Seasonal changes in flesh weight and biochemical composition of mussels (Mytilus edulis L.) in the Conwy Estuary,North Wales

Sublittoral Mytilus edulis L. from natural mussel beds of the Conwy Estuary fishery exhibited an annual cycle of dry flesh weight, biochemical composition, and caloric value during 1971–1974.Mean percentage values of the main components of dry flesh, with seasonal extremes in parentheses, were: protein 58.7 (46.4–73.1), carbohydrates 22.5 (4.1–36.7), lipids 7.0 (3.9–9.6), and ash 11.8 (8.8–17.2). The mean caloric values of dry flesh were 5.57 kcal/g ash-free and 4.92 kcal/g ashinclusive.Individual dry flesh weight was highest in summer and autumn, when protein and carbohydrate were maximal, and decreased through the winter to a post-spawning minimum in spring. Weight loss in winter resulted from rapid utilization of carbohydrate (glycogen) reserves and a depletion of both protein and lipid content. It is considered likely that mussels were then stressed by food shortage at the time when metabolic demands, due to gametogenesis, were highest.During the six main fishing months, October to March, the average weight of dry flesh fell by 30–50 % and caloric content by 35–45 %. The likelihood of similar losses in cultivated mussel stocks is indicated and the need for comparable information in fishery management is emphasized. The extent to which predators compensate for these seasonal changes in prey quality also requires examination.     

Changes in biochemical composition and energy utilization during metamorphosis of leptocephalous larvae of the bonefish (Albula)

Synopsis Energy use and changes in whole-body content of lipid, protein, nitrogen, carbohydrate and ash were followed during metamorphosis of leptocephalous larvae of the bonefish (Albula). During metamorphosis, which requires about 8–12 days, larvae lost about 3–4 mg of lipid, or about 50% of the total lipid content. Lipid levels, calculated on a dry weight basis, showed no discernible trends, with values ranging from 138–185 mg (g dry wt)^–1. Protein content was 8.4 mg per larva and showed no significant change. However, protein levels increased from 147 to 329 mg (g dry wt)^–1. Nitrogen content decreased slightly from about 3.5 to 3.2 mg per larva. A comparison of protein and nitrogen values, expressed as % dry weight, showed that, in larvae which were just beginning to metamorphose, 70% of the total nitrogen was non-protein nitrogen (NPN). The NPN decreased to 58% of the total nitrogen towards the end of metamorphosis. Carbohydrate content fell from about 3.5 to 0.6 mg per larva, which represents an 83% loss. Carbohydrate levels also fell from about 81 to 32 mg (g dry wt)^–1. In addition, most of the carbohydrate appears to be bound to protein. Ash content decreased by 52%, from 4.6 to 2.2 mg per larva. Caloric content fell slightly from about 182 to 141 calories per larva whereas caloric density showed no discernible trends, with values ranging from 4.180 to 4.725 kcal (g dry wt)^–1. These results indicate that metamorphosing leptocephali, which apparently do not feed, probably derive most of their energy requirements from metabolizing endogenous lipid and carbohydrate stores formed during the premetamorphic interval.     

Organic,inorganic, and caloric composition of eggs,pentaculae, and adults of the brooding sea cucumber Cucumaria curata cowles (Echinodermata: Holothuroidea)

Levels (percentage composition) of water, ash, carbohydrate, lipid, protein, and calories were determined for eggs, pentaculae, and adults of the sea cucumber Cucumaria curata Cowles. Component contents (μg/individual) were calculated for eggs and pentaculae. During the 28 days of development to hatching, the large yolky eggs gain water and ash, the total dry weight increasing from 169 to 190 μg/egg during embryogenesis. There were no statistically significant changes in lipid, protein, and caloric contents during embryogenesis, but carbohydrate decreased by 0.82 μg/egg.The decrease in carbohydrate is sufficient to account for estimated embryonic energy requirements. Based on the utilization of carbohydrate, embryos of C. curata show a nutritional pattern similar to that of the planktonic embryos of sea urchins and different from that of embryos developing from terrestrial eggs, freshwater eggs, and planktonic and demersal marine eggs.Although broods varied widely in egg number and mean egg dry weight, C. curata gives eggs which contain a constant proportion of organic components.Levels of ash, water, and protein in the adults exceeded those in the pentacula, and lipid comprises a much smaller proportion of the adult body than it did of the pentacula.     

The biochemical and energetic composition of somatic body components of echinoderms from the northern Gulf of Mexico

• 1.1. The biochemical and energetic compositions of the somatic body components of seven species of asteroids, one ophiuroid, and four echinoids from the northern Gulf of Mexico (30–95 m depth) were ascertained.
• 2.2. Levels of ash were high (68.5–90.8% dry wt) in all body-wall tissues, with the exception of the asteroid Echinaster modestus (51.6% dry wt). Levels of ash were low in the pyloric cecae (nutrient storage organ) of asteroids (4.6–30.8% dry wt).
• 3.3. Levels of lipid (8.1–34.5% dry wt), soluble protein (15.9–28.7% dry wt), and insoluble protein (18.1–48.6%, dry wt) were high in the pyloric cecae of all asteroids, but generally low in ophiuroid and echinoid body-wall tissues. High protein levels (28.5–44.5% dry wt) in the body-wall of the asteroids Echinaster modestus and Anthenoides pierceisuggest it may play a role in nutrient storage.
• 4.4. All somatic tissues contained low levels of carbohydrate (0.2–1.4% dry wt).
• 5.5. Levels of energy in pyloric cecal tissues (12.99–26.05 kJ/g dry wt) were 4–8 times higher than in echinoderm body-wall tissues (2.92–11.91 kJ/g dry wt).
• 6.6. The biochemical and energetic compositions of echinoderms from the northern Gulf of Mexico are similar to those of species from other latitudes and depths.

     

A seasonal study of the red seaweeds Solieria tenera and three species of Gracilaria from Jamaica

Three species of Gracilaria viz G. cervicornis, G. domingensis, G. verrucosa and Solieria tenera (Gigartinales, Rhodophyta) have been studied for their monthly variation in dry wt yields, ash, soluble carbohydrate, protein, lipid and insoluble carbohydrate contents for one year. The dry wt yields were higher in G. domingensis. Soluble carbohydrate and ash contents showed an inverse relationship in all the species. Protein content was lower, below 5% of the dry wt for all the species. A comparison of protein:carbohydrate ratios showed a similarity between morphologically similar G. domingensis and G. cervicornis in that there was less variation in the ratio. From this, it is assumed that flattened morphology probably is more efficient in maintaining nutrient balance to keep up the growth rates.     

Temporal and morphological factors related to mineral composition in Myriophyllum heterophyllum michx

The emergent floral stem, apex, sub-apex, mid-stem, lower stem, and roots of Myriophyllum heterophyllum Michx were analyzed for ash, P, Na, K, Ca, Mg, Fe, Mn, Zn, Cu and Pb. Samples were collected 14 times from June 1979 through July 1980 from Lake Winnipesaukee, New Hampshire, U.S.A.The plant segments sampled differed significantly in mineral content, but seasonal pulses for each mineral were usually in synchrony between the different segments sampled. Sodium (range, 0.8–2.7% dry wt.) and potassium (range, 1.4–3.3% dry wt.) were the dominant elements in the submersed stem. The dominant element in the floral spike was Ca (range, 2.4–4.1% dry wt.) and in the roots was Fe (range, 2.8–8.0% dry wt.). Sodium concentrations were greater in the submersed stem (range, 0.8–2.7% dry wt.), relative to the roots (range, 0.5–0.9% dry wt.) and flora stem (range, 0.3–1.1% dry wt.). Lead concentrated in the roots significantly more (range, 0.0040–0.0115% dry wt.), than in other plant parts (range, 0–0.0037% dry wt.).The submersed stem had spring or summer peaks in ash, P, Na, K, Ca, Mg, and Zn content, whereas Fe and Mn exhibited late winter to early spring peaks. No evidence of nutrient storage during the non-growing season was evident in the segments sampled. Explanations for the seasonal and morphological differences observed are presented.     

Carbon, nitrogen and caloric content of eggs, larvae, and juveniles of the walleye pollock, Theragra chalcogramma

Measurements of dry weight (wt), carbon (C), nitrogen (N) and calories were made on walleye pollock eggs (0.24 mg, 35.3% C, 8.3% N, and 4.6 kcal g⁻¹ dry wt), larvae (0.16 g, 42.9% C, 11.1% N and 5.1 kcal g⁻¹ dry wt) and juveniles (22.4 g, 47.2% C, 9.0% N and 5.6 kcal g⁻¹ dry wt). For juvenile fish (9–360 g wet wt) the measured values were related to dry weight and Fulton's condition factor index (CFI) by regression models. The CFI was a better predictor of body composition than dry weight. As CFI improved from a minimum starvation level of 0.42 to a maximum of 1.16, body caloric content, percentage C, and the C/N ratio increased (kcal g⁻¹ dry wt = 4.4 CFI + 1.7, percentage carbon = 49.7 CFI^0.5, C/N ratio = 5.0 CFI + 0.9), while percentage N and percentage ash decreased (percentage N =−3.5 CFI + 12.1; percentage ash = 9.1 CFI^−1.4). The results of this study suggest that seasonal C, N and caloric content of young pollock can be estimated from measurements of Fulton's condition factor index.     

Biomass and elemental composition (C.H.N.) of the rotifer Brachionus plicatilis cultured as larval food

Changes in dry weight, carbon, nitrogen, hydrogen and ash content of the rotifer Brachionus plicatilis were investigated during population growth in culture. Also caloric equivalent was estimated from carbon content. Body dry weight and weight of C, N, and H increased with increasing the egg/female ratio of the population, while ash content remained constant. As percentage of dry weight, C content increased with fecundity, H and N remained constant and ash content decreased. The caloric equivalent ranged from 1278 µcal to 4406 µcal for rotifers from 314 µg to 846 µg of dry weight.     

The biochemical composition of krill, Euphausia superba Dana,from South Georgia

Krill, Euphausia superba Dana, sampled from waters around South Georgia in 1978 contained 10–11% protein, 2–6% lipid, 0.3–0.6% carbohydrate, 2% chitin, and 3–4% mineral ash (all mean values, % fresh weight).Lipid content varied greatly with sexual maturity: males contained 2–4% lipid, immature animals 4% (both increasing to 5–6% later in the season) and mature females 5–6% (although some contained as much as 9%). Gravid females lost ≈60% of their lipid at spawning, and a biochemical estimate of fecundity gave values in the range 7000 to 15 000.The major lipid classes were phospholipid, triacylglyceropl, and free sterol, and there was 1–2% wax ester. The mean pigment content was 21.5 μg/g fresh weight. Triacylglycerol fatty acids were low in polyenoic acids and contained up to 4% phytanic acid; compositions were variable and showed the probable influence of dietary input. Phospholipids were rich in polyenoic acids, especially 20 : 5ω3 and 22 : 6ω3, and usually had 18 : 1ω7 > 18 : 1ω9. Ovarian triacylglycerol contained almost no polyenoic acids, but ovarian phospholipid was fairly unsaturated.These results are discussed in relation to the Antarctic environment, and compared with the results of previous work on caridean decapods.     

Changes in composition of harvested mushrooms (Agaricus bisporus)

Post-harvest changes in the biochemical composition of the mushroom were studied. Non-structural polysaccharide was found at levels greater than 10% dry wt in the fresh mushroom. After 4 days storage, the level had decreased to below 5% dry weight. The polysaccharide appeared to contain only glucose residues joined by α-1,4 and α-1,6 linkages. The chitin content of cell walls increased by ca 50% during 4 days storage, while cell wall glucan decreased. There was a large increase in urea content.     

Chemical composition of antarctic zooplankton during austral fall and winter

Water level, ash content, proximate (protein, lipid, carbohydrate and chitin) and elemental (carbon and nitrogen) composition were analyzed in twentythree species of Antarctic Zooplankton collected during the austral fall (1986) and winter (1988) from the Scotia/Weddell Sea region. Extremes in water level, ash content and organic components were typified by copepods and gelatinous forms. Ostracods and polychaetes were generally similar in composition to copepods, being only slightly higher in water level and ash content. Chaetognaths exhibited a composition intermediate in character with some components similar in value to that shown by crustaceans (i.e. protein) while other components were more in the range of values seen in gelatinous forms (i.e. water level and ash content). Protein was the major proximate component and measured values (as % Afdw) were fairly uniform among non-gelatinous species (x=33.9±6.9). Lipid levels were variable, with high values (>30% AFDW) only found for the copepods Calanoides acutus, Calanus propinquus and Euchaeta antarctica. Carbohydrate values were low in all species examined. Chitin was measured in crustacean species only. With the exception of C. acutus (x=2.5% AFDW chitin), values were similar among species with mean values being slightly higher in fall (x=11.8±2.5) than in winter (x=6.7±1.8). Among non-gelatinous species, the ratio of carbon to nitrogen was positively correlated with the lipid to protein ratio, underscoring the compositional association between elemental and proximate components in these groups. In gelatinous species, the relationship between carbon:nitrogen and lipid:protein was inconsistent and less pronounced. Caloric content was estimated from recovered organic matter for nongelatinous species. As a function of wet weight and dry weight, values reflected differences in water level and ash content among individual species. As a function of ashfree dry weight, values were similar among all species (x=3.6±0.9 kcal/g).Seasonal comparisons were possible for 12 of the 23 species. Among crustaceans, changes in water level and organic components were variable reflecting dissimilar trophic, reproductive or ecological habits among different species. Essentially no change in composition between fall and winter was observed for diapause species (e.g. Calanoides acutus and Rhincalanus gigas) as well as for omnivorous/ carnivorous species (e.g. Gaetanus tenuispinus). Conversely, large compositional changes were evident for Calanus propinquus, a small-particle grazer that relies heavily on lipid reserves. Chaetognaths and some gelatinous species exhibited a considerable decrease in ash content from fall to winter which, for most cases, was mirrored by some degree of increase in lipid level. At present, however, scant data are available to help explain the observed patterns of compositional change within non-crustacean species.     

Protein, lipid, water and caloric contents of immature rainbow trout, Salmo gairdneri Richardson, growing at different rates

Protein, lipid, water and caloric contents of immature rainbow trout, relative to size of whole fish, growing at different rates were examined by use of allometric analysis (y = ax^b, Huxley, 1932). Fish grew at different rates as a result of differences in ration size (satiation, or 4–5% of dry body weight), temperature (7 and 12°C) and bGH (bovine growth hormone) administration. In fingerlings, protein, lipid and caloric contents tended to increase (v. body weight) as a percentage of body composition, whereas above fingerling size, protein decreased while lipid and caloric contents still increased. These trends occurred regardless of growth rate differences. The correlations between protein, lipid, caloric contents and body weight were high so reliable estimates of body components can be made from body weight for all experimental treatments. At satiation rations (7 and 12°C), there were no significant differences in protein content, but lipid and caloric contents were significantly higher in control fish. At low rations, protein and caloric contents were lower than those at satiation rations and lipid was lower than in the control group. On a dry weight basis, in uninjected fish at 12°C, ration size did not influence the percentage composition (protein and lipid) but the low ration group had lower energy values per unit of body dry weight. At low temperature (7°C satiation), fish had lower lipid and higher protein content (dry weight basis) than their controls (12°C satiation), thereby resembling bGH injected fish at satiation rations. Values of caloric content estimated from protein and lipid values by use of standard conversion factors differed sufficiently from caloric values directly determined by bomb calorimetry to suggest that caloric values of lipids may change during growth. The increase in body caloric content during growth apparently results mainly from an increase in the percentage of lipid. The similarity of body composition between different growth rate groups implied a tendency for conservation of relative proportions of components such that body composition can be approximated from body weight. Equations were also given to describe the relationship between water content and body constituents, and the relationship between condition factor (K) and both the body dry weight and lipid content.     

Nutritional composition of edible Hawaiian seaweeds

Fresh seaweeds, both wild and cultivated,are commonly eaten as food in the HawaiianIslands. Before Western contact, limu (seaweed) was a regular part of thediet, and is thought to have contributedvitamins and essential mineral nutrientsnot found in other staple food items. Twenty-two species of edible Hawaiianmacroalgae (6 Chlorophyta, 4 Phaeophyta, 12Rhodophyta) were analyzed for protein,lipid, carbohydrate, ash, caloric, mineraland vitamin content. Halymeniaformosa and Porphyra vietnamensisranked highest in total protein contentamong the species analyzed. Most speciescontained less than 5% crude lipid,although two Dictyota species hadover 16% crude lipid based on dry weight. Soluble carbohydrates ranged from 4.5 to39.9% dry weight. Ash values ranged from22.4% to 64.2%. Dictyotasandvicensis and Monostromaoxyspermum had caloric content each over3000 cal g^-1 ash-free dry weight. Allspecies contained measurable quantities of11 essential mineral elements. The majorityof Hawaiian seaweeds tested contained-carotene (vitamin A), and Enteromorpha flexuosa contained thehighest amount of vitamin C (3 mg g^-1).     

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.     

The composition of fresh and stored oyster mushrooms (Pleurotus ostreatus)

Soluble carbohydrate, protein, polysaccharide and cell wall composition were assayed in freshly harvested Pleurotus ostreatus sporophores and those stored for 4 days at 2° or 18°. Mannitol and trehalose were present at 1.8 and 6.5% dry wt respectively in fresh sporophores, and at reduced levels in those stored at 18°. In sporophores stored at 2°, trehalose levels increased by up to 122%. Soluble polysaccharide appeared to be composed of glycogen-like material, which was susceptible to post-harvest breakdown, and components containing mannose and other sugars. The total protein content was 42% dry wt; no protein degradation was seen in sporophores stored at 2°, but about 25% of the protein disappeared during storage at 18°. Cell wall polysaccharide was utilised during storage. Respiration rate was about 8–10 ml CO₂/g dry wt/hr at harvest and declined to about 5 ml/g dry wt/hr after 40 hr storage at 18°.     

Tissue accumulation and the moult cycle in juveniles of the Australian freshwater crayfish Cherax destructor

1. This paper investigates moult stage and size-specific changes in whole body composition during growth in juvenile crayfish in order to better describe the nature of growth and energy use. 2. Composition is described in terms of moult stage and size-specific wet, dry and ash-free dry weight, water, carbon, protein nitrogen, non-protein nitrogen, ash and energy. Dry weight and ash-free dry weight (AFDW) peaked in the middle and in the later stages of premoult. Both peaks were about 2–2.3 times postmoult weight. Losses in tissue weight during ecdysis were substantial in the smallest crayfish but declined with size. Water was taken up between late premoult and early postmoult. Tissue accumulation occurred primarily between B and D₁.₃, with further weight gain largely the result of fluid uptake. Ash increased immediately postmoult with a major peak occurring during intermoult. Mean organic carbon varied between 33 and 35.5% of the body and 49% of the exuvia. Chitin varied between 9 and 17% of body AFDW and made up about 50.5% of the exuvia. Protein content varied between 47 and 62% of body AFDW and about 25% of the exuvia. Carbon, chitin and protein were not affected by moult stage but protein declined with ocular carapace length (OCL) in larger crayfish. Mean caloric content varied between 19 and 22 J mg-¹ AFDW depending on size and moult stage. Caloric content increased with OCL during premoult and early intermoult then declined with size until part of the way through premoult. 3. Relationships between protein, chitin and remaining carbon (organic carbon minus chitin) were examined. It is suggested that protein and some carbon are catabolized during the moulting process, possibly to fuel metabolism. Models are presented showing changes in proximate composition over the moult cycle for two sizes of crayfish, and tissue and energy accumulation and loss over a series of moult cycles and sizes from 3.1 mm to 17 mm OCL.     

Biochemical characterisation and fatty acid profiles of 25 benthic marine diatoms isolated from the Solthörn tidal flat (southern North Sea)

Twenty-five intertidal diatom species were isolated from the Solthörn tidal flat (Lower Saxony, southern North Sea) and grown in semi-continuous cultures under standardised conditions, in order to observe differences in their biochemical gross compositions (e.g. protein, lipid, carbohydrate and ash contents). Composition, expressed as % dry weight, indicated that the majority of species (52 %) contained only <15 % protein but had nearly twice the total amount of carbohydrate and two to three times higher ash content. In addition, most species contained a relatively constant percentage of lipids (19.4 to 25.6 %), whereas extraordinary high lipid contents (>30 %) were found for Amphora exigua, Gyrosigma spenceri, Pleurosigma angulatum and Gyrosigma littorale. Glucose, galactose, mannose and ribose constituted the majority of the sugars detected, although the levels of these varied between species. Lipid class composition showed high concentrations of phospholipids and galactolipids as major constituents (19–22 % and 40–43 % of total lipids). The major fatty acids in most species were 14:0, 16:0, 16:1(n-7) and 20:5(n-3). Significant differences in biochemical gross compositions were found in the temperature (10, 30 °C) and salinity tests (20, 35 PSU), suggesting special intracellular acclimatisation processes that provide possible explanations for the adaptability of the species to environmental variations and the distinct differences in the diatom assemblages.     

Cell wall of Fusarium sulphureum: I. Chemical composition of the hyphal wall

The hyphae wall of Fusarium sulphureum Schlect. (Isolate 1) was isolated and purified. Electron microscopy studies showed that the isolated cell wall consisted of two distinct layers, an outer electron dense layer and a broader electron transparent inner layer. Chemical analysis revealed that the cell wall contained 66% carbohydrate, 7.3% protein, 5.5% lipid and 1.8% ash.The major cell wall component N-acetylglucosamine (39%) was shown by X-ray diffraction analysis to be present as chitin. Glucose constituted 14% of the cell wall, while mannose, galactose, and glucuronic acid, accounted for 15% of the cell wall. Glucorunic acid appears to be predominantly linked to galactose in the intact wall.     

Absorption efficiencies of Lytechinus variegatus (Lamarck) (Echinodermata: Echinoidea) for selected marine plants

The absorption efficiencies of the sea urchin Lytechinus variegatus (Lamarck) were calculated by an indicator method. Absorption efficiencies for total organic material, protein, lipid, and carbohydrate were highest with Halimeda incrassata Ellis as food (43 %, 65 %, 71 % and 35 %, respectively), and lowest with Eucheuma isiforme C. Agardh as food (?35%, ?42%, ?56%and ?34%, respectively). Moderately positive absorption efficiencies for total organic material were found with Thalassia testudinum König & Sims and Ulva lactuca L. as food, and low positive absorption efficiencies for total organic material are found with Syringodium filiformis Kützing and Sargassum sp. as food. Absorption efficiencies of the sea urchin Strongylocentrotus purpuratus (Stimpson) (calculated from the literature) were much greater than those of Lytechinus for carbohydrate, but less for protein and lipid. Both sea urchins showed negative efficiencies for some nutrient fractions of their foods. The absorption index (mg nutrient fraction absorbed/g dry wt ingested) showed that Thalassia supplied the most protein and total organic material (43 mg/g dry wt ingested and 142 mg/g dry wt ingested, respectively). In general, the absorption indices indicate that Lytechinus obtains more protein and lipid, but less carbohydrate from its food than does Strongylocentrotus. In the field Lytechinus has primarily a detrital diet.