Observations on the size, dry weight and energy content of the eggs of some demersal fish species from British marine waters

The diameters, dry weights and calorific value of the eggs of seven gadoid species (cod, Gadus morhua , haddock, Melanogrammus aeglefinus , whiting, Merlangius merlangus , Norway pout, Trisopterus esmarkii , lythe. Pollachius pollachius , saithe, P. virens , ling. Molva molva ) and one pleuronectid (plaice, Pleuronectes platessa ) were measured. Ling eggs contain an oil globule; the eggs of the other species do not.
Preservation in formaldehyde solution caused a small (<4%) reduction in egg diameter but a large (15–30%) reduction in dry weight. There was no significant difference between the dry weights of unpreserved eggs weighed after (a) oven-drying at 60° C or (b) freeze-drying. Equations relating the dry weight of unpreserved eggs to unpreserved diameter and to preserved diameter are given for six species, and general equations that may apply to all North Sea gadoids whose eggs lack an oil globule are calculated. The calorific values of the dried, unpreserved eggs of all species except ling were similar (mean 23.19 kJ g⁻¹, S.D. 1.50) but the value for ling was higher (mean 26.92 kJ g⁻¹, S.D. 2.29). The estimated energy content (kJ 1000 eggs⁻¹) of eggs of each species are tabulated.     

Hatching time in spherical,pelagic, marine fish eggs in response to temperature and egg size

Synopsis The relationship between egg diameter ((, mm), temperature (T, °C) and egg development time to hatching (D, in days) was established for approximately spherical, pelagic marine fish eggs as log₁₀D = 7.10 + 0.608 log₁₀ – 4.09 log₁₀ (T + 26), which explains 82% of the variance of a data set of 140 cases, covering 84 species of teleost fishes, for temperatures from 2.8 to 29.5° C and eggs of 0.6 to 3.4 mm diameter.From this relationship it appears that temperature has 4.7 times as much effect on development time as egg diameter when all variables are expressed in standard deviation units. A discussion of these and related factors is given.ICLARM Contribution No. 308.     

Bromophenol accumulation and sediment contamination by the marine annelids Notomastus lobatus and Thelepus crispus

The occurrence of bromophenols in Notomastus lobatus and Thelepus crispus and associated sediment and porewater was determined. 4-Bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol were identified in N. lobatus with the highest concentrations occurring in the anterior and posterior abdomen and substantially less in the thorax (345, 209, and 6.6 μg/ml of worm, respectively). The concentration of dibromobenzyl alcohol was highest in the tail (last 15 setigers) of T. crispus (1.02 mg/ml of worm), but did not differ among body parts as the bromophenols did in N. lobatus. Concentrations in sediments were significantly reduced from those in the worms and decreased from the inner burrow lining out to 5 cm from N. lobatus burrows. Similarly for T. crispus, concentrations of dibromobenzyl alcohol in the surrounding sediments and porewater were low and increased with proximity to the burrow. For both species, concentrations in surface sediment (upper 1 cm) did not differ from those at 6 cm depth. Several lines of evidence indicate that these compounds are produced by the worms and hence their presence in sediments is derived from the worms. The contamination of sediment by these bromophenols has important implications for the structure and activities of benthic-associated communities.     

An experimental approach to energy balance in a microbial process using the dichromate oxidation method

The dichromate oxidation method was used to determine the number of reduction equivalents of organic substrates, cell mass and extracellular products in aerobical batch cultivations of Bordetella pertussis. The reduction equivalents obtained by this method were transformed into caloric values based on the fact that heat of reaction per equivalent oxygen consumed by oxidation of different organic substances is relatively constant. According to the law of conservation of energy a complete energy balance associated with an aerobical microbial process was developed using the caloric values mentioned above.     

Spectroscopic properties of bulk and dichromate oxidation resistant soil organic matter from an anthroposequence in a Mediterranean environment

The shallow soils of Pianosa—a small calcareous island in the Mediterranean Sea, facing Tuscany, central Italy—developed under the same pedogenic factors with the exception of vegetation and, in the last two centuries, human impact. Originally, they were covered by “macchia,” a tangled mix of bushy species, or, in a few more fertile sites, by Quercus ilex L. Currently there are six land uses on the island: (1) pristine macchia, (2) groves of Olea europaea L. totally reinvaded by macchia, (3) degraded residual thickets of Q. ilex, (4) cropland, (5) recently abandoned pastures, and (6) stands of Pinus halepensis Mill. The related soils were analysed by solid-state cross polarisation/magic angle spinning ¹³C-nuclear magnetic resonance (NMR) to compare the spectroscopic properties of their organic pool. The prevalence of O-alkyl C over other C forms is evident in all cases, while there is large variability with respect to the alkyl C to aromatic C ratio between both the different soils, and the horizons of a same soil. On the whole, the results show that on Pianosa Island, human impact has profoundly altered not only the amount but also the quality of soil organic matter (SOM). The SOM residual of the dichromate oxidation in the Walkley–Black method—a widely used method to measure soil organic C—was also analysed by NMR. It comprised almost exclusively alkyl C and aromatic C, as a result of the removal of carbonyl and O-alkyl C. Most of the aromatic C seems to belong to charcoal.     

What the hen can tell about her eggs: egg development on the basis of energy budgets

By a simple model involving the state variables size and storage, it is possible to describe a wide variety of observations on the feeding, growth, energy storage and reproduction of animals. The model is based on the assumption that reproduction, growth as well as maintenance depend on the stored energy only and not directly on feeding. If an egg is thought of as a non-feeding animal, the model predicts the respiration ontogeny and growth of the embryo inside the egg. These predictions seem to hold well for published data on the development of eggs of fish and ratite, precocial and altricial birds. The latter two are known to follow different respiration ontogenies, but both are described well, differing only in one (compound) parameter value. The model explains why the incubation times of eggs of different species tend to increase linearly with egg size to the power 1/4, and why kiwis and petrels, which lay relatively large eggs, have to brood them much longer than larger birds with eggs of the same size. Conversely, it explains why the small eggs of the (parasitic) European cuckoo, hatch earlier than the still smaller eggs of their tiny hosts.Furthermore, it has been shown how the maintenance rate constant, which frequently appears in the microbial literature, can be obtained from measurements on the respiration and weight ontogeny in embryos, so linking independent lines of research. Application of the model shows an increase of the maintenance rate constant from bacteria, crustaceans, up to fish and birds, and a decrease from bacteria to green algae, suggesting lines of evolutionary development.     

Changes in egg colour, egg weight and oviposition rate with the number of eggs laid by wild females of the small heath butterfly, Coenonympha pamphilus

ABSTRACT. 1. The colour of eggs laid by individual Coenonympha pamphilus (L.) (Lep., Satyridae) females changed over their lifespan. The first laid eggs were green, but after having laid about 100 eggs, females laid only yellow eggs.
2. By following females in the field, or by capturing wild females, and noting the colour of their eggs, it was established that younger females showed higher oviposition rates and laid heavier eggs than older females.
3. Hence, wild C.pamphilus females are unable to sustain a constant egg production by extracting amino acids or any other nutrients from nectar. We hypothesize that this is a general phenomenon in nectar feeding butterflies.
4. The egg colour did not seem to match the colour of the substrate on which the female chose to deposit the egg.     

Ultraviolet reflectance of great spotted cuckoo eggs and egg discrimination by magpies

Hosts of obligate avian brood parasites use visual cues to distinguishbetween their own eggs and those of the parasite. Despite majordifferences between human and bird vision, most previous studieson cuckoo egg mimicry estimated color matching based on humancolor vision. Undetected by humans, ultraviolet reflectance(UVR) may play a previously ignored role for rejection behaviorin avian brood parasite systems. We explored this possibilityby manipulating UVR of great spotted cuckoo Clamator glandariuseggs and assessing the response of magpie Pica pica hosts. Wecoated cuckoo eggs with an ultraviolet (UV) light blocker thatreduced UVR but left the human visible reflectance (400–700nm) unaltered. The first control treatment also coated the eggsbut did not alter their reflectance. A second control groupof cuckoo eggs was maintained uncoated to control for handlingeffects on magpie discrimination. We artificially parasitizeda third of a breeding magpie population with each type of experimentalegg and studied the rejection of cuckoo eggs. We failed to findsignificant differences between rejection rate of cuckoo eggswith and without reduced reflectance in the UV region. Our resultsindicate that artificial reduction of UVR of cuckoo eggs doesnot affect the probability of ejection by magpie hosts.     

Cleavage inhibition in marine eggs by puromycin and 6-dimethylaminopurine

The possibility is discussed that puromycin may not inhibit cleavage in marine eggs solely by inhibiting protein synthesis. It is suggested that part of the effect of puromycin is through 6-dimethylaminopurine (DMAP) (the purine component of puromycin) a potent cleavage inhibitor which appears to enhance protein synthesis in sea urchin eggs.     

Comparative estimations of the energy content of fish tissue from bomb calorimetry, wet oxidation and proximate analysis

SUMMARY. Four methods were used to determine the energy content of somatic tissues of Perca fluviatilis . Two forms of direct calorimetry (both adiabatic and non-adiabatic) and wet (dichromate) oxidation gave similar results. When energy contents were calculated from proximate analysis using accepted conversion factors (9.45 cal mg⁻¹ for lipid, 5.65 cal mg⁻¹ for protein) results were higher than those from the other methods. The discrepancy was eliminated when a lower, directly determined energy content for the extracted lipid fraction was used.
Some historic and technical aspects of the comparison are discussed.     

Bacterial abundance in relation to surface area and organic content of marine sediments

Based on direct measurements on surface sediments collected from an intertidal salt marsh, a positive relationship was demonstrated between bacterial abundance and specific surface area of sediment. While this relationship has been postulated previously, this is the first direct confirmation that it holds over a wide range of sediment types. A laboratory experiment was conducted to determine the effects of specific surface area, distribution of surface area, and organic loading on bacterial colonization. Model sediments included angular silica particles, kaolin, and spherical glass beads, used singly or in mixtures. Organic loading resulted in substantial enhancement of bacterial colonization. Distribution of surface area controlled by textural, shape, and sorting, had a complex effect, with glass bead sediments generally supporting better colonization than silica particles or kaolin. The effect of specific surface area was noted only in restricted comparisons of similarly shaped glass beads.     

Identification of pelagic eggs of marine fishes by rearing method

Pelagic fish eggs are usually fixed by formalin solution just after collection in the field. Most of these eggs are difficult to be identified to species, because only limited characters are available for identification and considerable changes in structures take place with fixation. In this study, species names of formalin fixed eggs were estimated by comparing their egg diameters and the diameter and number of oil globules with those of the fresh ones identified by the rearing method. Materials were collected in Wakasa Bay in May, August, and October, 1979–1982. Fresh eggs were classified into 40 species or types by the rearing method, but fixed eggs were divided into only 24 types. Comparison of fresh and fixed eggs revealed that 7 out of 24 types of fixed eggs were referable to species, and 13 types were composed of species groups. The rearing method is surely a useful step in indentifying species names and/or species types of fixed eggs.     

Composition and energy density of eggs from two species of freshwater turtle with twofold ranges in egg size

Lipid, protein, ash, carbohydrate and water content and energy density of eggs were measured from different clutches over a range of egg size in two species of freshwater turtle. Dry egg contents consisted of protein (54-60%), lipid (25-31%) and ash (5-6%) while carbohydrate was found to be negligible (<1%). Albumen consisted principally of water ( approximately 98%), and the dry component was composed of protein (47-51%), ash (19-26%) and lipid (18-21%), but contributed only a small amount ( approximately 2%) to overall dry egg contents. Energy density of dry albumen (15-17 kJ/g) was significantly lower than for dry yolk (26-27 kJ/g). Yolk consisted of 62-70% water, and the dry component was composed of protein (54-61%), lipid (25-31%) and ash (5-6%). Fractional concentrations of water, lipid, protein and ash and energy density remained constant over the range of egg size in Emydura signata eggs. In contrast, an increase in the yolk to albumen ratio and a decrease in water content of yolk as egg size increased caused the composition and energy density of Chelodina expansa eggs to vary systematically with egg size.