shell per unit of resistant area, which is known as mechanical tension or stress. Intrinsic properties of shells were also measured through mineralogical and morphological characterisation. Shells were mainly composed of aragonite and varied in size and shell thickness, being P. canaliculata (biovolume = 104 mm3) the largest and H. australis and H. parchappii (3.35 and 7.93 mm3, respectively) the smallest ones. The dominant microstructure was cross-lamellar, with layers that varied between one and four. The organic matter of the matrix varied between 1.58% and 4.24%. Shell strength differs among mollusc species. Smallest species have higher shell strength than larger ones because they have a smaller resistant area on which the load is applied, and therefore the resulting value of fracture stress increases abruptly. This may explain the dominance of H. parchappii in death and fossil assemblages from Pampa sediments. [ABSTRACT FROM AUTHOR]

Eggshell is a naturally engineered packaging of its interior content and prediction of the egg fracture force (F) under non-destructive elastic shell deformation (D) remains a challenge. Specifically, since shell deflection function under a constant load is linear, it is difficult to calculate the maximum point for F and the respective value of D. The aim was to solve this problem experimentally by employing a measurement instrument commonly used to analyse the deformation of metals and alloys. The experiments were conducted on chicken eggs aligned in their morphological parameters. A curvilinear characteristic of the change in the function F = f (D), was achieved at extremely low shell compression speeds (0.010–0.065 mm s−1). This enabled us to (i) describe the obtained functions accurately with Gaussian curves; (ii) expand the range of non-destructive load on a chicken egg to 30 N; and (iii) develop empirical equations for a reasonably accurate prediction of maximum shell deformation (R 2 = 0.906) and shell strength (R 2 ≈ 1). It is suggested that it is possible to calculate shell strength by measuring its deformation at five points that corresponded to non-destructive loads of 10, 15, 20, 25 and 30 N. The methodological approach proposed can be used for the development of an effective shell strength calculation procedure by non-destructive testing. It depends on the appropriate tool for assessing and controlling the elastic shell deformation as well as the features of strength properties of the studied eggs. • A curvilinear function of egg fracture force on elastic shell deformation derived. • Dependences were considered for non-destructive prediction of shell strength. • Equation for egg fracture force was inferred from 5 values of elastic deformation. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare physical, morphological and mechanical characteristics of eggs collected from two duck breeds (Pekin duck and Cherry Valley duck). A total sample of 120 eggs (60 eggs of each duck breed) was collected from one-year-old free range raised ducks. The Cherry Valley duck eggs were significantly heavier (94.23 vs. 71.91 g) than Pekin ducks (P

To evaluate the effect of stocking density on pre-fattening growth and survival, Manila clam seeds from three different batches (B1, B2, and B3) were farmed in plastic net lanterns at two sites (western and northern) in Sacca degli Scardovari (Italy). Different stocking densities were compared, i.e. EXTRA (50,000 clams m−2), HIGH (30,000), and MEDIUM (20,000) for B1 and B2 clams; HIGH, MEDIUM, and LOW (10,000 clams m−2) for B3 clams. At the end of pre-fattening at the western site, the shell length decreased with increasing stocking density of both B1 (14.2 mm vs. 13.6 mm vs. 12.9 mm at HIGH vs. MEDIUM vs. EXTRA density; P < 0.001) and B2 (14.9 mm vs. 13.6 mm vs. 12.5 mm at MEDIUM vs. HIGH vs. EXTRA density; P < 0.001) clams. At the northern site, the shell length decreased in the following manner: MEDIUM to HIGH to EXTRA density for B1 clams (P < 0.001) and MEDIUM to EXTRA to HIGH density for B2 clams (P < 0.001). The same trend was recorded for B3 clams at both western (16.1 mm vs. 14.3 mm vs. 12.7 mm at LOW vs. MEDIUM vs. HIGH density; P < 0.001) and northern (15.6 mm vs. 13.9 mm vs. 13.2 mm; P < 0.001) sites. The stocking density did not affect the survival rate at the northern site and of the B3 clams, whereas the survival rate significantly decreased from MEDIUM and HIGH to EXTRA density for B1 (84.8 % and 85.4 % vs. 52.8 %; P < 0.05) and B2 (92.5 % and 87.6 % vs. 67.0 %; P < 0.01) clams at the western site where pre-fattening ended one week later than at the northern site. In the present conditions, clams in suspended lanterns reached the minimum sowing size (shell length 11 mm, weight 0.3 g) in 10 weeks. However, an increase in stocking density decreased clam growth and drastically increased mortality when water conditions became less favourable.

A total of 240 white Shaver laying hens from 22 to 34 weeks of age were assigned to 3 treatments and 5 replications. The treatments included: i) Conventional (hens were kept in experimental building without access to outdoor area and fed with the conventional diet), ii) Semi-organic (hens were kept in experimental building with access to outdoor area and fed with the organic diet plus amino acids and vitamin-minerals supplement), and iii) Organic (hens were kept in experimental building with access to outdoor and fed with the organic diet). The results showed statistically significant differences in the feed intake, egg production, egg mass, egg weight, and change body weight(g) means among the treatments (p < 0.05). The hens kept in the organic treatment had fecal highest contain of oocytes coccidia (p < 0.05). The yolk color index and shell strength in the organic treatment significantly increased in comparison with that of other treatments (p < 0.05). The highest HDL was in the semi-organic and organic treatments (p < 0.05). The lowest egg yolk cholesterol concentration was found in hens kept in the semi-organic and organic treatments (p < 0.05). It is concluded that organic production system is useful for improving egg quality. [ABSTRACT FROM AUTHOR]

Laboratory experiments have indicated that tench (Tinca tinca) is an effective predator of Potamopyrgus antipodarum. However, few P. antipodarum have been found in the gastrointestinal tracts of wild caught benthivorous fishes, including tench. This had led to the assumption that the shell properties of the snail act against native predators. In general, it has been predicted that this is due to P. antipodarum possessing a thicker shell and a lower amount of soft tissues than native snails; the latter will thus be preferred by benthivorous fishes. In the current study, shell-crushing resistance and the soft tissue mass / shell mass ratio were compared between the non-native P. antipodarum and three native species. Results indicated a similar shell-crushing resistance for P. antipodarum relative to the native Bithynia tentaculata, the latter of which is a common food object in tench diet. However, the soft tissue mass / shell mass ratio of the invader was significantly lower than in most of the studied native snails, indicating a lower amount of soft tissues in P. antipodarum. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Egg laying genotypes have been selected for generations due to their high yield and egg quality, resulting in efficient feed utilization and low body weight; hence, they are not suitable for meat production. This imposes an issue for the male layer chicks, which are killed at one day old. Because of ethical and food waste concerns, the search for suitable dual-purpose genotypes in order to avoid euthanasia of male day-old chicks has intensified. The aim of the present study is to evaluate potential dual-purpose genotypes for their egg quality compared to a representative egg laying genotype. Two dual-purpose genotypes with divergent characteristics were evaluated: genotype A represented an experimental crossbreed based on a broiler type male and an egg layer female, and genotype C was a crossbreed of a layer type. These were compared to a rustic genotype B and a control genotype D, which was an egg layer. Eggs were collected six times during the period of 21–54 weeks of hen age, i.e., a total of 990 shell eggs were analyzed. Examined parameters were weights of egg, shell, yolk, and albumen, by calculating their relative proportions. Shell quality was assessed by shell strength, shell stiffness, and shell thickness. Yolk quality was determined as yolk color and inclusions of blood and meat spots, and albumen quality was evaluated in terms of pH and dry matter (DM) content. The egg layer genotype produced the smallest eggs with least blood and meat spot inclusions compared to that produced by the three dual-purpose genotypes. Shell quality was superior for the layer genotype. However, the experimental genotype A laid eggs of comparable shell quality, albumen DM, and yolk weight, but also with the darkest and most red-yellow colored yolk. The two other dual-purpose genotypes produced eggs of low-medium quality. In conclusion, the genotype A could serve as dual-purpose genotype from an egg quality perspective.

Abstract Compaction is one of the taphonomic processes responsible for fragmenting invertebrate shells, thereby removing them from the fossil record. Studies of drilling predation intensities in the fossil record depend on equal preservation of drilled and undrilled shells. However, predatory drill holes may weaken shells, and these shells may be preferentially destroyed during compaction, thus overprinting predation signals in the fossil record. Previous studies have experimentally compacted drilled and undrilled bivalve valves. Such experiments have not previously been performed with gastropod shells, which may respond differently to compaction. To test if drilled gastropod shells are preferentially removed by compaction, 227 undrilled and 28 drilled Olivella biplicata shells were subjected to compaction (70,602 N) within a sediment column. Multiple shells were tested together but were given ample space so as not to rest on one another, thereby avoiding forming point contacts. Many drilled and undrilled shells possessed aperture damage, removed apices, pinhole bores, and spionid worm bores, which in conjunction with shell size, were hypothesized to lower compactional shell strength. Shell strength was assessed by using the frequency of shell failure. Binomial logistic regression models were utilized to identify the variables controlling shell failure. Three models were created each using the whole O. biplicata sample. Each model used a unique and different definition of shell strength: any damage, breakage, and obliteration (<50% intact). Predatory drill holes were not found to predict shell failure significantly, regardless of shell failure definition. Instead, compaction tends to damage larger shells and obliterate shells with removed apices. Therefore, drilling predation intensities of fossil assemblages are not influenced by compaction. Highlights • Predatory drill holes do not weaken gastropod compactional shell strength. • Compaction does not alter drill hole frequencies in gastropod assemblages. • Larger shells damage more frequently than smaller shells. • Shells without apices are more frequently obliterated than shells with intact apices. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the commercial eggs quality in eastern Algeria. A total of 5004 eggs from three genetic types (local hens -PL, industrial -PI- hens and chickens from crossing local chickens and industrial-PLPI- hens) were analyzed. Eggs weight, albumen weight and maximum breaking strength of the shell from the industrial strain were significantly higher than those from other genotypes (P <0.001). Eggs from local chickens, despite a lower weight to other genotypes (PL: 54.15g; PLPI: 59.74g; PI: 66.62g; P <0.05) while yellow/albumen ratio (0.57, 0.50 and 0.44 respectively) was higher (P <0.05). Maximum breaking strength of the shell was significantly (P <0.05) lowest in PL (35,99N) compared to PLPI (36.76N) and PI (37.30N). Significant correlation coefficients (P <0.001) were recorded between egg weight and albumen weight (0.95), yolk weight (0.50), shell weight (0.69), albumen percentage (0.79), proportions of yellow (-0.74) and shell percentage (-0.37), the average thickness of the shell (0.60), Haugh units (-0.18), shape index (0.19), yellow / albumen ratio (-0.75) and the maximum breaking strength of the shell (0.10). The origin of the eggs (PL, PLPI and PI) influences significantly on composition and quality of commercial eggs in eastern Algeria. [ABSTRACT FROM AUTHOR]

At present the laying hen rearing is transformed into alternative housing systems which include a deep litter system. As for the poultry nutrition, the replacement of animal protein with vegetable protein in poultry feed is applied. Therefore, in an experiment we evaluated the quality of eggs from laying hens in the cage system as compared to the deep litter system with vegetable protein substituted for animal protein in their feed. 72 ISA Brown laying hens were placed into the experiment. 36 laying hens were kept in the deep litter system and 36 laying hens were kept in conventional cages for laying hens. For the period of 9 months, 36 eggs from the group in the deep litter system were examined, always at intervals of five weeks (i.e. 8 × 36 eggs) and so were 36 eggs from the group in the cage system (i.e. 8 × 36 eggs). We found out that in the deep litter system the mean egg weight was higher (P < 0.01), shell weight was lower (P < 0.01), egg albumen was higher (P < 0.01), yolk weight did not differ (P > 0.05), yolk cholesterol was higher (P < 0.01), yolk colour was darker (P < 0.05), shell strength did not differ (P > 0.05), all in comparison with the cage system of laying hen keeping. The results of the experiment show that where vegetable protein was substituted for animal protein in the nutrition of laying hens, there were differences in the quality of eggs from laying hens kept in the deep litter system and eggs from laying hens kept in the cage system.

The survival and reproductive success of hermit crabs is intrinsically linked to the quality of their domicile shells. Because damaged or eroded shells can result in greater predation, evaluating shell structure may aid our understanding of population dynamics. We assessed the structural attributes ofCerithium atratumshells through assessments of (a) density using a novel approach involving computed tomography and (b) tolerance to compressive force. Our goal was to investigate factors that may influence decision making in hermit crabs, specifically those that balance the degree of protection afforded by a shell (i.e. density and strength) with the energetic costs of carrying such resources. We compared the density and relative strength (i.e. using compression tests) of shells inhabited by live gastropods, hermit crabs (Pagurus criniticornis) and those found empty in the environment. Results failed to show any relationship between density and shell size, but there was a notable effect of shell density among treatment groups (gastropod/empty/hermit crab). There was also a predictable effect of shell size on maximum compressive force, which was consistent among occupants. Our results suggest that hermit crabs integrate multiple sources of information, selecting homes that while less dense (i.e. reducing the energy costs of carrying these resources), still offer sufficient resistance to compressive forces (e.g. such as those inflicted by shell-breaking predators). Lastly, we show that shell size generally reflects shell strength, thus explaining the motivation of hermit crabs to search for and indeed fight over the larger homes. [ABSTRACT FROM AUTHOR]

Copyright of Krmiva is the property of Croatian Society of Agronomists and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Variations in egg quality and yolk colour in relation to eggshell colour in commercial brown layer eggs were studied using 734 eggs. The traits of interest were eggshell colour, yolk colour, egg weight, Haugh unit value and shell strength. The results showed that egg weight and shell strength increased as the darkness of the shell increased, whereas the Haugh score decreased. A highly significant positive correlation was found between yolk a* (redness) and yolk colour (DSM) (0.655) (p< 0.001) and could be used to indicate the darkness of the egg yolk. No correlation was observed between shell colour and egg yolk colour. The shell L* (lightness) value could be used to measure the dark or light colour of the eggshell and could possibly be accepted as a colour criterion for eggshells. Some egg quality traits varied with the colour of the eggshell. [ABSTRACT FROM AUTHOR]

The article discusses the study that investigates the effects of substituting soybean oil (SO) with two commercial palm fatty acid powders (PFAP) in the diet of Hy-Line W-36 Leghorn hens, on performance, egg quality measurements and yolk lipids oxidative stability. Although the study found no significant effect of dietary treatments on egg production from 27-32 weeks of age, hen-day egg production during 32 to 37 week of age was reduced with incremental levels of PFAP.

important insight to egg quality. Understanding how processing and handling procedures affect both dynamic and static shell properties can enhance the safety and quality of eggs reaching the consumer. A study was conducted to determine if dynamic shell properties were altered due to modified pressure microcrack detection technology exposure in brown and white shell eggs. Three replicates of 100 eggs each of brown and white retail shell eggs were conducted. Dynamic stiffness (Kdyn) and egg weight were monitored immediately before and after microcrack detection. No changes in Kdyn or egg weight were detected for either shell color. Static compression shell strength and deformation were subsequently monitored and a correlation analysis conducted. A strong correlation (R² = 0.53; P < 0.0001) between Kdyn and static compression shell strength was seen for extra large white shell eggs. A smaller (R² = 0.31; P < 0.0001) correlation was found for large brown eggs. The use of modified pressure microcrack detection technology did not affect shell dynamic properties. [ABSTRACT FROM AUTHOR]

Invasive habitat-forming species cause large changes to the abiotic environment, which may lead to lethal and sublethal effects on native fauna. In this study, we tested whether morphological anti-predator traits of an infaunal bivalve, Anadara trapezia, differed between areas invaded by the habitat-forming seaweed Caulerpa taxifolia and uninvaded habitats in estuaries in New South Wales, Australia. Caulerpa changes the abiotic environment in ways that may affect traits of native species. In particular, there is lower water flow, lower dissolved oxygen in the water and sediments are more silty and anoxic than in unvegetated habitat. To test our hypotheses, we collected Anadara from Caulerpa and uninvaded habitats and measured shell thickness, shell strength and resistance to opening of valves. We found that all three traits were reduced in Anadara from Caulerpa habitat compared with Anadara from uninvaded habitats. These findings are consistent with the idea that trait modifications in native fauna in response to invasive habitat-forming species can potentially increase susceptibility to predation. Invasive habitat-forming species modify important environmental factors with major consequences for associated fauna. We examined how the invasive habitat-forming seaweed Caulerpa taxifolia affects anti-predator traits of a native bivalve and found that bivalves in Caulerpa habitat have thinner, weaker shells and low resistance to opening of their valves. These trait modifications are likely to increase their susceptibility to predation. [ABSTRACT FROM AUTHOR]

Vasconcelos, P., Morgado-André, A., Morgado-André, C., and Gaspar, M. B. 2011. Shell strength and fishing damage to the smooth clam (Callista chione): simulating impacts caused by bivalve dredging. – ICES Journal of Marine Science, 68: 32–42. The smooth clam Callista chione is exploited by a fleet of dredgers along the southwestern coast of Portugal and suffers from a high incidence of shell damage. The force required to break C. chione shells in relation to fishing impacts and dredge damage is quantified. Fishing trials and shell-strength measurements (compression and compaction experiments) were performed to determine whether shell damage was attributable to the direct impact of the dredge teeth or to sediment compaction. A three-dimensional model of C. chione was subjected to simulated force by the finite element method. Analyses of damage areas and breakage patterns revealed two groups of samples, one containing the samples from compression experiments and another with the samples from dredging and compaction experiments, suggesting that most shell damage was attributable to compaction within the sediment. Information is provided to help improve the design of bivalve dredges, by increasing both length and angle of the dredge teeth, which would reduce the compaction force and distribute it differentially within the sediment, forcing upward movement of the bivalves. [ABSTRACT FROM PUBLISHER]

There are a number of specialty shell eggs available to consumers in the US retail market. A survey consisting of white and brown large shell eggs with various production and nutritional differences (traditional, cage-free, free-roaming, pasteurized, nutritionally enhanced, and fertile) was conducted to determine if physical quality and compositional differences exist. Identical brands of eggs were purchased from the same retail outlets on 3 occasions (replicates) in a single city. The average range of time from processing to purchase for all eggs was 7.67 to 25.33 d, with traditional white eggs in retail having the shortest time. Haugh unit values ranged from 66.67 (cage-free, docosahexaenoic acid, and n-3 enhanced) to 84.42 (traditional white). Albumen height followed a similar pattern. Egg weight was greater for brown eggs (61.12 vs. 58.85 g). Brown eggs also had greater static compression shell strength than white eggs (4,130.61 vs. 3,690.31 g force). Vitelline membrane strength was greatest for traditional brown eggs (2.24 g force). Percentage of total solids and crude fat was greatest in the cage-free, n-3-enhanced white eggs (25.07 and 11.71%, respectively). Although significant differences were found between white and brown shell eggs and production methods, average values for quality attributes varied without one egg type consistently maintaining the highest or lowest values. [ABSTRACT FROM AUTHOR]

Abstract: Three species of the mussel, Mytilus, occur in the North Atlantic region, M. edulis, M. galloprovincialis and M. trossulus, and hybrid zones are present where their distributions overlap. M. edulis is a native species in the UK. M. galloprovincialis originated in the Mediterranean and its distribution extends northwards along the Atlantic seaboard to Scotland. Baltic Sea mussels have a M. trossulus ancestry but are highly introgressed by M. edulis. In recent decades, farming of mussels on long-line rope culture systems has been introduced into Scotland. On farms in Loch Etive, a form of mussel with a fragile shell and a different shape to either M. edulis or M. galloprovincialis has been increasing in frequency over recent years. Samples of fragile shelled, normal strong shelled and intermediate mussel types were sampled from two farms in 2006 and compared with samples of M. edulis, M. galloprovincialis and M. trossulus from other sources where their species identity is well established. Abundance relative to depth, shell strength, condition index and shell morphology were analysed together with 5 allozyme loci and one nuclear DNA genetic marker (Me 15/16). The fragile shelled mussels, and many of those classed as intermediate, were identified as a mixture of M. trossulus and M. trossulus x M. edulis hybrids. This identification was strongly supported by both morphological and genetic data and is the first record of the presence of M. trossulus in UK waters. M. trossulus in Loch Etive are most likely to be a post-glacial relict population restricted to the low salinity area of the Loch that has recently increased in abundance due to commercial mussel growing activity. In addition, individual mussels of all three species and their hybrids were detected amongst Loch Etive mussels. This is the first genetic demonstration of all three species and their hybrids occurring together in one location in the Atlantic region and provides a unique opportunity to study the processes of speciation, divergence, and introgression in the genus Mytilus. [Copyright &y& Elsevier]

Researchers are currently developing new value-added uses for almond shells, an abundant agricultural by-product. Almond varieties are distinguished by processors as being either hard or soft shelled, but these two broad classes of almond also exhibit varietal diversity in shell morphology and physical characters. By defining more precisely the physical and chemical characteristics of almond shells from different varieties, researchers will better understand which specific shell types are best suited for specific industrial processes. Eight diverse almond accessions were evaluated in two consecutive harvest seasons for nut and kernel weight, kernel percentage and shell cracking strength. Shell bulk density was evaluated in a separate year. Harvest year by almond accession interactions were highly significant (p ⩽0.01) for each of the analyzed variables. Significant (p ⩽0.01) correlations were noted for average nut weight with kernel weight, kernel percentage and shell cracking strength. A significant (p ⩽0.01) negative correlation for shell cracking strength with kernel percentage was noted. In some cases shell cracking strength was independent of the kernel percentage which suggests that either variety compositional differences or shell morphology affect the shell cracking strength. The varietal characterization of almond shell materials will assist in determining the best value-added uses for this abundant agricultural by-product. [Copyright &y& Elsevier]

We investigated the correlations between different eggshell and membrane strength parameters and their changes over time. Eggshell and membrane characteristics were measured for 2 different lines of laying hens, Hisex Brown and Bovans Brown, from wk 33 up to wk 78. Several parameters were investigated: 2 parameters concerning total eggshell strength (static and dynamic stiffness), 1 structural parameter (i.e., eggshell thickness), 2 parameters describing the material characteristics of the shell [dynamic Young's modulus (EM) and nitrogen content], and 3 parameters to measure the membrane characteristics (attachment force breaking strength and nitrogen content). This study shows that the correlations among parameters change during the laying period and among lines. The EM of the eggshell increased during the laying period for the Hisex line. No difference was observed in case of the Bovans line. In general, a negative correlation was obtained between eggshell thickness and the EM. The correlation between static and dynamic stiffness increased during lay. Finally, the attachment force and breaking strength of the membranes declined during the laying period. [ABSTRACT FROM AUTHOR]

Abstract: In snails there is an intimate relation between shell size, thickness, strength and calcium content that may be influenced by environmental factors such as predation and heavy metal pollution. The snail Cepaea nemoralis shows variability for shell colour and banding pattern, and frequencies of colour morphs are highly variable in natural populations. We used C. nemoralis to investigate (i) the relations between shell morphology, shell Ca and heavy metal content (Cd, Cr, Pb, Zn), and shell strength, (ii) differences in shell morphology and shell strength among localities and yellow and pink shells and (iii) whether snails from polluted sites show increased levels of heavy metals in their shell. Larger shells were heavier, thicker, needed a higher force to be crushed but did not have a higher Ca concentration. Cd and Zn concentrations were higher in shells from polluted plots compared to shells from unpolluted plots but Ca levels in the shell were comparable among plots. Zn concentration was negatively correlated with shell traits. Although there was substantial variation in shell strength, thickness and dry weight among localities, none of the shell traits differed between individuals from polluted and reference plots nor between colour morphs. Our results suggest that the effect of heavy metal pollution on shell strength and morphology is limited in the investigated populations. [Copyright &y& Elsevier]

Abstract: Shell strength development of the scallop Pecten maximus collected from wild stocks and from suspended cultures was described over the culture period when most of the growth takes place (20–110 mm shell height). Shell strength, shell height and shell thickness were determined in scallops of age groups 2–5 years. Wild and cultured scallops showed a strong divergence in shell strength development in scallops older than age group 3, which was not reflected in the concurrent development of shell height and thickness, indicating that factors other than shell height and shell thickness explain the differences in observed shell strength. In wild scallops, shell height, shell thickness and age accounted for about 65% of the variation in shell strength, while the same variables accounted for about 30% in cultured scallops. Wild scallops had stronger shells than the cultured scallops of the same size (53–68 mm shell height) grown at the same site, suggesting that factors related to suspended culture could explain the weak shells in cultured scallops. The results indicate that conditions related to suspended culture can have a negative impact on shell strength development in P. maximus. As the shell is the primary protection against decapod predation in scallops, a better understanding of what affects the shell strength is of importance for the development of release strategies in bottom culture of P. maximus. [Copyright &y& Elsevier]

Abstract: Mollusc shells provide a major defense against predators, but changes in shell properties may alter the effectiveness of this defense. An endolithic boring sponge, Cliona sp., infests many shells of the gastropod Littorina littorea in the southern Gulf of Maine. Cliona excavates ramifying chambers within the shell but does not affect tissue directly. Field surveys showed that 22–83% of snails were infected with Cliona at the Isles of Shoals; the prevalence of infection declined with increasing tidal height and increased with increasing snail size. We also investigated potential costs to L. littorea of infection by Cliona. L. littorea appeared to respond to sponge boring by laying down additional material on the interior of the shell, which reduced interior shell volume and was associated with smaller dry body mass for a given shell length. Biomechanical studies showed that sponge boring weakened shells: the mean compressive force required to break severely bored L. littorea was 29% lower than that required to break unbored snails. Cliona infection increased vulnerability of snails to predation by the crab, Cancer borealis Stimpson, which attacks molluscs by crushing or peeling shells. Unlike uninfected snails, predation risk did not decline with increasing size in bored L. littorea. In addition, bored snails were generally crushed by the crab, regardless of snail size, whereas large unbored snails could only be attacked by peeling. Thus, costs to L. littorea of Cliona boring included the following: (1) increased vulnerability to predation due to structural changes in the shell; (2) reduction or elimination of the size-refuge advantage; and (3) a potential decrease in growth and fecundity due to diversion of energy to supplemental interior layers to the shell and the consequent reduction in interior shell living space and body mass. [Copyright &y& Elsevier]

Eggs were collected from a single inline processing facility weekly for 3 wk (replicates). The eggs were stored at 4°C and 80% RH. Sampling began the day after collection and continued each week for 10 wk. During analysis, 24 eggs were examined for egg weight, albumen height, Haugh units (MU), shell strength, and vitelline membrane strength for each replicate. Egg weight decreased (P < 0.0001) from approximately 61 to 57 g after 10 wk of storage. Eggs from the second replicate were significantly (P < 0.0001) heavier than the other replicates by an average of 3 g. On average, albumen height decreased with extended storage (P <0.0001) from 7.05 to 4.85 mm. Albumen height was approximately 0.2 mm higher for the eggs in replicate 2 compared with the other replicates (P < 0.01). Haugh unit values decreased during cold storage from 82.59 to 67.43 (P < 0.0001). There were no differences between replicates for HU values. No differences were detected for shell strength between replicates or during extended storage. A significant difference (P < 0.05) was found in detectable vitelline membrane strength between replicates, but this difference was less than 0.05 g. The elasticity of the vitelline membrane decreased during storage (P < 0.01) remaining low after 6 wk. Extended cold storage led to decreases in egg weight, albumen height, and HU. However, average HU values were still within the range for grade A. Shell strength was not affected by extended storage. Vitelline membrane elasticity also decreased, which could lead to yolks more easily rupturing as consumers crack the eggs. The results indicated that although the physical quality factors monitored in this study decreased during storage, egg quality was still acceptable beyond current recommended shelf life guidelines. [ABSTRACT FROM AUTHOR]

Egg laying genotypes have been selected for generations due to their high yield and egg quality, resulting in efficient feed utilization and low body weight; hence, they are not suitable for meat production. This imposes an issue for the male layer chicks, which are killed at one day old. Because of ethical and food waste concerns, the search for suitable dual-purpose genotypes in order to avoid euthanasia of male day-old chicks has intensified. The aim of the present study is to evaluate potential dual-purpose genotypes for their egg quality compared to a representative egg laying genotype. Three dual-purpose genotypes with divergent characteristics were evaluated: genotype A represented an experimental crossbreed based on a broiler type male and an egg layer female, genotype B was a pure breed, and genotype C was a crossbreed of a layer type. These were compared to a control genotype D, which was an egg layer. Eggs were collected six times during the period of 21–54 weeks of hen age, i.e., a total of 1080 shell eggs were analyzed. Examined parameters were weights of egg, shell, yolk, and albumen, by calculating their relative proportions. Shell quality was assessed by shell strength, shell stiffness, and shell thickness. Yolk quality was determined as yolk color and inclusions of blood and meat spots, and albumen quality was evaluated in terms of pH and dry matter (DM) content. The egg layer genotype produced the smallest eggs with least blood and meat spot inclusions compared to that produced by the three dual-purpose genotypes. Shell quality was superior for the layer genotype. However, the experimental genotype A laid eggs of comparable shell quality, albumen DM, and yolk weight, but also with the darkest and most red-yellow colored yolk. The two other dual-purpose genotypes produced eggs of low-medium quality. In conclusion, the genotype A could serve as dual-purpose genotype from an egg quality perspective. [ABSTRACT FROM AUTHOR]

Marine bivalve molluscs, such as scallops, mussels and oysters, are crucial components of coastal ecosystems, providing a range of ecosystem services, including a quarter of the world's seafood. Unfortunately, coastal marine areas often suffer from high levels of metals due to dumping and disturbance of contaminated material. We established that increased levels of metal pollution (zinc, copper and lead) in sediments near the Isle of Man, resulting from historical mining, strongly correlated with significant weakening of shell strength in king scallops, Pecten maximus. This weakness increased mortality during fishing and left individuals more exposed to predation. Comparative structural analysis revealed that shells from the contaminated area were thinner and exhibited a pronounced mineralisation disruption parallel to the shell surface within the foliated region of both the top and bottom valves. Our data suggest that these disruptions caused reduced fracture strength and hence increased mortality, even at subcritical contamination levels with respect to current international standards. This hitherto unreported effect is important since such non-apical responses rarely feed into environmental quality assessments, despite potentially significant implications for the survival of organisms exposed to contaminants. Hence our findings highlight the impact of metal pollution on shell mineralisation in bivalves and urge a reappraisal of currently accepted critical contamination levels. Unlabelled Image • Lethal damage to scallops was higher during fishing at a metal contaminated site. • Higher damage correlated with lower shell strength and disrupted shell structure. • A wide range of alternative explanations to metal contamination were ruled out. • Bivalve shell characteristics should be used more in ecotoxicology assessments. [ABSTRACT FROM AUTHOR]

Ocean acidification and increased ocean temperature from elevated atmospheric carbon dioxide can significantly influence the physiology, growth and survival of marine organisms. Despite increasing research efforts, there are still many gaps in our knowledge of how these stressors interact to affect economically and ecologically important species. This project is the first to explore the physiological effects of high pCO 2 and temperature on the acclimation potential of the purple-hinge rock scallop (Crassadoma gigantea), a widely distributed marine bivalve, important reef builder, and potential aquaculture product. Scallops were exposed to two pCO 2 (365 and 1050 μatm) and temperature (14 and 21.5 °C) conditions in a two-factor experimental design. Simultaneous exposure to high temperature and high pCO 2 reduced shell strength, decreased outer shell density and increased total lipid content. Despite identical diets, scallops exposed to high pCO 2 had higher content of saturated fatty acids, and lower content of polyunsaturated fatty acids suggesting reorganization of fatty acid chains to sustain basic metabolic functions under high pCO 2. Metagenomic sequencing of prokaryotes in scallop tissue revealed treatment differences in community composition between treatments and in the presence of genes associated with microbial cell regulation, signaling, and pigmentation. Results from this research highlight the complexity of physiological responses for calcifying species under global change related stress and provide the first insights for understanding the response of a bivalve's microbiome under multiple stressors. Unlabelled Image • Warming and acidification reduced shell strength & increased total lipid content. • Exposed scallops reorganized fatty acids to sustain metabolic functions. • Treatments lead to differences in microbiome community composition. • This was the first multi-stressor experiment on Crassadoma gigantea. • This was the first multi-stressors experiment to define microbiome community composition in a bivalve. [ABSTRACT FROM AUTHOR]