Influence Of Food Availability Research Articles

Parental body condition and high energy value of fish determine nestling success in Magellanic penguin (Spheniscus magellanicus)

Nestling growth and survival of marine birds are influenced by multiple factors. Oceanic conditions influence food availability and energy value of the diet and affect nestling condition. Climate variables, like heavy rains, could drown or cause hypothermia of nestlings. Besides oceanic conditions, parental conditions and hatching asynchrony can also affect nestling growth and survival. Magellanic penguins are long-lived seabirds with multiple breeding opportunities that lay a two-egg clutch, but they may raise only one of the two chicks depending on the breeding season. We studied nestling growth and survival for four breeding seasons (2010–2013) and related these to parents’ body condition and hatching asynchrony. We also analysed the effect of nestling diet, rainfall, chlorophyll a concentrations (c-a), and sea surface temperature (SST) of known foraging sites to evaluate nestling performance. We found that parents’ body condition, especially that of males, were positively related to nestling growth. Hatching asynchrony appears not to have an important role in nestling growth/survival. Nestling growth/survival, rain, diet, c-a and SST differed drastically among breeding seasons. During the breeding season with the highest mortality and lowest asymptotic mass of nestlings (2012), we registered heavy daily rains within the first stage of the raising period. We also found that high/low concentrations of c-a were related to high/low mortality of nestlings, respectively, and that SST was inversely related to asymptotic mass. Nonetheless, neither of these oceanic variables was related clearly to nestling growth/survival during breeding seasons with intermediate breeding success. On the contrary, the estimated proportion of low quality compared to high quality items in nestling diets coincided in every breeding season with the survival/growth of nestlings. We concluded that c-a and SST were not precise enough to determine nestling success or survival of nestlings during breeding seasons with intermediate nestling success, but that the proportion of high quality compared to low quality items in the diet were key for nestling survival and growth. Although the breeding seasons did not seem to be so “unfavourable” in terms of c-a and SST, when low quality items predominated in the diet, this had a strong impact on the condition of the chicks.

Benefits of frontal waters for the growth of Engraulis anchoita larvae: The influence of food availability

We studied the abundance, size and growth rates of Engraulis anchoita larvae during the end of the species’ spawning season in relation to environmental variables. Two sampling transects, one in Península Valdés (northern transect: NT) and the other in Isla Escondida (southern transect: ST), with four stations each, were established in late summer. Both locations are characterized by high concentrations of E. anchoita larvae in spring, strongly associated with the presence of frontal waters, at the beginning of the species’ spawning season. Zooplankton and ichthyoplankton were sampled, and temperature profiles and chlorophyll-a satellite images were analyzed for each sampling station. Zooplankton samples were divided in size fractions, and composition and abundances were estimated. Standard length (SL), ontogenetic stages, and abundance (including eggs) were estimated. Additionally, age and growth rates were determined by otolith analysis. Two different scenarios were observed in both transects. In the NT, a frontal structure was found, while at the ST, the water column was completely homogeneous. Total zooplankton abundance was maximum at frontal waters, with 22,195 ind. m−3, being the small size fraction (<200 μm) the most abundant, mainly composed of nauplii (9000 ind. m−3) and cyclopoid copepodites (4000 ind. m−3). The NT showed higher abundance (mean of 126.5 ind. m−2 per station in NT; 29.75 ind. m−2 in ST), faster growth rates of E. anchoita larvae (NT: 0.45 ± 0.04 mm day−1; ST: 0.34 ± 0.09 mm day−1; n = 90), and higher mean SL at frontal waters (7.57 ± 1.52 mm SL) than the ST. In the NT, E. anchoita growth rates were constant in time, whereas in the ST, they decreased with age. Our results support the classical theory, which states that frontal waters provide advantageous environmental conditions for fish larvae feeding, growth and, thus, survival.

Influence of food availability on mate-guarding behaviour of ladybirds.

A recent study on ladybird, Menochilus sexmaculatus (Fabricius) demonstrates that males perform post-copulatory mate guarding in the form of prolonged mating durations. We investigated whether food resource fluctuation affects pre- and post-copulatory behaviour of M. sexmaculatus. It has not been studied before in ladybirds. For this, adults were subjected to prey resource fluctuations sequentially at three levels: post-emergence (Poe; 10 days), pre-mating (Prm; 24 h) and post-mating (Pom; 5 days; only female). The food resource conditions at each level could be any one of scarce, optimal or abundant. Pre-copulatory and post-copulatory behaviour, and reproductive output were assessed. Post-emergence and pre-mating nutrient conditions significantly influenced the pre-copulatory behaviour. Males reared on scarce post-emergence conditions were found to require significantly higher number of mating attempts to establish mating unlike males in the other two food conditions. Under scarce post-emergence and pre-mating conditions, time to commencement of mating and latent period were high but opposite result was obtained for mate-guarding duration. Fecundity and per cent egg viability were more influenced by post-mating conditions, with scarce conditions stopping oviposition regardless of pre-mating and post-emergence conditions. Present results indicate that pre- and post-copulatory behaviour of ladybird is plastic in nature in response to food resource fluctuations.

Weather Conditions Influence Egg Volume Repeatability in Clutches of the Red-backed Shrike Lanius collurio.

Artur Golawski and Cezary Mitrus (2018) Birds show considerable variation in egg size, both within and between clutches. There are many factors affecting egg dimensions including features of the birds themselves, territory quality, food abundance and weather conditions. One feature that varies in clutches is repeatability of egg dimensions within a clutch. We studied variation in egg size in clutches of the Red-backed Shrike Lanius collurio in east-central Poland and examined the effects of territory quality and weather conditions on egg size repeatability. Repeatability of egg size was low and ranged from 0.51 to 0.55. No significant differences in egg dimensions were found between clutch size classes (3 to 7 eggs, modal clutch size of 6). Weather conditions only influenced repeatability of egg volume. This parameter was affected by the year and one environmental factor - total rainfall immediately before egg laying. With increasing rainfall, the repeatability of egg volume decreased. Weather conditions can influence food availability and in this way also affect egg size. The Red- backed Shrike diet consists mainly of insects, the activity of which significantly decreased during rainfall. In such conditions, birds have to spend more energy to gain food, which could consequently lead to differences in egg size.

Influence of Food Availability on Matrilineal Site Fidelity of Female Asian Black Bears

Abstract. To describe the maintenance process of matrilineal site fidelity in large, solitary mammals, we investigated both the site fidelity over time and the effect of kinship on the space use at a fine (home range) scale under different levels of food availability. We collected location data for female Asian black bears, Ursus thibetanus, using GPS collars and identified microsatellite DNA markers from bears in the Ashio-Nikko Mountains, Japan. We investigated autumn food resources by assessing hard mast productivity. We found high site fidelity over the years from the denning to summer season, and there was spatial proximity among related females (i.e., mother—daughter, grandmother—granddaughter, and sister—sister pairs) from spring to summer and through mid-autumn in moderate/good hard mast years. In autumns of poor hard mast years, although females used sites far from their primary home ranges, they returned to sites near their primary range before den entry. In habitats, where good denning habitat ...

African apes coexisting with logging: Comparing chimpanzee (Pan troglodytes troglodytes) and gorilla (Gorilla gorilla gorilla) resource needs and responses to forestry activities

The extraction of timber often conflicts with the well-being and conservation of wildlife. In particular, there is a need to better understand the impact of tree removal under selective logging regimes on local ecological communities. We conducted ape nest counts along line transects before, during, and after logging to assess the impact of timber harvesting and associated activities on sympatric chimpanzees and gorillas in a forestry concession in northern Republic of Congo. We used generalized linear models to relate ape nest counts to a set of predictor variables, representing the impact of logging and controlled for variation in environmental conditions including food availability, habitat and rainfall. Commercial forest inventory data were used to assess the baseline influence of food availability and forest structure on ape distribution. Higher numbers of chimpanzees were found in proximity to their preferred tree foods, whereas gorillas were associated with more heterogeneous habitats. Chimpanzee nest encounter rates decreased with increasing intensity of human impacts. Gorillas also avoided areas with active timber exploitation and roads, but were attracted to recently logged areas with abundant terrestrial herbaceous vegetation. Species-specific responses were consistent with theoretical predictions of niche partitioning and cumulative human influence. Based on these findings, we provide recommendations to improve existing guidelines and forest certification standards aimed at safeguarding ape populations.

Determinants of seasonal changes in availability of food patches for elephants (Loxodonta africana) in a semi-arid African savanna.

Loss of biodiversity caused by impact of elephants (Loxodonta africana) on African woodlands may require a management response, but any action should be based on an understanding of why elephants choose to utilise trees destructively. Comprehension of elephant feeding behaviour requires consideration of the relative value of the plant groups they may potentially consume. Profitability of available food is partly determined by the time to locate a food patch and, therefore, as a foundation for understanding the influence of food availability on diet selection, key controls on the density of grass, forb, and browse patches were investigated across space and time in a semi-arid African savanna. Density of food patches changed seasonally because plant life-forms required different volumes of soil water to produce green forage; and woody plants and forbs responded to long-term changes in soil moisture, while grasses responded to short-term moisture pulses. Soil texture, structure of woody vegetation and fire added further complexity by altering the soil water thresholds required for production of green forage. Interpolating between regularly-timed, ground-based measurements of food density by using modelled soil water as the predictor in regression equations may be a feasible method of quantifying food available to elephants in complex savanna environments.

Secondary production of caddisflies reflects environmental heterogeneity among tropical Andean streams

Macroinvertebrate life history and secondary production have rarely been measured in tropical highland streams even though these streams are highly heterogeneous and display unique ecological settings compared to both those in the tropical lowlands or in the temperate zone. We evaluated secondary production and life history attributes of the periphyton grazer caddisfly (Helicopsyche spp.) using the size-frequency method in three Ecuadorian highland stream reaches (2990–3727 meters above sea level) with contrasting riparian vegetative characteristics and differing flow and temperature regimes and periphyton biomass (as chlorophyll-a). Helicopsyche displayed strong differences among streams in life history attributes and secondary production. We estimated the least productive reach (89 mg m−2 year−1) to be an order of magnitude less than that of the two more productive reaches (1556–2164 mg m−2 year−1). Secondary production positively correlated with annual mean periphyton biomass and negatively correlated with annual mean water temperature. Compared to previous studies, mean secondary production of Helicopsyche was relatively high. We conclude that Helicopsyche secondary production in tropical highland streams is highly heterogeneous among stream types. This strong variation among streams might ultimately depend on environmental factors influencing food availability (biomass of periphyton) and larval development rates (temperature regime).

&lt;strong&gt;Influence of food availability, predation risk and initial body size on growth and maturation of &lt;em&gt;Cloeon dipterum&lt;/em&gt; (Ephemeroptera: Baetidae)&lt;/strong&gt;

Larval growth and maturation in aquatic insects are phenotypically plastic and can change in response to the amount and quality of resources, or under predation risk. While better food conditions typically lead to faster growth and earlier maturation at larger body size and hence higher fecundity, the effects of predation risk can vary depending on its strength and selectivity with respect to size or stage. Studies on lotic mayflies (Ephemeroptera) have reported two direct and two indirect life history responses to increased predation risk: slower growth rate and later maturation at the same or smaller size, and faster or unaltered growth rate and earlier maturation at smaller body size. However, life history responses of standing water mayflies to predation risk are unknown. To fill this gap, we carried out a full-factorial laboratory experiment to study the influence of food availability (full/reduced) and predation risk (present/absent predator cues) by dragonfly larvae on growth and maturation of larvae of the lentic mayfly Cloeon dipterum. Males and females responded similarly to food limitation and predation risk. Predation risk had no effect on maturation size, larval mortality and metamorphic failure. However, growth rate, number of moults and development time were all affected by predation risk, and its net effect was modified by food availability and initial body size of the larvae. These results suggest that life history responses to suboptimal conditions depend on body size at the onset of such conditions. Finally, a small group of larvae grew at much slower rates and developed much longer than other individuals of similar initial size, possibly due to bet-hedging or inclusion of multiple genotypes in the experiment.

Abyssal hills: Influence of topography on benthic foraminiferal assemblages

Abyssal plains, often thought of as vast flat areas, encompass a variety of terrains including abyssal hills, features that constitute the single largest landscape type on Earth. The potential influence on deep-sea benthic faunas of mesoscale habitat complexity arising from the presence of abyssal hills is still poorly understood. To address this issue we focus on benthic foraminifera (testate protists) in the >150-μm fraction of Megacorer samples (0–1cmlayer) collected at five different sites in the area of the Porcupine Abyssal Plain Sustained Observatory (NE Atlantic, 4850mwater depth). Three sites are located on the tops of small abyssal hills (200–500m elevation) and two on the adjacent abyssal plain. We examined benthic foraminiferal assemblage characteristics (standing stock, diversity, composition) in relation to seafloor topography (hills vs. plain). Density and rarefied diversity were not significantly different between the hills and the plain. Nevertheless, hills do support a higher species density (i.e. species per unit area), a distinct fauna, and act to increase the regional species pool. Topographically enhanced bottom-water flows that influence food availability and sediment type are suggested as the most likely mechanisms responsible for these differences. Our findings highlight the potential importance of mesoscale heterogeneity introduced by relatively modest topography in regulating abyssal foraminiferal diversity. Given the predominance of abyssal hill terrain in the global ocean, we suggest the need to include faunal data from abyssal hills in assessments of abyssal ecology.

Associations Between Swedish Mothers' and 3- and 5-Year-Old Children's Food Intake

ObjectiveTo investigate associations between mothers' and children's food intake. DesignCross-sectional study. Background variables collected through self-reports and from the register of the total population. Mothers recorded their own and their children's food intake in a diary during 2 4-day periods. SettingEight counties in mid Sweden. ParticipantsThree- and 5-year-old children and their mothers were randomly selected from the register of the total population. A total of 2,045 families were invited, 355 of whom accepted. Mothers who accepted were older and to a larger extent born in Sweden. The final sample of mother–child pairs with complete food records was 189. Main Outcome MeasuresMothers' and children's food intake (16 food items). AnalysisSpearman rank-order correlation with 95% confidence intervals (2-sided). Moderation was investigated using generalized estimation equations with robust variance. ResultsThe strongest correlations between mothers' and children's food intake were found for pizza and oily fish (r = .70–.80). The weakest correlations were found for sugared drinks and fruit and berries (r = .24–.26). Children's age moderated the relationship between mothers' and children's intake of savoury snacks, as did place of residence for pizza intake. Conclusions and ImplicationsThere were substantial correlations between children's and mothers' intake of various foods. Modeling of mothers' intake might be more effective in influencing young children's intake of certain foods, whereas other strategies, such as encouraging parents to influence food availability (eg, gatekeeping), might be more useful for some foods.

Lifestyle mediates seasonal changes in metabolic health among the yakut (sakha) of northeastern siberia.

Among indigenous circumpolar populations, extreme seasonality influences food availability and energy metabolism. Furthermore, subsistence patterns and wage labor opportunities shift with season. Thus, health measures among circumpolar populations likely exhibit seasonal changes that are influenced by lifestyle factors. This study examines how markers of cardio-metabolic health vary between summer and winter as a function of an individual's lifestyle and sex among the Yakut of northeastern Siberia. Anthropometric dimensions, serum lipids and glucose levels, blood pressure, and lifestyle data were collected for a sample of 115 Yakut participants (71 women, 44 men) in Berdygestiakh, Sakha Republic, Russia in the summer of 2009 and winter of 2011. Men and women experienced significant increases in total and HDL cholesterol and triglyceride levels from summer to winter. Women exhibited winter-time increases in adiposity and glucose levels. Men who reported greater market integration were more likely to have lower winter blood pressure levels. Additionally, time spent fishing was associated with lower winter-time LDL cholesterol, while foraging time was associated with higher HDL cholesterol. While seasonal changes in anthropometric dimensions were modest, Yakut men and women experienced significant increases in total cholesterol and HDL cholesterol from summer to winter. These results also suggest that while Yakut individuals with greater subsistence participation are more buffered from adverse seasonal changes in cholesterol levels, they may be at a greater risk for winter increases in blood pressure. Furthermore, the interactions between lifestyle and seasonal change in metabolic health appear to differ between Yakut women and men. Am. J. Hum. Biol. 28:868-878, 2016. © 2016Wiley Periodicals, Inc.

Breeding biology of a winter-breeding procellariiform in the North Atlantic, the Macaronesian shearwater Puffinus lherminieri baroli

The breeding success of burrow-nesting seabirds may be influenced by both nest site characteristics and oceanographic conditions influencing food availability at sea. In this study we describe the breeding biology of the winter-breeding Macaronesian shearwater (Puffinus lherminieri baroli), including nest site characteristics and interspecific competition. We also evaluate the possible effects of changing oceanographic conditions on breeding phenology and breeding success. The study was carried out over two breeding seasons on two islands in the North Atlantic Ocean, Cima Islet and Selvagem Grande. Oceanographic characteristics differed between years. On a regional scale, the North Atlantic Oscillation (NAO) index was low and negative in 2011, and on a local scale, birds used areas with significantly lower values of chlorophyll a concentration and significantly higher values of sea surface temperature anomalies. Hatching success was higher in 2012 than in 2011. At both colonies, egg cracking was the main cause of hatching failure, but in 2011 several eggs on Selvagem Grande were deserted. In 2012 birds laid earlier and chicks had longer wings and were heavier. At both colonies, nests that were deeper, were sheltered from prevailing winds and had small chambers and a soil substrate had a higher probability of being used successfully by the birds. Nests occupied solely by Macaronesian shearwaters were much deeper and had less volume than nests shared with other species. Our study suggests that the breeding success of Macaronesian shearwaters is strongly related to nest site characteristics and that at-sea environmental conditions exert a strong influence on reproductive parameters, with birds breeding in a poor year (evaluated in terms of lower marine productivity) laying much later and their chicks growing at a slower rate than in a good year. The influence of nest site characteristics and environmental conditions may be very important for understanding the breeding ecology of Procellariiformes and may help explain the negative population trend of Macaronesian shearwaters.

High sea surface temperatures driven by a strengthening current reduce foraging success by penguins.

The world’s oceans are undergoing rapid, regionally specific warming. Strengthening western boundary currents play a role in this phenomenon, with sea surface temperatures (SST) in their paths rising faster than the global average. To understand how dynamic oceanography influences food availability in these ocean warming “hotspots”, we use a novel prey capture signature derived from accelerometry to understand how the warm East Australian Current shapes foraging success by a meso-predator, the little penguin. This seabird feeds on low trophic level species that are sensitive to environmental change. We found that in 2012, prey capture success by penguins was high when SST was low relative to the long-term mean. In 2013 prey capture success was low, coincident with an unusually strong penetration of warm water. Overall there was an optimal temperature range for prey capture around 19–21 °C, with lower success at both lower and higher temperatures, mirroring published relationships between commercial sardine catch and SST. Spatially, higher SSTs corresponded to a lower probability of penguins using an area, and lower prey capture success. These links between high SST and reduced prey capture success by penguins suggest negative implications for future resource availability in a system dominated by a strengthening western boundary current.

Influence of food availability on the spatial distribution of juvenile fish within soft sediment nursery habitats

Soft sediments in coastal shallow waters constitute nursery habitats for juveniles of several flatfishes. The quality of a nursery is defined by its capacity to optimize the growth and the survival of juvenile fish. The influence of biotic factors, such as food availability, is poorly studied at the scale of a nursery ground. Whether food availability limits juvenile survival is still uncertain. A spatial approach is used to understand the influence of food availability on the distribution of juvenile fish of various benthic and demersal species in the Bay of Vilaine (France), a productive nursery ground. We quantified the spatial overlap between benthic macro-invertebrates and their predators (juvenile fish) to assess if the latter were spatially covering the most productive areas of the Bay. Three scenarios describing the shapes of the predator–prey spatial relationship were tested to quantify the strength of the relationship and consequently the importance of food availability in determining fish distribution. Our results underline that both food availability and fish densities vary greatly over the nursery ground. When considering small organisational levels (e.g., a single fish species), the predator–prey spatial relationship was not clear, likely because of additional environmental effects not identified here; but at larger organisational level (the whole juvenile fish community), a strong overlap between the fish predators and their prey was identified. The evidence that fish concentrate in sectors with high food availability suggests that either food is the limiting factor in that nursery or/and fish display behavioural responses by optimising their energetic expenditures associated with foraging. Further investigations are needed to test the two hypotheses and to assess the impact of benthic and demersal juvenile fish in the food web of coastal nurseries.

Patterns and trends in coral reef macroalgae browsing: a review of browsing herbivorous fishes of the Indo-Pacific

Browsing fishes have been identified as an important component of coral reef resilience, because in contrast to other herbivorous fishes they are able to feed on established macroalgae. Climate change and local anthropogenic impacts have contributed to phase shifts in many coral reefs from coral to macroalgae dominance, and recent research suggests the potential ability of browsers to reverse such phase shifts. However, there is high variation among studies and some contradicting findings exist. Here, we review the relevant literature to assemble a list of species currently known to contribute to browsing in the Indo-Pacific. Furthermore, we identify spatial and temporal patterns, outline factors influencing browsing, and discuss the probability of phase shift reversal. We formulate research recommendations addressing the identified gaps in knowledge about the interactions of browsing fishes and their environment. To date, 37 species of fishes have been observed consuming macroalgae in the Indo-Pacific. The most important groups are the family Siganidae, the subfamily Scarinae (Labridae), and the subfamily Nasinae (Acanthuridae). Browsing species vary between studies depending on location, season and macroalgae species examined. Several influencing factors, such as structural complexity, palatability of macroalgae and ecosystem connectivity have been suggested to cause these discrepancies. The most promising avenues for future research are the effect of structural complexity, the importance of mobile link species and influences of food availability on the selectivity of browsing species. Increasing our knowledge in these fields will provide a better basis for successful management strategies directed at increasing the resilience of coral reefs.

Abyssal hills – hidden source of increased habitat heterogeneity, benthic megafaunal biomass and diversity in the deep sea

Abyssal hills are the most abundant landform on Earth, yet the ecological impact of the resulting habitat heterogeneity on the wider abyss is largely unexplored. Topographic features are known to influence food availability and the sedimentary environment in other deep-sea habitats, in turn affecting the species assemblage and biomass. To assess this spatial variation, benthic assemblages and environmental conditions were compared at four hill and four plain sites at the Porcupine Abyssal Plain. Here we show that differences in megabenthic communities on abyssal hills and the adjacent plain are related to environmental conditions, which may be caused by local topography and hydrodynamics. Although these hills may receive similar particulate organic carbon flux (food supply from the surface ocean) to the adjacent plain, they differ significantly in depth, slope, and sediment particle size distribution. We found that megafaunal biomass was significantly greater on the hills (mean 13.45gm−2, 95% confidence interval 9.25–19.36gm−2) than the plain (4.34gm−2, 95% CI 2.08–8.27gm−2; ANOVA F(1,6)=23.8, p<0.01). Assemblage and trophic compositions by both density and biomass measures were significantly different between the hill and plain, and correlated with sediment particle size distributions. Hydrodynamic conditions responsible for the local sedimentary environment may be the mechanism driving these assemblage differences. Since the ecological heterogeneity provided by hills in the abyss has been underappreciated, regional assessments of abyssal biological heterogeneity and diversity may be considerably higher than previously thought.

Chronic toxicity of silver nanoparticles to Daphnia magna under different feeding conditions

Despite substantial information on the acute toxicity of silver nanoparticles (AgNP) to aquatic organisms, little is known about their potential chronic effects and the applicability of current test guidelines for testing nanomaterials. The purpose of this study was to study the influence of food availability on toxicity. This was done through a series of Daphnia magna 21-day reproduction tests (OECD 211) using 30nm citric acid stabilized AgNP aimed at studying the influence of food abundance on the reproductive toxicity of AgNP in D. magna. The experiments were carried out as static renewal tests with exposure concentrations from 10 to 50μgAg/L, and test animals were fed green algae Pseudokirchneriella subcapitata in low and high food treatments. The endpoints recorded were survival, growth of parent animals and number of live neonates produced. Detrimental effects of AgNP on survival, growth and reproduction were observed in concentrations higher than 10μgAg/L, whereas the animals exposed to 10μgAg/L had larger body length and produced more offspring than controls at both food treatments. High food treatment resulted in higher animal survival, growth and reproduction compared to result found for low food treatment.

Physiological response of adult Antarctic krill, Euphausia superba, to long-term starvation

Adult Euphausia superba survive winter without or with little feeding. It is not exactly known whether the scarcity of food or an internal clock, set by the natural Antarctic light regime, are responsible for non-feeding. Our research questions were therefore the following: (1) How will physiological and biochemical conditions of krill change during long-term starvation at constant light regime? (2) If and how do enzyme activities change during such starvation? (3) What is the influence of food availability versus that of light regime? To answer these questions, adult krill were starved under laboratory conditions for 12 weeks with constant light regime (12:12; dark/light) and the impact on physiological functions was studied. Initial experimental condition of krill resembled the condition of late spring krill in the field with fully active metabolism and low lipid reserves. Metabolic activity and activities of enzymes catabolising lipids decreased after the onset of starvation and remained low throughout, whereas lipid reserves declined and lipid composition changed. Mass and size of krill decreased while the inter-moult period increased. Depletion of storage- and structural metabolites occurred in the order of depot lipids and glycogen reserves after onset of starvation until proteins were almost exclusively used after 6–7 weeks of starvation. Results confirmed various proposed overwintering mechanisms such as metabolic slowdown, slow growth or shrinkage and use of lipid reserves. However, these changes were set in motion by food shortage only, i.e. without the trigger of a changing light regime.

The past, present, and future of soils and human health studies

Abstract. The idea that human health is tied to the soil is not a new one. As far back as circa 1400 BC the Bible depicts Moses as understanding that fertile soil was essential to the well-being of his people. In 400 BC the Greek philosopher Hippocrates provided a list of things that should be considered in a proper medical evaluation, including the properties of the local ground. By the late 1700s and early 1800s, American farmers had recognized that soil properties had some connection to human health. In the modern world, we recognize that soils have a distinct influence on human health. We recognize that soils influence (1) food availability and quality (food security), (2) human contact with various chemicals, and (3) human contact with various pathogens. Soils and human health studies include investigations into nutrient supply through the food chain and routes of exposure to chemicals and pathogens. However, making strong, scientific connections between soils and human health can be difficult. There are multiple variables to consider in the soil environment, meaning traditional scientific studies that seek to isolate and manipulate a single variable often do not provide meaningful data. The complete study of soils and human health also involves many different specialties such as soil scientists, toxicologists, medical professionals, anthropologists, etc. These groups do not traditionally work together on research projects, and do not always effectively communicate with one another. Climate change and how it will affect the soil environment/ecosystem going into the future is another variable affecting the relationship between soils and health. Future successes in soils and human health research will require effectively addressing difficult issues such as these.