Small Eggs Research Articles

Invasion of pumpkinseed Lepomis gibbosus is facilitated by phenotypic plasticity across its invasion gradient

As a non-native species invades a new region, individuals at the range front are often characterised by differences in their traits and behaviours versus individuals in the established ‘core’ area. Here, differences in life history traits of invading pumpkinseed Lepomis gibbosus were assessed across a fine spatial scale in the Saricay Stream, Turkey, with seven locations sampled between their core area and the invasion front. Following genetic analyses that suggested the pumpkinseed all originated from the same founding population, life history trait analyses revealed pronounced differences between the sites at the core and front that were independent of environmental factors. Pumpkinseed in sites towards the invasion front were of relatively low abundance and displayed relatively high reproductive investment, with heavier gonads, higher fecundity and smaller eggs. They also had faster growth rates than pumpkinseed in sites towards the core of the invasion. The traits displayed by pumpkinseed at sites in the mid-range were intermediate between the extremes displayed by fish at core and frontal sites. These results suggested high plasticity in life history traits of these pumpkinseed across this fine-scale invasion gradient and was considered to be most likely due to responses to low intra-specific competition at the invasion front that had shifted selective pressures towards higher investment in somatic growth and reproduction.

INTESTINAL MICROBIOME BY HISTOCOPROLOGICAL ANALYSIS AND ITS CLINICAL SIGNIFICANCE

The histocoprological method was used to study stool samples from patients with gastrointestinal diseases to determine the presence of helminths and assess the state of the intestinal microbiome. The main complaints of patients were abdominal pain, bloating, constipation and diarrhea. The patients were divided into two groups: those who took antibiotics and those who did not. Evaluation of the microbial background by histological stool preparations was carried out in total, morphologically by the density of the location of microbial colonies and the intensity of their color. Helminthiasis was ascertained by the detection of fragments of small nematodes, larvae, their cuticles and eggs. A high percentage of depletion of the microbial background for drugs with a decrease in the number of microbial colonies was noted in the first group (65.1% of those who took antibiotics). Among children, a weakening of the microbiome was found in 42 (88% – who also took antibiotics), that is, more often. The negative effect of antibiotics and other pathogens on the microbial background required its correction with the appointment of sorbents and prebiotics. All examined patients were found to have helminthiases (nematodes and mixed forms). Deworming was carried out with nemazole at age-specific dosages. In 57 patients who re-passed the analysis, after complex treatment, there was a positive trend, clearly traced in feces preparations.

New method of poultry selection

Purpose: Install the influence of the «small diameter of the egg» on the living mass and the reproductive qualities of chickens of meat crosses and the quail of meat breeds.Materials and methods. The selection was carried out along egg production and mass of eggs and additionally on the average small diameter of 5 eggs by value of ≥0.5σ from the average for the herd, while the evaluation on the basis of the «small diameter of the egg» was carried out in chickens aged 238 days of life, quails — 70 days of life. Calculated the average for each female and the average for the herd. For further reproduction, chickens carrying eggs with a small egg diameter ≥0.5σ from the average for the herd. Studies were held in SibNIP on quail and on the courses.Results. In the initial period of the egg laying, the individual variability of the small diameter of the egg — more than 10% (in the future, the figure decreased). The close correlation rate of the small egg diameter in the first half of the egg laying with such at the end of the bird's operation period was revealed. It has been established that the large diameter of the egg has a positive reliable connection with a lively mass, but negative with egg production. The reliable correlation rate of the small diameter of the egg with a live weight at a 42-day age, as well as with the derivation of eggs. The inheritance coefficients of the small diameter of the egg are comparable to the inheritance coefficients of the mass of eggs and significantly exceed those for a large diameter of the egg. The selection according to the small diameter of the eggs by ≥0.5σ from the average for the herd led to the fact that the chickens of the experimental groups reliably exceeded the live weight in the SB level of 1.57%, in the line G8 — by 1.35%. The superiority of a lively mass of quail of experienced groups was more pronounced than that of the chickens: the Pharaoh breed — by 4.15%, the Texas white breed is 4.22%. In relation to the derivation of eggs, a similar trend was traced. The derivation of eggs in quails of experienced groups was more than 4.59–4.98%; Country, respectively, 4.57–5.22%. Egg production of females of comparable groups of both chickens and quail was almost on the same level, and the difference was unreliable.Conclusion. It was established that a new method of breeding the poultry of the meat direction of productivity allows without decreasing egg production to increase the living mass of chickens of meat crosses by 1.5%, rewinds of meat breeds — by 4%, the derivation of eggs, respectively, by 4–5%. The method is intended for early prediction of females productivity during breeding selection.

Microplastics reduce net population growth and fecal pellet sinking rates for the marine copepod, Acartia tonsa

Microplastics (<5 mm) are ubiquitous in the global environment and are increasingly recognized as a biological hazard, particularly in the oceans. Zooplankton, at the base of the marine food web, have been known to consume microplastics. However, we know little about the impacts of microplastics across life history stages and on carbon settling. Here, we investigated the effects of ingestion of neutrally buoyant polystyrene beads (6.68 μm) by the copepod Acartia tonsa on (1) growth and survival across life history stages, (2) fecundity and egg quality, (3) and fecal characteristics. We found that microplastic exposure reduced body length and survival for nauplii and resulted in smaller eggs when copepods were exposed during oogenesis. Combining these life history impacts, our models estimate a 15% decrease in population growth leading to a projected 30-fold decrease in abundance over 1 year or 20 generations with microplastic exposure. In addition, microplastic-contaminated fecal pellets were 2.29-fold smaller and sinking rates were calculated to be 1.76-fold slower, resulting in an estimated 4.03-fold reduction in fecal volume settling to the benthos per day. Taken together, declines in population sizes and fecal sinking rates suggest that microplastic consumption by zooplankton could have cascading ecosystem impacts via reduced trophic energy transfer and slower carbon settling.

Egg-trading worms start reciprocation with caution, respond with confidence and care about partners\u2019 quality

Conditional reciprocity (help someone who helped you before) explains the evolution of cooperation among unrelated individuals who take turns helping each other. Reciprocity is vulnerable to exploitations, and players are expected to identify uncooperative partners who do not return the help they received. We tested this prediction in the simultaneously hermaphroditic worm, Ophryotrocha diadema, which engages in mutual egg donations by alternating sexual roles (one worm releases’ eggs and the other fertilizes them). We set up dyads with different cooperativeness expectations; partners were either the same or a different body size (body size predicts clutch size). Large worms offered larger clutches and did so sooner when paired with large rather than small partners. They also released smaller egg clutches when they started egg donations than when they responded to a partners’ donation, fulfilling the prediction that a players’ first move will be prudent. Finally, behavioral bodily interactions were more frequent between more size-dissimilar worms, suggesting that worms engaged in low-cost behavioral exchanges before investing in such costly moves as egg donations. These results support the hypothesis that simultaneously hermaphroditic worms follow a conditional reciprocity paradigm and solve the conflict over sexual roles by sharing the costs of reproduction via the male and the female functions.

Development and performance of an automated fecal egg count system for small ruminant strongylids

An automated equine fecal egg count test, known as the Parasight System, was modified for use with small ruminants. Modifications included the introduction of a short centrifugation step in a floatation medium, an adjustment in pre-test sample filtering, and training of an image analysis-based egg counting algorithm to recognize and enumerate trichostrongylid eggs. In preliminary assessments, the modified method produced trichostrongylid egg counts comparable to manual McMaster analyses of the same samples from both ovine and caprine sources. The coefficient of determination (R2) for the linear correlation between McMaster and automated counts from these samples was 0.958, and there were no significant differences when comparing counts using feces from either sheep or goats. More extensive comparison utilized ovine samples split into three groups based on trichostrongylid egg content: Low (201–500 EPG), Medium (501–1000 EPG) and High (1001 or greater EPG). Each group contained 5 samples, each of which was used to produce individual slurries that were counted 8 times each using both McMaster and the automated method. This, again, showed no difference in accuracy between the techniques, but revealed significantly higher precision, as assessed by coefficients of variation (CoV), for the automated method for determining egg counts in the Low and Medium groups. The CoV of the McMaster method was 2.2, 2.5 and 1.3 times greater than the automated in the Low, Medium and High groups, respectively. Overall, the automated egg counting system showed good linear agreement with trichostrongylid egg counts determined with the McMaster method, and demonstrated significantly better precision. This technology reduces operator error and the results presented here illustrate its utility for determination of small ruminant trichostrongylid fecal egg counts.

Tiny, ornamented eggs and eggshell from the Upper Cretaceous of Utah represent a new ootaxon with theropod affinities

A new Cretaceous ootaxon (eggshell type) from the Kaiparowits Formation of Grand Staircase-Escalante National Monument is among a growing number of very small eggs described from the Mesozoic. Analyses of two partial eggs (~ 17.7 mm in diameter) and 29 eggshell fragments reveal that this new ootaxon exhibits nodose ornamentation with distinctive branching pore canals that open atop the nodes. Its two-layered microstructure consists of a mammillary layer and a continuous layer with rugged grain boundaries between calcite grains. Although the exact identity of the egg producer is unknown, the eggshell microstructure and small size is consistent with a small-bodied avian or non-avian theropod. The specific combination of small egg size, branching pores, two-layered microstructure, and dispersituberculate ornamentation preserved in this new ootaxon is unique among theropod eggs. This underscores that both eggshell and skeletal fossils of Cretaceous theropods can display a mosaic of transitional morphological and behavioural features characteristic of both avian and non-avian taxa. As such, this new ootaxon increases the diversity of Cretaceous eggs and informs our understanding of the evolution of theropod eggshell microstructure and morphology.

Population origin, maternal effects, and hydric conditions during incubation determine embryonic and offspring survival in a desert-dwelling lizard.

While the effects of incubation environment on embryonic development and offspring traits have been extensively studied in oviparous vertebrates, studies into how genetic inheritance (population origin), maternal effects, and incubation environment interact to produce varying phenotypes, are rare. To elucidate the interactive role of those three factors during incubation in shaping offspring phenotypes through hydric conditions, we conducted a fully factorial experiment [arid and semiarid populations × maternal dry and wet treatments (MDT and MWT) × embryonic dry and wet treatments (EDT and EWT)] with a desert-dwelling lacertid lizard (Eremias argus). Female lizards in dry conditions produced larger clutch sizes but smaller eggs. The incubation period and hatching success were significantly affected by embryonic but not by maternal moisture treatments. Eggs in the EDT hatched later than those in the EWT in both arid and semiarid populations. Hatching success was lower in EDT than in EWT in the semiarid population, but not in the arid population. Hatchlings from the EDT had a slower post-hatch increase in body mass than those from the EWT. EDT would decrease the survival rates of hatchlings in the semiarid population only. In addition, structural equation models revealed that population had a stronger effect on embryonic and offspring survival than maternal and embryonic moisture. Our study demonstrates locally adaptive strategies of drought resistance at multiple life-history stages in lizard populations from diverse hydric habitats and highlights the importance of genetic factors in determining embryonic drought resistance in oviparous lizards.

Cухі яєчні продукти та визначення їх безпечності та якості

With the invention of technologies for processing eggs into dry egg products (EP), the food industry was able to harvest the contents of eggs and store it for a long time, using it when the need arises, and not by the presence or absence of fresh eggs. Transportation was also simplified. Dry egg products include protein egg powder, dry egg yolk, dry mélange, as well as dry omelet - proteins and yolks mixed with whole or skim milk. They have a number of advantages in comparison with frozen egg products and even with fresh eggs. They can be stored for long periods outside refrigerators; they are conveniently used in the confectionery industry, in public catering, and for other culinary needs. Microorganisms do not develop in dry egg powder: they die during the drying of the egg mass. To obtain egg powder, whole eggs, as well as eggs with a damaged shell, but without signs of leakage, with a shelf life of not more than a day after laying, small eggs and frozen mélange after thawing are used. The approximate yield of egg powder with a moisture content of 17% is 27.4% of the used egg mass. The nutritional properties of the powder are almost the same as chicken eggs. The caloric content of egg powder is 542 kcal per 100 g of product - this is equivalent to eight large eggs. Dry EP are divided into two subgroups: for the industrial consumer (confectionery, oil and fat, bakery, meat and other industries) and for the household, as well as catering. Demand for these products is constantly increasing. The technological scheme for the production of dry egg products includes the following operations: receiving eggs, sorting, sanitizing breaking and releasing the eggs from the shell with or without separation into protein and yolk, thawing (using frozen egg products), filtering and mixing, homogenization, pasteurization, drying, packaging, transportation, storage. Dry egg products are stored at a temperature not exceeding 20 °C and a relative humidity of 75% for no more than 6 months, and at a temperature of 2 °C and a relative humidity of 60-70% for no more than two years. The article provides data on the quality indicators of dry egg products from various manufacturers of Ukraine. Organoleptic studies of dry egg products were carried out, and their physical and chemical parameters were determined. According to the results of studies of dry egg products, its qualitative and safe indicators were evaluated.

Pseudocapillaria (Ichthyocapillaria) bumpi n. sp. (Nematoda: Capillariidae) Parasitising West African Lungfish Protopterus annectens (Owen, 1839) (Lepidosireniformes: Protopteridae) in Mozambique and Its Phylogenetic Position Within Capillariid Nematodes.

Pseudocapillaria (Ichthyocapillaria) bumpi n. sp. (Nematoda: Capillariidae) is described from specimens infecting the digestive tract of the West African lungfish, Protopterus annectens (Owen) (Lepidosireniformes: Protopteridae). Nematodes were collected in Karingani Game Reserve, Southern Mozambique and studied using light microscopy; obtained sequences of the 18S ribosomal (18S rRNA) gene used for phylogenetic studies. The new species is assigned to Pseudocapillaria Freitas, 1959 by having a stichosome consisting of a single row of stichocytes and ventrolateral lobes on the male tail as well as by lacking spines on the specular sheath, caudal alae, a membranous caudal bursa, and a lateral expansion of the caudal end. It is also assigned to the sub-genus Ichthyocapillaria Moravec, 1982 by having a membrane between the ventrolateral lobes and by lacking a vulvar appendage. Pseudocapillaria (I.) bumpi n. sp. differs from its nominal congeners by having a comparatively large body size with relatively long spicule, bearing the thin membrane non-extending further than ventrolateral lobes in males and relatively smaller eggs without protruding polar plugs. It is the 20th species of the genus, the first from the Afrotropical Realm, and the first from any lungfish species. Phylogenetic analyses suggested that P. (I.) bumpi is deeply nested in a clade that associates species of the genera Pearsonema, Aonchotheca and Baruscapillaria.

Differences in prostaglandin e-related factors between silkworm strains [lepidoptera: Bombycidae] producing small eggs (d32) and giant eggs (d20)

Differences in prostaglandin e-related factors between silkworm strains [lepidoptera: Bombycidae] producing small eggs (d32) and giant eggs (d20)

Adaptive variation in the development of extraembryonic membranes of gekkotan embryos: A meta-analytical approach.

Highly mineralized rigid-shelled eggs characterize one lineage of gekkotans. In contrast, poorly mineralized flexible-shelled eggs characterize basal lineages of gekkotans and all other squamates. Low oxygen permeability of rigid-shelled eggs is associated with small eggs and hatchlings, and long incubation lengths compared to flexible-shelled gekkotan eggs. These features represent a demographic cost for species with rigid-shelled eggs. This cost is offset, at least in part, because mortality due to desiccation and predation is reduced for rigid-shelled eggs relative to flexible-shelled eggs. Developmental traits may also compensate for the low oxygen permeability of rigid-shelled eggs. Oviposition, for example, occurs at earlier developmental stages for gekkotans with rigid- versus flexible-shelled eggs. Such early oviposition facilitates development because eggs move from the relatively hypoxic oviduct to the much better oxygenated nest environment. In this study, I tested the hypothesis that the growth of the yolk sac (YS) and chorioallantoic membrane (CAM) of gekkotans with rigid-shelled eggs is initiated and completed earlier than those of gekkotans with flexible-shelled eggs. I measured the surface area of eggs covered by the YS and CAM from oviposition to hatching and determined which of four nonlinear models provide the best fit for growth curves. I also compiled a data set on embryonic metabolism of gekkotans and other lizards in order to place growth of the YS and CAM in the context of energy utilization of lizard embryos overall. Growth of the YS and CAM of gekkotans with rigid-shelled eggs is accelerated relative to that of gekkotans with flexible-shelled eggs and may serve to separate the cost of YS and CAM development from that of the embryo itself. Adaptive variation in YS and CAM development may extend to birds, crocodilians, and turtles as they also exhibit life history variation that affects oxygen availability to embryos during development.

Management and biosecurity practices by small to medium egg producers in Scotland

ABSTRACT 1. Information about procedures and biosecurity practices used by small and medium egg producers (SMEPs) is scarce. Anecdotal evidence suggests that biosecurity in such enterprises may be poor, as personnel and equipment move freely between sites and this may be compounded by personnel working on commercial units who keep their own poultry. 2. To fill this knowledge gap, a questionnaire was designed and implemented targeting SMEPs in Scotland. Small enterprises were defined as egg producers that have ≥50 laying hens but <350 laying hens; while medium enterprises were defined as egg producers that have ≥350 laying hens but ≤32 000 laying hens. The questionnaire consisted of a total of 56 questions divided into multiple sections, covering the characteristics of the primary keeper, location of the enterprise and size of the flocks, husbandry, marketing of products and health/biosecurity. 3. The questionnaire was posted to 375 holdings at the beginning of March 2017 and the survey remained open until the end of May 2017. In total 90 questionnaires were received by the cut-off date of which 76 questionnaires were from SMEPs. Forty were small enterprises and 36 were medium enterprises. For three questionnaires, it was not possible to identify the enterprise type. 4. Differences were observed between SMEPs in terms of reported biosecurity and management practices, with medium enterprises reporting the adoption of more biosecurity measures than small enterprises. Furthermore, SMEPs behave differently from backyard poultry keepers and large commercial companies in terms of disease risk. 5. In conclusion, it is important to ensure that SMEPs are considered in contingency plans and disease control programmes and that engagement with them is promoted so that the uptake of relevant information, such as awareness of disease control programmes, is optimised.

Kondisi fisik kerabang telur ayam ras petelur cokelat di Pasar Pinasungkulan Manado

THE EGGSHELLS’ PHYSICAL CONDITION OF BROWN CHICKEN EGGS AT PINASUNGKULAN MARKET MANADO. A study was conducted to examine the eggshells’ physical condition of fresh-brown chicken eggs (table eggs) at the Pinasungkulan market, in Manado city. The variables taken were egg weight in three general size categories (small, medium and large) and eggshells condition (cleanliness, smoothness/ texture and color). The averages egg weight of the fresh-brown chicken eggs in three size categories made by egg sellers were 51.57 grams for small size eggs, 62.03 grams for medium size eggs and 70.68 grams for large size eggs, respectively. The eggshells’ condition values of fresh-brown eggs were from slightly clean to clean (3.58 - 3.82) on cleanliness; from slightly smooth to smooth (3.64 - 3.85) on texture; and from slightly faded to brown (2.79 - 3.85) on color. T-test paired was showed that the eggshells’ physical condition of small size eggs was better than that of medium size and large size eggs seen from their eggshells’ cleanliness, smoothness/ texture and their color, It found also that the egg seller in Pinasungkulan Market, Manado had not been carefully made and well standardized the egg size or egg weight categories.Keywords: brown eggs, eggshell, cleanliness, smoothness/texture, color.

Nest predation of an African Paradise Flycatcher (Terpsiphone viridis) by an Olive Sunbird (Cyanomitra olivacea)

Nest predation is the dominant cause of nest failure in the tropics. However, our knowledge about tropical nest predator identity and community structure is still quite limited. On 9 January 2019, we video-recorded an Olive Sunbird (Cyanomitra olivacea) removing and flying off with an egg from an African Paradise Flycatcher (Terpsiphone viridis) nest in the East Usambara Mountains, Tanzania. This observation is surprising because the Olive Sunbird is a specialized nectarivore. Nectar, however, is a poor source of nitrogen and cannot meet the protein requirements for nectarivores. We hypothesize that bird eggs are a potential source of protein for selected long-billed sunbird species—species that can grasp and handle small bird eggs. Our observation of nest predation by an Olive Sunbird adds a heretofore unknown behavior to nectarivores in general and to sunbirds specifically.

First record of the runt eggs of the Imperial Cormorant &lt;em&gt;Phalacrocorax atriceps&lt;/em&gt; and the Rock Shag &lt;em&gt;P. magellanicus&lt;/em&gt; in the San Jorge Gulf, Argentina

[The present study describes for the first time the abnormally small (runt) eggs of the Imperial Cormorant (IC) and Rock Shag (RS) observed during the breeding seasons of 1990/91, 1992/93, 1993/1994, 1994/95 and 1996/97 on the Isabel Island (45°07’S, 66°30’W) and the Galiano Island (45°06’S, 66°25’W), located in the northern San Jorge Gulf, Argentina. The frequency of occurrence of IC runt eggs was 0.2% (n = 995) and their average volume was significantly lower than normal eggs (t = 17.4, P&lt; 0.0001, n = 824). The runt eggs were more spherical than those of normal size (Shape Index: 70.6 vs 64.5 for CI and 74.9 vs 63.9 for RS). The volume of the RS runt egg was 21.1 cm3. The cutoff between normal and runt eggs is between 30 and 35 cm3 for the IC and between 24 and 30 cm3 for the RS. The volume of the runt egg was 42.1% and 53.4% the average volume of the two remaining eggs of the clutch for CI and RS, respectively. None of the consistently observed IC runt eggs hatched and it seems that none of the eggs showing a volume lower than the proposed cutoff is destined to hatch]. [Article in Italian]

The ctenophore &lt;i&gt;Beroe&lt;/i&gt; cf. &lt;i&gt;ovata&lt;/i&gt; in the Caspian Sea. The beginning of a new stage in the evolution of the Caspian ecosystem?

Aim. Analysis of the first data regarding the arrival of the predatory ctenophore Beroe cf. ovata in the Caspian Sea and assessment of possible effects of its introduction for the Caspian ecosystem.Material and Methods. The material was obtained in the deep-water region of the western shelf of the middle Caspian Sea in the first ten days of October 2020. Zooplankton samples were collected using a Juday plankton net (0.1 m2 opening, 180 μm mesh size). Large ctenophores were collected using a big cone plankton net (CB) with a 0.5 m2 opening, 500 μm mesh size. Samples were taken at five stations in the 0-40 m layer. Combs larger than 5 mm were counted and measured on board the ship. The number and size of small ctenophores, larvae and eggs were determined in zooplankton samples fixed with formalin to a final concentration of 4%.Results. The presence of a new alien Beroe cf. ovata was recorded in the Dagestan shelf waters of the Caspian Sea in the beginning of October 2020. The average number of Beroe cf. ovata for five stations was 22 ind/m2 and the biomass was 6.15 g/m2. Larvae and small individuals from 5 to 20 mm in size predominated. Mnemiopsis leidyi was absent in the area investigated. The structure of mesozooplankton was dominated by the small copepod Acartia tonsa, which accounted for 92% of the zooplankton community and 78% of its biomass.Conclusion. The size structure of the B. ovata population with a predominance of larvae and small individuals indicates a recently completed breeding cycle and adaptation of the ctenophore to the conditions of the Caspian Sea. The first impacts of the new invasive ctenophore on the population of M. leidyi were demonstrated. This event may be the beginning of a new stage in the evolution of the Caspian Sea ecosystem and the restoration of its bio resources affected by the invasion of Mnemiopsis leidyi. The structure of mesozooplankton with total dominance, in abundance and biomass, of the small copepod Acartia tonsa did not differ from that in the previous period, indicating that the Caspian zoocenosis did not respond to the short-term reduction of the impact of M. leidyi. A brief analysis of the history of the introduction of ctenophores to the Black and Caspian Seas is presented and their impact on ecosystems and biological resources of these seas is studied. Based on longterm observations of the invasive ctenophores' interactions in the Black Sea, the possible outcomes of the penetration of Beroe cf. ovata in the Caspian Sea are discussed.

Egg morphology may underpin the successful distribution of large branchiopods in temporary waters

Invertebrate species from temporary aquatic ecosystems produce resistant dormant stages (i.e. eggs) that accumulate in long lived mixed egg banks in the sediment. These dormant eggs not only bridge dry phases but also act as propagules for passive dispersal. Large branchiopod crustaceans (e.g. Notostraca, Anostraca and Spinicaudata) produce dormant eggs of variable shapes, sizes and external ornamentation. While these characteristics are often species-specific and have been used in taxonomy, little is known about their ecological significance, for example, their contribution to colonisation success. Here, we explore the idea that variation in egg morphology may impact vector-mediated dispersal and colonisation success of large branchiopods. We studied egg banks from 98 temporary waters across the Northern Cape, South Africa and assessed whether distribution and densities of eggs carried a morphological signal. Overall, our results imply that both size and external structures may impact dispersal to and successful colonisation of temporary waters by large branchiopods. Specifically, our results show that small propagules ( 400 µm), smooth eggs and medium sized (200–300 µm), polygonal eggs were most widely distributed. Ultimately, our approach provides insight in actual colonisation success of species with different egg types and not only on the propensity of the eggs to be picked up and transported by vectors.

THE RELATIONSHIPS BETWEEN SELECTED EGG QUALITY TRAITS AND EGG SIZE

The relationships between selected egg quality traits and sizes of eggs were studied in a part of the South Western Nigeria with a view to egg marketers and to investigating the variation in egg quality egg size changes. 320 market eggs and 40 freshly-laid eggs collected from a poultry farm were used for the study in which egg weight, specific gravity, haugh units, percent yolk, percent albumen, shell thickness and percent shell measurements were obtained. Quality traits for small and large-sized eggs were observed as: Egg Weight (53.34 vs 67.07 g), shell thickness (0.375 mm Vs 0.377mm), Percent shell (9.60 Vs 8.94), specific gravity (1.073 1.069), haugh unit (67.65 Vs 61.38), Percent albumen (62.28 Vs 64.35) and percent yolk (28.13 Vs 26.71), respectively. Egg size was observed to correlate positively with percent albumen (P&lt;0.05) and shell thickness. It, however, correlated negatively with all other quality traits measured. Regression models between eggsize and the various quality traits were also established. It was concluded that small-sized eggs could be of better quality in terms of the traits measured.

Heavy decline of the largest European Arctic Skua Stercorarius parasiticus colony: interacting effects of food shortage and predation

ABSTRACT Capsule The number of breeding pairs of Europe’s largest Arctic Skua Stercorarius parasiticus colony at Slettnes, Norway, showed a dramatic decline of at least 50% over two decades, with food shortage in four years and increasing predation by Red Fox Vulpes vulpes leading to total breeding failure in five out of six recent study years. Aims To document the decline of Europe’s largest Arctic Skua colony and quantify bottom-up and top-down effects on reproduction. Methods We compared nest counts between 1997–1998 and 2014–2019 and collected data on egg size, clutch size and nest success for all years, and adult body mass, nest attendance, at-sea activity, aggressive nest defence, Red Fox Vulpes vulpes encounters, daily nest survival and adult survival for 2014–2019. We deployed nest cameras to identify predators in 2018–2019. In addition, we developed a demographic model to estimate the fecundity required for a stable population. Results A higher proportion of time spent at sea, small eggs, low adult female body mass and indirect assessment of foraging fish availability suggested food shortages in four of six recent study years. At the same time, nest predation by Red Foxes, the likely predator involved, increased during the six-year study. The combined effects of food shortage and nest predation led to total breeding failures in 2017–2019. Conclusion We provide evidence of both bottom-up (food shortage) and top-down (predation) effects on reproductive investment and hatching success in this colony. The reproductive output in recent years is far too low to sustain a stable population. The severe decline of the Arctic Skua colony at Slettnes fits reported trends for this species across most of its European breeding range, as well as for its important host species, the Arctic Tern Sterna paradisaea and the Black-legged Kittiwake Rissa tridactyla.