Differences In Nutritional Status Research Articles

Empirical investigation of the agriculture–malnutrition nexus in Africa: Spatial clustering and spillover effects

AbstractMany studies have been conducted to examine the direct effect of agriculture on the prevalence of malnutrition; however, there is little solid evidence on spatial spillover effects and much less on the heterogeneous effects stemming from spatial differences in nutritional conditions. We make up this gap by using a dynamic spatial Durbin model to characterize the impact of agricultural productivity on malnutrition in Africa. Our results show that countries in Eastern Africa are more likely to suffer from severe malnutrition than other regions. We find evidence for convergence in agricultural productivity across countries with moderate and high prevalence of malnutrition as disparities in their agricultural productivity narrow down over the sample period. It appears that the negative effect of agriculture on malnutrition is more evident in countries where the prevalence of malnutrition is lower. This implies that agricultural development does not play a substantial role in reducing malnutrition in the worst affected areas. We also report that poor agricultural development can deteriorate the nutritional status among neighboring countries in the short term, consistent with the spatial‐locking effect of agriculture.

Parenteral, non-live rotavirus vaccine: recent history and future perspective.

Since the widespread introduction of oral and live attenuated rotavirus vaccines around the world in 2009, the impacts of disease burden and the effects of disease reduction in developing countries have been proven. However, in low and middle-income countries, the vaccine efficacy is somewhat lower than in developed countries due to differences in nutritional conditions, microbial environments of individuals, and other factors. In addition, as oral, live vaccines have been found to be associated with rare but serious side effects, the development of a next-generation vaccine with safety, improved effectiveness, and ease of storage is currently underway. New vaccine strain developed by the Centers for Disease Control and Prevention in the United States are undergoing preclinical testing of efficacy, antigen dose, and administration route in the form of a heat-treated inactive vaccine, and a recombinant protein-based trivalent subunit vaccine developed by the Program for Appropriate Technology in Health is undergoing clinical trial in phase III. Several research groups are also developing non-replicating protein-based rotavirus vaccines using virus-like particles and nanoparticles. This review provides a brief overview of the development status and technology of parenteral, non-live rotavirus vaccines worldwide.

Morphological and biochemical approaches to assess the nutritional condition of the Argentine hake Merluccius hubbsi larvae from two different nursery areas.

The Argentine hake, Merluccius hubbsi, is one of the most important fishing species in the Argentine Sea due to its great abundance and high-quality meat. The study of the nutritional condition is widely used to determine the physiological state of the fish larvae and to estimate their survival possibilities. The larval nutritional condition reflects the environmental conditions to which they have been exposed and represents a useful instrument to determine favourable nursery areas. It also provides tools for the comprehensive management of a population subjected to fishing exploitation. This study aimed to determine potential differences in the nutritional condition of M. hubbsi larvae from the two fishing stocks (Northern and Southern) of the species. The authors assessed the nutritional condition of larvae captured during the 2012 main reproductive peak in the nursery areas of each population. Two different methodologies were applied: a morphometrical approach, by recording five morphometric variables, and a biochemical technique, employing the RNA/DNA index (RDs ) and its derived index of growth performance. The morphometrical indexes did not show differences in the larval condition between both stocks. Nonetheless, the RDs index did detect differences in the nutritional condition of larvae from different stocks. The RDs index of larvae in pre-flexion and flexion stages showed significant differences between stocks, indicating that these stages are more susceptible to starvation. The results suggest that the biochemical indexes prove to be more sensitive than the morphometric indexes to detect slight differences in hake larvae nutritional condition. The scope and limitations of these techniques for the analysis of the nutritional condition of larvae are discussed.

Protein and lipid requirements of three-spot cichlid Cichlasoma trimaculatum larvae.

Determination of the main nutritional requirements at different developmental stages is a prerequisite in the formulation of feeds for newly cultured fish species. In the present study, the lipid and protein requirements of larvae of a native Mexican fish, the three-spot cichlid Cichlasoma trimaculatum, were assessed using a two-factor experimental design that considered four protein (35, 40, 45, and 50%) and two lipid levels (16 and 22%) on growth, survival, and digestive enzyme activities. The best growth and feed efficiency results were obtained when larvae were fed diets including 45% protein and 22% lipids. Comprehensive evaluation of the profile of digestive enzymes using multivariate analysis also demonstrated significant differences in nutritional condition generated by varying inclusion of nutrients. Thus, an increase in protein led to an increase in alkaline protease activity and a reduction in leucine aminopeptidase activity, and the reduction of dietary lipid content led to a significant increase in lipase and trypsin enzymatic activities. Based on our results, C. trimaculatum larvae have a high capacity to hydrolyze both nutrients (protein and lipids) for the high digestive enzyme activities and increase their growth, particularly with a diet containing 45% protein and 22% lipids.

Nutritional condition and otolith growth of Engraulis anchoita larvae: The comparison of two life traits indexes

Abstract Engraulis anchoita larvae were captured in 16 surveys carried out at a fixed sampling station (EPEA) in the Argentinean Sea between 2008 and 2017. Nutritional condition and growth of 214 anchovy larvae were estimated through RNA/DNA index and analysis of otolith microstructure. Standard length, developmental stage, age, weight, otolith radius, recent otolith growth rate (RGR), daily otolith growth rate (DGR), RNA/DNA index (sRD) and a derived index of growth performance were determined for each larva. Significant differences in nutritional condition and otolith growth rates were found among seasons and developmental stages, with slower RGR and lower sRD in larvae captured during winter and in the preflexion stage. On a long time scale, a similar seasonal pattern was observed with DGR. However, the amount of variability explained by ontogeny and seasonality was not equal in both RGR and sRD indexes. RGR was better explained with the analyzed variables, while future studies are required to improve the understanding of the nature of sRD. We observed signs that spring and autumn would be the most propitious season for larval survival in a short time scale, while winter would be the worst one, both in short and in long term scale.

Swimming energetics of the postlarvae of the spiny lobster Jasus edwardsii in New Zealand

Postlarval spiny lobsters require sufficient energy reserves to enable them to actively move across the continental shelf and settle successfully in shallow coastal waters. Recent declines in settlement in lobster populations around the world have been associated with changing ocean climate impacts on the accumulation and use of energy reserves during this phase of the lifecycle. Here, we experimentally measured the energy requirements of swimming postlarvae of the Australasian red spiny lobster, Jasus edwardsii (Hutton, 1875). Wild-caught postlarvae actively swimming in tanks were found to have high energy demands, on average catabolizing 1.6 (SE 0.2) mg of lipid d–1, which is consistent with previous estimates for pueruli of this species using indirect estimations. In contrast, the protein reserves of experimentally swum pueruli only began to be used following the depletion of lipid reserves. A large observed difference in the nutritional condition of pueruli arriving at the sampling site between years is likely to translate into marked interannual differences in the survival and recruitment of pueruli into the population. To begin to understand the dramatic interannual fluctuations in the recruitment of spiny lobsters, it is necessary to determine the environmental factors leading to differences in nutritional condition of their pueruli. Differences in water temperature and zooplankton food availability that impact the ability of lobster larvae to accumulate nutrients appear to be likely candidates for closer examination in future studies.

Linking landscape-scale differences in forage to ungulate nutritional ecology.

Understanding how habitat and nutritional condition affect ungulate populations is necessary for informing management, particularly in areas experiencing carnivore recovery and declining ungulate population trends. Variations in forage species availability, plant phenological stage, and the abundance of forage make it challenging to understand landscape-level effects of nutrition on ungulates. We developed an integrated spatial modeling approach to estimate landscape-level elk (Cervus elaphus) nutritional resources in two adjacent study areas that differed in coarse measures of habitat quality and related the consequences of differences in nutritional resources to elk body condition and pregnancy rates. We found no support for differences in dry matter digestibility between plant samples or in phenological stage based on ground sampling plots in the two study areas. Our index of nutritional resources, measured as digestible forage biomass, varied among land cover types and between study areas. We found that altered plant composition following fires was the biggest driver of differences in nutritional resources, suggesting that maintaining a mosaic of fire history and distribution will likely benefit ungulate populations. Study area, lactation status, and year affected fall body fat of adult female elk. Elk in the study area exposed to lower summer range nutritional resources had lower nutritional condition entering winter. These differences in nutritional condition resulted in differences in pregnancy rate, with average pregnancy rates of 89% for elk exposed to higher nutritional resources and 72% for elk exposed to lower nutritional resources. Summer range nutritional resources have the potential to limit elk pregnancy rate and calf production, and these nutritional limitations may predispose elk to be more sensitive to the effects of harvest or predation. Wildlife managers should identify ungulate populations that are nutritionally limited and recognize that these populations may be more impacted by recovering carnivores or harvest than populations inhabiting more productive summer habitats.

Malnutrition and body composition in urban and rural schoolchildren: A cross-sectional study in San Rafael, Mendoza (Argentina).

The aim of the present study was to analyze the nutritional status and body composition of children from San Rafael, Mendoza, avoiding urban and rural categorization by generating subpopulations as a function of their socio-environmental characteristics. A cross-sectional study was performed in 3,596 schoolchildren from 4.0 to 13.9 years of age. Body weight, height, upper arm circumference, and triceps skinfold were measured. Body mass index, total muscle, and fat areas of the arm were calculated. To estimate nutritional status and body composition, the NHANES III reference was used. The socio-environmental variables were surveyed using a structured questionnaire. These variables were processed by categorical principal-component analysis (catPCA). The catPCA allowed the differentiation of four groups, three with urban characteristics (high urban, medium urban, impoverished urban), and a rural group. Stunting occurred at a higher rate in the impoverished urban group, and the occurrence of underweight children was higher in the rural group. The prevalence of excess weight varied in the range of 20-26%. The latter value corresponded to children of the high urban group, who also did not show reduced muscle mass. Children from San Rafael presented differences in nutritional condition and body composition associated with pronounced socio-environmental heterogeneity. Thus, we could observe a gradient from the "high urban" group, with better social, economic, and sanitation conditions and at the same time a more obesogenic environment to the "impoverished urban" and "rural" groups, whose vulnerability reflected a higher prevalence of child undernutrition and the association with excess weight and reduced muscle mass. Am. J. Hum. Biol. 28:796-803, 2016. © 2016Wiley Periodicals, Inc.

Effect of serum lipid level change on 10-year coronary heart risk distribution estimated by means of seven different coronary risk scores during one-year treatment

This study was done in order to evaluate the effect of serum levels of total cholesterol, triglycerides, low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol on 10-year coronary heart disease risk distribution change. This study included 110 subjects of both genders (71 female and 39 male), aged 29 to 73, treated at the Outpatient Department of Atherosclerosis Prevention, Centre for Laboratory Medicine, Clinical Centre Vojvodina. The 10-year coronary heart disease risk was estimated on first examination and after one-year treatment by means of Framingham, PROCAM and SCORE coronary risk scores and their modifications (Framingham Adult Treatment Panel III, Framingham Weibul, PROCAM NS and PROCAM Cox Hazards). Age, gender, systolic and diastolic blood pressure, smoking, positive family history and left ventricular hypertrophy are risk factors involved in the estimation of coronary heart disease besides lipid parameters. There were no significant differences in nutritional status, smoking habits, systolic and diastolic pressure, and no development of diabetes mellitus or cardiovascular incidents during one-year follow. However, a significant reduction in cholesterol level (p < 0.001), triglycerides (p < 0.001), low-density lipoprotein cholesterol (p < 0.001) and an increase in high-density lipoprotein cholesterol (p < 0.02) was present although therapeutic target values were not achieved. In addition, a significant increase was observed in the category of low 10-year coronary heart disease risk (Framingham- p < 0.001; Framingham ATP III- p < 0.001; Framingham Weibul- p < 0.001; PROCAM- p < 0.05; PROCAM NS- p < 0.05; PROCAM Cox Hazards- p < 0.001: SCORE- p < 0.001) and a reduction in high-risk category (Framingham- p < 0.001; Framingham ATP III- p < 0.005; Framingham Weibul- p < 0.005; PROCAM- p < 0.001; PROCAM NS-p < 0.001; PROCAM Cox Hazards- p < 0.001; SCORE- p < 0.005) in comparison with the risk at the beginning of the study. Our results show that the correction of lipid level after one-year treatment leads to a significant redistribution of 10-year coronary heart disease risk estimated by means of seven different coronary risk scores. This should stimulate patients and doctors to persist in prevention measures.

Simultaneous degradation of atrazine and simazine by a binary culture of Stenotrophomonas maltophilia and Arthrobacter sp. in a two-stage biofilm reactor

BACKGROUND: The impact of mixtures of chloro-triazinic herbicides, such as atrazine and simazine, on aquatic ecosystems is of environmental concern. To study their biodegradation under various operational conditions, a binary community comprising Stenotrophomonas maltophilia and Arthrobacter sp. attached to the porous support of a packed bed reactor, was evaluated. RESULTS: The genetic analysis of the two atrazine-degrading strains revealed that genes atzA, atzB, atzC are present in both bacteria, but only S. maltophilia possess atzD. Thus, by cultivating Arthrobacter sp. on these herbicides, cyanuric acid accumulation was observed. When the binary community was cultivated in the biofilm reactor, at all the loading rates probed, both herbicides were entirely removed. However, complete biodegradation of cyanuric acid was not achieved. CONCLUSIONS: Even with a two-stage reactor, cyanuric acid was only partially removed. This fact could be attributed to the absence, in the second stage, of an easily degradable energy source, required by S. maltophilia for the uptake and cometabolic degradation of the recalcitrant heterocyclic ring. Responding to differences in nutritional conditions prevailing at each reactor stage, local differences in species' predominance were clearly detected by microbiological and molecular biology methods. Copyright © 2010 Society of Chemical Industry

Early Fasting Is Long Lasting: Differences in Early Nutritional Conditions Reappear under Stressful Conditions in Adult Female Zebra Finches

Conditions experienced during early life can have profound effects on individual development and condition in adulthood. Differences in nutritional provisioning in birds during the first month of life can lead to differences in growth, reproductive success and survival. Yet, under natural conditions shorter periods of nutritional stress will be more prevalent. Individuals may respond differently, depending on the period of development during which nutritional stress was experienced. Such differences may surface specifically when poor environmental conditions challenge individuals again as adults. Here, we investigated long term consequences of differences in nutritional conditions experienced during different periods of early development by female zebra finches (Taeniopygia guttata) on measures of management and acquisition of body reserves. As nestlings or fledglings, subjects were raised under different nutritional conditions, a low or high quality diet. After subjects reached sexual maturity, we measured their sensitivity to periods of food restriction, their exploration and foraging behaviour as well as adult resting metabolic rate (RMR). During a short period of food restriction, subjects from the poor nutritional conditions had a higher body mass loss than those raised under qualitatively superior nutritional conditions. Moreover, subjects that were raised under poor nutritional conditions were faster to engage in exploratory and foraging behaviour. But RMR did not differ among treatments. These results reveal that early nutritional conditions affect adult exploratory behaviour, a representative personality trait, foraging and adult's physiological condition. As early nutritional conditions are reflected in adult phenotypic plasticity specifically when stressful situations reappear, the results suggest that costs for poor developmental conditions are paid when environmental conditions deteriorate.

A more detailed seasonal division of the energy balance and the protein balance of Japanese macaques (Macaca fuscata) on Kinkazan Island, northern Japan

Nakagawa (Am J Primatol 41:267-288, 1997) reported that both the gross energy and gross protein intakes of an adult female Japanese macaque (Macaca fuscata) on Kinkazan Island, northern Japan, were high in spring (March-May) and fall (September-November) and low in summer (June-August) and winter (December-February), and that these values reflected the seasonal differences in nutritional conditions (defined as whether the intakes of energy and protein satisfy the requirements). We estimated the energy balance (energy intake minus its expenditure) and the protein balance (protein intake minus its requirement) of the monkeys on Kinkazan Island every month over the course of 1 year (2004--2005) in order to verify Nakagawa's conclusions. Like Nakagawa, we found that the energy balance of the monkeys in the fall was higher than in the summer and winter, whereas the protein balance in the fall was higher than in the winter. However, we did not find that spring energy and protein values were greater than summer and winter values. We also did not find that summer protein values were low. Both the energy balance and the protein balance changed rapidly within the same season. The energy intakes and the energy balances were higher in mid-spring and mid- and late fall and lower in late spring and early summer, whereas the protein intakes and the protein balances were higher in mid-spring and mid-summer and lower in early and mid-winter. Since Japanese macaques respond to seasonal changes in food supply by changing their foods, continuous data collection with short intervals is recommended in order to accurately document the energy and protein balances of the monkeys.

Feeding ecology of juvenile spiny lobster, Panulirus interruptus, on the Pacific coast of Baja California Sur, Mexico

Many aspects of the early life history of the red lobster Panulirus interruptus are little known, including the relationship between habitat structure, food resource availability, and nutrition of juveniles. We investigated the spatial and temporal differences in food intake, diet composition, and nutritional condition of juveniles at two sites along the Pacific coast of the Baja California Peninsula (Mexico) with contrasting oceanographic and biological conditions. One site (Arvin) is located inside a protected bay, Bahía Tortugas, where the waters are cooler and temperate seagrasses and macroalgae are the dominant benthic flora. The second site (Queen) in Bahía Sebastían Vizcaíno was located along a more open coastline where seawater temperatures were higher and the benthic flora more indicative of warmer seas. At both sites, we randomly sampled epifauna within vegetated habitats to estimate the seasonal availability of food resources for juvenile lobsters from autumn 2001 until summer 2002. Concurrently, we used traps to sample P. interruptus juveniles for stomach content analysis. At both sites, Amphipoda, Gastropoda, and Polychaeta dominated the epifauna assemblages, as determined by an Index of Importance. Juvenile P. interruptus primarily consumed crustaceans (mostly amphipods and isopods) and vegetal material (surf‐grass Phyllospadix spp. and calcareous algae), but their food spectrum was wide. Manly's Index of Resource Selection indicated that lobsters preferred some prey (e.g., Brachyurans) over others despite their low Index of Importance. Despite marked differences in the types of food and their availability between sites, there were no significant differences in the nutritional condition (e.g., relative weight of the digestive gland) of lobsters at the two sites. However, the nutritional condition of lobsters was effected during some seasons. In particular, their condition deteriorated during the spring (April 2002) at Arvin, as did the proportion of individuals with empty stomachs. This study shows the feeding adaptation capacity of the juvenile California spiny lobster P. interruptus to different environmental conditions prevalent in Centre Baja California Peninsula.

Spatial and temporal variability in the diet of juvenile Pacific herring (Clupea pallasi) in Prince William Sound, Alaska

The diet of juvenile Pacific herring, Clupea pallasi, from four bays in Prince William Sound, Alaska, varied spatially and seasonally. In Zaikof Bay, which was sampled in each season, stomach fullness of this herring was highest in May and declined significantly through the winter. Diversity of prey taxa in the diet was highest in June, after the spring phytoplankton bloom. In October, Oikopleura species were dominant in the fish diets of all bays. In March, fish eggs, Cirripedia nauplii, small Calanoida, and large Calanoida were the dominant prey in Eaglek, Simpson, Whale, and Zaikof bays, respectively. Energy density of stomach contents was highest in May, highlighting the importance of high lipid copepod taxa in Zaikof Bay. Estimated assimilation rates suggest that the diets of smaller age-0 herring provide close to maintenance levels of energy prior to winter. Therefore, variability in diet composition and diet energy density could account for relative differences in nutritional conditions of age-0 herring in Prince William Sound.

Morphological aspects of aging liver: half a century of progress in Japan

The most important morphological aspects of the physiological changes of the liver with age are decreases in the numbers of hepatocytes and their mitochondria, coupled with increases in their volumes. The latter is considered to partially compensate for the decrease in numbers of hepatocytes and mitochondria, but leads to a more limited reserve capacity and thus to a condition in which liver function can be more readily exhausted. The binuclearity and polyploidization of the hepatocytes increase with age and are considered to be due to inhibition of their cell division process. Our studies on the parabiosis between young and old rats and mice, on the implantation of isolated hepatocytes in the spleens of rats of different ages, and on the regenerative process after partial hepatectomy in rats of different ages, suggested the existence of humoral inhibitory factor(s) for the division of the cells and their mitochondria. Morphological studies on the native and Hawaiian Japanese, as well as on the USA Caucasians and the Costa Rican Latinos revealed that a difference in the process of the age-related decrease in hepatocyte number among different ethnicities is mainly due to differences in nutritional conditions rather than to genetic factors. Experimental studies are now being carried out on the effect(s) of various dietary conditions on age-related changes of the liver, and the results obtained support the findings of the geographical studies.

Soybean response to nodulation by rhizobitoxine-producing bradyrhizobia as influenced by nitrate application

Foliar chlorosis of soybean (Glycine max [L.] Merr.) resulting from nodulation by rhizobitoxine-producing (RT+) strains of Bradyrhizobium japonicum is commonly less severe in the field than under greenhouse conditions. Differences in nutritional conditions between the field and greenhouse may contribute to this phenomenon. In particular, field-grown plants obtain some N from soil sources, whereas in the greenhouse soybean is often grown in low-N rooting media to emphasize symbiotic responses. Therefore, we examined the effect of NO3- on the expression of RT-induced symptoms. Soybean plants inoculated with RT+ bradyrhizobia were grown for 42 days in horticultural vermiculite receiving nutrient solution amended with 0.0, 2.5, or 7.5 mM KNO3. Foliar chlorosis decreased with increasing NO3- application whereas nodule mass per plant was generally increased by NO3- application. Total amounts of nodular RT remained constant or increased with NO3- application, but nodular concentrations of RT decreased. Chlorosis severity was negatively correlated with shoot dry weight, chlorophyll concentration, and total shoot N content. It was concluded that application of NO3- can reduce the negative effects of RT production on the host plant. This suggests that any NO3- present in field soils may serve to limit chlorosis development in soybeans.

Population ecology of western grey kangaroos in a remnant of wandoo woodland at Baker's Hill, southern Western Australia

A subpopulation of western grey kangaroos (Macropus fuliginosus) living in a 305-ha remnant of wandoo woodland in the mediterranean climate of the south-west of Western Australia was studied for 10 years. Measurements and estimates were made of a wide range of population characteristics including population size, composition, reproductive rate, emigration and immigration rates and death rates. Growth rates of males and females were established and yearly differences in nutritional status assessed. The population increased over four years from 146 � 22 to a plateau of around 200 before being culled to 95. The numbers then increased slowly over another six years to 158 individuals. The population had an average of 46 adult males per 100 adult females. Subadults plus juveniles made up 10-36% of the population, depending on the year. Breeding was seasonal, being earlier in years with early autumn rain. Reproductive rate was higher, overall, in these years. Females became sexually mature at about 16 kg, their reproductive rate increased with weight until they reached 24 kg; 91% of adult females over 24 kg had pouch young annually. Mortality of young appeared to be high, and to be the factor regulating the population. On average, only 27% of young survived the first year after leaving the pouch. Emigration rate was estimated to exceed immigration by 5% per annum. The estimated mortality rate of adults was 5% per annum. The nutritional status of individuals varied from year to year; within a year, only females were heavier in early summer than in later summer. It was concluded from faecal nitrogen levels that nitrogen was not a major factor influencing nutritional status in summer. Fifteen years after this remnant woodland was established by clearing, the subpopulation of kangaroos living in it appeared to be relatively stable in numbers, and certainly was not showing the marked fluctuations known to occur in semi-arid areas of Australia.

Nutritional condition of rock scallop, Crassadoma gigantea (Gray), larvae fed mixed algal diets

Larvae of C. gigantea were fed a binary diet of Isochrysis aff. galbana (T-iso) and Chaetoceros calcitrans, and two ternary diets consisting of the binary diet with either Tetraselmis suecica or Thalassiosira pseudonana. In a second feeding study, larvae were fed three ternary diets consisting of I. aff. galbana (T-iso) and C. calcitrans with either T. pseudonana, Chaetoceros gracilis or Skeletonema costatum. The biochemical composition, energy contents, and fatty acid compositions of the diets and resultant premetamorphic larvae were determined and compared, both within and between the studies. It was concluded that nutritional condition of the larvae correlated with the content of dietary carbohydrate rather than dietary lipid or protein. Differences in content of macronutrients in the diet, I. aff. galbana (T-iso), C. calcitrans and T. pseudonana, used in both feeding studies, resulted in substantial differences in nutritional condition of the premetamorphic larvae from the two studies. Determination of macronutrients in algal diets, even when the algae were cultured under conditions considered to be standard, was shown to be essential before any estimate of food value. Fatty acid composition of total lipid in the larvae reflected that of the diets, but levels of saturated, monoethylenic, polyethylenic, and polyunsaturated n3 or n6 fatty acids in the diets were not correlated with nutritional condition of the larvae. Accumulation of 16:0, 18:0, 18:1 n7, 20:5 n3, and 22:6 n3 fatty acids by the larvae, irrespective of diet supplied, suggested a need for these acids during larval growth and development. The importance of carbohydrate in providing a balanced diet for effective conversion of dietary macronutrients to tissue and energy reserves has hitherto been overlooked in larval nutrition.

The significance of various environmental parameters for growth of the Iceland scallop, Chlamys islandica (Pectinidae), in hanging culture

Iceland scallops, Chlamys islandica (O.F. Müller), were grown in hanging culture at 3 different depths (2, 12 and 40 m below the sea surface) in a northern Norwegian fjord. The growth of the soft parts of the body and the shell increment were monitored throughout the growing season (March until September). At the same time, temperature, salinity, water density, current speed, chlorophyll, particulate organic matter (POM) and particulate inorganic matter (PIM) were monitored at each of the experimental depths. Analysis of the environmental data together with the growth data showed that growth differences between the experimental depths were essentially the results of differences in nutritional conditions for the scallops, defined by the relationship between PIM and POM in the water column. The results also showed that growth in Iceland scallops can be increased significantly by suspending the animals in a more favourable nutritional environment than that found on the natural scallop beds.